Drug Groups

approved

Description

A fibric acid derivative used in the treatment of hyperlipoproteinemia type III and severe hypertriglyceridemia. (From Martindale, The Extra Pharmacopoeia, 30th ed, p986)

Indication

For Primary Dysbetalipoproteinemia (Type III hyperlipidemia) that does not respond adequately to diet. This helps control high cholesterol and high triglyceride levels.

Pharmacology

Clofibrate is an antilipidemic agent similar to gemfibrozil. It acts to lower elevated serum lipids by reducing the very low-density lipoprotein fraction (S_f 20-400) rich in triglycerides. Serum cholesterol may be decreased, particularly in those patients whose cholesterol elevation is due to the presence of IDL as a result of Type III hyperlipoproteinemia. Several investigators have observed in their studies that clofibrate may produce a decrease in cholesterol linoleate but an increase in palmitoleate and oleate, the latter being considered atherogenic in experimental animals. The significance of this finding is unknown at this time. Reduction of triglycerides in some patients treated with clofibrate or certain of its chemically and clinically similar analogs may be associated with an increase in LDL cholesterol. Increase in LDL cholesterol has been observed in patients whose cholesterol is initially normal. Animal studies suggest that clofibrate interrupts cholesterol biosynthesis prior to mevalonate formation.

Toxicity

Oral, mouse: LD₅₀ = 1220 mg/kg; Oral, rabbit: LD₅₀ = 1370 mg/kg; Oral, rat: LD₅₀ = 940 mg/kg. No reported case of overdosage in humans.

Affected Organisms

Biotransformation

Hepatic and gastrointestinal: rapid de-esterification occurs in the gastrointestinal tract and/or on first-pass metabolism to produce the active form, clofibric acid (chlorophenoxy isobutyric acid [CPIB]).

Absorption

Completely but slowly absorbed from the intestine. Between 95% and 99% of an oral dose of clofibrate is excreted in the urine as free and conjugated clofibric acid; thus, the absorption of clofibrate is virtually complete.

Half Life

Half-life in normal volunteers averages 18 to 22 hours (range 14 to 35 hours) but can vary by up to 7 hours in the same subject at different times.

Protein Binding

Highly protein-bound (95% to 97%).

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