Atazanavir Sulfate

• Atazanavir sulfate capsules must be taken with food.
• Do not open the capsules.
• The recommended oral dosage of atazanavir sulfate capsules depends on the treatment history of the patient and the use of other coadministered drugs. When coadministered with H ₂-receptor antagonists or proton-pump inhibitors, dose separation may be required [see Dosage and Administration ( 2.3, 2.4, and 2.6) and Drug Interactions ( 7)].
• Atazanavir sulfate capsules without ritonavir are not recommended for treatment-experienced adult or pediatric patients with prior virologic failure [see Clinical Studies ( 14)].
• Efficacy and safety of atazanavir sulfate capsules with ritonavir when ritonavir is administered in doses greater than 100 mg once daily have not been established. The use of higher ritonavir doses may alter the safety profile of atazanavir (cardiac effects, hyperbilirubinemia) and, therefore, is not recommended. Prescribers should consult the complete prescribing information for ritonavir when using ritonavir.

Renal laboratory testing should be performed in all patients prior to initiation of atazanavir sulfate capsules and continued during treatment with atazanavir sulfate capsules. Renal laboratory testing should include serum creatinine, estimated creatinine clearance, and urinalysis with microscopic examination [see Warnings and Precautions ( 5.5, 5.6)] .

Hepatic laboratory testing should be performed in patients with underlying liver disease prior to initiation of atazanavir sulfate capsules and continued during treatment with atazanavir sulfate capsules [see Warnings and Precautions ( 5.4)] .

Table 1 displays the recommended dosage of atazanavir sulfate capsules in treatment-naive and treatment-experienced adults. Table 1 also displays recommended dosage of atazanavir sulfate capsules and ritonavir when given concomitantly with other antiretroviral drugs and H ₂-receptor antagonists (H2RA). Ritonavir is required with several atazanavir sulfate capsule dosage regimens (see the ritonavir complete prescribing information about the safe and effective use of ritonavir). The use of atazanavir sulfate capsules in treatment-experienced adult patients without ritonavir is not recommended.

The recommended daily dosage of atazanavir capsules and ritonavir in pediatric patients (6 years of age to less than 18 years of age) is based on body weight (see Table 2).

When transitioning between formulations, a change in dose may be needed. Consult the dosing table for the specific formulation.

Table 4 includes the recommended dosage of atazanavir sulfate capsules and ritonavir in treatment-naive and treatment-experienced pregnant patients. In these patients, atazanavir sulfate capsules must be administered with ritonavir. There are no dosage adjustments for postpartum patients (see Table 1 for the recommended atazanavir sulfate capsules dosage in adults) [see Use in Specific Populations ( 8.1)].

For patients with renal impairment, including those with severe renal impairment who are not managed with hemodialysis, no dose adjustment is required for atazanavir sulfate capsules. Treatment-naive patients with end-stage renal disease managed with hemodialysis should receive atazanavir sulfate capsules 300 mg with ritonavir 100 mg. Atazanavir sulfate capsules are not recommended in HIV-treatment‑experienced patients with end-stage renal disease managed with hemodialysis  [see Use in Specific Populations ( 8.7)].

Table 5 displays the recommended atazanavir sulfate capsule dosage in treatment-naive patients with hepatic impairment. The use of atazanavir sulfate capsules in patients with severe hepatic impairment (Child-Pugh Class C) is not recommended. The coadministration of atazanavir sulfate capsules with ritonavir in patients with any degree of hepatic impairment is not recommended.

Atazanavir sulfate has been shown to prolong the PR interval of the electrocardiogram in some patients. In healthy volunteers and in patients, abnormalities in atrioventricular (AV) conduction were asymptomatic and generally limited to first-degree AV block. There have been reports of second-degree AV block and other conduction abnormalities [see Adverse Reactions (6.2) and Overdosage ( 10)] . In clinical trials that included electrocardiograms, asymptomatic first-degree AV block was observed in 5.9% of atazanavir-treated patients (n = 920), 5.2% of lopinavir/ritonavir-treated patients (n = 252), 10.4% of nelfinavir-treated patients (n = 48), and 3.0% of efavirenz-treated patients (n = 329). In Study AI424-045, asymptomatic first-degree AV block was observed in 5% (6/118) of atazanavir/ritonavir-treated patients and 5% (6/116) of lopinavir/ritonavir-treated patients who had on-study electrocardiogram measurements. Because of limited clinical experience in patients with preexisting conduction system disease (e.g., marked first-degree AV block or second- or third-degree AV block). ECG monitoring should be considered in these patients [see Clinical Pharmacology ( 12.2)] .

In controlled clinical trials, rash (all grades, regardless of causality) occurred in approximately 20% of patients treated with atazanavir sulfate. The median time to onset of rash in clinical studies was 7.3 weeks and the median duration of rash was 1.4 weeks. Rashes were generally mild-to-moderate maculopapular skin eruptions. Treatment-emergent adverse reactions of moderate or severe rash (occurring at a rate of ≥ 2%) are presented for the individual clinical studies [see Adverse Reactions ( 6.1)]. Dosing with atazanavir sulfate was often continued without interruption in patients who developed rash. The discontinuation rate for rash in clinical trials was < 1%. Cases of Stevens-Johnson syndrome, erythema multiforme, and toxic skin eruptions, including drug rash, eosinophilia, and systemic symptoms (DRESS) syndrome, have been reported in patients receiving atazanavir sulfate [see Contraindications ( 4) and Adverse Reactions ( 6.1)]. Atazanavir sulfate should be discontinued if severe rash develops.

Patients with underlying hepatitis B or C viral infections or marked elevations in transaminases before treatment may be at increased risk for developing further transaminase elevations or hepatic decompensation. In these patients, hepatic laboratory testing should be conducted prior to initiating therapy with atazanavir sulfate and during treatment [see Dosage and Administration ( 2.2), Adverse Reactions ( 6.1), and Use in Specific Populations ( 8.8)] .

Chronic kidney disease in HIV-infected patients treated with atazanavir, with or without ritonavir, has been reported during postmarketing surveillance. Reports included biopsy-proven cases of granulomatous interstitial nephritis associated with the deposition of atazanavir drug crystals in the renal parenchyma. Consider alternatives to atazanavir sulfate in patients at high risk for renal disease or with preexisting renal disease. Renal laboratory testing (including serum creatinine, estimated creatinine clearance, and urinalysis with microscopic examination) should be conducted in all patients prior to initiating therapy with atazanavir sulfate and continued during treatment with atazanavir sulfate. Expert consultation is advised for patients who have confirmed renal laboratory abnormalities while taking atazanavir sulfate. In patients with progressive kidney disease, discontinuation of atazanavir sulfate may be considered [see Dosage and Administration ( 2.2 and 2.7) and Adverse Reactions ( 6.2)].

