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.

A randomized, double-blind, placebo-controlled study of the effect of sustained-release bupropion on blood pressure in individuals with mild untreated hypertension.

The effects of bupropion on blood pressure and heart rate were evaluated in a double-blind, placebo-controlled study of community volunteers with untreated mild (stage 1) hypertension (systolic blood pressure [SBP], 140-159 mm Hg, and/or diastolic blood pressure, 90-99 mm Hg). Three hundred subjects were randomly assigned (1:1:1:1) to 4 weeks of placebo or bupropion sustained release (SR) 150, 300, or 400 mg/d. Mean clinical blood pressures decreased from baseline to the end of protocol in all groups (n = 296): -6.53, -6.46, -4.20, -4.87 mm Hg for SBP; and -2.36, -2.27, -1.95, -1.55 mm Hg for diastolic blood pressure, for each group, respectively. Although decreases in mean clinical blood pressure were observed in all groups, the reduction in SBP was less on bupropion SR 300 mg/d than on placebo (-4.20 vs -6.53 mm Hg, respectively; Delta = 2.33, P = 0.020). Neither mean 24-hour ambulatory blood pressure measurements nor the proportion of subjects with clinically significant increases in blood pressure differed between any bupropion SR dose and placebo. Mean heart rate increases were small but statistically significant at 400 mg/d versus placebo (2.28 vs -0.64 beats/min; Delta = 2.92, P = 0.004). Although only minor effects on blood pressure were observed in this trial, an infrequent association of bupropion therapy and treatment-emergent hypertension cannot be ruled out.

Efficacy of a once-daily formulation of carvedilol for the treatment of hypertension.

Beta-blockers with pharmacologic effects that differ from conventional agents might add to antihypertensive treatment options. This study evaluated a new once-daily formulation of the beta-/alpha1-blocker, carvedilol controlled-release (CR), in hypertensive patients off treatment or while still taking up to 2 (non-beta-blocker) agents. After a 4-week run-in phase, patients were randomized either to placebo (n=76) or carvedilol CR 20 mg (n=82), 40 mg (n=76), or 80 mg (n=86) once daily. After 6 weeks of treatment, ambulatory blood pressure monitoring was repeated to measure the primary end point of changes in mean 24-hour diastolic blood pressure. During treatment, 24-hour diastolic blood pressure fell in the placebo and carvedilol CR 20-mg, 40-mg, and 80-mg groups by (mean +/- SE) 0.4+/-0.9, 4.4+/-0.9, 7.9+/-0.9, and 9.6+/-0.9 mm Hg, respectively (P< or =.001, trend test for all carvedilol CR doses with placebo). Corresponding 24-hour systolic blood pressure changes were 0.6+/-1.4, 6.8+/-1.3, 10.1+/-1.4, and 12.5+/-1.3 mm Hg, respectively (P< or =.001, trend test). Diastolic blood pressure trough-to-peak ratios (placebo-corrected) based on ambulatory blood pressure monitoring (trough = mean of 20- to 24-hour post-dose readings; peak = mean of 3- to 7-hour post-dose readings) for 20-mg, 40-mg, and 80-mg doses were 0.73, 0.64, and 0.65, respectively. Adverse events, including clinical chemistry values, were similar in the drug-treated and placebo groups. Carvedilol CR has a clinically meaningful defined dose-dependent antihypertensive effect that persists throughout a 24-hour period.

Controlled-release carvedilol in the treatment of essential hypertension.

Carvedilol is a beta1-, beta2-, and alpha1-adrenergic blocker that is approved for the treatment of hypertension. A new once-daily, controlled-release (CR) formulation of carvedilol has been shown to be effective in a double-blind, randomized, multicenter, placebo-controlled, parallel-group study. In this article, we summarize the primary results of, and present additional analyses from, that trial. A total of 338 patients with essential hypertension (sitting diastolic blood pressure [DBP] >/=90 and 0.6 for each carvedilol CR dose. Heart rate and pulse pressure were each significantly reduced compared with placebo for each carvedilol CR dose. We conclude that carvedilol CR is a very effective antihypertensive agent with clear dose-related peak blood pressure reduction and continuous 24-hour control.