Low density porous carrier - Drug adsorption and release study by response surface methodology using different solvents

Low density porous carriers are widely used in the pharmaceutical applications. Response surface methodology, using 3 2 factorial design was used to study drug adsorption on and its release patterns from microporous polypropylene (Accurel MP 1000((R))) in the absence of additives. Ibuprofen, as model drug, was adsorbed on the polymer by solvent evaporation using two organic solvents methanol (M) and dichloromethane (DCM). The amount of carrier (100 mg) and its particle size range (250-350 mu m) were kept invariant while solvent volume (X-1) and drug amount (X-2) were taken as variables. Drug adsorption pattern depended on the type and amount of solvent used. DSC, XRD, FTIR and TGA, predict crystalline nature and physical form of adsorption. SEM showed the penetration and adsorption of the drug in and on the microporous polymer. Accurel NIP 1000((R)) had a pore volume of 1.992 g/cm(3) and surface area of 55.9855 m(2)/g as detected by mercury porosimetery. On drug adsorption, pore volume ranged from 0.413 to 1.198 g/cm(3) for methanol and 0.280-0.759 g/cm(3) for DCM. Similarly surface area was in the range 38.445-25.497 m(2)/g for methanol and 18.710-32.528 m(2)/g for DCM. The drug release was investigated in phosphate buffer pH 7.2. All batches showed excellent in vitro floating property. Drug release was partial with recovery to complete dependent on type and volume of solvent. R 2 values relating to bulk density, pore volume, surface area and drug release at 60, 120 and 180 min were estimated. Effect of solvent properties shows a positive influence on drug adsorption and release. Release profiles of some batches could be considered as gastroretentive drug delivery system. (c) 2006 Elsevier B.V. All rights reserved.