Abstract

Dosage forms are designed to deliver drugs in a suitable form for absorption. Various routes are used for drug administration, each with their own advantages and disadvantages. The administration of drugs by routes other that the oral one has to be considered when the patient is unable to make use of the oral route or when the drug is not suited for oral administration. The rectal route has been used to deliver many types of drugs, but patient acceptability differs due to discomfort arising from the administered dosage forms. Drugs given rectally are generally administered for local rather than systemic effects. This route is also indicated for drugs inactivated by the gastrointestinal fluids when given orally, drugs that cause local stomach or upper GI tract irritation, drugs that require doses in excess of 500 mg and for the local treatment of disease of the rectum such as hemorrhoids. Drugs absorbed from the rectum enter the systemic circulation directly and the rectal route is therefore useful for drugs undergoing extensive first-pass metabolism. In this chapter, background on the rectal route, rectal formulations available, the advantages, disadvantages, and current market trends of rectal dosage forms will be discussed.