Matrix Tablets for Controlled Release of Drugs Incorporated Using Capillary Absorption

Cost and time effectiveness make direct tableting still the favored method for tablet production. Among its most noticeable limitations in application is the non-uniformity (and/or inhomogeneities) in the contents of the resulting tablets, possibly leading to inconsistencies in required tablet properties. The efficiency of direct tableting is mostly affected by surface properties of the components to be tableted, which govern the final tablet mechanical and chemical properties and can influence the liquid capillary rise that the tablets exhibit after ingestion. By using capillary rise as a driving force, we developed a simple, yet powerful procedure for filling blank tablets with a repeatable drug amount. Blank tablets were prepared by direct compression of the excipient and filled with an organic solution of hydrochlorothiazide. Tablets were characterized regarding their structure and morphology, while their applicability was monitored using in vitro drug release studies. By utilizing the mentioned filling of blank tablets, we were able to incorporate the desired dose of the drug inside while maintaining the tablets initial mechanical properties. Moreover, most of the drug was incorporated in the tablet pores and the rest was homogeneously distributed over the tablet surface in the form of small particles, by which we also eliminated content non-uniformity (homogenous drug distribution through the tablet). To sum up, we not only developed a cheap, simple, and reproducible variation of direct tableting, but were also able to eliminate some of its biggest disadvantages (e.g., segregation of components, leading to inhomogeneities in contents, and incompatibility between different base ingredients due to their different surface properties). All mentioned make the proposed approach highly interesting for future use, especially in potential therapy individualization.