Clinical pharmacokinetics of almotriptan, a serotonin 5-HT(1B/1D) receptor agonist for the treatment of migraine.

The pharmacokinetics of almotriptan are linear over a range of oral doses up to 200mg in healthy volunteers. The compound has a half-life of approximately 3 hours. Almotriptan is well absorbed after oral administration and the mean absolute bioavailability is 69.1%. Maximal plasma concentrations are achieved between 1.5 and 4 hours after dose administration; however, within 1 hour after administration, plasma concentrations are approximately 68% of the value at 3 hours after administration. Food does not significantly affect almotriptan absorption. Almotriptan is not highly protein bound and is extensively distributed in the body. Approximately 50% of an almotriptan dose is excreted unchanged in the urine; this is the predominant single mechanism of elimination. Renal clearance is mediated, in part, through active tubular secretion, while the balance of the almotriptan dose is metabolised to inactive compounds. The predominant route of metabolism is via monoamine oxidase-A, and cytochrome P450 (CYP) mediated oxidation (via CYP3A4 and CYP2D6) occurs to a minor extent. Almotriptan clearance is moderately reduced in elderly subjects, but the magnitude of this effect does not warrant a dose reduction. Sex has no significant effect on almotriptan pharmacokinetics. Almotriptan pharmacokinetic parameters do not differ between adolescents and adults, and absorption is not affected during a migraine attack. As expected, renal dysfunction results in reduced clearance of almotriptan. Patients with moderate-to-severe renal dysfunction should use the lowest dose of almotriptan and the total daily dose should not exceed 12.5 mg. Similar dosage recommendations are valid for patients with hepatic impairment, based on the clearance mechanisms for almotriptan. Drug-drug interaction studies were conducted between almotriptan and the following compounds: fluoxetine, moclobemide, propranolol, verapamil and ketoconazole. No significant pharmacokinetic or pharmacodynamic interactions with almotriptan were observed for fluoxetine or propranolol. Almotriptan clearance was reduced, to a modest degree, by moclobemide and verapamil, which was consistent with the contribution of monoamine oxidase-A and CYP3A4 to the metabolic clearance of almotriptan. Although ketoconazole has a greater effect on almotriptan clearance than verapamil, no dosage adjustment is required when almotriptan is given with these drugs.

Electrocardiographic identification of drug-induced QT prolongation: assessment by different recording and measurement methods.

BACKGROUND: Careful assessment of QT interval prolongation is required before novel drugs are approved by regulatory authorities. The choice of the most appropriate method of electrocardiogram (ECG) acquisition and QT/RR interval measurement in clinical trials requires better understanding of the differences among currently available approaches. This study compared standard and Holter-derived 12-lead ECGs for utility in detecting sotalol-induced QT/QTc and RR changes. Manual methods (digitizing pad and digital on-screen calipers) were compared for precision of QT and RR interval measurement. METHODS AND RESULTS: Sixteen hundred pairs of serial 12-lead digital ECGs were recorded simultaneously by standard resting ECG device and by continuous 12-lead digital Holter over 3 days in 39 healthy male and female volunteers. No therapy was given on the 1st day followed by 160 mg and 320 mg of sotalol on the 2nd and 3rd day, respectively. Holter-derived and standard ECGs produced nearly identical sotalol-induced QT/QTc and RR changes from baseline, as did the manual digipad and on-screen caliper measurements. The variability of on-screen QT measurement in this study was greater than that of digipad. CONCLUSIONS: Digital 12-lead Holter and standard 12-lead ECG recorders, as well as the manual digitizing pad and digital on-screen calipers, are of equal utility for the assessment of drug-induced change from baseline in QT and RR interval, although the variability of the on-screen method in this study was greater than of the digipad.

Cardiovascular effect of almotriptan in treated hypertensive patients.

OBJECTIVE: Our objective was to investigate the cardiovascular effects of almotriptan, a 5-hydroxytryptamine 1B/1D agonist, in treated patients with hypertension. METHODS: Twenty patients with hypertension controlled by medication received the following treatments in a randomized, double-blind, crossover design: one placebo tablet, one 12.5-mg almotriptan tablet, and one 25-mg almotriptan tablet. Serial blood samples for analysis of almotriptan were obtained through 24 hours after administration. Serial measurements of supine blood pressure, 12-lead electrocardiograms, and Holter electrocardiographic recordings were also obtained. Plasma almotriptan concentrations were measured with use of a liquid chromatography-tandem mass spectrometry assay. Differences between treatments in pharmacokinetic parameters were assessed with an ANOVA model appropriate for a crossover design. Blood pressure measures and QTc intervals were analyzed for treatment effects with use of a similar model. Analyses were performed on weighted mean and maximal changes from baseline for intervals from 0 to 4 and 0 to 12 hours after administration. RESULTS: Significant linear effects of dose were observed for the maximal change in diastolic blood pressure and for the maximal and mean changes in systolic blood pressure. These effects were consistent for both the 4- and 12-hour periods after dosing. Mean changes from baseline during the interval from 0 to 4 hours were 1.59 +/- 3.88, 1.85 +/- 5.94, and 4.84 +/- 5.99 mm Hg for systolic pressure and 1.38 +/- 6.95, 6.25 +/- 9.54, and 11.0 +/- 10.6 mm Hg for diastolic pressure for placebo, 12.5 mg almotriptan, and 25 mg almotriptan, respectively. No instances of hypertensive crisis were observed. No QTc interval prolongation was observed. CONCLUSIONS: Almotriptan has effects on blood pressure in subjects with controlled hypertension that are consistent with those of other members of the pharmalogic class.