Cases of nephrolithiasis and/or cholelithiasis have been reported during postmarketing surveillance in HIV-infected patients receiving atazanavir sulfate therapy. Some patients required hospitalization for additional management and some had complications. Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made. If signs or symptoms of nephrolithiasis and/or cholelithiasis occur, temporary interruption or discontinuation of therapy may be considered [see Adverse Reactions (6.2)].

Initiation of atazanavir sulfate with ritonavir, a CYP3A inhibitor, in patients receiving medications metabolized by CYP3A or initiation of medications metabolized by CYP3A in patients already receiving atazanavir sulfate with ritonavir, may increase plasma concentrations of medications metabolized by CYP3A. Initiation of medications that inhibit or induce CYP3A may increase or decrease concentrations of atazanavir sulfate with ritonavir, respectively. These interactions may lead to:

• clinically significant adverse reactions potentially leading to severe, life-threatening, or fatal events from greater exposures of concomitant medications.
• clinically significant adverse reactions from greater exposures of atazanavir sulfate with ritonavir.
• loss of therapeutic effect of atazanavir sulfate with ritonavir and possible development of resistance.
  

See Table 16 for steps to prevent or manage these possible and known significant drug interactions, including dosing recommendations [see Drug Interactions ( 7)]. Consider the potential for drug interactions prior to and during atazanavir sulfate/ritonavir therapy; review concomitant medications during atazanavir sulfate/ritonavir therapy; and monitor for the adverse reactions associated with the concomitant medications [see Contraindications ( 4) and Drug Interactions ( 7)].

Most patients taking atazanavir sulfate experience asymptomatic elevations in indirect (unconjugated) bilirubin related to inhibition of UDP-glucuronosyl transferase (UGT). This hyperbilirubinemia is reversible upon discontinuation of atazanavir sulfate. Hepatic transaminase elevations that occur with hyperbilirubinemia should be evaluated for alternative etiologies. No long-term safety data are available for patients experiencing persistent elevations in total bilirubin > 5 times the upper limit of normal (ULN). Alternative antiretroviral therapy to atazanavir sulfate may be considered if jaundice or scleral icterus associated with bilirubin elevations presents cosmetic concerns for patients. Dose reduction of atazanavir is not recommended since long-term efficacy of reduced doses has not been established [see Adverse Reactions ( 6.1)] .

New-onset diabetes mellitus, exacerbation of preexisting diabetes mellitus, and hyperglycemia have been reported during postmarketing surveillance in HIV-infected patients receiving protease inhibitor therapy. Some patients required either initiation or dose adjustments of insulin or oral hypoglycemic agents for treatment of these events. In some cases, diabetic ketoacidosis has occurred. In those patients who discontinued protease inhibitor therapy, hyperglycemia persisted in some cases. Because these events have been reported voluntarily during clinical practice, estimates of frequency cannot be made and a causal relationship between protease inhibitor therapy and these events has not been established [see Adverse Reactions (6.2)].

Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including atazanavir sulfate. During the initial phase of combination antiretroviral treatment, patients whose immune system responds may develop an inflammatory response to indolent or residual opportunistic infections (such as Mycobacterium avium infection, cytomegalovirus, Pneumocystis jiroveci pneumonia, or tuberculosis), which may necessitate further evaluation and treatment.

Autoimmune disorders (such as Graves’ disease, polymyositis, and Guillain-Barré syndrome) have also been reported to occur in the setting of immune reconstitution; however, the time to onset is more variable, and can occur many months after initiation of treatment.

Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and “cushingoid appearance” have been observed in patients receiving antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.

There have been reports of increased bleeding, including spontaneous skin hematomas and hemarthrosis, in patients with hemophilia type A and B treated with protease inhibitors. In some patients additional factor VIII was given. In more than half of the reported cases, treatment with protease inhibitors was continued or reintroduced. A causal relationship between protease inhibitor therapy and these events has not been established.

Various degrees of cross-resistance among protease inhibitors have been observed. Resistance to atazanavir may not preclude the subsequent use of other protease inhibitors [see Microbiology ( 12.4)] .

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Adverse Reactions in Treatment-Naive Adult Patients

The safety profile of atazanavir sulfate in treatment-naive adults is based on 1625 HIV-1 infected patients in clinical trials. 536 patients received atazanavir 300 mg with ritonavir 100 mg and 1089 patients received atazanavir 400 mg or higher (without ritonavir).

The most common adverse reactions were nausea, jaundice/scleral icterus, and rash.

Selected clinical adverse reactions of moderate or severe intensity reported in ≥ 2% of treatment-naive patients receiving combination therapy including atazanavir 300 mg with ritonavir 100 mg and atazanavir 400 mg (without ritonavir) are presented in Tables 7 and 8, respectively.

Adverse Reactions in Treatment-Experienced Adult Patients

The safety profile of atazanavir sulfate in treatment-experienced adults is based on 119 HIV-1 infected patients in clinical trials.

The most common adverse reactions are jaundice/scleral icterus and myalgia.

Selected clinical adverse reactions of moderate or severe intensity reported in ≥ 2% of treatment-experienced patients receiving atazanavir sulfate/ritonavir are presented in Table 9.

Laboratory Abnormalities in Treatment-Naive Patients

The percentages of adult treatment-naive patients treated with combination therapy including atazanavir 300 mg with ritonavir 100 mg and atazanavir 400 mg (without ritonavir) with Grade 3 to 4 laboratory abnormalities are presented in Tables 10 and 11, respectively.

Laboratory Abnormalities in Treatment-Experienced Patients

The percentages of adult treatment-experienced patients treated with combination therapy including atazanavir sulfate/ritonavir with Grade 3 to 4 laboratory abnormalities are presented in Table 14.

Change in Lipids from Baseline in Treatment-Experienced Patients

For Study AI424-045, changes from baseline in LDL-cholesterol, HDL-cholesterol, total cholesterol, and triglycerides are shown in Table 15. The observed magnitude of dyslipidemia was less with atazanavir sulfate/ritonavir than with lopinavir/ritonavir. However, the clinical impact of such findings has not been demonstrated.

Adverse Reactions in Pediatric Patients: Atazanavir Sulfate Capsules

The safety and tolerability of atazanavir sulfate capsules with and without ritonavir have been established in pediatric patients at least 6 years of age from the open-label, multicenter clinical trial PACTG 1020A.

The safety profile of atazanavir sulfate in pediatric patients (6 to less than 18 years of age) taking the capsule formulation was generally similar to that observed in clinical studies of atazanavir sulfate in adults. The most common Grade 2 to 4 adverse events (≥ 5%, regardless of causality) reported in pediatric patients were cough (21%), fever (18%), jaundice/scleral icterus (15%), rash (14%), vomiting (12%), diarrhea (9%), headache (8%), peripheral edema (7%), extremity pain (6%), nasal congestion (6%), oropharyngeal pain (6%), wheezing (6%), and rhinorrhea (6%).

