Semprex ® -D Capsules (acrivastine and pseudoephedrine hydrochloride)

Acrivastine was absorbed rapidly from the combination capsule following oral administration and was as bioavailable as a solution of acrivastine. After administration of SEMPREX-D Capsules, maximum plasma acrivastine concentrations were achieved at 1.14 ± 0.23 hours. A mass balance study in 7 healthy volunteers showed that acrivastine is primarily eliminated by the kidneys. Over a 72-hour collection period, about 84% of the administered total radioactivity was recovered in urine and about 13% in feces, for a combined recovery of about 97%. Further, 67% of the administered radioactive dose was recovered in urine as the unchanged drug, 11% as the propionic acid metabolite, and 6% as other unknown metabolites.

Acrivastine exhibits linear kinetics over dosages ranging from 2 to 32 mg t.i.d. The mean ± SD terminal half-life for acrivastine was 1.9 ± 0.3 hours following single oral doses and increased to 3.5 ± 1.9 hours at steady state. The terminal half-life for the propionic acid metabolite was 3.8 ± 1.4 hours. Because of the short half-lives of both acrivastine and its metabolites, accumulation in the plasma following multiple dosing is not expected.

The steady-state maximum acrivastine plasma concentration was 227 ± 47 ng/mL. The oral clearance, and apparent volume of distribution were 2.9 ± 0.7 mL/min/kg and 0.46 ± 0.05 L/kg, respectively, following a single oral dose; oral clearance did not change at steady state (2.86 ± 0.75 mL/min/kg). The apparent volume of distribution increased to 0.82 ± 0.6 L/kg to parallel the increase in the elimination half-life of the drug.

Acrivastine binding to human plasma proteins was 50% ± 2.0% and was concentration-independent over the range of 5 to 1000 ng/mL. The main binding protein was serum albumin although the drug was slightly bound to α-1-acid glycoprotein. No displacement interaction was observed between acrivastine and either phenytoin or theophylline. The binding of acrivastine was not affected by the presence of pseudoephedrine.

Pseudoephedrine hydrochloride was also rapidly absorbed from the combination capsule, and the capsule was as bioavailable as a solution of pseudoephedrine. Steady state maximum plasma concentration for pseudoephedrine was 498 ± 129 ng/mL. The terminal half-life, oral clearance and apparent volume of distribution were 6.2 ± 1.8 hours, 5.9 ± 1.7 mL/min/kg, and 3.0 ± 0.4 L/kg, respectively. Elimination of pseudoephedrine is primarily through the renal route as 55% to 75% of an administered dose appears unchanged in the urine. Pseudoephedrine elimination, however, is highly dependent upon urine pH; the plasma half-life decreased to about 4 hours at pH 5 and increased to 13 hours at pH 8.

Pseudoephedrine did not bind to human plasma proteins over the concentration range of 50 to 2000 ng/mL.

Acrivastine and pseudoephedrine do not influence the pharmacokinetics of the other drug when administered concomitantly.

A single dose pharmacokinetic study showed that the elimination half-lives of acrivastine, the propionic acid metabolite of acrivastine, and pseudoephedrine were prolonged in patients with chronic renal insufficiency. Compared to normal volunteers, the elimination half-life of acrivastine was about 50% increased in patients with mild renal insufficiency (creatinine clearance = 26 to 48 mL/min) and was increased by about 130% in patients with moderate (creatinine clearance = 12 to 17 mL/min) or severe (creatinine clearance 6 to 10 mL/min) renal insufficiency. Oral clearance of acrivastine was diminished by the same magnitude as the half-life was prolonged in each of the three renally impaired groups. The elimination half-life of the propionic acid metabolite of acrivastine was about 140% increased in patients with mild renal insufficiency and about 5 times increased in patients with moderate or severe renal insufficiency.

