Ciprofloxacin and Clozapine: A Potentially Fatal but Underappreciated Interaction

Table 4

US FDA classification of in vivo cytochrome P450 inhibitors by impact on area under the curve (AUC) and clearance [21].

Strength of interaction	Definition
Strong	A strong inhibitor for a specific CYP is defined as an inhibitor that increases the AUC of a substrate for that CYP by equal to or more than 5-fold (or >80% decrease in clearance)
Moderate	A moderate inhibitor for a specific CYP is defined as an inhibitor that increases the AUC of a sensitive substrate for that CYP by less than 5-fold but equal to or more than 2-fold (or 50%–80% decrease in clearance)
Weak	A weak inhibitor for a specific CYP is defined as an inhibitor that increases the AUC of a sensitive substrate for that CYP by less than 2-fold but equal to or more than 1.25-fold (or 20%–50% decrease in clearance)