Performance Parameters and Characterizations of Nanocrystals: A Brief Review.

Poor bioavailability of drugs associated with their poor solubility limits the clinical effectiveness of almost 40% of the newly discovered drug moieties. Low solubility, coupled with a high log p value, high melting point and high dose necessitates exploration of alternative formulation strategies for such drugs. One such novel approach is formulation of the drugs as "Nanocrystals". Nanocrystals are primarily comprised of drug and surfactants/stabilizers and are manufactured by "top-down" or "bottom-up" methods. Nanocrystals aid the clinical efficacy of drugs by various means such as enhancement of bioavailability, lowering of dose requirement, and facilitating sustained release of the drug. This effect is dependent on the various characteristics of nanocrystals (particle size, saturation solubility, dissolution velocity), which have an impact on the improved performance of the nanocrystals. Various sophisticated techniques have been developed to evaluate these characteristics. This article describes in detail the various characterization techniques along with a brief review of the significance of the various parameters on the performance of nanocrystals.

Second generation lipid nanoparticles (NLC) as an oral drug carrier for delivery of lercanidipine hydrochloride.

Lercanidipine hydrochloride is a calcium channel blocker used in the treatment of hypertension. It is a poor water soluble drug with absolute bioavailability of 10%. The aim of this study was to design lercanidipine hydrochloride-loaded nanostructured lipid carriers to investigate whether the bioavailability of the same can be improved by oral delivery. Lercanidipine hydrochloride nanostructured lipid carriers were prepared by the method of solvent evaporation at a high temperature and solidification by freeze drying. The nanostructured lipid carriers were evaluated for particle size analysis, zeta potential, entrapment efficiency, in vitro drug diffusion, ex vivo permeation studies and pharmacodynamic study. The resultant nanostructured lipid carriers had a mean size of 214.97 nm and a zeta potential of -31.6 ± 1.5 mV. More than 70% lercanidipine hydrochloride was entrapped in the NLCs. The SEM studies indicated the formation of type 2 nanostructured lipid carriers. The in vitro release studies demonstrated 19.36% release in acidic buffer pH 1.2 indicating that the drug entrapped in the nanostructured lipid carriers remains entrapped at acidic pH. The ex vivo studies indicated that the drug release was enhanced from 10% to 60.54% at blood pH in 24h. The in vivo pharmacodynamic study showed that NLCs released lercanidipine hydrochloride in a controlled manner for a prolonged period of time as compared to plain drug. These results clearly indicate that nanostructured lipid carriers are a potential controlled release formulation for lercanidipine hydrochloride and may be a promising drug delivery system for the treatment of hypertension.