Asymptomatic second-degree atrioventricular block was reported in < 2% of patients. The most common Grade 3 to 4 laboratory abnormalities occurring in pediatric patients taking the capsule formulation were elevation of total bilirubin (≥ 3.2 mg/dL, 58%), neutropenia (9%), and hypoglycemia (4%). All other Grade 3 to 4 laboratory abnormalities occurred with a frequency of less than 3%.

Adverse Reactions in Patients Co-Infected with Hepatitis B and/or Hepatitis C Virus

In Study AI424-138, 60 patients treated with atazanavir/ritonavir 300 mg/100 mg once daily, and 51 patients treated with lopinavir/ritonavir 400 mg/100 mg twice daily, each with fixed dose tenofovir DF-emtricitabine, were seropositive for hepatitis B and/or C at study entry. ALT levels > 5 times ULN developed in 10% (6/60) of the atazanavir sulfate/ritonavir-treated patients and 8% (4/50) of the lopinavir/ritonavir-treated patients. AST levels > 5 times ULN developed in 10% (6/60) of the atazanavir sulfate/ritonavir-treated patients and none (0/50) of the lopinavir/ritonavir-treated patients.

In Study AI424-045, 20 patients treated with atazanavir/ritonavir 300 mg/100 mg once daily, and 18 patients treated with lopinavir/ritonavir 400 mg/100 mg twice daily, were seropositive for hepatitis B and/or C at study entry. ALT levels > 5 times ULN developed in 25% (5/20) of the atazanavir sulfate/ritonavir-treated patients and 6% (1/18) of the lopinavir/ritonavir-treated patients. AST levels > 5 times ULN developed in 10% (2/20) of the atazanavir sulfate/ritonavir-treated patients and 6% (1/18) of the lopinavir/ritonavir-treated patients.

In Studies AI424-008 and AI424-034, 74 patients treated with 400 mg of atazanavir once daily, 58 who received efavirenz, and 12 who received nelfinavir were seropositive for hepatitis B and/or C at study entry. ALT levels > 5 times ULN developed in 15% of the atazanavir sulfate-treated patients, 14% of the efavirenz-treated patients, and 17% of the nelfinavir-treated patients. AST levels > 5 times ULN developed in 9% of the atazanavir sulfate-treated patients, 5% of the efavirenz-treated patients, and 17% of the nelfinavir‑treated patients. Within atazanavir sulfate and control regimens, no difference in frequency of bilirubin elevations was noted between seropositive and seronegative patients [see Warnings and Precautions ( 5.8)] .

The following events have been identified during postmarketing use of atazanavir sulfate. Because these reactions are reported voluntarily from a population of unknown size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Body as a Whole: edema

Cardiovascular System: second-degree AV block, third-degree AV block, left bundle branch block, QT _c prolongation [see Warnings and Precautions ( 5.1)]

Gastrointestinal System: pancreatitis

Hepatic System: hepatic function abnormalities

Hepatobiliary Disorders: cholelithiasis [see Warnings and Precautions ( 5.6)] , cholecystitis, cholestasis

Metabolic System and Nutrition Disorders: diabetes mellitus, hyperglycemia [see Warnings and Precautions ( 5.9)]

Musculoskeletal System: arthralgia

Renal System: nephrolithiasis [see Warnings and Precautions ( 5.6)], interstitial nephritis, granulomatous interstitial nephritis, chronic kidney disease [see Warnings and Precautions ( 5.5)]

Skin and Appendages: alopecia, maculopapular rash [see Contraindications ( 4)  and  Warnings and Precautions ( 5.2)], pruritus, angioedema

Atazanavir is an inhibitor of CYP3A and UGT1A1. Coadministration of atazanavir sulfate and drugs primarily metabolized by CYP3A or UGT1A1 may result in increased plasma concentrations of the other drug that could increase or prolong its therapeutic and adverse effects.

Atazanavir is a weak inhibitor of CYP2C8. Use of atazanavir sulfate without ritonavir is not recommended when coadministered with drugs highly dependent on CYP2C8 with narrow therapeutic indices (e.g., paclitaxel, repaglinide). When atazanavir sulfate with ritonavir is coadministered with substrates of CYP2C8, clinically significant interactions are not expected [see Clinical Pharmacology, Table 22 ( 12.3)].

The magnitude of CYP3A-mediated drug interactions on coadministered drug may change when atazanavir sulfate is coadministered with ritonavir. See the complete prescribing information for ritonavir for information on drug interactions with ritonavir.

Atazanavir is a CYP3A4 substrate; therefore, drugs that induce CYP3A4 may decrease atazanavir plasma concentrations and reduce atazanavir sulfate’s therapeutic effect.

Atazanavir solubility decreases as pH increases. Reduced plasma concentrations of atazanavir are expected if proton-pump inhibitors, antacids, buffered medications, or H ₂-receptor antagonists are administered with atazanavir sulfate [see Dosage and Administration ( 2.3, 2.4, and 2.6)].

Table 16 provides dosing recommendations in adults as a result of drug interactions with atazanavir sulfate. These recommendations are based on either drug interaction studies or predicted interactions due to the expected magnitude of interaction and potential for serious events or loss of efficacy.

No clinically significant drug interactions were observed when atazanavir sulfate was coadministered with methadone, fluconazole, acetaminophen, atenolol, or the nucleoside reverse transcriptase inhibitors lamivudine or zidovudine [see Clinical Pharmacology, Tables 21 and 22 ( 12.3)] .

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to atazanavir sulfate during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263.

Risk Summary

Atazanavir has been evaluated in a limited number of women during pregnancy. Available human and animal data suggest that atazanavir does not increase the risk of major birth defects overall compared to the background rate [see  Data]. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. No treatment-related malformations were observed in rats and rabbits, for which the atazanavir exposures were 0.7 to 1.2 times of those at the human clinical dose (300 mg/day atazanavir boosted with 100 mg/day ritonavir). When atazanavir was administered to rats during pregnancy and throughout lactation, reversible neonatal growth retardation was observed [see  Data].

Clinical Considerations

Dose Adjustments during Pregnancy and the Postpartum Period

• Atazanavir sulfate must be administered with ritonavir in pregnant women.
• For pregnant patients, no dosage adjustment is required for atazanavir sulfate with the following exceptions:
• For treatment-experienced pregnant women during the second or third trimester, when atazanavir sulfate is coadministered with either an H ₂-receptor antagonist or tenofovir DF, atazanavir 400 mg with ritonavir 100 mg once daily is recommended. There are insufficient data to recommend an atazanavir sulfate dose for use with both an H ₂-receptor antagonist and tenofovir DF in treatment-experienced pregnant women.
• No dosage adjustment is required for postpartum patients. However, patients should be closely monitored for adverse events because atazanavir exposures could be higher during the first 2 months after delivery [see Dosage and Administration ( 2.6) and Clinical Pharmacology ( 12.3)] .
  

Maternal Adverse Reactions

Cases of lactic acidosis syndrome, sometimes fatal, and symptomatic hyperlactatemia have occurred in pregnant women using atazanavir sulfate in combination with nucleoside analogues, which are associated with an increased risk of lactic acidosis syndrome.

