Cyclodextrins and their derivatives play an important role in improving the therapeutic efficacy of drugs with poor solubility and/or stability problems. They are capable of alleviating the undesirable properties of drug molecules through the formation of inclusion complexes (1). Hydroxypropyl-b-cyclodextrin (HPbCD) is mainly selected for its higher solubility than other cyclodextrins and this generally results in more extensive solubilization ability toward lipophilic molecules, with a good safety profile (2). Ternary complexes of meloxicam (ME) (a poorly water soluble anti-inflammatory drug) with hydroxypropyl-b--cyclodextrin (HPbCD) and either a hydrophilic polymer, namely, polyvinyl pyrrolidone (PVP) or a basic amino acid such as L-arginine, were prepared by the spray-drying technique. The solubilizing efficiency, physical properties and dissolution behaviour of each ternary system of ME--HPbCD with either PVP or L-arginine were compared with those of the corresponding binary system of ME--HPbCD. Tablets compressed from the ternary system of ME-HPbCD-L-arginine were compared with plain and commercial tablets. Phase solubility experiments suggested the formation of an inclusion complex of A L type. Ternary system of ME-HPbCD-L-arginine exhibited a stability constant 30.3 times higher than the binary system of ME-HPbCD, while the ternary system of ME-HPbCD--PVP increased the stability constant 2.2 times only. The prepared complexes were characterized by scanning electron microscopy, differential scanning calorimetry and infra red spectroscopy. Ternary solid complexes indicated the presence of strong interactions between the components. The dissolution behaviour of ME from different ternary complexes was higher than its dissolution from the binary system. Tablets compressed from ternary complexes of ME-HPbCD-L-arginine highly improved drug release compared to plain and commercial tablets.

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Extravasation of PAMAM dendrimers across the microvascular endothelium showed size and molecular weight dependence. Results suggest that in addition to size and molecular weight, other physicochemical properties of polymeric drug carriers such as molecular geometry and charge may influence their microvascular extravasation. Systematic studies of the influence of the physico-chemical properties of polymeric drug carriers on their microvascular extravasation will aid in the design of novel macromolecular drug carriers with controlled extravasation profiles.

The aim of this research was to investigate the effect of pseudoephedrine (PE), polymer ratio, and polymer loading on the release of acetaminophen (APAP) from hydroxypropyl methyl cellulose (HPMC)/polyvinylpyrrolidone (PVP) matrices. Granules formulated with APAP or both APAP and PE, and various blends of HPMC and PVP were compressed into tablets at varying compression forces ranging from 2000 to 6000 Ib. In vitro drug release from the matrix tablets was determined and the results correlated with those of tablet water uptake and erosion studies. Drug release from the formulations containing both APAP and PE was slower than those containing only APAP (P < 0.05, F = 3.10). Drug release from tablets formulated with APAP only showed an initial burst at pH 1.16 or 7.45, and at high total polymer loading (> or = 9.6%). Formulations containing both APAP and PE showed slower drug release at pH 1.16 than at pH 7.45. At pH 1.16, a decline in the percentage of APAP released occurred after 18 hours. This was due to the hydrolysis of APAP to p-aminophenol. The drug dissolution data showed good fit to the Korsmeyer and Peppas model, and the values of the release exponents ranged from 0.20 to 0.62, indicating a complex drug release pattern. Tablet erosion studies indicated that the amount of APAP released was linearly related to the percentage of tablet weight loss. The kinetics of tablet water uptake was consistent with a diffusion and stress relaxation controlled mechanism. Overall, the results of this study indicated that PE, as a co-active in the formulation, modified the matrix, and hence retarded APAP release.

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