Purpose: To develop controlled release osmotic pump tablets (COPT) of glipizide (GZ) solid dispersion (SD).
Methods: In elementary osmotic pump (EOP) tablets, an osmotic core with the drug is surrounded by a semi-permeable
membrane which is drilled with a delivery orifice. COPT tablets eliminate the need of drilling process as controlled release
can be achieved by the presence of osmogen in the coating. Poorly water soluble drug molecule cannot give satisfactory
drug release hence GZ solid dispersion was prepared in the present study. The SDs having different ratio of drug to
Poloxamer (PXM) 188 were prepared by hot melt method and optimized by solubility study, drug content estimation and
in vitro dissolution study. Effect of two independent variables, amount of osmogen (potassium chloride) and hydrophilic
polymer (polyethylene oxide WSR 303), were investigated using 32 factorial design. Core and coated tablets were evaluated
for pharmacotechnical parameters. In-vitro drug release profiles of COPT tablets were compared with marketed with
push-pull osmotic pump tablet, Glucotrol XL. Results: Prepared core and coated tablets showed acceptable pharmacotechnical
parameters. Drug release was directly proportional to initial level of hydrophilic polymer, but inversely related
to the osmogen, confirming osmotic mechanism. Zero order drug release pattern was achieved which was comparable
to marketed product. Conclusion: Novel oral controlled release of glipizide was successfully achieved by incorporating
glipizide solid dispersion into osmotic system.
Keywords: Controlled release osmotic pump tablets, glipizide, poloxamer 188, solid dispersion.
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