The following tables include information about various P450 enzyme subtypes and their interaction with various chemicals. Rational approach to investigate antimicrobial drug-drug interactions. Psychotropic Drug Handbook, page 143 Table 2-1. Concentration rises to a new steady state consistent with a change in its clearance. The time to achieve the new steady state is greater than the time to achieve the initial steady state, because the half-life is now prolonged from its original value.
Drug interactions are graded phenomena.
The degree of interaction depends on the concentration of interacting drugs and, therefore, on the dose and timing of administration. Drug interactions are most likely to be detected when therapy with an interacting drug is initiated or discontinued. The clinical significance will depend on the particular drugs involved, the physiological state of the patient, the Presence of concurrent illness, and other factors. Drugs with a narrow concentration range over which therapeutic effects are present without incurring toxicity are more likely to be involved in clinically significant drug interactions. The most thoroughly studied reaction is the competitive inhibition of CYP2D6.