CLINICAL PHARMACOLOGY
Mechanism of Action
The active moiety of Trilipix is fenofibric acid. The pharmacological effects of fenofibric acid in both animals and humans have been extensively studied through oral administration of fenofibrate.
The lipid-modifying effects of fenofibric acid seen in clinical practice have been explained in vivo in transgenic mice and in vitro in human hepatocyte cultures by the activation of peroxisome proliferator activated receptor α (PPARα). Through this mechanism, fenofibric acid increases lipolysis and elimination of triglyceride-rich particles from plasma by activating lipoprotein lipase and reducing production of Apo CIII (an inhibitor of lipoprotein lipase activity).
The resulting decrease in TG produces an alteration in the size and composition of LDL from small, dense particles (which are thought to be atherogenic due to their susceptibility to oxidation), to large buoyant particles. These larger particles have a greater affinity for cholesterol receptors and are catabolized rapidly. Activation of PPARα also induces an increase in the synthesis of HDL-C and Apo AI and AII.
Pharmacodynamics
Elevated levels of Total-C, LDL-C, and Apo B, and decreased levels of HDL-C and its transport complex, Apo AI and Apo AII, are risk factors for human atherosclerosis. Epidemiologic studies have established that cardiovascular morbidity and mortality vary directly with the levels of Total-C, LDL-C, and TG, and inversely with the level of HDL-C. The independent effect of raising HDL-C or lowering TG on the risk of cardiovascular morbidity and mortality has not been determined.
Pharmacokinetics
Trilipix contains fenofibric acid, which is the only circulating pharmacologically active moiety in plasma after oral administration of Trilipix. Fenofibric acid is also the circulating pharmacologically active moiety in plasma after oral administration of fenofibrate, the ester of fenofibric acid.
Plasma concentrations of fenofibric acid after administration of one 135 mg Trilipix delayed release capsule are equivalent to those after one 200 mg capsule of micronized fenofibrate administered under fed conditions.
Absorption Fenofibric acid is well absorbed throughout the gastrointestinal tract. The absolute bioavailability of fenofibric acid is approximately 81%.
Peak plasma levels of fenofibric acid occur within 4 to 5 hours after a single dose administration of Trilipix capsule under fasting conditions.
Fenofibric acid exposure in plasma, as measured by Cmax and AUC, is not significantly different when a single 135 mg dose of Trilipix is administered under fasting or nonfasting conditions.
Distribution Upon multiple dosing of Trilipix, fenofibric acid levels reach steady state within 8 days. Plasma concentrations of fenofibric acid at steady state are approximately slightly more than double those following a single dose. Serum protein binding is approximately 99% in normal and dyslipidemic subjects.
Metabolism 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 after fenofibrate administration indicate that fenofibric acid does not undergo oxidative metabolism (e.g., cytochrome P450) to a significant extent.
Excretion After absorption, Trilipix is primarily excreted in the urine in the form of fenofibric acid and fenofibric acid glucuronide.
Fenofibric acid is eliminated with a half-life of approximately 20 hours, allowing once daily administration of Trilipix.
Specific Populations Geriatrics In five elderly 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 an equivalent dose of Trilipix can be used in elderly subjects with normal renal function, without increasing accumulation of the drug or metabolites [see USE IN SPECIFIC POPULATIONS ].
Pediatrics Trilipix has not been investigated in adequate and well-controlled trials in pediatric patients.
Gender No pharmacokinetic difference between males and females has been observed for Trilipix.
Race The influence of race on the pharmacokinetics of Trilipix has not been studied.
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 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. Patients with mild to moderate renal impairment (CrCl 30-80 mL/min) 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 Trilipix should be avoided in patients who have severe renal impairment and dose reduction is required in patients having mild to moderate renal impairment.
Hepatic Impairment No pharmacokinetic studies have been conducted in patients with hepatic impairment.
Drug-drug Interactions In vitro studies using human liver microsomes indicate that fenofibric acid is not an inhibitor of cytochrome (CYP) P450 isoforms CYP3A4, CYP2D6, CYP2E1, or CYP1A2. It is a weak inhibitor of CYP2C8, CYP2C19, and CYP2A6, and mild-to-moderate inhibitor 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 other drugs.
