Introduction: principles of drug action
Medical pharmacology is the science of chemicals that interact with the human body. These interactions are divided into two classes: • pharmacodynamics Effects of the drug on the body • pharmacokinetics way the body affects the drug with time. A few drugs act by virtue of their physicochemical properties, and this is called non‐specific drug action. Some drugs act as inhibitors for certain transport systems or enzymes. However, most drugs produce their effects by acting on specific protein molecules, located in the cell membrane. These proteins are called receptors, and respond to endogenous chemicals in the body. These chemicals are either synaptic transmitter substances or hormones. For example, acetylcholine is a transmitter substance released from motor nerve endings, it activates receptors in skeletal muscle, initiating a sequence of events that results in contraction of the muscle. Chemicals (e.g. acetylcholine) that activate receptors and p...