Enhancement of Solubility and Dissolution Properties of Lacidipine by Solid Dispersion

Abstract

Lacidipine is a 1, 4-dihydropyridine derivative categorized as an anti-hypertensive Ca+2 channel blocker having very low
solubility, and thus very low oral bioavailability, which presents a challenge to the formulation scientists. Homogeneous
distribution of poorly water-soluble drugs like lacidipine in PVP-K30 and Poloxamer-188 is definitely a suitable way to
improve the bioavailability of such drugs. Solid dispersion is the most promising strategy to improve oral bioavailability of
poorly soluble drugs. The aim of study was to compare the effect of PVP-K30 and Poloxamer-188 as carrier in solid
dispersion formulation of lacidipine. Solid dispersion of PVP-K30 or Poloxamer-188 were prepared at different ratios (1: 2,
1: 4, 1: 6, 1: 8 and 1: 10%w/w) by solvent evaporation methods. The characterization of samples was performed using FTIR,
DSC and XRD. Dissolution and solubility studies were also performed. The FT-IR spectroscopic analysis revealed the
possibility of intermolecular hydrogen bonding in various solid dispersions. The DSC and XRD studies indicated the
transformation of crystalline lacidipine to amorphous lacidipine by the solid dispersion technology. The dissolution rate was
dependent on the ratio of drug: carrier. The results obtained showed that the rate of dissolution and solubility were
considerably improved when formulated in solid dispersions as compared to pure drug. The order of increasing dissolution
rate observed with PVP-K30 and Poloxamer-188 in different concentration was poloxamer-188 > PVP-K30 > pure drug.