Unless a drug acts topically (i.e., at its site of application), it first must enter the bloodstream and then be
distributed to its site of action. The mere presence of a drug in the blood, however, does not lead to a
pharmacological response. To be effective, the drug must leave the vascular space and enter the intercellular or intracellular spaces or both.The rate at which a drug reaches its site of action depends on two rates: absorption and distribution. Absorption is the passage of the drug from its site of administration into the blood; distribution is the delivery of the drug to the tissues.To reach its site of action, a drug must cross a number of biological barriers and membranes, predominantly lipid. Competing processes, such as binding to plasma proteins, tissue
storage,metabolism, and excretion , determine the amount of drug finally available for interaction with
specific receptors.
distributed to its site of action. The mere presence of a drug in the blood, however, does not lead to a
pharmacological response. To be effective, the drug must leave the vascular space and enter the intercellular or intracellular spaces or both.The rate at which a drug reaches its site of action depends on two rates: absorption and distribution. Absorption is the passage of the drug from its site of administration into the blood; distribution is the delivery of the drug to the tissues.To reach its site of action, a drug must cross a number of biological barriers and membranes, predominantly lipid. Competing processes, such as binding to plasma proteins, tissue
storage,metabolism, and excretion , determine the amount of drug finally available for interaction with
specific receptors.
Unknown
Drug Absorption and Distribution
