Comparative In Vitro Dissolution Studies between Different Types of Acetaminophen Suppository Dosage Forms Using a Novel Modified Basket Method

Objective: Diverse studies have demonstrated that no single method of dissolution testing is suitable for different types of suppository dosage forms by either current USP and Ph.Eur methodologies. The objective of the research work was to overcome the methodological problem and limitations by a novel modified basket method. Materials and Methods: USP dissolution apparatus-I was modified by placing a dialysis membrane of specific molecular weight cut off to prevent any kind of clogging which may give irreproducible, inconsistent results. Physical properties like melting range, liquefaction and solidification time, disintegration time and mechanical strength were studied as per Ph.Eur III. Results: The amount of drug released from water soluble bases were fast with 94.5  1.8 %, 96.8  2.2% during 1h and slow with lipophilic bases with 91.6±2.3% and 92.7%±3.7% respectively during 6h. There was no significant difference between the dissolution profiles by flow through cell and modified basket method (P>0.005). Average lag time was 8.2, 9.8 min for water soluble suppositories and 14.4 and 11.8 min for lipophilic suppositories respectively. Release kinetics showed first order release rate for water miscible suppositories and zero order release profiles for lipophilic suppositories till 3 h and first order release after this time interval. Disintegration time of water soluble suppositories was 12-15 min but lipophilic suppositories demonstrated an extended disintegration time of 20-22 min Determination of plastic viscosity versus temperature indicated higher yield value for fatty bases compared to water soluble bases. Conclusion: Based on the data, it was concluded that proposed method could be used as a substitute for flow through cell of Ph.Eur. We further hypothesized that change in viscoelastic behavior due to the variation in temperature and aging may be responsible for the differences in the dissolution behavior between different suppositories bases.