Hyperbilirubinemia occurs frequently in patients who take atazanavir sulfate [see  Warnings and Precautions ( 5.8)], including pregnant women [see  Data].

Advise pregnant women of the potential risks of lactic acidosis syndrome and hyperbilirubinemia.

Fetal/Neonatal Adverse Reactions

All infants, including neonates exposed to atazanavir sulfate in utero, should be monitored for the development of severe hyperbilirubinemia during the first few days of life [see  Data].

Data

Human Data

In clinical trial AI424-182, atazanavir/ritonavir (300 mg/100 mg or 400 mg/100 mg) in combination with zidovudine/lamivudine was administered to 41 HIV-infected pregnant women during the second or third trimester. Among the 39 women who completed the study, 38 women achieved an HIV RNA less than 50 copies/mL at time of delivery. Six of 20 (30%) women on atazanavir/ritonavir 300 mg/100 mg and 13 of 21 (62%) women on atazanavir/ritonavir 400 mg/100 mg experienced hyperbilirubinemia (total bilirubin greater than or equal to 2.6 times ULN). There were no cases of lactic acidosis observed in clinical trial AI424-182.

Atazanavir drug concentrations in fetal umbilical cord blood were approximately 12% to 19% of maternal concentrations. Among the 40 infants born to 40 HIV-infected pregnant women, all had test results that were negative for HIV-1 DNA at the time of delivery and/or during the first 6 months postpartum. All 40 infants received antiretroviral prophylactic treatment containing zidovudine. No evidence of severe hyperbilirubinemia (total bilirubin levels greater than 20 mg/dL) or acute or chronic bilirubin encephalopathy was observed among neonates in this study. However, 10/36 (28%) infants (6 greater than or equal to 38 weeks gestation and 4 less than 38 weeks gestation) had bilirubin levels of 4 mg/dL or greater within the first day of life.

Lack of ethnic diversity was a study limitation. In the study population, 33/40 (83%) infants were Black/African American, who have a lower incidence of neonatal hyperbilirubinemia than Caucasians and Asians. In addition, women with Rh incompatibility were excluded, as well as women who had a previous infant who developed hemolytic disease and/or had neonatal pathologic jaundice (requiring phototherapy).

Additionally, of the 38 infants who had glucose samples collected in the first day of life, 3 had adequately collected serum glucose samples with values of less than 40 mg/dL that could not be attributed to maternal glucose intolerance, difficult delivery, or sepsis.

Based on prospective reports from the APR of approximately 1600 live births following exposure to atazanavir-containing regimens (including 1037 live births in infants exposed in the first trimester and 569 exposed in second/third trimesters), there was no difference between atazanavir and overall birth defects compared with the background birth defect rate. In the U.S. general population, the estimated background risk of major birth defects in clinically recognized pregnancies is 2 to 4%.

Animal Data

In animal reproduction studies, there was no evidence of mortality or teratogenicity in offspring born to animals at systemic drug exposure levels (AUC) 0.7 (in rabbits) to 1.2 (in rats) times those observed at the human clinical dose (300 mg/day atazanavir boosted with 100 mg/day ritonavir). In pre- and postnatal development studies in the rat, atazanavir caused neonatal growth retardation during lactation that reversed after weaning. Maternal drug exposure at this dose was 1.3 times the human exposure at the recommended clinical exposure. Minimal maternal toxicity occurred at this exposure level.

Risk Summary

The Centers for Disease Control and Prevention recommend that HIV-1 infected mothers not breastfeed their infants to avoid risking postnatal transmission of HIV-1. Atazanavir has been detected in human milk. No data are available regarding atazanavir effects on milk production. Atazanavir was present in the milk of lactating rats and was associated with neonatal growth retardation that reversed after weaning.

Because of both the potential for HIV-1 transmission and the potential for serious adverse reactions in breastfed infants, advise women not to breastfeed.

Atazanavir sulfate is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection in pediatric patients 6 years of age and older and weighing at least 15 kg. Atazanavir sulfate is not recommended for use in pediatric patients below the age of 3 months due to the risk of kernicterus [see Indications and Usage ( 1)]. All atazanavir sulfate contraindications, warnings, and precautions apply to pediatric patients [see Contraindications ( 4) and Warnings and Precautions ( 5)].

The safety, pharmacokinetic profile, and virologic response of atazanavir sulfate in pediatric patients at least 6 years of age and older and weighing at least 15 kg were established in an open-label, multicenter clinical trial: PACTG 1020A [see Clinical Pharmacology ( 12.3) and Clinical Studies ( 14.3)]. The safety profile in pediatric patients was generally similar to that observed in adults [see Adverse Reactions ( 6.1)]. See Dosage and Administration ( 2.4) for dosing recommendations for the use of atazanavir sulfate capsules.

Clinical studies of atazanavir sulfate did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently from younger patients. Based on a comparison of mean single-dose pharmacokinetic values for C _max and AUC, a dose adjustment based upon age is not recommended. In general, appropriate caution should be exercised in the administration and monitoring of atazanavir sulfate in elderly patients reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

A study of the pharmacokinetics of atazanavir was performed in young (n = 29; 18 to 40 years) and elderly (n = 30; ≥ 65 years) healthy subjects. There were no clinically significant pharmacokinetic differences observed due to age or gender.

Atazanavir sulfate is not recommended for use in HIV-treatment-experienced patients with end-stage renal disease managed with hemodialysis [see Dosage and Administration ( 2.7) and Clinical Pharmacology ( 12.3)].

Atazanavir sulfate is not recommended for use in patients with severe hepatic impairment. Atazanavir sulfate/ritonavir is not recommended in patients with any degree of hepatic impairment [see Dosage and Administration ( 2.8) and Clinical Pharmacology ( 12.3)].

Atazanavir is an HIV-1 antiretroviral drug [see Microbiology ( 12.4)].

Cardiac Electrophysiology

Concentration- and dose-dependent prolongation of the PR interval in the electrocardiogram has been observed in healthy volunteers receiving atazanavir. In a placebo-controlled study (AI424-076), the mean (± SD) maximum change in PR interval from the predose value was 24 (± 15) msec following oral dosing with 400 mg of atazanavir (n = 65) compared to 13 (± 11) msec following dosing with placebo (n = 67). The PR interval prolongations in this study were asymptomatic. There is limited information on the potential for a pharmacodynamic interaction in humans between atazanavir and other drugs that prolong the PR interval of the electrocardiogram [see Warnings and Precautions ( 5.1)].

Electrocardiographic effects of atazanavir were determined in a clinical pharmacology study of 72 healthy subjects. Oral doses of 400 mg (maximum recommended dosage) and 800 mg (twice the maximum recommended dosage) were compared with placebo; there was no concentration-dependent effect of atazanavir on the QT _c interval (using Fridericia’s correction). In 1793 HIV-infected patients receiving antiretroviral regimens, QT _c prolongation was comparable in the atazanavir and comparator regimens. No atazanavir-treated healthy subject or HIV-infected patient in clinical trials had a QT _c interval > 500 msec [see Warnings and Precautions ( 5.1)].

