EVALUATION OF IRVINGIA KERNEL MUCILAGE AS A MATRIX SYSTEM AND COMPRESSION COATING MATERIAL FOR CONTROLLED DRUG DELIVERY

Abstract

Reliance on imported pharmaceutical excipients has led to increased cost of finished products, necessitating the development of local excipients. Natural polymers have been used extensively as matrix systems for controlled drug release and drug targeting due to their wide-availability, biodegradability, and low toxicity. Previous studies on Irvingia gabonensis mucilage (IGM) suggested controlled release potentials. Therefore, IGM obtained from the seeds of Irvingia gabonensis (O’Rorke) Bail (Irvingiaceae), was evaluated as matrix system for controlled delivery of ibuprofen and as a compression coating material for colon targeted drug delivery. Irvingia mucilage was extracted using established methods. Batches of oven-dried, and freeze-dried IGM were characterized for pH, elemental analysis, morphology and crystallinity. Irvingia matrices were prepared by direct compression and wet granulation with varying drug concentration(10-50%w/w), excipients (lactose, Avicel®, and dicalcium phosphate, DCP), and polymer (xanthan gum, hydroxypropylmethylcellulose) alone and in combination with IGM. The compressional characteristics of IGM and tablets were determined using density measurements, and Heckel and Kawakita equations. The mechanical properties of the tablets were assessed by measuring crushing strength and friability. Drug release from the matrices was evaluated using disintegration and dissolution times. The drug release mechanisms were determined by fitting the dissolution data into classic kinetic equations. Irvingia mucilage was used as compression coating material (300 and 400 mg) for ibuprofen (100 mg). Drug release from the matrices and compression-coated tablets was evaluated in simulated gastric conditions. The results were analyzed using ANOVA at ɑ0.05. Irvingia kernel mucilage was slightly acidic, free of heavy metals, with irregularly shaped particles that exhibited some degree of crystallinity. Irvingia mucilage was directly compressible and formed intact non-disintegrating tablets. The Heckel and Kawakita equations indicated that IGM deformed plastically with fast onset and high amount of plastic deformation compared to xanthan gum and hydroxypropylmethylcellulose. Wet granulation enhanced the mechanical properties of the matrix tablets while increasing ibuprofen concentration generally decreased the mechanical properties and increased drug release. The ranking of dissolution times was xanthan gum>freeze-dried IGM>hydroxypropylmethylcellulose>oven-dried IGM. Irvingia mucilage containing 50%w/w ibuprofen facilitated controlled drug release for over 9 h. Avicel® and DCP improved the mechanical properties of the matrix tablets, facilitated ibuprofen release from IGM, and altered the release kinetics, which was mainly by Korsemeyer-Peppas model while xanthan gum and hydroxypropylmethylcellulose was by Hixson-Crowell. Increasing the proportion of xanthan gum and hyroxypropylmethylcellulose in IGM matrices resulted in decreased rate and percentage of ibuprofen released after 9 h with xanthan gum having the greater effect. The mechanism of drug release at all concentrations for all polymers was super case II except 10%w/w ibuprofen-xanthan gum matrices which was anomalous (non-Fickian diffusion). For the compression-coated tablets, oven-dried and freeze-dried IGM prevented ibuprofen release in conditions mimicking the stomach and small intestine, but fast drug release was obtained in simulated colonic fluid. Irvingia kernel mucilage compared favourably with xanthan gum and hydroxypropylmethyl-cellulose as matrices for controlled drug delivery and could serve as an alternative to the two standard polymers. Irvingia kernel mucilage also showed good potential as a coating material for colon targeted drug delivery