Fenofibrate is a pro-drug of the active chemical moiety fenofibric acid. Fenofibrate is converted by ester hydrolysis in the body to fenofibric acid which is the active constituent measurable in the circulation.
Absorption: The absolute bioavailability of fenofibrate cannot be determined as the compound is virtually insoluble in aqueous media suitable for injection. Fenofibrate is insoluble in water and its bioavailability is optimized when taken with meals. However, after fenofibrate is dissolved, fenofibrate is well absorbed from the gastrointestinal tract. Following oral administration in healthy volunteers, approximately 60% of a single dose of radiolabeled fenofibrate appeared in urine, primarily as fenofibric acid and its glucuronate conjugate, and 25% was excreted in the feces. Peak plasma levels of fenofibric acid from Antara capsules 90 mg occur within 2 to 6 hours after administration.
Effect of Food
The extent of absorption of fenofibric acid was unaffected when Antara was taken either in fasted state or with a low-fat meal. However, the Cmax of Antara increased in the presence of a low-fat meal. Tmax was unaffected in the presence of a low-fat meal. In the presence of a high-fat meal, there was a 26.7% increase in AUC and 15.35% increase in Cmax of fenofibric acid from Antara capsule 30mg relative to fasting state.
Distribution: In healthy volunteers, steady-state plasma levels of fenofibric acid were shown to be achieved within a week of dosing and did not demonstrate accumulation across time following multiple dose administration. Serum protein binding was approximately 99% in normal and hyperlipidemic subjects.
Elimination
Metabolism: Following oral administration, fenofibrate is rapidly hydrolyzed by esterases to the active metabolite, fenofibric acid; no unchanged fenofibrate is detected in plasma.
Fenofibric acid is primarily conjugated with glucuronic acid and then excreted in urine. A small amount of fenofibric acid is reduced at the carbonyl moiety to a benzhydrol metabolite which is, in turn, conjugated with glucuronic acid and excreted in urine.
In vivo metabolism data indicate that neither fenofibrate nor fenofibric acid undergo oxidative metabolism (e.g., cytochrome P450) to a significant extent.
Excretion: After absorption, fenofibrate is mainly excreted in the urine in the form of metabolites, primarily fenofibric acid and fenofibric acid glucuronide. After administration of radio-labelled fenofibrate, approximately 60% of the dose appeared in the urine and 25% was excreted in the feces. Fenofibric acid is eliminated with a half-life of 23 hours, allowing once daily dosing.
Specific Populations
Geriatric Patients: In elderly volunteers aged 77 to 87 years, the oral clearance of fenofibric acid following a single oral dose of fenofibrate was 1.2 L/h, which compares to 1.1 L/h in young adults. This indicates that a similar dosage regimen can be used in the elderly with normal renal function, without increasing accumulation of the drug or metabolites [see Dosage and Administration (2.4) and Use in Special Populations (8.5)].
Pediatric Patients: Pharmacokinetics of Antara has not been studied in pediatric patients.
Male and Female Patients: No pharmacokinetic difference between males and females has been observed for fenofibrate.
Racial and Ethnic Groups: The influence of race on the pharmacokinetics of fenofibrate has not been studied; however, fenofibrate is not metabolized by enzymes known for exhibiting inter-ethnic variability.
Patients with Renal Impairment: The pharmacokinetics of fenofibric acid was examined in patients with mild, moderate, and severe renal impairment. Patients with severe renal impairment [creatinine clearance(CrCl) ≤ 30 mL/min or estimated glomerular filtration rate(eGFR) < 30 mL/min/1.73m2] showed 2.7-fold increase in exposure for fenofibric acid and increased accumulation of fenofibric acid during chronic dosing compared to that of healthy subjects. Patients with mild to moderate renal impairment (CrCl 30 mL/min to 80 mL/min or eGFR 30 mL/min/1.73m2to 59 mL/min/1.73m2) had similar exposure but an increase in the half-life for fenofibric acid compared to that of healthy subjects. Based on these findings, the use of Antara is contraindicated in patients with severe renal impairment, including end-stage renal disease (ESRD) or those receiving dialysis. Dose reduction is required in patients having mild to moderate renal impairment [see Dosage and Administration (2.4)].
