Pharmaceutical Evaluation of Hollow Type Suppositories. IV.1) Improvement of Bioavailability of Propranolol in Rabbits After Rectal Administration

Abstract

Three kinds of suppositories were constructed with oleaginous base material (Witepsol H-15): a conventional type suppository containing propranolol (PPL) hydrochloride mixed with a base material (I), a hollow type suppository containing PPL in a form of aqueous solution (PPL was dissolved in isotonic NaCl solution) in its cavity (II), a hollow type suppository containing PPL as powder (hydrochloride salt) in its cavity (III). Bioavailability was estimated after rectal administration of each suppository in rabbits and compared with oral administration. The peak plasma PPL concentration (Cmax) and the area under the plasma concentration-time curve (AUC) were lower with I than with II or III. The Cmax and the AUC measured after rectal administration of III were significantly higher than those in the case of oral administration. By using III, the highest values of the mean Cmax (795 ± 160 ng/ml) and of the mean AUC (459 ±21 h -ng/ml) were obtained. It was found that systemic availability was increased by rectal administration of PPL hollow type suppositories. These data on bioavailability suggested that PPL was absorbed more efficiently with the hollow type suppository than with the conventional one. PPL was released faster from II and III than from I. It was concluded that the hollow type suppository was a suitable device for absorption of PPL into the rectum. © 1986, The Pharmaceutical Society of Japan. All rights reserved.