Pharmacology is the study of drugs (chemicals) that alter
functions of living organisms. Drug therapy, also called
pharmacotherapy, is the use of drugs to prevent, diagnose, or
treat signs, symptoms, and disease processes. When prevention
or cure is not a reasonable goal, relief of symptoms can
greatly improve quality of life and ability to function in activities
of daily living. Drugs given for therapeutic purposes
are usually called medications. Medications may be given for various reasons. In many
instances, the goal of drug therapy is to lessen disease
processes rather than cure them. To meet this goal, drugs
may be given for local or systemic effects. Drugs with local
effects, such as sunscreen lotions and local anesthetics, act
mainly at the site of application. Those with systemic effects
are taken into the body, circulated through the bloodstream
to their sites of action in various body tissues, and eventually
eliminated from the body. Most drugs are given for
their systemic effects. Drugs may also be given for relatively
immediate effects (eg, in acute problems such as pain or infection)
or long-term effects (eg, to relieve signs and symptoms
of chronic disorders). Many drugs are given for their
long-term effects.