Patients with Hepatic Impairment: No pharmacokinetic studies have been conducted in patients having hepatic impairment.
Drug-Drug Interaction Studies: In vitro studies using human liver microsomes indicate that fenofibrate and fenofibric acid are not inhibitors of cytochrome (CYP) P450 isoforms CYP3A4, CYP2D6, CYP2E1, or CYP1A2. They are weak inhibitor of CYP2C8, CYP2C19 and CYP2A6, and mild-to-moderate inhibitors of CYP2C9 at therapeutic concentrations.
Table 3 describes the effects of co-administered drugs on fenofibric acid systemic exposure.
Table 4 describes the effects of co-administered fenofibric acid on exposure to other drugs.
Table 3 Effects of Co-Administered Drugs on Fenofibric Acid Systemic Exposure from Antara or Fenofibrate Administration |
|
Co-Administered Drug
| Dosage Regimen of Co-Administered Drug
| Dosage Regimen of Fenofibrate
| Changes in Fenofibric Acid Exposure
|
| | | AUC
| Cmax
|
Lipid-lowing agents
|
Atorvastatin
| 20 mg once daily for 10 days
| Fenofibrate 160 mg1 once daily for 10 days
| ↓2%
| ↓4%
|
Pravastatin
| 40 mg as a single dose
| Fenofibrate 3 x 67 mg2 as a single dose
| ↓1%
| ↓2%
|
Fluvastatin
| 40 mg as a single dose
| Fenofibrate 160 mg1 as a single dose
| ↓2%
| ↓10%
|
Anti-diabetic agents
|
Glimepiride
| 1 mg as a single dose
| Fenofibrate 145 mg1 once daily for 10 days
| ↑1%
| ↓1%
|
Metformin
| 850 mg three times daily for 10 days
| Fenofibrate 54 mg1 three times daily for 10 days
| ↓9%
| ↓6%
|
Rosiglitazone
| 8 mg once daily for 5 days
| Fenofibrate 145 mg1 once daily for 14 days
| ↑10%
| ↑3%
|
Table 4 Effects of Antara or Fenofibrate on Systemic Exposure of Co-Administered Drugs |
|
Dosage Regimen of Fenofibrate
| Dosage Regimen of Co- Administered Drug
| Changes in Co-Administered Drug Exposure
|
| | Analyte
| AUC
| Cmax
|
Lipid-lowing agents
|
Fenofibrate 160 mg1 once daily for 10 days
| Atorvastatin, 20 mg once daily for 10 days
| Atorvastatin
| ↓17%
| 0%
|
Fenofibrate 3 x 67 mg2 as a single dose
| Pravastatin, 40 mg as a single dose
| Pravastatin
| ↑13%
| ↑13%
|
| | 3α-Hydroxyl-iso-pravastatin
| ↑26%
| ↑29%
|
Fenofibrate 160 mg1 as a single dose
| Fluvastatin, 40 mg as a single dose
| (+)-3R, 5S Fluvastatin
| ↑15%
| ↑16%
|
Anti-diabetic agents
|
Fenofibrate 145 mg1 once daily for 10 days
| Glimepiride, 1 mg once daily as a single dose
| Glimepiride
| ↑35%
| ↑18%
|
Fenofibrate 54 mg1 three times daily for 10 days
| Metformin, 850 mg three times daily for 10 days
| Metformin
| ↑3%
| ↑6%
|
Fenofibrate 145 mg1 once daily for 14 days
| Rosiglitazone, 8 mg once daily for 5 days
| Rosiglitazone
| ↑6%
| ↓1%
|