Tissue-selective inhibition of sterol synthesis in mice by pravastatin sodium after a single or repeated oral administrations

Probable Statin-Induced Testicular Pain

Objective:

To describe a case of a patient experiencing testicular pain on 3 occasions after taking 3 different statins.

Case Summary:

A 54-year-old man with hyperlipidemia was started on lovastatin therapy. His other medications included aspirin, levothyroxine, buspirone, and atenolol. Seven months after starting lovastatin, the patient experienced testicular discomfort that resolved upon discontinuation of the drug. Afterward, he started simvastatin and again experienced testicular discomfort. The simvastatin was changed to atorvastatin, and the pain resolved. However, 3 months after starting atorvastatin, the patient developed testicular pain, which resolved after the drug was stopped. During each of the episodes, the patient's pain increased when he was sitting, driving, or wearing tight clothing. The Naranjo probability scale indicates that statins probably caused the patient's pain.

Discussion:

Testicular pain is rarely caused by medications. Product labeling for statins does not list urinary adverse events as common. However, labeling for atorvastatin and pravastatin lists rare urologic adverse effects. A literature search did not reveal any previously reported cases of testicular adverse effects from statins. However, statins have been shown to inhibit cholesterol synthesis in the testis. Some data indicate that statins reduce serum testosterone concentrations, but other data indicate that statins have no effect on sex hormones or spermatogenesis. Data are also available indicating that aspirin might affect testosterone concentrations and testicular function. It is difficult to know whether either of the above hormonal mechanisms was associated with our patient's testicular discomfort, but the time course and challenge/rechallenge aspects of the case suggest that the statins were the cause.

Conclusions:

Urologic adverse effects of statins rarely occur but should not be overlooked by medical providers.

The effect of prenatal pravastatin treatment on altered fetal programming of postnatal growth and metabolic function in a preeclampsia-like murine model

OBJECTIVE

Preeclampsia alters fetal programming and results in long-term metabolic consequences in the offspring. Pravastatin has been shown to prevent preeclampsia in animal models. Our aim was to characterize the effects of preeclampsia on fetal programming of adult growth and metabolic function, and evaluate the role of preventive pravastatin therapy, using a well characterized murine model.

STUDY DESIGN

CD-1 mice were injected through the tail vein with adenovirus carrying soluble fms-like tyrosine kinase 1 (sFlt-1) and randomly allocated to pravastatin (5 mg/kg/day; sFlt-1/prav, n = 7) or water (sFlt-1, n = 6) until weaning. A control group was injected with adenovirus carrying the murine immunoglobulin G2α Fc fragment (mFc, n = 8). Male and female offspring (6-8/group) were weighed every month until 6 months of age. Intraperitoneal glucose tolerance testing was performed after 16 hours of fasting at 3 and 6 months of age; glucose and insulin responses were measured.

RESULTS

sFlt-1 offspring weight was lower than mFc control (P < .001) until 2 months of age for females and 5 months of age for males (P < .001). There were no differences in postnatal growth between mFc and sFlt-1/prav offspring. At 3 and 6 months, female sFlt-1 offspring had higher glucose response compared with mFc and sFlt-1/prav. Three-month-old male sFlt-1 had lower insulin response compared with mFc offspring.

CONCLUSION

Preeclampsia alters postnatal growth and metabolic function in the adult offspring in this animal model. Maternal therapy with prav prevents some of these alterations in the offspring.

Guinea pigs as models to study the hypocholesterolemic effects of drugs

Guinea pigs are useful models to investigate the mechanisms of the hypocholesterolemic effects of drugs. Like humans, guinea pigs are one of the few species that carry the majority of cholesterol in LDL. This animal model has also been shown to develop atherosclerosis when challenged with hypercholesterolemic diets. In addition, plasma lipid profiles in males, females and ovariectomized guinea pigs, a model for menopause, follow similar patterns to those observed in humans. In this report, drugs aimed at lowering plasma cholesterol and triglycerides in hyperlipidemic individuals are reviewed. Studies analyzing the hypolipidemic effect of HMG-CoA reductase inhibitors, acyl CoA cholesterol acyltransferase inhibitors, fibrates, bile acid resins, apical sodium bile acid transporter inhibitors, and others show that guinea pigs and humans have comparable responses to drug therapy. In addition, results from the limited clinical reports addressing specific effects of drugs on LDL catabolism or VLDL synthesis are in agreement with observations in guinea pigs. From the review of these studies, it is apparent that the guinea pig is a useful animal model to further explore the mechanisms of action of lipid lowering drugs including effects on specific receptors and regulatory enzymes involved in cholesterol metabolism and on early atherosclerosis development.

