Rajashree Hirlekar

Studies on the Effect of Water-Soluble Polymers on Drug–Cyclodextrin Complex Solubility

The effect of complexation of irbesartan (IRB), a practically water-insoluble drug, with cyclodextrins in presence of different concentrations of water-soluble polymers (PEG 4000 and PVP K-90) on the dissolution rate of the drug has been investigated. Phase solubility studies were carried out to evaluate the solubilizing power of βCD in association with water-soluble polymers towards IRB and to determine the apparent stability constant (KS) of the complexes. Improvement in KS value for ternary complexes (IRB–βCD–polymers) clearly proved the benefit on the addition of water-soluble polymer to increase complexation efficiency. The dissolution rate of the drug from ternary systems containing PEG 4000 and PVP K-90 was higher as compared to the binary system. An optimum increase in the dissolution rate of the drug was observed at a polymer concentration of 5% w/w for PVP K-90 and 10% w/w for PEG 4000. DSC, FTIR, SEM, and XRD studies were carried out to characterize the complexes.

Hexosomes: A Novel Drug Delivery System

Polar lipids and various surfactants exhibit rich phase behavior depending on the composition of the lipids and the physicochemical conditions. Lamellar (L(alpha)), hexagonal (Inverted [H(II)]) and normal or inverted cubic (bicontinuous or micellar) structures are some of the most common lyotropic liquid crystalline phases. Hexosomes are the reverse hexagonal phases comprised of hexagonally close-packed infinite water layers covered by surfactants monolayer. Hexosomes (dispersed HII phases) due to their special structural properties have potential to be used as alternative delivery vehicle for pharmaceuticals. Biologically active molecules can either be accommodated within the aqueous domains or can be directly coupled to the lipid hydrophobic moieties oriented radially outwards from the centre of the water rods. Due to these special properties of hexosomes, they are used to improve solubility of poorly water soluble drugs and to transport therapeutic peptides and proteins by oral, transdermal, and parenteral routes. This article includes various methods of preparation of hexosomes and their application in drug delivery through various routes.

Formulation and evaluation of a gastroretentive dosage form of labetalol hydrochloride

Labetalol hydrochloride (LBT), 2-hydroxy-5-[1-hydroxy-2-[(1-methyl-3-phenylpropyl) amino] ethyl]-benzamide, a non-selective α, β-adrenoceptor antagonist is used in the treatment of hypertension. It shows variable bioavailability ranging from 10–80% which may be attributed to its minimum solubility in pH range 6 to 10, the pH conditions prevailing at the major site of absorption i.e. small intestine. Also due to its half life of 3 to 6 hrs it is administered twice daily. In the present work non-effervescent sustained release gastroretentive floating tablets of labetalol hydrochloride have been developed using various grades of HPMC and Poloxamer M127 as wetting agent. The tablets were evaluated for in vitro drug release, floating time, floating lag time, swelling studies etc. The tablets formulated with HPMC K4M CR and HPMC K15M CR along with Poloxamer showed negligible floating lag time with a total floating time over 12 hrs with complete release. Formulation was optimized using Stat-Ease Design Expert 7.1 software. Optimized batch was evaluated for the effect of change of osmolarity and pH on drug release, floating and swelling behaviour.