The pharmacokinetics of atazanavir were evaluated in healthy adult volunteers and in HIV-infected patients after administration of atazanavir 400 mg once daily and after administration of atazanavir 300 mg with ritonavir 100 mg once daily (see Table 17).

Figure 1 displays the mean plasma concentrations of atazanavir at steady state after atazanavir 400 mg once daily (as two 200 mg capsules) with a light meal and after atazanavir 300 mg (as two 150 mg capsules) with ritonavir 100 mg once daily with a light meal in HIV-infected adult patients.

Figure 1: Mean (SD) Steady-State Plasma Concentrations of Atazanavir 400 mg (n = 13) and 300 mg With Ritonavir (n = 10) for HIV-Infected Adult Patients

figure one

Absorption

Atazanavir is rapidly absorbed with a T _max of approximately 2.5 hours. Atazanavir demonstrates nonlinear pharmacokinetics with greater than dose-proportional increases in AUC and C _max values over the dose range of 200 to 800 mg once daily. Steady state is achieved between Days 4 and 8, with an accumulation of approximately 2.3 fold.

Food Effect

Administration of atazanavir sulfate with food enhances bioavailability and reduces pharmacokinetic variability. Administration of a single 400 mg dose of atazanavir with a light meal (357 kcal, 8.2 g fat, 10.6 g protein) resulted in a 70% increase in AUC and 57% increase in C _max relative to the fasting state. Administration of a single 400 mg dose of atazanavir with a high-fat meal (721 kcal, 37.3 g fat, 29.4 g protein) resulted in a mean increase in AUC of 35% with no change in C _max relative to the fasting state. Administration of atazanavir sulfate with either a light meal or high-fat meal decreased the coefficient of variation of AUC and C _max by approximately one-half compared to the fasting state.

Coadministration of a single 300 mg dose of atazanavir and a 100 mg dose of ritonavir with a light meal (336 kcal, 5.1 g fat, 9.3 g protein) resulted in a 33% increase in the AUC and a 40% increase in both the C _max and the 24 hour concentration of atazanavir relative to the fasting state. Coadministration with a high-fat meal (951 kcal, 54.7 g fat, 35.9 g protein) did not affect the AUC of atazanavir relative to fasting conditions and the C _max was within 11% of fasting values. The 24 hour concentration following a high-fat meal was increased by approximately 33% due to delayed absorption; the median T _max increased from 2.0 to 5.0 hours. Coadministration of atazanavir sulfate with ritonavir with either a light or a high-fat meal decreased the coefficient of variation of AUC and C _max by approximately 25% compared to the fasting state.

Distribution

Atazanavir is 86% bound to human serum proteins and protein binding is independent of concentration. Atazanavir binds to both alpha-1-acid glycoprotein (AAG) and albumin to a similar extent (89% and 86%, respectively). In a multiple-dose study in HIV-infected patients dosed with atazanavir 400 mg once daily with a light meal for 12 weeks, atazanavir was detected in the cerebrospinal fluid and semen. The cerebrospinal fluid/plasma ratio for atazanavir (n = 4) ranged between 0.0021 and 0.0226 and seminal fluid/plasma ratio (n = 5) ranged between 0.11 and 4.42.

Metabolism

Atazanavir is extensively metabolized in humans. The major biotransformation pathways of atazanavir in humans consisted of monooxygenation and dioxygenation. Other minor biotransformation pathways for atazanavir or its metabolites consisted of glucuronidation, N-dealkylation, hydrolysis, and oxygenation with dehydrogenation. Two minor metabolites of atazanavir in plasma have been characterized. Neither metabolite demonstrated in vitro antiviral activity. In vitro studies using human liver microsomes suggested that atazanavir is metabolized by CYP3A.

Elimination

Following a single 400 mg dose of ¹⁴C-atazanavir, 79% and 13% of the total radioactivity was recovered in the feces and urine, respectively. Unchanged drug accounted for approximately 20% and 7% of the administered dose in the feces and urine, respectively. The mean elimination half-life of atazanavir in healthy volunteers (n = 214) and HIV-infected adult patients (n = 13) was approximately 7 hours at steady state following a dose of 400 mg daily with a light meal.

Specific Populations

Renal Impairment

In healthy subjects, the renal elimination of unchanged atazanavir was approximately 7% of the administered dose. Atazanavir sulfate has been studied in adult subjects with severe renal impairment (n = 20), including those on hemodialysis, at multiple doses of 400 mg once daily. The mean atazanavir C _max was 9% lower, AUC was 19% higher, and C _min was 96% higher in subjects with severe renal impairment not undergoing hemodialysis (n = 10), than in age-, weight-, and gender-matched subjects with normal renal function. In a 4 hour dialysis session, 2.1% of the administered dose was removed. When atazanavir was administered either prior to, or following hemodialysis (n = 10), the geometric means for C _max, AUC, and C _min were approximately 25% to 43% lower compared to subjects with normal renal function. The mechanism of this decrease is unknown. Atazanavir sulfate is not recommended for use in HIV-treatment-experienced patients with end-stage renal disease managed with hemodialysis [see Dosage and Administration ( 2.7)].

Hepatic Impairment

Atazanavir sulfate has been studied in adult subjects with moderate-to-severe hepatic impairment (14 Child-Pugh B and 2 Child-Pugh C subjects) after a single 400 mg dose. The mean AUC _(0-∞) was 42% greater in subjects with impaired hepatic function than in healthy volunteers. The mean half-life of atazanavir in hepatically impaired subjects was 12.1 hours compared to 6.4 hours in healthy volunteers. A dose reduction to 300 mg is recommended for patients with moderate hepatic impairment (Child-Pugh Class B) who have not experienced prior virologic failure as increased concentrations of atazanavir are expected. Atazanavir sulfate is not recommended for use in patients with severe hepatic impairment. The pharmacokinetics of atazanavir sulfate in combination with ritonavir has not been studied in subjects with hepatic impairment; thus, coadministration of atazanavir sulfate with ritonavir is not recommended for use in patients with any degree of hepatic impairment [see Dosage and Administration ( 2.8)].

Pediatrics

The pharmacokinetic parameters for atazanavir at steady state in pediatric patients taking the capsule formulation were predicted by a population pharmacokinetic model and are summarized in Table 19 by weight ranges that correspond to the recommended doses [see Dosage and Administration ( 2.4)].

Pregnancy

The pharmacokinetic data from HIV-infected pregnant women receiving atazanavir sulfate capsules with ritonavir are presented in Table 20.

Drug Interaction Data

Atazanavir is a metabolism-dependent CYP3A inhibitor, with a K _inact value of 0.05 to 0.06 min ^-1 and K _i value of 0.84 to 1.0 µM. Atazanavir is also a direct inhibitor for UGT1A1 (K _i = 1.9 µM) and CYP2C8 (K _i = 2.1 µM).

