217 Assessment of the dissolution characteristics of Rumensin® 90 and Monovet® 90

Abstract Continued evaluation of physical attributes of monensin Type A medicated articles is needed to keep customers apprised of product characteristics. Two randomly chosen lots of Rumensin® 90 (P1 and P2) and Monovet® 90 (A1 and A2) with dates of manufacture between May and September 2019 were used to evaluate dissolution properties according to US Pharmacopeia in vitro procedures and FDA guidance for interpretation of dissolution data. A synthetic rumen fluid (lacking microorganisms) that simulated an animal fed a high-forage diet (pH = 6.8) was used in Exp. 1, whereas a synthetic rumen fluid simulating an animal fed a high-concentrate diet (pH = 5.5) was used in Exp. 2. Samples were added to dissolution vessels containing 1 L of the appropriate media and maintained at 39°C with constant stirring (250 rpm). Aliquots (10 mL) were collected after 15, 30, 45, 60, 90, 120, 240, 360, and 480 min, filtered, and subsequently analyzed for monensin by HPLC procedures. The Rumensin lot with the lowest dissolution was designated as the reference (P2); A1 and A2 were compared to this reference using f1 and f2 test statistics computed following FDA guidance. Dissolution profile comparisons were considered statistically different if the f1 statistic was > 15 and the f2 statistic was < 50. In both experiments, Monovet dissolution profiles were lower than Rumensin profiles. In Exp. 1, f1 = 45 and 50 and f2 = 23 and 20 for A1 and A2, respectively. Likewise in Exp. 2, f1 = 41 and 27 and f2 = 31 and 41 for A1 and A2, respectively. Although the Monovet and Rumensin dissolution profiles were deemed similar in the studies used for FDA approval of Monovet, these data indicate that they are not similar using the most recent industry-standard procedures.