The comparison of a novel continuous-flow dissolution apparatus for suppositories with the rotating basket technique

Abstract

The dissolution rate of a drug from a solid dosage unit is an important parameter affecting drug bioavailability. Whjile dissolution testing has received much attention in the cases of tablets and capsules, it has received much less attention with suppositories. It was for this reason that the performance of a novel flow-through bead-bed apparatus was assessed in our laboratories. A flow-through dissolution chamber based on a published American design was constructed. It was tested in two ways: firstly using fatty based benzocaine suppositories, dissolution rates were determined at different temperatures. The data obtained agreed well with original published data indicating that the apparatus can be easily fashioned from standard laboratory equipaient and can give reproducible results in different laboratories. For comparison the benzocaine suppositories were also tested using a rotating basket method. Similar dissolution profiles Were obtained using the two methods at 37°C. Secondly the dissolution profiles of two commercially available indomethacin suppositories were measured using both the flow-through bead-bed apparatus and the more established rotating basket method. Although both products contained the same dose of indomethacin in a polyethylene glycol base, clear differences were noted between the dissolution profiles of the two products. The difference, however, was much more marked when using the flow-through bead-bed apparatus. These data therefore indicate that the latter technique may be a more precise tool for monitoring the effects of subtle formulation changes on dissolution profiles. In the case of indomethacin, from a pharmacological standpoint, a slower release rate is advantageous as such a product is likely to be more effective at relieving early morning stiffness after an evening dose.