In ecology, commensalism is a class of relationship between two organisms where one organism benefits without affecting the other. It compares with mutualism, in which both organisms benefit, amensalism, where one is harmed while the other is unaffected, and parasitism, where one benefits while the other is harmed.n ecology, commensalism is a class of relationship between two organisms where one organism benefits without affecting the other. It compares with mutualism, in which both organisms benefit, amensalism, where one is harmed while the other is unaffected, and parasitism, where one benefits while the other is harmed.
Drug interactions also may occur when two drugs that have similar (additive) effects or opposite (canceling) effects on the body are administered together. For example, there may be major sedation when two drugs that have sedation as side effects are given, for example, narcotics and antihistamines.
Definition. An inverse agonist is a molecule that binds to the same site as an agonist and is considered to be a full agonist. However, it elicits the opposite effect to that of a normal agonist, i.e.: demonstrates negative efficacy.n antagonist reduces the effect of an agonist by preventing it from binding to receptors. Both antagonists and inverse agonists reduce the activity if a receptor and, in the presence of an agonist, reduce its activity.