Compared to normal volunteers, the elimination half-life of pseudoephedrine was about 3 times increased in patients with mild renal insufficiency, about 7 times increased in patients with moderate renal insufficiency, and about 10 times increased in patients with severe renal insufficiency. Oral clearance of pseudoephedrine was diminished by about the same magnitude as the half-life was prolonged in each of the three renally impaired groups (see PRECAUTIONS , Use in Patients with Diminished Renal Function ).

The total body load removed by dialysis is approximately 20%, 27% and 38% for acrivastine, the propionic acid metabolite of acrivastine, and pseudoephedrine, respectively, and therefore, a supplemental dose after a dialysis session is not required.

Based on a multiple dose cross study comparison, the apparent volume of distribution for acrivastine was 44% lower in elderly (n = 36, 65-75 yr) than in young volunteers (n = 16, 19-33 yr). This difference could be attributed to the decrease in total body water that occurs with aging. Despite this difference, no appreciable differences in plasma acrivastine concentrations were seen in the elderly compared to the young, and no appreciable accumulation of acrivastine occurred in plasma at steady-state. The elimination half-life for pseudoephedrine was 18% longer in elderly (7.9 hours) than in younger subjects (6.7 hours), presumably due to the decline in average renal function that occurs with aging. Despite this difference, clearance of pseudoephedrine was not appreciably different in elderly and younger subjects. Elderly patients can therefore be given the same dosage as younger patients. SEMPREX-D Capsules are not recommended, however, in patients with renal impairment (see PRECAUTIONS , Use in Patients with Diminished Renal Function and Geriatric Use).

The effect of age and sex on the pharmacokinetic parameters of acrivastine and pseudoephedrine was determined in 93 healthy volunteers who participated in various studies. All of the 93 volunteers were Caucasian (81 males and 12 females); 57 were between the ages of 18 and 38 years and 36 were between the ages of 65 and 75 years. There were no age- or sex-related differences in the pharmacokinetic parameters of either acrivastine or pseudoephedrine.

The effect of race on acrivastine and pseudoephedrine pharmacokinetics was examined by screening data obtained from 1035 patients, age 12 to 71 years, who participated in the eight safety and efficacy studies. No race-related differences were observed in the pharmacokinetics of either acrivastine or pseudoephedrine.

Acrivastine is sedating in some patients. In controlled clinical trials, somnolence (i.e., drowsiness, sedation, sleepiness) was more common with SEMPREX-D Capsules (by an average of 6%) than with placebo (see ADVERSE EXPERIENCES).

Patients should be advised to assess their individual responses to SEMPREX-D Capsules before engaging in any activity requiring mental alertness, such as driving a motor vehicle or operating machinery. Concurrent use of SEMPREX-D Capsules with alcohol or other CNS depressants may cause additional reductions in alertness and impairment of CNS performance and should be avoided (see PRECAUTIONS, Drug Interactions).

Acrivastine and pseudoephedrine are excreted primarily through the kidney. Both compounds therefore accumulate in patients with impaired renal function. Due to the differential effects of renal failure on the serum half-life and clearance of acrivastine and pseudoephedrine, use of SEMPREX-D Capsules, a fixed combination product, in patients with renal impairment (creatinine clearance ≤ 48 mL/min) is not recommended (see OVERDOSAGE and CLINICAL PHARMACOLOGY).

Patients taking SEMPREX-D Capsules should receive the following information. SEMPREX-D Capsules are prescribed to reduce symptoms associated with seasonal allergic rhinitis. Patients should be instructed to take SEMPREX-D Capsules only as prescribed and not to exceed the prescribed dose. Patients should be advised against the concurrent use of SEMPREX-D with over-the-counter antihistamines and decongestants. Patients who are or may become pregnant should be told that this product should be used in pregnancy or during lactation only if the potential benefit justifies the potential risks to the fetus or nursing infant. Due to the risk of hypertensive crisis, patients should be instructed not to take SEMPREX-D Capsules (acrivastine and pseudoephedrine hydrochloride) if they are presently taking a monoamine oxidase inhibitor or for 14 days after stopping use of an MAO inhibitor. Patients should be advised to assess their individual responses to SEMPREX-D Capsules before engaging in any activity requiring mental alertness, such as driving a car or operating machinery. Patients should be advised that the concurrent use of SEMPREX-D Capsules with alcohol and other CNS depressants may lead to additional reductions in alertness and impairment of CNS performance and should be avoided.

