Evaluation of molecular pharmaceutical and in-vivo properties of spray-dried isolated andrographolide-PVP

Objectives Andrographolide, a natural lipophilic molecule, has a wide range of pharmacological actions. However, due to low aqueous solubility, it has low oral bioavailability. The purpose of the study was to increase the solubility and dissolution rate of isolated andrographolide by formulating its solid dispersion. Method Solid dispersions were obtained by a spray-drying technique using different ratios of drug to polyvinylpyrrolidine (PVP K-30). Solid dispersions in compression with isolated drug and corresponding physical mixtures were characterized for various molecular pharmaceutical properties and subjected to stability study for up to 3 months. Key findings A five-fold increase in saturation solubility of andrographolide with higher values of Q(5min) (cumulative percentage release in 5 min) and lower values of t(75%) (time required for 75% w/w drug release) for solid dispersion was observed in different dissolution mediums. This was attributed to the formation of amorphous nature and intermolecular hydrogen bonding between drug and PVP K-30. The stability study showed there to be no significant change in molecular pharmaceutical properties and dissolution profile over the period of 3 months. Moreover, the in-vivo study in Wistar albino rats also justified improvement in the therapeutic efficacy of andrographolide after solid dispersion. Conclusions This study demonstrates the utility of solid dispersion to improve primary and secondary pharmaceutical properties of andrographolide using PVP K-30 as a carrier.