Influence of free-flow excipients on functional performance of noveonaa1 in controlled-release tablets

Objective: The aim of this work is the assessment of an eventual improvement in flowability of free flowing excipients on formulations containing Noveon AA1 and their influence on compactibility and release profile. Methods: Mixtures containing 20% Noveon AA1 and variable proportions of metronidazole and the free flowing excipients Prosolv EasyTab and GalenIQ 720 and 721were tested in their powder flow rate and the tablets compactibility and released profiles. Results: The powder flowability obtained with GalenIQ is about 20% better than that obtained with EasyTab. However, it is lesser than that considered as acceptable for a high-speed tableting machine. EasyTab reduces the drug release up to a half along with a continuing flattening of the release profile. This is attributed to an increasing tortuosity of the drug release path as the proportion EasyTab increases. GalenIQ restricts drug release in about a third with a lesser change in the release mechanism. This is attributed to competition for the available water inside the tablet, between the hydrating Noveon AA1 and the dissolving GalenIQ. The compactibility of the metronidazole/Noveon AA1 mixtures increases after addition of EasyTab in about 3.5 N per unit percentage of the added excipient while GalenIQ does it in about 2.6 N. Conclusion: The powder flowability of mixtures of metronidazole with Noveon AA1 was not suited for direct compression after addition of 40% of the free-flow excipient. The free-flow excipients reduce the metronidazole release rate and increase its compactibility. It was not observed a different clear functioning between both types of GalenIQ.