Smart tablets based on halloysite nanotubes for controlled delivery and photoprotection of active pharmaceutical ingredients

Abstract

The current direction of nanomedicine is the creation of smart systems for the controlled release of therapeutic drugs with simultaneous protection against photodegradation under the influence of UV and visible light. The aim of the investigation was to study the level of photoprotection and the kinetics of release of photosensitive pharmaceutical ingredients (α-lipoic acid and moxifloxacin hydrochloride) encapsulated in halloysite nanotubes in the composition of the tablets. It was established that halloysite, like the widely used microcrystalline cellulose, meets a sufficient level in terms of fluidity and compressibility, which indicates the possibility of its use as an auxiliary component in the composition of pharmaceutical tablet forms. The physical and mechanical properties (disintegration, hardness, friability and abrasion tests, tensile strength) of the obtained tablet based on halloysite (45 %), microcrystalline cellulose (50 %) and auxiliary components (5 %) indicate their compliance with the standardized requirements of the European Pharmacopoeia. In the native state, the ingredients are almost completely released from the tablets within the first 60 min. Encapsulation in halloysite promotes their controlled release from tablets within 24 h. With a change in the pH of the model medium from 1.2 to 6.8, the level of release and dissolution of both pharmaceutical ingredients increases. In 24 h, the release level reaches 60–80 % for α-lipoic acid and 42–75 % for moxifloxacin hydrochloride. It was found that encapsulation in halloysite contributes to an increase in the photostability of pharmaceutical ingredients. The reduction in the effective concentration of ingredients encapsulated in halloysite after the photostability test is no more than 2–5 %. Thus, halloysite can be used in smart tablet formulations as an effective nanocarrier to enhance photostability and control release of pharmaceutical ingredients.