MAO inhibitors and beta-adrenergic agonists increase the effects of sympathomimetic amines. Concomitant use of sympathomimetic amines with MAO inhibitors can result in a hypertensive crisis (see CONTRAINDICATIONS). Because MAO inhibitors are long-acting, SEMPREX-D Capsules should not be taken with an MAO inhibitor or for 14 days after stopping use of an MAO inhibitor.

Because of their pseudoephedrine content, SEMPREX-D Capsules may reduce the antihypertensive effects of drugs that interfere with sympathetic activity. Care should be taken in the administration of SEMPREX-D Capsules concomitantly with other sympathomimetic amines because the combined effects on the cardiovascular system may be harmful to the patient.

Concomitant administration of SEMPREX-D Capsules with alcohol and other CNS depressants may result in additional reductions in alertness and impairment of CNS performance and should be avoided.

No formal drug interaction studies between SEMPREX-D Capsules and other possibly co-administered drugs have been performed.

Carcinogenicity studies with the combination of acrivastine and pseudoephedrine have not been performed. Oral doses of acrivastine alone at levels up to 40 mg/kg/day (236 mg/m²/day or 10 times the recommended human daily dose) for 20 to 22 months in rats and up to 250 mg/kg/day (750 mg/m²/day or 32 times the recommended human daily dose) for 20 to 24 months in mice revealed no evidence of carcinogenic potential. No evidence of mutagenicity (with or without metabolic activation) was observed in the Ames Salmonella mutagenicity assay or in the L5178Y/tk+/- mouse lymphoma assay. In an in vitro cytogenetic study performed in cultured human lymphocytes, acrivastine induced structural chromosomal abnormalities in the absence of metabolic activation, but not in its presence. In an in vivo cytogenetic study in rats given single oral doses of acrivastine up to 1000 mg/kg (5900 mg/m² or 249 times the recommended human daily dose) there were no structural chromosomal alterations.

Reproduction-fertility studies in rats given acrivastine alone at levels up to 200 mg/kg/day (1180 mg/m²/day or 50 times the recommended human daily dose) had no effect on male or female fertility. Similarly, no effect on fertility was seen in male rats given acrivastine 20 mg/kg/day and pseudoephedrine 100 mg/kg/ day (118 and 590 mg/m²/day or 5 and 3 times the recommended human daily doses, respectively) or in female rats given acrivastine 4 mg/kg/day and pseudoephedrine 20 mg/kg/day (23.6 and 118 mg/m²/day or 1 and 0.7 times the recommended human daily doses, respectively).

It is not known whether acrivastine is excreted in human milk; pseudoephedrine is excreted in human milk. SEMPREX-D Capsules should only be used in nursing mothers when the potential benefit justifies the potential risks to the nursing infant.

Safety and effectiveness of SEMPREX-D Capsules in pediatric patients under the age of 12 years have not been established.

Of the total number of subjects in clinical studies of SEMPREX-D, 349 were 60 years of age or older and 53 were 70 years of age and older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. Antihistamines, however, as a pharmaceutical class, are more likely to cause dizziness, sedation, bladder-neck obstruction, and hypotension in elderly patients. The elderly are also more likely to have adverse reactions to sympathomimetics such as pseudoephedrine (see CLINICAL PHARMACOLOGY and WARNINGS).

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. Use of SEMPREX-D in patients with renal impairment (creatinine clearance ≤ 48 mL/min) is not recommended (see PRECAUTIONS , Use in Patients with Diminished Renal Function ).

Store at 15°C to 25° C (59°F to 77° F) in a dry place and protected from light.

Keep out of the reach of children.