Atazanavir has been shown in vivo not to induce its own metabolism, nor to increase the biotransformation of some drugs metabolized by CYP3A. In a multiple-dose study, atazanavir sulfate decreased the urinary ratio of endogenous 6β-OH cortisol to cortisol versus baseline, indicating that CYP3A production was not induced.

Clinically significant interactions are not expected between atazanavir and substrates of CYP2C19, CYP2C9, CYP2D6, CYP2B6, CYP2A6, CYP1A2, or CYP2E1. Clinically significant interactions are not expected between atazanavir when administered with ritonavir and substrates of CYP2C8. See the complete prescribing information for ritonavir for information on other potential drug interactions with ritonavir.

Based on known metabolic profiles, clinically significant drug interactions are not expected between atazanavir and dapsone, trimethoprim/sulfamethoxazole, azithromycin, or erythromycin. Atazanavir does not interact with substrates of CYP2D6 (e.g., nortriptyline, desipramine, metoprolol).

Drug interaction studies were performed with atazanavir sulfate and other drugs likely to be coadministered and some drugs commonly used as probes for pharmacokinetic interactions. The effects of coadministration of atazanavir sulfate on the AUC, C _max, and C _min are summarized in Tables 21 and 22. Neither didanosine EC nor diltiazem had a significant effect on atazanavir exposures (see Table 22 for effect of atazanavir on didanosine EC or diltiazem exposures). Atazanavir sulfate did not have a significant effect on the exposures of didanosine (when administered as the buffered tablet), stavudine, or fluconazole. For information regarding clinical recommendations, see Drug Interactions ( 7) .

NA = not available.

NA = not available.

Mechanism of Action

Atazanavir (ATV) is an azapeptide HIV-1 protease inhibitor (PI). The compound selectively inhibits the virus-specific processing of viral Gag and Gag-Pol polyproteins in HIV-1 infected cells, thus preventing formation of mature virions.

Antiviral Activity in Cell Culture

Atazanavir exhibits anti-HIV-1 activity with a mean 50% effective concentration (EC ₅₀) in the absence of human serum of 2 to 5 nM against a variety of laboratory and clinical HIV-1 isolates grown in peripheral blood mononuclear cells, macrophages, CEM-SS cells, and MT-2 cells. ATV has activity against HIV-1 Group M subtype viruses A, B, C, D, AE, AG, F, G, and J isolates in cell culture. ATV has variable activity against HIV-2 isolates (1.9 to 32 nM), with EC ₅₀ values above the EC ₅₀ values of failure isolates. Two-drug combination antiviral activity studies with ATV showed no antagonism in cell culture with PIs (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir) , NNRTIs (delavirdine, efavirenz, and nevirapine), NRTIs (abacavir, didanosine, emtricitabine, lamivudine, stavudine, tenofovir DF, and zidovudine), the HIV-1 fusion inhibitor enfuvirtide, and two compounds used in the treatment of viral hepatitis, adefovir and ribavirin, without enhanced cytotoxicity.

Resistance

In Cell Culture: HIV-1 isolates with a decreased susceptibility to ATV have been selected in cell culture and obtained from patients treated with ATV or atazanavir/ritonavir (ATV/RTV). HIV-1 isolates with 93 to 183 fold reduced susceptibility to ATV from three different viral strains were selected in cell culture by 5 months. The substitutions in these HIV-1 viruses that contributed to ATV resistance include I50L, N88S, I84V, A71V, and M46I. Changes were also observed at the protease cleavage sites following drug selection. Recombinant viruses containing the I50L substitution without other major PI substitutions were growth impaired and displayed increased susceptibility in cell culture to other PIs (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir). The I50L and I50V substitutions yielded selective resistance to ATV and amprenavir, respectively, and did not appear to be cross-resistant.

Clinical Studies of Treatment-Naive Patients: Comparison of Ritonavir-Boosted Atazanavir Sulfate vs. Unboosted Atazanavir Sulfate: Study AI424-089 compared atazanavir 300 mg once daily with ritonavir 100 mg vs. atazanavir 400 mg once daily when administered with lamivudine and extended-release stavudine in HIV-infected treatment-naive patients. A summary of the number of virologic failures and virologic failure isolates with ATV resistance in each arm is shown in Table 23.

Clinical Studies of Treatment-Naive Patients Receiving Atazanavir 300 mg With Ritonavir 100 mg: In Phase III Study AI424-138, an as-treated genotypic and phenotypic analysis was conducted on samples from patients who experienced virologic failure (HIV-1 RNA ≥ 400 copies/mL) or discontinued before achieving suppression on ATV/RTV (n = 39; 9%) and LPV/RTV (n = 39; 9%) through 96 weeks of treatment. In the ATV/RTV arm, one of the virologic failure isolates had a 56 fold decrease in ATV susceptibility emerge on therapy with the development of PI resistance-associated substitutions L10F, V32I, K43T, M46I, A71I, G73S, I85I/V, and L90M. The NRTI resistance-associated substitution M184V also emerged on treatment in this isolate conferring emtricitabine resistance. Two ATV/RTV-virologic failure isolates had baseline phenotypic ATV resistance and IAS-defined major PI resistance-associated substitutions at baseline. The I50L substitution emerged on study in one of these failure isolates and was associated with a 17 fold decrease in ATV susceptibility from baseline and the other failure isolate with baseline ATV resistance and PI substitutions (M46M/I and I84I/V) had additional IAS-defined major PI substitutions (V32I, M46I, and I84V) emerge on ATV treatment associated with a 3 fold decrease in ATV susceptibility from baseline. Five of the treatment failure isolates in the ATV/RTV arm developed phenotypic emtricitabine resistance with the emergence of either the M184I (n = 1) or the M184V (n = 4) substitution on therapy and none developed phenotypic tenofovir disoproxil resistance. In the LPV/RTV arm, one of the virologic failure patient isolates had a 69 fold decrease in LPV susceptibility emerge on therapy with the development of PI substitutions L10V, V11I, I54V, G73S, and V82A in addition to baseline PI substitutions L10L/I, V32I, I54I/V, A71I, G73G/S, V82V/A, L89V, and L90M. Six LPV/RTV virologic failure isolates developed the M184V substitution and phenotypic emtricitabine resistance and two developed phenotypic tenofovir disoproxil resistance.

Clinical Studies of Treatment-Naive Patients Receiving Atazanavir 400 mg Without Ritonavir: ATV-resistant clinical isolates from treatment-naive patients who experienced virologic failure on atazanavir 400 mg treatment without ritonavir often developed an I50L substitution (after an average of 50 weeks of ATV therapy), often in combination with an A71V substitution, but also developed one or more other PI substitutions (e.g., V32I, L33F, G73S, V82A, I85V, or N88S) with or without the I50L substitution. In treatment-naive patients, viral isolates that developed the I50L substitution, without other major PI substitutions, showed phenotypic resistance to ATV but retained in cell culture susceptibility to other PIs (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir); however, there are no clinical data available to demonstrate the effect of the I50L substitution on the efficacy of subsequently administered PIs.

