SYNERGISM

in chemotherapy, the situation in which the combined effects of two drugs that produce different particular effects (i.e., are heterergic) are greater than those of each drug alone. The term potentiation, often used as a synonym for synergism, is sometimes erroneously used to mean clinical superiority of a drug. Synergism may result from changes in the distribution, biotransformation, or excretion of the drugs. An example of synergism is the treatment of migraine with both ergotamine and caffeine; in fact, there are preparations available that contain both drugs. Caffeine potentiates the effects of ergotamine, which decreases the amplitude of pulsations of the cranial arteries, by constricting blood vessels in the brain, thereby reducing the flow of blood. See also antagonism.