LAUSR

Objective: Butorphanol is a commonly used medication for the management of postoperative pain and suffers low bioavailability and high first-pass metabolism. The objective of the current studies was to develop a butorphanol tartrate-loaded dissolving microneedle patch to overcome the limitation of first-pass metabolism without causing any discomfort to the patient. Methods: Butorphanol tartrate-loaded microneedle patch was prepared using Lapox resin micro-molds. The microneedle patch was optimized using the box-Behnken design and the quantity of PVA, HPMC K4M, and HPMC K15M was optimized and evaluated for fractured axial force, microscopic evaluation, in vitro drug permeation studies, and ex-vivo permeation experiments. Results: The developed microneedle patch meets all the evaluation parameters within the desired range. The height and tip diameter of the microneedles were found to be 700 µm to 800 µm and 60 µm to 61 µm. An axial fractured force of the optimized microneedle patch was found to be 189.67 N, suitable for penetrating the stratum corneum. The in vitro cumulative % drug permeated showed the permeation of the drug for 8 h with a total of 89.12 %, which shows the permeation of the drug occurred in a controlled manner. Conclusion: Butorphanol tartrate-loaded microneedle patch was successfully developed and the results concluded that the microneedles were hard enough to pass the stratum corneum and release the drug into the systemic circulation without reaching the pain receptors; further, the release study suggested that the drug was released for a prolonged period eliminating the problem of first-pass effect and frequent administration.