Clinical Studies of Treatment-Experienced Patients: In studies of treatment-experienced patients treated with ATV or ATV/RTV, most ATV-resistant isolates from patients who experienced virologic failure developed substitutions that were associated with resistance to multiple PIs and displayed decreased susceptibility to multiple PIs. The most common protease substitutions to develop in the viral isolates of patients who failed treatment with ATV 300 mg once daily and RTV 100 mg once daily (together with tenofovir DF and an NRTI) included V32I, L33F/V/I, E35D/G, M46I/L, I50L, F53L/V, I54V, A71V/T/I, G73S/T/C, V82A/T/L, I85V, and L89V/Q/M/T. Other substitutions that developed on ATV/RTV treatment including E34K/A/Q, G48V, I84V, N88S/D/T, and L90M occurred in less than 10% of patient isolates. Generally, if multiple PI resistance substitutions were present in the HIV-1 virus of the patient at baseline, ATV resistance developed through substitutions associated with resistance to other PIs and could include the development of the I50L substitution. The I50L substitution has been detected in treatment-experienced patients experiencing virologic failure after long-term treatment. Protease cleavage site changes also emerged on ATV treatment but their presence did not correlate with the level of ATV resistance.

Cross-Resistance

Cross-resistance among PIs has been observed. Baseline phenotypic and genotypic analyses of clinical isolates from ATV clinical trials of PI-experienced patients showed that isolates cross-resistant to multiple PIs were cross-resistant to ATV. Greater than 90% of the isolates with substitutions that included I84V or G48V were resistant to ATV. Greater than 60% of isolates containing L90M, G73S/T/C, A71V/T, I54V, M46I/L, or a change at V82 were resistant to ATV, and 38% of isolates containing a D30N substitution in addition to other changes were resistant to ATV. Isolates resistant to ATV were also cross-resistant to other PIs with > 90% of the isolates resistant to indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir, and 80% resistant to amprenavir. In treatment-experienced patients, PI-resistant viral isolates that developed the I50L substitution in addition to other PI resistance-associated substitution were also cross-resistant to other PIs.

Baseline Genotype/Phenotype and Virologic Outcome Analyses

Genotypic and/or phenotypic analysis of baseline virus may aid in determining ATV susceptibility before initiation of ATV/RTV therapy. An association between virologic response at 48 weeks and the number and type of primary PI resistance-associated substitutions detected in baseline HIV-1 isolates from antiretroviral-experienced patients receiving ATV/RTV once daily or lopinavir (LPV)/RTV twice daily in Study AI424-045 is shown in Table 24.

Overall, both the number and type of baseline PI substitutions affected response rates in treatment-experienced patients. In the ATV/RTV group, patients had lower response rates when 3 or more baseline PI substitutions, including a substitution at position 36, 71, 77, 82, or 90, were present compared to patients with 1 to 2 PI substitutions, including one of these substitutions.

The response rates of antiretroviral-experienced patients in Study AI424-045 were analyzed by baseline phenotype (shift in susceptibility in cell culture relative to reference, Table 25). The analyses are based on a select patient population with 62% of patients receiving an NNRTI-based regimen before study entry compared to 35% receiving a PI-based regimen. Additional data are needed to determine clinically relevant break points for atazanavir sulfate.

Carcinogenesis

Long-term carcinogenicity studies in mice and rats were carried out with atazanavir for two years. In the mouse study, drug-related increases in hepatocellular adenomas were found in females at 360 mg/kg/day. The systemic drug exposure (AUC) at the NOAEL (no observable adverse effect level) in females, (120 mg/kg/day) was 2.8 times and in males (80 mg/kg/day) was 2.9 times higher than those in humans at the clinical dose (300 mg/day atazanavir boosted with 100 mg/day ritonavir, non-pregnant patients). In the rat study, no drug-related increases in tumor incidence were observed at doses up to 1200 mg/kg/day, for which AUCs were 1.1 (males) or 3.9 (females) times those measured in humans at the clinical dose.

Mutagenesis

Atazanavir tested positive in an in vitro clastogenicity test using primary human lymphocytes, in the absence and presence of metabolic activation. Atazanavir tested negative in the in vitro Ames reverse-mutation assay, in vivo micronucleus and DNA repair tests in rats, and in vivo DNA damage test in rat duodenum (comet assay).

Impairment of Fertility

At the systemic drug exposure levels (AUC) 0.9 (in male rats) or 2.3 (in female rats) times that of the human clinical dose, (300 mg/day atazanavir boosted with 100 mg/day ritonavir) significant effects on mating, fertility, or early embryonic development were not observed.

Study AI424-138: a 96 week study comparing the antiviral efficacy and safety of atazanavir sulfate/ritonavir with lopinavir/ritonavir, each in combination with fixed-dose tenofovir DF‑emtricitabine in HIV-1 infected treatment-naive subjects. Study AI424-138 was a 96 week, open-label, randomized, multicenter study, comparing atazanavir (300 mg once daily) with ritonavir (100 mg once daily) to lopinavir with ritonavir (400 mg/100 mg twice daily), each in combination with fixed-dose tenofovir DF with emtricitabine (300 mg/200 mg once daily), in 878 antiretroviral treatment-naive treated patients. Patients had a mean age of 36 years (range: 19 to 72), 49% were Caucasian, 18% Black, 9% Asian, 23% Hispanic/Mestizo/mixed race, and 68% were male. The median baseline plasma CD4+ cell count was 204 cells/mm ³ (range: 2 to 810 cells/mm ³) and the mean baseline plasma HIV-1 RNA level was 4.94 log ₁₀ copies/mL (range: 2.60 to 5.88 log ₁₀ copies/mL). Treatment response and outcomes through Week 96 are presented in Table 26.

Through 96 weeks of therapy, the proportion of responders among patients with high viral loads (i.e., baseline HIV RNA ≥ 100,000 copies/mL) was comparable for the atazanavir sulfate/ritonavir (165 of 223 patients, 74%) and lopinavir/ritonavir (148 of 222 patients, 67%) arms. At 96 weeks, the median increase from baseline in CD4+ cell count was 261 cells/mm ³ for the atazanavir sulfate/ritonavir arm and 273 cells/mm ³ for the lopinavir/ritonavir arm.

