Effects of lamotrigine and phenytoin on the pharmacokinetics of atorvastatin in healthy volunteers.

PURPOSE: Statins and antiepileptic drugs (AEDs) are frequently coprescribed to individuals with hypercholesterolemia and new-onset seizures. Statins are metabolized by the cytochrome P450 (CYP) enzyme system. Interactions between statins and agents that undergo CYP metabolism are common. In this study, the effects of two commonly prescribed AEDs, lamotrigine and phenytoin, with different routes of metabolism (CYP3A4 versus glucuronic acid conjugation) on atorvastatin pharmacokinetics were evaluated. METHODS: Healthy volunteers (n=119) received atorvastatin 40 mg/day for 7 days followed by addition of lamotrigine (target 300 mg/day) or phenytoin (target ~4 mg/kg per day) in this open-label, single-sequence, two-cohort study. Serial pharmacokinetic sampling of atorvastatin was conducted on day 7 of atorvastatin dosing and day 70 of lamotrigine + atorvastatin dosing or day 28 of phenytoin + atorvastatin dosing. Main outcome measures were steady-state area under the curve over the 24-h dosing interval (AUC((0-τ)) ) and maximum concentration (C(max) ) of atorvastatin and its metabolites, 2OH-atorvastatin and 4OH-atorvastatin, in the presence of lamotrigine or phenytoin. KEY FINDINGS: When atorvastatin was administered with lamotrigine compared with when atorvastatin was administered alone, atorvastatin AUC((0-τ)) was within bounds indicating no interaction, whereas C(max) was slightly higher(14%); AUC((0-τ)) and C(max) were 3% and 20% higher, respectively, for 2OH-atorvastatin and 25% and 21% higher, respectively, for 4OH-atorvastatin.When atorvastatin was administered with phenytoin compared with when atorvastatin was administered alone, reductions in AUC((0-τ)) and C(max) were observed for atorvastatin (54% and 24%, respectively), 2OH-atorvastatin (53% and 22%, respectively), and 4OH-atorvastatin (44% and 52%, respectively). SIGNIFICANCE: Pharmacokinetics of atorvastatin were not significantly affected by coadministration with lamotrigine. Phenytoin significantly reduced atorvastatin bioavailability. Consistent with the published literature, these data are consonant with the possibility that atorvastatin does not require dose adjustment when coadministered with lamotrigine at doses to 300 mg/day, whereas atorvastatin coadministered with phenytoin may require atorvastatin dose adjustment to maintain atorvastatin exposure.

Clinical and imaging findings suggesting human herpesvirus 6 encephalitis.

We sought to distinguish patients testing positive for human herpesvirus 6 from those testing negative, based on clinical features and magnetic resonance images. Sixteen immunosuppresed patients were tested by polymerase chain reaction for human herpes virus 6 DNA in cerebrospinal fluid (nine positive results). Medical records were examined for agitation, altered mental status, hallucinations, insomnia, memory loss, and seizures. Patients were sorted by viral status. Clinical features were compared with imaging findings. Insomnia, agitation, and hallucinations were preferentially evident in human herpes virus 6-positive patients. Imaging abnormalities were evident in the hippocampus of both groups. However, extrahippocampal involvement was more common in human herpes virus 6-positive patients and among those with insomnia and hallucinations or seizures. Patients with memory loss and imaging abnormalities in the entorhinal cortex or amygdala were likely to test positive, as were patients with hallucinations and abnormal magnetic resonance signal in the hippocampus. Human herpes virus 6 encephalitis patients present with diverse clinical features that are also common among patients who test negative. This entity should be suspected in patients who present with insomnia, seizures, or hallucinations when imaging abnormalities are evident in the hippocampus, amygdala, and limbic structures beyond the medial temporal lobe.