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4114811 
Journal Article 
Rectal bioavailability of ibuprofen from hard gelatin capsules containing sodium phosphates as adjuvants and soft gelatin capsules or suppositories as references 
Leino, J; Salmela, O; Alastalo, H; Eerikainen, S; Klinge, E; Marvola, M 
1999 
STP Pharma Sciences
ISSN: 1157-1489 
579-585 
The rectal bioavailability of ibuprofen can be affected by including different diluents in hard gelatin capsules. In the present study, sodium phosphates were used as additives in order to increase the dissolution rate of an acidic drug, ibuprofen, in the rectum. The results showed shortened-times,les at the beginning of drug absorption, while thereafter the t(max) and mean residence time decreased. In addition, adjusting the levels of sodium phosphates increased the C-max value. The addition of phosphates had no marked effect on the degree of bioavailability of ibuprofen. The effect of the number of capsules on the I-ectal bioavailability of ibuprofen was also studied. When the single 400 mg dose of ibuprofen was administered in two, 200 mg capsules (size 1), bioavailability was about 25% higher than? that achieved with one, 400 mg capsule. The hypothesis was that the first unit was pushed deeper into the rectum by the other capsule, thus increasing the absorption area. On the other hand rectal drug administration was more agreeable if only one unit was used Precoating the capsules with hard fat facilitated administration, thus increasing compliance. Finally during this study, the rectal bioavailability of ibuprofen from hard gelatin capsules containing sodium phosphates (30 mg) was compared with a commercial soft gelatin capsule and a suppository. which were used as reference products. The conclusion was that a hard gelatin capsule is almost bioequivalent to the suppository and may be slightly more effective than the soft gelatin capsule. Thus the hard gelatin capsule is a noteworthy dosage form for rectal use in some special cases such as drug therapy for seriously ill patients. 
bioavailability; bioequivalence; coating agent; hard gelatin capsule; disodium hydrogen phosphate; ibuprofen; rectal administration; sodium dihydrogen phosphate; soft gelatin capsule; suppository