In adults, the condition refers to any penis smaller than 2.8 inches in length. (2) In infants, a Micropenis is classed as any penis that is less than 0.75 inches in length. This is considered significantly smaller than a ânormalâ male newbornâs penis, which is between 1.1 and 1.6 inches in length when stretched gently.
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.
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.