Absorption: The absolute bioavailability of fenofibrate cannot be determined as the compound is virtually insoluble in aqueous media suitable for injection. However, 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 occur within approximately 5 hours after oral administration.
The absorption of fenofibrate is increased when administered with food. With fenofibrate, the extent of absorption is increased by approximately 58% and 25% under high-fat fed and low-fat fed conditions as compared to fasting conditions, respectively.
In a single dose and multiple dose bioavailability study with fenofibrate capsules 200 mg, the extent of absorption (AUC) of fenofibric acid, the principal metabolite of fenofibrate, was 42% larger at steady state compared to single-dose administration. The rate of absorption (Cmax) of fenofibric acid was 73% greater after multiple-dose than after single-dose administration.
The extent of absorption of fenofibrate capsules in terms of AUC value of fenofibric acid increased in a less than proportional manner while the rate of absorption in terms of Cmax value of fenofibric acid increased proportionally related to dose.
Distribution: Upon multiple dosing of fenofibrate, fenofibric acid steady state is achieved after 5 days. Plasma concentrations of fenofibric acid at steady state are slightly more than double those following a single dose. Serum protein binding was approximately 99% in normal and hyperlipidemic subjects.
Metabolism: Following oral administration, fenofibrate is rapidly hydrolyzed by esterases to the active metabolite, fenofibric acid; unchanged fenofibrate is detected at low concentrations in plasma compared to fenofibric acid over most of the single dose and multiple dosing periods.
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 vitro and in vivo metabolism data indicate that neither fenofibrate nor fenofibric acid undergo oxidative metabolism (e.g., cytochrome P450) to a significant extent.
Elimination: After absorption, fenofibrate is mainly excreted in the urine in the form of metabolites, primarily fenofibric acid and fenofibric acid glucuronide. After administration of radiolabeled fenofibrate, approximately 60% of the dose appeared in the urine and 25% was excreted in feces.
Fenofibric acid is eliminated with a half-life of approximately 20 hours allowing once daily dosing.
Geriatrics: In elderly volunteers 77 to 87 years of age, the apparent 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 an equivalent dose of fenofibrate can be used in elderly subjects with normal renal function, without increasing accumulation of the drug or metabolites [see Dosage and Administration (2.5) and Use in Specific Populations (8.5)].
Pediatrics: Pharmacokinetics of fenofibrate has not been studied in pediatric patients.
Gender: No pharmacokinetic difference between males and females has been observed for fenofibrate.
Race: 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.
Renal Impairment: The pharmacokinetics of fenofibric acid was examined in patients with mild, moderate and severe renal impairment. Patients with mild (estimated glomerular filtration rate eGFR 60-89 ml/min/1.73m2) to moderate (eGFR 30-59 mL/min/1.73m2) renal impairment had similar exposure but an increase in the half-life for fenofibric acid was observed as compared to that of healthy subjects. Patients with severe renal impairment (eGFR <30 mL/min/1.73m2) showed a 2.7-fold increase in exposure for fenofibric acid and increased accumulation of fenofibric acid during chronic dosing compared to that of healthy subjects. In patients with mild to moderate renal impairment, treatment with fenofibrate should be initiated at a dose of 50 mg per day, and increased only after evaluation of the effects on renal function and lipid levels at this dose. Based on these findings, the use of fenofibrate should be avoided in patients who have severe renal impairment.
Hepatic Impairment: No pharmacokinetic studies have been conducted in patients having hepatic impairment.
Drug-Drug Interactions: In vitro studies using human liver microsomes indicate that fenofibrate and fenofibric acid are not inhibitors of cytochrome P450 (CYP) isoforms CYP3A4, CYP2D6, CYP2E1, or CYP1A2. They are weak inhibitors of CYP2C8, CYP2C19 and CYP2A6, and mild to moderate inhibitors of CYP2C9 at therapeutic concentrations.
Table 2 describes the effects of co-administered drugs on fenofibric acid systemic exposure. Table 3 describes the effects of fenofibrate on co-administered drugs.