ABBREVIATIONS

ACAT, acyl-CoA:cholesterol acyltransferase; ASBT, apical sodium co-dependent bile acid transporter; ApoB, apolipoprotein B; CHD, coronary heart disease; CYP7, cholesterol 7alpha-hydroxylase; HDL, high density lipoprotein; HMG-CoA, 3-hydroxy-3-methylglutaryl coenzyme A; FCR, free catabolic rate; LDL, low density lipoprotein; PPAR, peroxisome proliferators-activated receptor; TC, total cholesterol; TG, triglycerides; VLDL, very low density lipoprotein.

Pravastatin Sodium, an Inhibitor of HMG-CoA Reductase, Decreases HDL Cholesterol by Transfer of Cholesteryl Ester from HDL to VLDL in Japanese White Rabbits

In a recent paper, we reported that pravastatin sodium (pravastatin), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme. A reductase, decreases the concentrations of low density lipoprotein (LDL) cholesterol through an LDL receptor pathway in Japanese White (JW) rabbits, whereas this agent lowers high density lipoprotein (HDL) cholesterol in a manner correlated with a reduction of very low density lipoprotein (VLDL) cholesterol secretion from the liver. In the present study, we administered pravastatin to JW rabbits at 30 mg/kg for 14 days and examined further the mechanisms for the reduction of HDL cholesterol. A striking finding was that the 4-day administration of pravastatin at 30 mg/kg selectively decreased the concentration of HDL cholesterol. Since 4-day administration of pravastatin to JW rabbits did not change the concentrations of hepatic LDL receptor proteins, these receptors were not likely to be involved in the reduction of HDL cholesterol. Another important finding was that pravastatin suppressed VLDL cholesteryl ester (CE) secretion from the liver, but not that of other VLDL lipids and VLDL proteins, indicating that the CE-poor VLDL particles were secreted by the consecutive administration of pravastatin. There were, however, no differences in the levels of VLDL cholesterol between the control and pravastatin-treated groups over the experimental period of 14 days. These observations raised the possibility that the reduction of HDL cholesterol in the pravastatin-treated group was due to the transfer of CE molecules from HDL particles to these CE-poor VLDL particles. Molecular species analysis supported this notion that the VLDL-CE in the pravastatin-treated group was rich in cholesteryl linoleate, indicating that the CE in this group mainly originated from HDL, whereas the VLDL-CE in the control group was rich in cholesteryl oleate, indicating that the CE in this group originated from the liver. The present study suggests that pravastatin lowers HDL cholesterol by transferring CE from these lipoproteins to VLDL in JW rabbits.

Liver-specific distribution of rosuvastatin in rats: comparison with pravastatin and simvastatin

Rosuvastatin is a new 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor. The liver is the target organ for the lipid-regulating effect of rosuvastatin; therefore liver-selective uptake of this drug is a desirable property. The aim of this study was to investigate, and compare with pravastatin and simvastatin, the tissue-specific distribution of rosuvastatin. Bolus intravenous doses (5 mg/kg) of radiolabeled rosuvastatin, pravastatin, and simvastatin were administered to rats, and initial uptake clearance (CL(uptake)) in various tissues was calculated. Hepatic CL(uptake) of rosuvastatin (0.885 ml/min/g tissue) was significantly (p < 0.001) larger than that of pravastatin (0.703 ml/min/g tissue), and rosuvastatin was taken up by the hepatic cells more selectively and efficiently than pravastatin. Hepatic CL(uptake) of simvastatin (1.24 ml/min/g tissue) was significantly larger than that of rosuvastatin (p < 0.01) and pravastatin (p < 0.001). However, adrenal CL(uptake) of simvastatin (1.55 ml/min/g tissue) was larger than hepatic CL(uptake), and simvastatin was distributed to other tissues more easily than rosuvastatin. Microautoradiography of the liver, spleen, and adrenal was undertaken 5 min after administration of the study drugs; distribution was quantified by counting the number of silver grains. After administration of rosuvastatin and pravastatin, silver grains were distributed selectively in the intracellular space of the liver, but more rosuvastatin (3.3 +/- 1.0 x 10(5) particles/mm(2)) than pravastatin (2.0 +/- 0.3 x 10(5) particles/mm(2)) tended to distribute to the liver. Simvastatin was less liver-specific (it also distributed to the spleen and adrenal). The results of this study indicated that rosuvastatin was taken up by hepatic cells more selectively and more efficiently than pravastatin and simvastatin.

