what is a drug to drug interaction
drug-drug interaction, a modification of the effect of a drug when administered with another drug. The effect may be an increase or a decrease in the action of either substance, or it may be an adverse effect that is not normally associated with either drug.he effect may be an increase or a decrease in the action of either substance, or it may be an adverse effect that is not normally associated with either drug.
A drug interaction is a situation in which a substance (usually another drug) affects the activity of a drug when both are administered together.he opposite effect to synergy is termed antagonism. Two drugs are antagonistic when their interaction causes a decrease in the effects of one or both of the drugs. Both synergy and antagonism can both occur during different phases of the interaction of a drug with an organism, with each effect having a different name.