Domperidone nanocrystals with boosted oral bioavailability: fabrication, evaluation and molecular insight into the polymer-domperidone nanocrystal interaction

The aim of this study was to employ experimental and molecular modelling approaches to use molecular level interactions to rationalise the selection of suitable polymers for use in the production of stable domperidone (DOMP) nanocrystals with enhanced bioavailability. A low-energy antisolvent precipitation method was used for the preparation and screening of polymers for stable nanocrystals of DOMP. Ethyl cellulose was found to be very efficient in producing stable DOMP nanocrystals with particle size of 130 ± 3 nm. Moreover, the combination of hydroxypropyl methylcellulose and polyvinyl alcohol was also shown to be better in producing DOMP nanocrystals with smaller particle size (200 ± 3.5 nm). DOMP nanosuspension stored at 2-8 °C and at room temperature (25 °C) exhibited better stability compared to the samples stored at 40 °C. Crystallinity of the unprocessed and processed DOMP was monitored by differential scanning calorimetry and powder X-ray diffraction. DOMP nanocrystals gave enhanced dissolution rate compared to the unprocessed drug substance. DOMP nanocrystals at a dose of 10 mg/kg in rats showed enhanced bioavailability compared to the raw drug substance and marketed formulation. A significant increase in plasma concentration of 2.6 μg/mL with a significant decrease in time (1 h) to reach maximum plasma concentration was observed for DOMP nanocrystals compared to the raw DOMP. Molecular modelling studies provided underpinning knowledge at the molecular level of the DOMP-polymer nanocrystal interactions and substantiated the experimental studies. This included an understanding of the impact of polymers on the size of nanocrystals and their associated stability characteristics.

Optimization of Halopemide for Phospholipase D2 inhibition

Halopemide, which was identified by HTS to inhibit phospholipase D2 (PLD2), provided the basis for an exploratory effort to identify potent inhibitors of PLD2 for use as inflammatory mediators. Parallel synthesis and purification were utilized to rapidly identify orally available amide analogs derived from indole 2-carboxylic acids with superior potency versus PLD2.

Design, optimization and evaluation of domperidone coevaporates

Coevaporates of domperidone were prepared using different polymers by solvent evaporation technique. Ethyl cellulose and hydroxypropyl methylcellulose phthalate were used in preparation of coevaporates. The coevaporates were characterized by X-ray diffraction studies, IR spectrophotometry and differential scanning calorimetry. The dissolution behavior of coevaporates was studied using buffer solution of pH 1.2 for the first 2 h and that of pH 6.8 thereafter up to 12 h. A two-factor, three-level design was used to quantitate the effect of polymers on dissolution profile of domperidone. The drug release rate was found to be dependent on the concentration of polymers in the coevaporates. Dissolution of drug in a pH 6.8 buffer improved with increasing concentration of hydroxypropyl methylcellulose phthalate in coevaporates. Bioavailability studies in human volunteers confirmed that domperidone coevaporates sustained drug release.