Suitability of a Miocene bentonite from North Western Desert of Egypt for pharmaceutical use

Abstract

This work examines the beneficial effects for human health of bentonite, describing their use in pharmaceutical formulations. The bentonite samples must comply with some general features of pharmacopeia, including high mineral and chemical purities and absence of microbial pathogens, before considering their use in pharmacy. Specific characteristics such as sediment volume, swelling power and gel formation are also important for particular applications such as their use as suspending agents. Mineralogical, geochemical, and microbiological analyses and pharmacopeia tests were carried out for a purified (raw and activated) Egyptian bentonite sample from North Western Desert (NWD), a Wyoming bentonite standard and a mineral currently used as a pharmaceutical product. The X-ray diffraction data revealed that the Egyptian sample has montmorillonite as a main mineral phase. The chemical composition (ICP-MS data) and particularly the trace element content, for both raw and activated samples fulfills the pharmacopeia requirements regarding Pb and As as toxic elements. The microbial test for the studied samples revealed that they meet the specifications of the pharmacopeia microbial limit test for pharmaceutical preparations in being both free from microbial pathogens and the total number of viable aerobic microorganisms being within the allowed limit of the test. Both raw and activated bentonites from NWD can be used after extensive purification as pharmaceutical excipients, moreover the Na-activated one can be used as an adsorbent of drugs and a drug carrier in drug release processes and in the formulation of suspension for oral products as it has a relatively high cation exchange capacity (CEC).