Table 2. Effects of Co-Administered Drugs on Fenofibric Acid Systemic Exposure from Fenofibrate Administration 1 TriCor (fenofibrate) oral tablet 2 TriCor (fenofibrate) oral micronized capsule |
Co-Administered Drug | Dosage Regimen of Co-Administered Drug | Dosage Regimen of Fenofibrate | Changes in Fenofibric Acid Exposure |
| | | AUC | Cmax |
Lipid-lowering 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 3. Effects of Fenofibrate on Systemic Exposure of Co-Administered Drugs Dosage Regimen of Fenofibrate | Dosage Regimen of Co-Administered Drug | Change in Co-Administered Drug Exposure |
|---|
| | Analyte | AUC | Cmax |
|---|
1 TriCor (fenofibrate) oral tablet 2 TriCor (fenofibrate) oral micronized capsule |
Lipid-lowering 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 | ↑5% | ↑16% |
Anti-diabetic agents | |
Fenofibrate 145 mg1 once daily for 10 days | Glimepiride, 1 mg 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% |
Carcinogenesis: Two dietary carcinogenicity studies have been conducted in rats with fenofibrate. In the first 24-month study, Wistar rats were dosed with fenofibrate at 10, 45 and 200 mg/kg/day, approximately 0.3, 1, and 6 times the maximum recommended human dose (MRHD), based on body surface are comparisons (mg/m2). At a dose of 200 mg/kg/day (at 6 times MRHD), the incidence of liver carcinoma was significantly increased in both sexes. A statistically significant increase in pancreatic carcinomas was observed in males at 1 and 6 times the MRHD; an increase in pancreatic adenomas and benign testicular interstitial cell tumors was observed in males at 6 times the MRHD. In a second 24-month study in a different strain of rats (Sprague-Dawley), doses of 10 and 60 mg/kg/day (0.3 and 2 times the MRHD) produced significant increases in the incidence of pancreatic acinar adenomas in both sexes and increases in testicular interstitial cell tumors in males at 2 times the MRHD.
A 117-week carcinogenicity study was conducted in rats comparing three drugs: fenofibrate 10 and 60 mg/kg/day (0.3 and 2 times the MRHD), clofibrate (400 mg/kg; 2 times the human dose), and gemfibrozil (250 mg/kg; 2 times the human dose, based on mg/m2 surface area). Fenofibrate increased pancreatic acinar adenomas in both sexes. Clofibrate increased hepatocellular carcinomas in males and hepatic neoplastic nodules in females. Gemfibrozil increased hepatic neoplastic nodules in males and females, while all three drugs increased testicular interstitial cell tumors in males.
In a 21-month study in CF-1 mice, fenofibrate 10, 45 and 200 mg/kg/day (approximately 0.2, 1, and 3 times the MRHD on the basis of mg/m2 surface area) significantly increased the liver carcinomas in both sexes at 3 times the MRHD. In a second 18 month study at 10, 60 and 200 mg/kg/day, fenofibrate significantly increased the liver carcinomas in male mice and liver adenomas in female mice at 3 times the MRHD.
Electron microscopy studies have demonstrated peroxisomal proliferation following fenofibrate administration to the rat. An adequate study to test for peroxisome proliferation in humans has not been done, but changes in peroxisome morphology and numbers have been observed in humans after treatment with other members of the fibrate class when liver biopsies were compared before and after treatment in the same individual.
Mutagenesis: Fenofibrate has been demonstrated to be devoid of mutagenic potential in the following tests: Ames, mouse lymphoma, chromosomal aberration and unscheduled DNA synthesis in primary rat hepatocytes.
Impairment of Fertility: In fertility studies rats were given oral dietary doses of fenofibrate, males received 61 days prior to mating and females 15 days prior to mating through weaning which resulted in no adverse effect on fertility at doses up to 300 mg/kg/day (approximately 10 times the MRHD, based on mg/m2 surface area comparisons).