THE EFFECTS OF SIMVASTATIN AND PRAVASTATIN ON OBJECTIVE AND SUBJECTIVE MEASURES OF NOCTURNAL SLEEP - A COMPARISON OF 2 STRUCTURALLY DIFFERENT HMG COA REDUCTASE INHIBITORS IN PATIENTS WITH PRIMARY MODERATE HYPERCHOLESTEROLEMIA

1 It has been suggested that HMG CoA reductase inhibitors which are administered as inactive, lipophilic lactones (e.g. simvastatin) have a greater propensity to evoke nocturnal sleep disturbances than pravastatin, an inhibitor given in the active, hydrophilic, open-acid form. 2 The effects of 4 weeks treatment with equipotent doses of simvastatin (20 mg day-1) and pravastatin (40 mg day-1) have been compared using polysomnography and subjective sleep assessments in a double-blind, placebo-controlled, two-period, incomplete block design study involving 24 male patients with primary moderate hypercholesterolaemia (mean LDL cholesterol 5.11 mmol l-1). 3 Analysis of sleep EEG measures relevant to insomnia provided no evidence of significant differences between pravastatin, simvastatin and placebo, except in terms of entries and latency to stage I sleep. The number of entries to stage I sleep was significantly greater after simvastatin treatment than after either pravastatin or placebo (P < 0.05), but by contrast the latency to stage I sleep was significantly prolonged only in the pravastatin group (P < 0.05 vs placebo). 4 Subjective ratings of sleep initiation, maintenance and quality made during and after therapy were not significantly different between the three treatment groups. 5 It appears that the inherent hydrophobicity of simvastatin does not increase the occurrence of sleep disturbances in this patient population at a dose shown to elicit a characteristic hypolipidaemic response.