چکیده (انگلیسی):

The aim of the current study was to design a porous osmotic
pump–based drug delivery system for controlled release
of oxybutynin. The porous osmotic pump contains
pore-forming water-soluble additives in the coating membrane,
which after coming in contact with water, dissolve,
resulting in an in situ formation of a microporous structure.
The dosage regimen of oxybutynin is one 5-mg tablet 2
to 3 times a day. The plasma half-life ranges from ~2 to
3 hours. Hence, oxybutynin was chosen as a model drug
with an aim to develop a controlled release system for a
period of 24 hours. Linear and reproducible release similar
to that of Ditropan XL was achieved for optimized formulation
(f2 950) independent of hydrodynamic conditions.
The effect of different formulation variables, namely, ratio
of drug to osmogent, membrane weight gain, and level of
pore former on the in vitro release was studied. Cellulose
acetate (CA) was used as the semipermeable membrane. It
was found that drug release rate increased with the amount
of osmogent because of the increased water uptake, and
hence increased driving force for drug release. Oxybutynin
release was inversely proportional to the membrane weight
gain; however, directly related to the level of pore former,
sorbitol, in the membrane. This system was found to deliver
oxybutynin at a zero-order rate for 20 hours. The effect of
pH on drug release was also studied. The optimized formulations
were subjected to stability studies as per International
Conference on Harmonisation (ICH) guidelines
and formulations were stable after a 3 month study.