Comparative release studies on suppositories using the basket, paddle, dialysis tubing and flow-through cell methods I. Acetaminophen in a lipophilic base suppository.

The release characteristics of lipophilic suppositories containing acetaminophen (AAP) were examined using four types of dissolution methods: the basket, paddle, dialysis tubing (DT) and flow-through cell (FTC) methods. The suitability of each apparatus for quality control in AAP compounded suppositories was evaluated using statistical procedures. More than 80% of the drug was released over 60 min in all the release methods studied, with the exception of the basket method. Reproducible and faster release was achieved using the paddle method at 100 and 200 rpm, whereas poor release occurred with the basket method. The mean dissolution time (MDT), maximum dissolved quantity of AAP at the end of the sampling time (Q) and dissolution efficiency (DE) were calculated by model-independent methods. The FTC method with a single chamber used in this study was also appreciable for AAP suppositories (Q of 100%, MDT of 71-91 min and DE of 75-80%). The DT apparatus is considered similar to the FTC apparatus from a quality control perspective for judging the release properties of lipophilic base suppositories containing AAP. However, even the single chamber FTC used in this study has potential as an in vitro drug release test for suppositories. The comparative dissolution method is expected to become one of the valuable tools for selecting an adequate dissolution test.