The effects of various factors on the release rate of a poorly soluble drug (carbamazepine) from hydroxypropyl methylcellulose matrices

Abstract

The effect of various surfactants, the particle size of carbamazepine and compression pressure on the drug release rate from hydroxypropyl methylcellulose matrices were evaluated. We results showed that sodium lauryl sulfate (1% w/w) significantly increased the release of rite drug, whereas above 1% w/w, the, release rate decreased. This decrease in release rate could be attributed to the reduction in the rate of erosion of hydroxypropyl methylcellulose matrices. The data showed that the drug release rare was unaffected by the HLB of non-ionic surfactant (polysorbates) or changes in compression pressure. The results showed that a decrease in drug particle size from 500 to 375 mum resulted in an increase in the release rate of the drug, whereas below 375 mum, particle size had no effect on the release rate. The delta were analyzed based on the equation Q = Kt(n) in order to investigate the mode of drug release from hydroxopyl methylcellulose matrices. The results showed that an increase in the concentration of sodium lauryl sulfate from I to 5% triggered an increase in the n value from 0.603 to 1.18, indicating both diffusion release and erosion mechanism. The n value was reduced from 1.11 to 0.72 as the particle size of carbamazepine fell from > 500 to < 125 <mu>m respectively.