Microparticle surface layering through dry coating: impact of moisture content and process parameters on the properties of orally disintegrating tablets

Objectives: The aim of this study was to investigate the influence of process parameters during dry coating on particle and dosage form properties upon varying the surface adsorbed moisture of microcrystalline cellulose (MCC), a model filler/binder for orally disintegrating tablets (ODTs). Methods: The moisture content of MCC was optimised using the spray water method and analysed using thermogravimetric analysis. Microproperty/macro-property assessment was investigated using atomic force microscopy, nano-indentation, scanning electron microscopy, tablet hardness and disintegration testing. Key findings: The results showed that MCC demonstrated its best flowability at a moisture content of 11.2% w/w when compared to control, comprising of3.9% w/w moisture. The use of the composite powder coating process (without air) resulted in up to 80% increase in tablet hardness, when compared to the control. The study also demonstrated that surface adsorbed moisture can be displaced upon addition of excipients during dry processing circumventing the need for particle drying before tabletting. Conclusions: It was concluded that MCC with a moisture content of 11% w/w provides a good balance between powder flowability and favourable ODT characteristics

Novi kopolimerni zwitterionski matriksi za polagano oslobađanje verapamil hidroklorida

Stable co-polymer [vinyl acetate-co-3-dimethyl(methacryloyloxyethyl)ammonium propane sulfоnate, p(VA-co-DMAPS)] latex of different compositions has been synthesized for the first time by emulsifier-free emulsion copolymerization. The unusual “overshooting” behavior of the co-polymer tablets has been explained by the formation of specific clusters from the opposite oriented dipoles zwitterionic species. The change of their concentration with the DMAPS unit fraction (mDMAPS), pH and ionic strength has been considered responsible for the differences observed in the swelling kinetics. The results obtained prove that mDMAPS and ionic strength could be used to control the swelling degree of the p(VA-co-DMAPS) matrices. In this way, p(VA-co-DMAPS) matrices could be effectively used to control the sustained release of drugs with basic properties like verapamil hydrochloride from model tablets.Metodom emulzijske polimerizacije sintetiziran je novi stabilni kopolimer [vinil acetat-ko-3-dimetil(metakriloiloksietill)amonijev propan sulfоnat, p(VA-co-DMAPS)] lateks promjenjivog sastava. Neobično “overshooting” ponašanje tableta pripravljenih iz tog kopolimera objašnjava se stvaranjem specifičnih klastera suprotno rijentiranih dipola zwitterionskih specija. Proučavan je utjecaj udjela DMAPS jedinica (mDMAPS), pH i ionske jakosti na kinetiku bubrenja. Dobiveni rezultati dokazuju da se promjenom mDMAPS i ionske jakosti može kontrolirati stupanj bubrenja p(VA-co-DMAPS) matriksa i oslobađanje verapamil hidroklorida iz tableta pa se ti matriksi mogu upotrijebiti za polagano oslobađanje bazičnih lijekova srodnih verapamilu