Characterization of Pakistani purified bentonite suitable for possible pharmaceutical application

•Karak bentonite from KPK Province, Pakistan was characterized for pharmaceutical uses.•The Karak bentonite mainly composed of montmorillonite.•The purification methods were used for removal of quartz and properties developments.•Purification processes made this bentonite suitable for safe pharmaceutical uses.

The aim of this study is to assess the suitability of Pakistani bentonite for its possible pharmaceutical use in raw and purified forms. The purified samples were obtained by two different methods i.e. simple sedimentation and classical NaCl treatment. Prior to bentonite application in pharmacy, it is imperative that they must comply with some general features as high mineral, chemical and microbial purity. The physicochemical properties especially gel formation and swelling capacity are also important to be tested to investigate its specific use. The mineralogical study reveals that the raw sample is bentonite containing mainly montmorillonite with minor contents of kaolinite, illite and quartz. The quartz impurities were removed by the purification methods as confirmed by the X-ray diffraction patterns and the other properties were also improved. In view of the fundamentals of major pharmacopeias for use of bentonite in pharmacy and considering the chemical composition, microbiological results we could designate a pharmaceutical acceptable denomination for Pakistani purified bentonite samples. The two purified samples vary in interlayer cations, chemical composition and other properties that would present different behavior in pharmacy. The studied bentonite in purified form could be used as suspending and disintegrating agent because of its excellent swelling capacity and sedimentation volume. The high cation exchange capacity, high surface area and pore size distribution suggest their use as a good adsorbent of drugs and a drug carrier in controlled drug release system.