Pharmacokinetics and safety of oral almotriptan in healthy male volunteers

QuEChERS-assisted ion pair chromatography/fluorescence detection method for determination of antimigraine combination therapy in rabbit plasma samples: Application to a pharmacokinetic study

Antimigraine combination therapy has shown significant effectiveness in relieving pain, as well as reducing the frequency, duration, and severity of migraine attacks if compared to a single migraine medication. This work represents the first analytical investigation for emphasizing the synergistic effect of combining ophthalmic beta blockers with triptans in migraine treatment. The presented study was conducted to investigate the pharmacokinetic profile of almotriptan (ALM), a serotonin (5-HT1B/1D) receptor agonist used to treat migraine, when coadministered with timolol (TIM) or verapamil (VER) which are considered as an adjuvant therapy in migraine prevention. Ion pair chromatography (IPC) with online fluorescence detection was applied to simultaneously detect and quantify the binary mixtures of ALM/TIM and ALM/VER in rabbit plasma samples. The separation was achieved using a Platinum C18 analytical column with a mobile phase composed of methanol: 35 mmol L-1 phosphate buffer solution containing 10 mmol L-1 SDS at pH = 6.8 (60:40 v/v). Several parameters were evaluated during the optimization of separation conditions including mobile phase composition, buffer concentration, buffer pH and concentration of ion pair reagent. A thorough investigation of the retention mechanism was performed, and the results showed that Coulomb forces were the main contributors to the overall retention mechanism, which may be hydrophobically assisted. QuEChERS extraction technique was utilized to extract the investigated drugs from plasma samples and a detailed study was carried out to optimize partition/extraction solvents, pH, extraction salts, sample volume and clean-up step. The method had a limit of detection and quantitation of 5.6 and 16.9 ng mL-1 for ALM in ALM/TIM mixture and 2.5 and 7.6 ng mL-1 for ALM in ALM/VER mixture, with an overall recovery not less than 95.22%. This newly proposed method offers a faster alternative to existing chromatographic methods for extraction and determination of ALM in binary mixtures with TIM or VER in rabbit plasma and provides a platform for studying pharmacokinetic parameters. The coadministration of either TIM or VER with ALM resulted in a notable rise in Cmax (maximum plasma concentration) and AUC (area under the plasma concentration-time curve) of ALM, implying possible alterations in the absorption and overall exposure of ALM.

Almotriptan: a review of 20 years' clinical experience

Introduction: Almotriptan (ALT), a serotonin 5-HT_1B/1D agonist has been used in the acute treatment of migraine with or without aura for 20 years, accumulating data on more than 15,000 patients in studies and from an estimated >150 million treated migraine attacks in daily clinical practice. The last major review of ALT was written almost 10 years ago. The current narrative review provides an overview of the experience gained with almotriptan over that time, and highlights data published in the last decade. Areas covered: Randomized clinical trials, observational studies, postmarketing studies and meta-analyses involving ALT for the treatment of acute migraine identified through a systematic literature search. Expert opinion: Triptans are a mainstay of anti-migraine treatment. Findings with ALT over the last 10 years have reinforced the positive efficacy and tolerability results that were reported during the first 10 years following its introduction. In particular, more recent clinical results have confirmed its efficacy in women with menstrual migraine, the usefulness of early intervention, long-term benefit in adults, and also its efficacy and safety in adolescents. Overall, ALT can be considered an optimal choice for managing acute migraine resistant to first-line drugs.

Improved Predictions of Drug-Drug Interactions Mediated by Time-Dependent Inhibition of CYP3A

Time-dependent inactivation (TDI) of cytochrome P450s (CYPs) is a leading cause of clinical drug-drug interactions (DDIs). Current methods tend to overpredict DDIs. In this study, a numerical approach was used to model complex CYP3A TDI in human-liver microsomes. The inhibitors evaluated included troleandomycin (TAO), erythromycin (ERY), verapamil (VER), and diltiazem (DTZ) along with the primary metabolites N-demethyl erythromycin (NDE), norverapamil (NV), and N-desmethyl diltiazem (NDD). The complexities incorporated into the models included multiple-binding kinetics, quasi-irreversible inactivation, sequential metabolism, inhibitor depletion, and membrane partitioning. The resulting inactivation parameters were incorporated into static in vitro-in vivo correlation (IVIVC) models to predict clinical DDIs. For 77 clinically observed DDIs, with a hepatic-CYP3A-synthesis-rate constant of 0.000 146 min-1, the average fold difference between the observed and predicted DDIs was 3.17 for the standard replot method and 1.45 for the numerical method. Similar results were obtained using a synthesis-rate constant of 0.000 32 min-1. These results suggest that numerical methods can successfully model complex in vitro TDI kinetics and that the resulting DDI predictions are more accurate than those obtained with the standard replot approach.

Almotriptan: a review of 10 years' clinical experience

Almotriptan, a serotonin 5-HT 1B/1D agonist, was developed for the acute treatment of migraine with or without aura and has been available for 10 years. This article evaluates the wealth of experience that has been obtained with almotriptan, including large randomized clinical trials (RCTs) and post-marketing studies that more closely reflect everyday clinical practice. Initial RCTs required patients to take almotriptan when migraine pain was of moderate or severe intensity, and found that 12.5 mg provided optimal outcomes for both pain relief and tolerability. Almotriptan effectively improved 2-h pain-relief, reduced migraine-associated symptoms and demonstrated low recurrence rates. These findings were also shown in patient subgroups, such as adolescents and menstrual migraineurs. A secondary finding in these trials was that patients who took almotriptan early, when the pain was still mild, achieved better outcomes. This prompted the initiation of studies designed to assess the effect of almotriptan in early intervention. Open-label trials reported improvements in pain-free end points (2 h, 24 h), and subsequent RCTs confirmed these findings. Pharmacovigilance data from more than 100 million tablets dispensed worldwide have confirmed that almotriptan is associated with a low occurrence of adverse effects, which, in clinical trials, has been shown to be similar to that observed with placebo. The clinical evidence obtained and comparisons made over a decade of use have demonstrated that almotriptan is one of the more effective and fast-acting triptans available, with a placebo-like tolerability profile. This suggests that almotriptan is an excellent choice for patients requiring specific acute migraine treatment.

Exploratory assessment of dose proportionality: review of current approaches and proposal for a practical criterion

This article reviews currently used approaches for establishing dose proportionality in Phase I dose escalation studies. A review of relevant literature between 2002 and 2006 found that the power model was the preferred choice for assessing dose proportionality in about one-third of the articles. This article promotes the use of the power model and a conceptually appealing extension, i.e. a criterion based on comparing the 90% confidence interval for the ratio of predicted mean values from the extremes of the dose range (R(dnm)) to pre-defined equivalence criterion (theta(L),theta(U)). The choice of bioequivalence default values of theta(L)=0.8 and theta(U)=1.25 seems reasonable for dose levels only a doubling apart but are impractically strict when applied over the complete dose range. Power calculations are used to show that this prescribed criterion lacks power to conclude dose proportionality in typical Phase I dose-escalation studies. A more lenient criterion with values theta(L)=0.5 and theta(U)=2 is proposed for exploratory dose proportionality assessments across the complete dose range.