Needle-free subcutaneous sumatriptan (Sumavel DosePro): bioequivalence and ease of use.

BACKGROUND: Subcutaneous (s.c.) injection of sumatriptan is currently associated with needle aversion in some patients, and sharps disposal issues. OBJECTIVES: To investigate whether a needle-free system can deliver s.c. sumatriptan. If so, to examine whether needle-free administration is bioequivalent to a 26-gauge needle-based auto-injector. Lastly, to assess the needle-free system for clinical acceptability and ease of use during migraine attacks. METHODS: Two clinical trials. Study A: Pharmacokinetics and bioequivalence was studied in normal adult volunteers (n = 57 total), directly comparing needle-free (Sumavel DosePro) with needle-based (Imitrex STATdose System) administration of 6 mg s.c. sumatriptan. An incomplete, randomized, partial factorial, crossover design was used. Each subject received 2 administrations of each product, at 2 of the 3 anatomical sites (abdomen, thigh or arm). There were appropriate "washout" periods between each. Pharmacokinetic sampling was at standard time points, and tests for bioequivalence then followed. Study B: The term "ease of use" was used for clinical acceptability and utility of the needle-free system when it was assessed among 52 outpatients treating migraine attacks. Instructional materials were used as would be provided after ordinary prescription. The primary endpoint was successful use of the needle-free system to administer sumatriptan at the first attempt, including appropriate injection site selection. Second and subsequent uses of the needle-free system were also documented. RESULTS: For administration sites in the thigh and the abdomen, but not the arm, the needle-free and needle-based systems were bioequivalent (for all pharmacokinetic endpoints the mean ratios between the 2 devices were always between 90.1% and 115%). Among outpatients treating a migraine attack with the needle-free system, 51 of 52 on first attempt used the needle-free system successfully when treating a migraine attack. CONCLUSIONS: Sumavel DosePro needle-free delivery system is a new presentation of s.c. sumatriptan that delivers drug effectively, is bioequivalent to the existing needle auto-injector when used at the thigh or abdomen, and is easy to use.

The effects of system parameters on in vivo injection performance of a needle-free injector in human volunteers.

PURPOSE: For a novel needle-free injection (NFI) system, the relationship between frequency of wet or incomplete injections and device-related factors and subject physiological variables was examined. MATERIALS AND METHODS: A total of 26 device configurations of a single-use pre-filled NFI system (Intraject) were used to deliver a total of 3,211 subcutaneous injections into the abdomen of 302 healthy volunteers. Two validated methods were used to determine completeness of each injection (defined as >or=90% dose delivery). Skin-fold thickness, body mass index (BMI), Fitzpatrick skin type, sex, age, and injection site were noted for each volunteer. RESULTS: The proportion of complete injections ranged from 59-98% among the various combinations of device configurations. Two device parameters and two subject-related variables showed strong association with injection performance; Device gas mass (chamber pressure) and orifice size demonstrated statistically significant, independent effects, with increasing gas mass and larger orifice size associated with improved injection performance. BMI and site of injection on the abdomen also demonstrated statistically significant effects with increasing BMI and lateral rather than medial injection sites associated with better injections. CONCLUSION: Both device-related factors and subject variables interact to mediate in vivo performance of a needle-free injector.