Atorvastatin. A review of its pharmacology and therapeutic potential in the management of hyperlipidaemias

Grapefruit juice greatly increases serum concentrations of lovastatin and lovastatin acid

BACKGROUND

Grapefruit juice increases the bioavailability of several drugs known to be metabolized by CYP3A4. We wanted to investigate a possible interaction of grapefruit juice with lovastatin, a cholesterol-lowering agent that is partially metabolized by CY P3A4.

METHODS

An open, randomized, two-phase crossover study with an interval of 2 weeks between the phases was carried out. Ten healthy volunteers took either 200 ml double-strength grapefruit juice or water orally three times a day for 2 days. On day 3, each subject ingested 80 mg lovastatin with either 200 ml grapefruit juice or water, and an additional dose of 200 ml was ingested 1/2 and 1 1/2 hours after lovastatin intake. Serum concentrations of lovastatin and lovastatin acid were measured up to 12 hours.

RESULTS

Grapefruit juice greatly increased the serum concentrations of both lovastatin and lovastatin acid. The mean peak serum concentration (Cmax) of lovastatin was increased about 12-fold (range, 5.2-fold to 19.7-fold; p < 0.001) and the area under the concentration-time curve [AUC(0-12)] was increased 15-fold (range, 5.7-fold to 26.3-fold; p < 0.001) by grapefruit juice. The mean Cmax and AUC(0-12) of lovastatin acid were increased about fourfold (range, 1.8-fold to 11.5-fold; p < 0.001) and fivefold (range, 2.4-fold to 23.3-fold; p < 0.001) by grapefruit juice, respectively. The half-lives of lovastatin and lovastatin acid remained unchanged.

CONCLUSIONS

Grapefruit juice can greatly increase serum concentrations of lovastatin and its active metabolite, lovastatin acid, probably by preventing CYP3A4-mediated first-pass metabolism in the small intestine. The concomitant use of grapefruit juice with lovastatin and simvastatin should be avoided, or the dose of these 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors should be reduced accordingly.

Role of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ("statins") in familial combined hyperlipidemia

Familial combined hyperlipidemia (FCHL) is a heterogeneous genetic disorder characterized by multiple lipoprotein phenotypes. The genetic defect is unknown, although linkage to the region of the apolipoprotein (apo) A-I-apoC-III-apo A-IV gene cluster on chromosome 11 has been suggested. The metabolic abnormality in many affected individuals is overproduction of apoB-containing lipoproteins causing elevated levels of plasma cholesterol, triglycerides, or both. Low levels of high-density lipoprotein (HDL) cholesterol and an abundance of dense low-density lipoprotein (LDL) particles are other features contributing to the high association of this disorder with premature coronary artery disease. Many affected individuals need drug therapy to lower their lipid levels. The hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or "statins," offer a potent therapeutic option in patients with FCHL. These drugs significantly decrease levels of total cholesterol, LDL cholesterol, and apoB, although their effects on HDL cholesterol and triglycerides are limited. The mechanisms by which statins exert their beneficial effects in patients with FCHL remain controversial. We studied 7 patients with FCHL and 5 genetically uncharacterized patients with mixed lipemia during treatment with pravastatin 20 mg/day. Metabolic parameters of very-low-density lipoprotein (VLDL)-apoB and LDL-apoB were studied using endogenous labeling with stable isotopes. In all patients pravastatin caused an increase in fractional catabolic rates of LDL-apoB without a significant effect on the production rates of apoB-containing lipoproteins. We cannot exclude the possibility that higher doses of statins may decrease VLDL and LDL production.