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. However, fenofibrate is well absorbed from the gastrointestinal tract. Peak plasma levels of fenofibric acid from fenofibrate tablets occur, on average, within 2 to 3 hours after administration. Doses of three fenofibrate tablets 40 mg tablets are equivalent to single dose of fenofibrate tablets 120 mg tablets.
Effect of Food
A high-fat meal did not affect the fenofibric acid AUC after fenofibrate tablets administration but did increase the mean C
maxby 44% compared to fasting conditions. Under high-fat conditions, plasma concentrations of fenofibric acid after a single 120 mg dose of fenofibrate tablets are comparable to a single 130 mg dose of a fenofibrate capsule formulation.
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 radiolabelled fenofibrate, approximately 60% of the dose appeared in the urine and 25% was excreted in the feces. Fenofibric acid from fenofibrate tablets are eliminated with a half-life of 23 hours, allowing once daily dosing.
Specific Populations
Geriatrics Patients: In geriatric volunteers 77 to 87 years of age, 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 geriatric patients with normal renal function, without increasing accumulation of the drug or metabolites
[see
Dosage and Administration (2.4) and
Use in Specific Populations (8.5)].
Pediatric Patients: The pharmacokinetics of fenofibrate tablets has not been studied in pediatric populations.
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 were 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/1.73 m
2) 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 to 59 mL/min/1.73 m
2) had similar exposure but an increase in the half-life for fenofibric acid compared to that of healthy subjects
[See
Dosage and Administration (2.3)].
Patients with Hepatic Impairment: No pharmacokinetic studies have been conducted in patients with hepatic impairment.
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 inhibitors 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 fenofibrate or fenofibric acid on systemic exposure of other drugs.
Table 3. Effects of Co-Administered Drugs on Fenofibric Acid Systemic Exposure from Fenofibrate Administration |
|
Co-Administered Drug
| Dosage Regimen of Co-Administered Drug
| Dosage Regimen of Fenofibrate
| Changes in Fenofibric Acid Exposure
|
AUC
| C
max
|
Lipid-lowering medications
|
Atorvastatin
| 20 mg once daily for 10 days
| Fenofibrate 160 mg
1 once daily for 10 days
| ↓ 2%
| ↓ 4%
|
Pravastatin
| 40 mg as a single dose
| Fenofibrate 3 x 67 mg
2 as a single dose
| ↓ 1%
| ↓ 2%
|
Fluvastatin
| 40 mg as a single dose
| Fenofibrate 160 mg
1 as a single dose
| ↓ 2%
| ↓ 10%
|
Anti-diabetic medications
|
Glimepiride
| 1 mg as a single dose
| Fenofibrate 145 mg
1 once daily for 10 days
| ↑ 1%
| ↓ 1%
|
Metformin
| 850 mg three times daily for 10 days
| Fenofibrate 54 mg
1three times daily for 10 days
| ↓ 9%
| ↓ 6%
|
Rosiglitazone
| 8 mg once daily for 5 days
| Fenofibrate 145 mg
1 once daily for 14 days
| ↑ 10%
| ↑ 3%
|
Table 4. Effects of Fenofibrate Co-Administration on Systemic Exposure of Other Drugs |
|
Dosage Regimen of Fenofibrate
| Dosage Regimen of Co-Administered Drug
| Change in Co-Administered Drug Exposure
|
Analyte
| AUC
| C
max
|
Lipid-lowering medications
|
Fenofibrate 160 mg
1 once daily for 10 days
| Atorvastatin, 20 mg once daily for 10 days
| Atorvastatin
| ↓ 17%
| 0%
|
Fenofibrate 3 x 67 mg
2 as a single dose
| Pravastatin, 40 mg as a single dose
| Pravastatin
| ↑ 13%
| ↑ 13%
|
3α-Hydroxyl-iso-pravastatin
| ↑ 26%
| ↑ 29%
|
Fenofibrate 160 mg
1 as a single dose
| Fluvastatin, 40 mg as a single dose
| (+)-3R, 5S-Fluvastatin
| ↑ 15%
| ↑ 16%
|
Anti-diabetic medications
|
Fenofibrate 145 mg
1 once daily for 10 days
| Glimepiride, 1 mg as a single dose
| Glimepiride
| ↑ 35%
| ↑ 18%
|
Fenofibrate 54 mg
1 three times daily for 10 days
| Metformin, 850 mg three times daily for 10 days
| Metformin
| ↑ 3%
| ↑ 6%
|
Fenofibrate 145 mg
1 once daily for 14 days
| Rosiglitazone, 8 mg once daily for 5 days
| Rosiglitazone
| ↑ 6%
| ↓ 1%
|