ABSTRACT
This chapter presents the usual dosage forms and routes of administration employed in clinical medicine. This is followed by an overview of additional methods of administration and absorption sites unique to substance abuse and the potential absorption of substances concealed in the body cavities for illegal transportation or to evade discovery and arrest. Following oral administration, absorption can occur from any surface within the gastrointestinal tract. The intact skin is a barrier to the absorption of most drugs. Only a few substances are absorbed after application to the skin. Accidental intra-arterial injections of drugs intended for intramuscular, subcutaneous, or intravenous use can be catastrophic. The intra-arterial injection of substances can cause severe tissue ischemia and necrosis. Individuals conceal drugs in body cavities to either illegally transport them across the borders, carry them into jails and prisons, or to avoid detection and arrest.
