Development and Validation of Discriminatory In-vitro Release Method for Intramammary Drug Product.

Abstract

Intramammary (IMM) formulations are locally acting and delivered intracisternally into the udder. No pharmacopeial in-vitro release method is available to differentiate between the IMM formulations. Our research aim is to develop in-vitro release methods that discriminate different IMM formulations (SPECTRAMAST® LC and in-house formulations). Different in-house formulations were developed to simulate SPECTRAMAST® LC generics. SPECTRAMAST® LC and the in-house formulations were characterized for physicochemical attributes, such as particle size, rheology, drug content, sedimentation rate, and flocculation rate. The in-vitro release method was optimized by evaluating drug release using USP apparatuses 1, 2 (with and without enhancer/customized cells), and 4. Various test parameters, including medium effect (whole homogenized bovine milk versus aqueous buffer), medium volume (200-900mL), and rotational speed (50-200rpm) were investigated. Two potential in-vitro systems can be used as discriminatory methods for IMM formulations: USP apparatus 2 with the IMM formulation loaded into two containers a) customized formulation container (83.1cm in height and 56.4cm in width) or b) enhancer cells with their top adapted with mesh #40 (rotation speed:125rpm and 900mL of whole homogenized bovine milk). The release profile of SPECTRAMAST® LC at 1h (99.8%) was not significantly different from formulations with similar physicochemical characteristics F-01 (99.1%) and F-02 (100.5%). Formulation with different physicochemical characteristics F-03 (44.3%) and F-04 (57.2%) showed slower release (1h) than SPECTRAMAST® LC (98.8%). The developed in-vitro release methods can be used as a potential tool for in-vitro comparability evaluations for IMM formulations.