A novel rizatriptan oral gel formulation: Bioavailability and bioequivalence

Objectives: To establish the relative bioavailability between a newly developed oral gel and a marketed oral lyophilisate-containing rizatriptan benzoate.

Materials and methods: A total of 47 out of 48 healthy subjects, aged 34 ± 10 (SD) years and body mass index 24.7 ± 3.3 (SD) kg/m2 completed this single-center, open-label, randomized, 2-period cross-over trial with single-dose fasted administrations. Intake of both investigational products was separated by a washout period of at least 6 days. For pharmacokinetic evaluation, blood samples were withdrawn until 24 hours post dose. A validated liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was applied for the determination of rizatriptan in plasma. The lower limit of quantitation (LLOQ) was 0.100 ng/mL. Adverse events (AEs) were descriptively analyzed in the study population. Palatability of the new product was investigated based on a questionnaire.

Results: The geometric means of the parameters related with the extent of total exposure, i.e., AUC_0-tlast and AUC_0-∞, were 60.285 ng × h/mL and 60.865 ng × h/mL for test and 62.729 ng × h/mL and 63.312 ng × h/mL for reference, respectively. The geometric means of the peak exposure, i.e., C_max, were 21.262 ng/mL for test and 21.447 ng/mL for reference. The point estimates (PEs) of the test/reference (T/R) adjusted geometric mean ratios of AUC_0-tlast, C_max, and AUC_0-∞ (secondary parameter) were 96.11%, 99.12%, and 96.15%, respectively, and all of them showed 90% confidence intervals (CIs) within the range of 80.00 - 125.00% as suggested by regulatory requirements for bioequivalence assessment. In total, 13 subjects experienced 20 AEs during the trial; the most frequently reported AEs were headache (5 cases) and dizziness (3 cases). No AEs of severe intensity were reported. Palatability assessment of the new product provided sufficient data to discuss its acceptability.

Conclusion: Bioequivalence was demonstrated in terms of rate and extent of absorption after administration of test and reference products. Concerning the safety evaluation, no negative implications on the possible use of the test formulation could be determined. Based on ratings by the subjects no relevant problem concerning acceptability of the new formulation in particular regarding taste and smell is to be expected.