Role of lipids in osteoporosis

Cardiovascular disease and osteoporosis together account for most of the morbidity and mortality in our aging population despite significant improvements in treatment. Recently, converging lines of evidence suggest that these 2 diseases share an etiologic factor--that hyperlipidemia contributes not only to atherosclerotic plaque formation, but also to osteoporosis, following a similar biologic mechanism involving lipid oxidation. In vitro studies indicate that lipid products of oxidation promote osteoblastic differentiation of vascular cells and inhibit such differentiation in bone cells. Ex vivo, in vivo, and clinical studies further suggest that lipid-lowering agents reduce both atherosclerotic calcification and osteoporosis. Whether lipid-lowering agents reduce osteoporosis directly or indirectly through lipid reduction remains controversial.

Comparative toxicity of high doses of vastatins currently used by clinicians, in CD-1 male mice fed with a hypercholesterolemic diet

The CD-1 male-mouse model was employed to evaluate comparatively the toxicity of four vastatins (VTS) currently used in clinical medicine: lovastatin (LVT), simvastatin (SVT), pravastatin (PVT) and fluvastatin (FVT). Each vastatin was used orally in doses of 500 mg/Kg body weight/day, in animals with a hypercholesterolemic diet (HD) 5 days, or with a control diet (CD) 30 days. The association of high doses of VTS + HD produced a significant increase in liver weight and liver weight to body weight ratio in animals with SVT and FVT. Cholesterol (Chol) and triacylglycerols (TAG) in the liver increased significantly with FVT but not with the other VTS; Chol increased and TAG decreased in serum very significantly with FVT and SVT. The serum aminotransferases increased quite significantly with FVT but not with other VTS. In the experiment with high doses of VTS + CD, the animals receiving SVT or FVT showed a moderate loss of body weight. Liver weight and liver weight to body weight ratios were similar among all groups. Liver Chol showed a significant decrease with all VTS. Serum Chol decreased moderately with LVT and FVT. TAG in serum and liver showed a moderate decrease with all VTS. The serum aminotransferases were not modified by any vastatin. Our results indicate that high doses of VTS in male mice with a hypercholesterolemic diet result in a decreasing toxicity as follows: FVT>SVT>LVT>PVT.

Synthesis and biological activity of methanesulfonamide pyrimidine- and N-methanesulfonyl pyrrole-substituted 3,5-dihydroxy-6-heptenoates, a novel series of HMG-CoA reductase inhibitors

A novel series of methanesulfonamide pyrimidine- and N-methanesulfonyl pyrrole-substituted 3,5-dihydroxy-6-heptenoates were synthesized and evaluated for their ability to inhibit the enzyme HMG-CoA reductase in vitro. Monocalcium bis(+)-7-[4-(4-fluorophenyl)-6-isopropyl-2-(N-methyl-N- methanesulfonylaminopyrimidin)-5-yl]-(3R,5S)-dihydroxy-(E)-6-he ptenoate (3a, S-4522) was selected as a candidate for further evaluation. Compound 3a was approximately four times more potent than lovastatin sodium salt (in inhibiting HMG-CoA reductase in vitro (IC50 = 11 nM). Compound 3a was shown to be the most potent cholesterol biosynthesis inhibitor in this series (IC50 = 1.12 nM) in rat isolated hepatocytes; its inhibitory activity was approximately 100 times more potent than pravastatin.