Fluvastatin 20 mg · Tablets

Fluvastatin sodium is a competitive inhibitor of HMG-CoA reductase, the rate limiting enzyme that converts 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) to mevalonate, a precursor of sterols, including cholesterol. The inhibition of cholesterol biosynthesis reduces the cholesterol in hepatic cells, which stimulates the synthesis of LDL receptors and thereby increases the uptake of LDL particles. The end result of these biochemical processes is a reduction of the plasma cholesterol concentration.

Absorption: — Following oral administration of the capsule, fluvastatin reaches peak concentrations in less than 1 hour. The absolute bioavailability is 24% (range 9% to 50%) after administration of a 10 mg dose.

At steady state, administration of fluvastatin with the evening meal results in a 50% decrease in Cmax, an 11% decrease in AUC, and a more than two-fold increase in tmax as compared to administration 4 hours after the evening meal. No significant differences in the lipid-lowering effects were observed between the two administrations. After single or multiple doses above 20 mg, fluvastatin exhibits saturable first-pass metabolism resulting in more than dose proportional plasma fluvastatin concentrations.

Fluvastatin administered as fluvastatin sodium extended-release 80 mg tablets reaches peak concentration in approximately 3 hours under fasting conditions, after a low fat meal, or 2.5 hours after a low fat meal. The mean relative bioavailability of the extended-release tablet is approximately 29% (range: 9% to 66%) compared to that of the fluvastatin immediate-release capsule administered under fasting conditions. Administration of a high fat meal delayed the absorption (Tmax: 6h) and increased the bioavailability of the extended-release tablet by approximately 50%. However, the maximum concentration of fluvastatin sodium extended-release tablets seen after a high fat meal is less than the peak concentration following a single dose or twice daily dose of the 40 mg fluvastatin capsule.

Distribution: — Fluvastatin is 98% bound to plasma proteins. The mean volume of distribution (VDss) is estimated at 0.35 L/kg. At therapeutic concentrations, the protein binding of fluvastatin is not affected by warfarin, salicylic acid and glyburide.

Metabolism: — Fluvastatin is metabolized in the liver, primarily via hydroxylation of the indole ring at the 5 and 6 positions. N-dealkylation and beta-oxidation of the side-chain also occurs. The hydroxy metabolites have some pharmacologic activity, but do not circulate in the blood. Fluvastatin has two enantiomers. Both enantiomers of fluvastatin are metabolized in a similar manner.

In vitro data indicate that fluvastatin metabolism involves multiple Cytochrome P450 (CYP) isozymes. CYP2C9 isoenzyme is primarily involved in the metabolism of fluvastatin (approximately 75%), while CYP2C8 and CYP3A4 isoenzymes are involved to a much less extent, i.e., approximately 5% and approximately 20%, respectively.

Excretion: — Following oral administration, fluvastatin is primarily (about 90%) excreted in the feces as metabolites, with less than 2% present as unchanged drug. Approximately 5% of a radiolabeled oral dose were recovered in urine. The elimination half-life (t1/2) of fluvastatin is approximately 3 hours.

Renal Impairment: — In patients with moderate to severe renal impairment (CLCr 10 to 40 mL/min), AUC and Cmax increased approximately 1.2 fold after administration of a single dose of 40 mg fluvastatin compared to healthy volunteers. In patients with end-stage renal disease on hemodialysis, the AUC increased by approximately 1.5 fold. Fluvastatin sodium extended-release tablets were not evaluated in patients with renal impairment. However, systemic exposures after administration of fluvastatin sodium extended-release tablets are lower than after the 40 mg immediate-release capsule.

Hepatic Impairment: — In patients with hepatic impairment due to liver cirrhosis, fluvastatin AUC and Cmax increased approximately 2.5 fold compared to healthy subjects after administration of a single 40 mg dose. The enantiomer ratios of the two isomers of fluvastatin in hepatic impairment patients were comparable to those observed in healthy subjects.

Geriatric: — Plasma levels of fluvastatin are not significantly different in patients age > 65 years compared to patients age 21 to 49 years.

Gender: — In a study evaluating the effect of age and gender on fluvastatin pharmacokinetics, there were no significant differences in fluvastatin exposures between males and females, except between younger females and younger males (both ages 21 to 49 years), where there was an approximate 30% increase in AUC in females. Adjusting for body weight decreases the magnitude of the differences seen.

Pediatric: — Pharmacokinetic data in the pediatric population are not available.