Preformulation Study to Enhance Solubility of Albendazole

Abstract

Many drug molecules that have been discovered in the recent past or are in the pipeline to be introduced into the medicine market belongs to either BCS class II or BCS class IV. These classes all have low aqueous drug solubility in common which presents a challenge during their formulation. Orally formulated drugs are popular to patients because they are cheap and also easy to administer as solid dosage forms or as liquids for the young and elderly. Orally administered drugs must undergo dissolution in the gastrointestinal tract in order to be absorbed into the body. These molecules (BCS class II) must have its aqueous solubility increased. One of the ways of increasing aqueous solubility is by making solid dispersions. The challenge of making solid dispersion is in choosing minimal amounts of appropriate carrier that would increase the drugs aqueous solubility while keeping the overall oral dosage size small. Solubility parameters have been used to predict solubility of drug in a carrier because the drug solubility in a carrier (a water soluble carrier) would determine the extent of the increase of the solubility in an aqueous medium. However solubility parameters alone are not enough to assure success due to other factors such as viscosity. To further perfect formulation, use of other parameters such as crystallinity index after analysis using FTIR can greatly go a long way in choosing carriers that can be used to improve solubility of drug molecules during formulation. Use of crystallinity index can assist in predicting the carriers that would show high solubility. This study used Solubility parameters and crystallinity index to choose the carriers which had potentiality of increasing the aqueous solubility of albendazole. Four polymers (PEG 8000, HPMC, PVP and CMC) were used as carriers. The study showed that CMC was a poor drug carrier with low dissolved albendazole though the solubility parameter difference was 4.PEG though having a small difference in SP (0.5) did not show the highest solubility among the carriers possibly due to recrystallization. PVP had the best aqueous solubility attested by both the solubility parameter and the crystallinity index. HPMC though expected to have low solubility because of high solubility parameter difference (8.4), showed good aqueous solubility of albendazole. Both solubility parameters and crystallinity index when used together have the potential of decreasing the time used in developing new oral dosage forms.