Study AI424-034: Atazanavir sulfate once daily compared to efavirenz once daily, each in combination with fixed-dose lamivudine + zidovudine twice daily. Study AI424-034 was a randomized, double-blind, multicenter trial comparing atazanavir (400 mg once daily) to efavirenz (600 mg once daily), each in combination with a fixed-dose combination of lamivudine (3TC) (150 mg) and zidovudine (ZDV) (300 mg) given twice daily, in 810 antiretroviral treatment-naive patients. Patients had a mean age of 34 years (range: 18 to 73), 36% were Hispanic, 33% were Caucasian, and 65% were male. The mean baseline CD4+ cell count was 321 cells/mm ³ (range: 64 to 1424 cells/mm ³) and the mean baseline plasma HIV-1 RNA level was 4.8 log ₁₀ copies/mL (range: 2.2 to 5.9 log ₁₀ copies/mL). Treatment response and outcomes through Week 48 are presented in Table 27.

Through 48 weeks of therapy, the proportion of responders among patients with high viral loads (i.e., baseline HIV RNA ≥ 100,000 copies/mL) was comparable for the atazanavir sulfate and efavirenz arms. The mean increase from baseline in CD4+ cell count was 176 cells/mm ³ for the atazanavir sulfate arm and 160 cells/mm ³ for the efavirenz arm.

Study AI424-008: Atazanavir 400 mg once daily compared to atazanavir 600 mg once daily, and compared to nelfinavir 1250 mg twice daily, each in combination with stavudine and lamivudine twice daily. Study AI424-008 was a 48 week, randomized, multicenter trial, blinded to dose of atazanavir sulfate, comparing atazanavir at two dose levels (400 mg and 600 mg once daily) to nelfinavir (1250 mg twice daily), each in combination with stavudine (40 mg) and lamivudine (150 mg) given twice daily, in 467 antiretroviral treatment-naive patients. Patients had a mean age of 35 years (range: 18 to 69), 55% were Caucasian, and 63% were male. The mean baseline CD4+ cell count was 295 cells/mm ³ (range: 4 to 1003 cells/mm ³) and the mean baseline plasma HIV-1 RNA level was 4.7 log ₁₀ copies/mL (range: 1.8 to 5.9 log ₁₀ copies/mL). Treatment response and outcomes through Week 48 are presented in Table 28.

Through 48 weeks of therapy, the mean increase from baseline in CD4+ cell count was 234 cells/mm ³ for the atazanavir 400 mg arm and 211 cells/mm ³ for the nelfinavir arm.

Study AI424-045: Atazanavir sulfate once daily + ritonavir once daily compared to atazanavir sulfate once daily + saquinavir (soft gelatin capsules) once daily, and compared to lopinavir + ritonavir twice daily, each in combination with tenofovir DF + one NRTI. Study AI424-045 was a randomized, multicenter trial comparing atazanavir (300 mg once daily) with ritonavir (100 mg once daily) to atazanavir (400 mg once daily) with saquinavir soft gelatin capsules (1200 mg once daily), and to lopinavir + ritonavir (400/100 mg twice daily), each in combination with tenofovir DF and one NRTI, in 347 (of 358 randomized) patients who experienced virologic failure on HAART regimens containing PIs, NNRTIs, and NRTIs. The mean time of prior exposure to antiretrovirals was 139 weeks for PIs, 85 weeks for NNRTIs, and 283 weeks for NRTIs. The mean age was 41 years (range: 24 to 74); 60% were Caucasian, and 78% were male. The mean baseline CD4+ cell count was 338 cells/mm ³ (range: 14 to 1543 cells/mm ³) and the mean baseline plasma HIV-1 RNA level was 4.4 log ₁₀ copies/mL (range: 2.6 to 5.88 log ₁₀ copies/mL).

Treatment outcomes through Week 48 for the atazanavir sulfate/ritonavir and lopinavir/ritonavir treatment arms are presented in Table 29. Atazanavir sulfate/ritonavir and lopinavir/ritonavir were similar for the primary efficacy outcome measure of time-averaged difference in change from baseline in HIV RNA level. Study AI424-045 was not large enough to reach a definitive conclusion that atazanavir sulfate/ritonavir and lopinavir/ritonavir are equivalent on the secondary efficacy outcome measure of proportions below the HIV RNA lower limit of quantification [see Microbiology, Tables 24 and 25 ( 12.4)] .

No patients in the atazanavir sulfate/ritonavir treatment arm and three patients in the lopinavir/ritonavir treatment arm experienced a new-onset CDC Category C event during the study.

In Study AI424-045, the mean change from baseline in plasma HIV-1 RNA for atazanavir 400 mg with saquinavir (n = 115) was -1.55 log ₁₀ copies/mL, and the time-averaged difference in change in HIV-1 RNA levels versus lopinavir/ritonavir was 0.33. The corresponding mean increase in CD4+ cell count was 72 cells/mm ³. Through 48 weeks of treatment, the proportion of patients in this treatment arm with plasma HIV-1 RNA < 400 (< 50) copies/mL was 38% (26%). In this study, coadministration of atazanavir sulfate and saquinavir did not provide adequate efficacy [see Drug Interactions ( 7)] .

Study AI424-045 also compared changes from baseline in lipid values [see Adverse Reactions ( 6.1)] .

Study AI424-043: Study AI424-043 was a randomized, open-label, multicenter trial comparing atazanavir (400 mg once daily) to lopinavir/ritonavir (400/100 mg twice daily), each in combination with two NRTIs, in 300 patients who experienced virologic failure to only one prior PI-containing regimen. Through 48 weeks, the proportion of patients with plasma HIV-1 RNA < 400 (< 50) copies/mL was 49% (35%) for patients randomized to atazanavir sulfate (n = 144) and 69% (53%) for patients randomized to lopinavir/ritonavir (n = 146). The mean change from baseline was -1.59 log ₁₀ copies/mL in the atazanavir sulfate treatment arm and -2.02 log ₁₀ copies/mL in the lopinavir/ritonavir arm. Based on the results of this study, atazanavir sulfate without ritonavir was inferior to lopinavir/ritonavir in PI-experienced patients with prior virologic failure and is not recommended for such patients.

Pediatric Trials with Atazanavir Sulfate Capsules

Assessment of the pharmacokinetics, safety, tolerability, and virologic response of atazanavir sulfate capsules was based on data from the open-label, multicenter clinical trial PACTG 1020A which included patients from 6 years to 21 years of age. In this study, 105 patients (43 antiretroviral-naive and 62 antiretroviral-experienced) received once daily atazanavir sulfate capsule formulation, with or without ritonavir, in combination with two NRTIs.

One-hundred five (105) patients (6 to less than 18 years of age) treated with the atazanavir sulfate capsule formulation, with or without ritonavir, were evaluated. Using an ITT analysis, the overall proportions of antiretroviral-naive and -experienced patients with HIV RNA < 400 copies/mL at Week 96 were 51% (22/43) and 34% (21/62), respectively. The overall proportions of antiretroviral-naive and -experienced patients with HIV RNA < 50 copies/mL at Week 96 were 47% (20/43) and 24% (15/62), respectively. The median increase from baseline in absolute CD4 count at 96 weeks of therapy was 335 cells/mm ³ in antiretroviral-naive patients and 220 cells/mm ³ in antiretroviral-experienced patients.