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.
Mechanism of Drug Action-Drug Enzyme Interactions. in Pharmacology. Drug enzyme interaction is similar to drug receptor interactions. The drugs resemble the natural substrates, bind enzymes and cause change in their activity. This may take place by:1  Activation of enzymes. 2  Inhibition of enzymes.rug enzyme interaction is similar to drug receptor interactions. The drugs resemble the natural substrates, bind enzymes and cause change in their activity. This may take place by: 1  Activation of enzymes. 2  Inhibition of enzymes.