Poster Presenter

Factors Affecting Hard Capsule Shell Dissolution
Amanda Solaiman, P.A. Carter, P.A. Hambleton and B. E. Jones
UK

To investigate the influence of dissolution medium composition, ionic strength and pH on the shell dissolution time of hydroxypropyl methylcellulose (HPMC) and gelatin hard capsules (size 0) after storage at 35 % and 53 % RH for 24 & 72 hours. Shell dissolution time was recorded as the time for a steel ball bearing to be released from the capsule body after immersing in stirred media.1

Shells were unaffected by storage conditions. For HPMC, dissolution time in Sörensen phosphate buffer (pH 5-8) decreased as pH increased and in citro-phosphate buffer dissolution time increased from pH 5 to 7. Gelatin dissolved more rapidly in these buffers and was unaffected by pH. In acetate buffer, HPMC did not dissolve in pH 6, whereas gelatin dissolution time increased as pH increased. Both gelatin and HPMC dissolved slowest in artificial gastric juice (pH 1.2). In potassium phosphate buffer (pH 7.4), HPMC gave an increased dissolution time with increase in concentration (0.1-0.5 M) whereas gelatin was unaffected. In sodium phosphate buffer (pH 7.4), increase in concentration affected HPMC dissolution to a lesser extent and gelatin remained unaffected.

Differences have been shown between the dissolution of gelatin and HPMC hard capsule shells due to dissolution media composition, ionic strength and pH.

1. Chiwele, I et al, Chem. Pharm.Bull. 48: 7 (2000) 951-956