Table 3. Effects of Co-Administered Drugs on Fenofibric Acid Systemic Exposure from Trilipix or Fenofibrate Administration Co-Administered Drug | Dosage Regimen of Co-Administered Drug | Dosage Regimen of Trilipix or Fenofibrate | Changes in Fenofibric Acid Exposure |
| | | AUC | Cmax |
| No dosing adjustment required for Trilipix with the following co-administered drugs |
| Lipid-lowering agents |
| Rosuvastatin | 40 mg QD for 10 days | Trilipix 135 mg QD for 10 days | ↓2% | ↓2% |
| Atorvastatin | 20 mg QD for 10 days | Fenofibrate 160 mg1 QD 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% |
| Simvastatin | 80 mg QD for 7 days | Fenofibrate 160 mg1 QD for 7 days | ↓5% | ↓11% |
| Ezetimibe | 10 mg QD for 10 days | Fenofibrate 145 mg1 QD for 10 days | 0% | ↑3% |
| Anti-diabetic agents | |
| Glimepiride | 1 mg as a single dose | Fenofibrate 145 mg1 QD for 10 days | ↑1% | ↓1% |
| Metformin | 850 mg TID for 10 days | Fenofibrate 54 mg1 TID for 10 days | ↓9% | ↓6% |
| Rosiglitazone | 8 mg QD for 5 days | Fenofibrate 145 mg1 QD for 14 days | ↑10% | ↑3% |
| Gastrointestinal agents | |
| Omeprazole | 40 mg QD for 5 days | Trilipix 135 mg as a single dose fasting | ↑6% | ↑17% |
| Omeprazole | 40 mg QD for 5 days | Trilipix 135 mg as a single dose with food | ↑4% | ↓2% |
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1 TriCor (fenofibrate) oral tablet
2 TriCor (fenofibrate) oral micronized capsule
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Table 4. Effects of Trilipix or Fenofibrate Co-Administration on Systemic Exposure of Other Drugs Dosage Regimen of Trilipix or Fenofibrate | Dosage Regimen of Co-Administered Drug | Change in Co-Administered Drug Exposure |
| | Analyte | AUC | Cmax |
| No dosing adjustments required for these co-administered drugs with Trilipix |
| Lipid-lowering agents |
| Trilipix 135 mg QD for 10 days | Rosuvastatin, 40 mg QD for 10 days | Rosuvastatin | ↑6% | ↑20% |
| Fenofibrate 160 mg1 QD for 10 days | Atorvastatin, 20 mg QD 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 QD for 10 days | Pravastatin, 40 mg QD for 10 days | Pravastatin | ↑28% | ↑36% |
| | 3α-Hydroxyl-iso-pravastatin | ↑39% | ↑55% |
| Fenofibrate 160 mg1 as a single dose | Fluvastatin, 40 mg as a single dose | (+)-3R, 5S-Fluvastatin | ↑15% | ↑16% |
| Fenofibrate 160 mg1 QD for 7 days | Simvastatin, 80 mg QD for 7 days | Simvastatin acid | ↓36% | ↓11% |
| | Simvastatin | ↓11% | ↓17% |
| | Active HMG-CoA Inhibitors | ↓12% | ↓1% |
| | Total HMG-CoA Inhibitors | ↓8% | ↓10% |
| Fenofibrate 145 mg1 QD for 10 days | Ezetimibe, 10 mg QD for 10 days | Total Ezetimibe | ↑43% | ↑33% |
| | Free Ezetimibe | ↑3% | ↑11% |
| | Ezetimibe Glucuronide | ↑49% | ↑34% |
| Anti-diabetic agents | |
| Fenofibrate 145 mg1 QD for 10 days | Glimepiride, 1 mg as a single dose | Glimepiride | ↑35% | ↑18% |
| Fenofibrate 54 mg1 TID for 10 days | Metformin, 850 mg TID for 10 days | Metformin | ↑3% | ↑6% |
| Fenofibrate 145 mg1 QD for 14 days | Rosiglitazone, 8 mg QD for 5 days | Rosiglitazone | ↑6% | ↓1% |
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1 TriCor (fenofibrate) oral tablet
2 TriCor (fenofibrate) oral micronized capsule
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NONCLINICAL TOXICOLOGY
Carcinogenesis, Mutagenesis, Impairment of Fertility
Trilipix (fenofibric acid)
No carcinogenicity and fertility studies have been conducted with choline fenofibrate or fenofibric acid. However, because fenofibrate is rapidly converted to its active metabolite, fenofibric acid, either during or immediately following absorption both in animals and humans, studies conducted with fenofibrate are relevant for the assessment of the toxicity profile of fenofibric acid. A similar toxicity spectrum is expected after treatment with either Trilipix or fenofibrate.
Fenofibrate
Two dietary carcinogenicity studies have been conducted in rats with fenofibrate. In the first 24-month study, 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 area comparisons (mg/m2). At a dose of 200 mg/kg/day (6 times the MRHD), the incidence of liver carcinomas 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 at 6 times the MRHD in males.
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/day; 2 times the human dose), and gemfibrozil (250 mg/kg/day; 2 times the human dose, based on mg/m2 surface area). Fenofibrate increased pancreatic acinar adenomas in both sexes and testicular interstitial cell tumors in males at 2 times the MRHD. Clofibrate increased hepatocellular carcinoma and pancreatic acinar adenomas 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 an 80-week study in 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 93-week study at 10, 60, and 200 mg/kg/day, fenofibrate significantly increased the liver carcinomas in male and 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.
Fenofibrate has been demonstrated to be devoid of mutagenic potential in the following tests: Ames, and micronucleus in vivo /rat. In addition, fenofibric acid, has been demonstrated to be devoid of mutagenic potential in the following tests: Ames, mouse lymphoma, chromosomal aberration and sister chromatid exchange in human lymphocytes, and unscheduled DNA synthesis in primary rat hepatocytes.
In a fertility study, rats were given oral dietary doses of fenofibrate. Males received doses for 61 days prior to mating and females for 15 days prior to mating through weaning, which resulted in no adverse effect on fertility at doses up to 300 mg/kg/day (~10 times the MRHD, based on mg/m2 surface area comparisons).
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