o. Synergism. Synergism is the joint action of two or more drugs such that their
combined effects are greater than the sum of their individual effects. A reduced dosage
may be necessary.
p. Antagonism. If only one of two drugs exhibits an effect, but that effect is
decreased when the two drugs are given in combination, they are antagonistic. An
increased dosage of the active component may be necessary.
q. Accumulation. When the body is unable to detoxify and excrete a drug as
rapidly as it is being absorbed, or when a drug is stored in the tissues for an appreciable
length of time, pronounced drug effects and poisoning can follow. Usually this is
noticed when a number of doses are administered over a period of time. This may
require progressively smaller doses (or "rest" days between doses) to allow the
accumulated drug to be expended.
r. Side Effects. Most drugs are not singular in action. They may produce
several different physiological responses at the same time. Antihistamines used for
their anti-allergic effect tend to produce drowsiness, which is a side effect of the drug.
Amphetamines are sometimes used to appease appetite in weight control, but at the
same time they cause nervousness and insomnia, which are side effects to the diet
client. Thus, to minimize undesirable side effects, a lower dose may be given, or
another drug may be given concomitantly to antagonize the side effect.
s. Drug Allergy (Hypersensitivity). A few individuals may be allergic, or
hypersensitive, to a drug because of prior contact with a particular substance called an
allergen (perhaps the same drug). This phenomenon of acquiring an allergy is called
sensitization. The symptoms of an allergic reaction are not related to the ordinary
effects of the drug. Thus, the allergic individual should not be confused with the
individual who is highly responsive to a drug and thus requires only a small dose to
achieve the desired therapeutic effect. Allergic reactions to a drug may range in
severity from a mildly irritating skin rash to a fatal state of shock (anaphylaxis). One
drug to which many clients are allergic is penicillin.
The antiseptic and disinfectant drugs are used extensively by both medical
personnel and the general public. These drugs act locally to produce their effects.
a. Antiparasitic. A preparation used to eliminate body parasites.