ABSTRACT
The rectum and vagina have a rich blood and lymph supply, and drugs can cross through their mucosa like the other lipid membranes. Thus, rectal and vaginal routes of drug administration can be of particular importance for drugs such as progesterone and estradiol, which are poorly bioavailable upon oral administration because they are extensively metabolized by the liver. The use of a hydrogel matrix for drug delivery involves the dispersal of the drug into the matrix, followed by drying of the system and concomitant immobilization of the drug. In order to understand the mechanism of drug absorption from the rectum and vagina it is important to know the anatomy and physiology of the region. The various types of rectal and vaginal dosage forms, depending upon the drug incorporated and specific use, are: suppositories, tablets and capsules, ointments, creams, and aerosol foams, gels and jellies, contraceptive sponges, intrauterine devices, powders and solutions.
