TABLE 2.

Example discrepancies in antidepressant recommendations based on phenotype.

Example Medication	Genotype	CL Phenotype	CPIC Phenotype	Potential discrepancy in CPIC recommendations for different phenotypes
CYP2D6
Nortriptyline (any TCA)	*2A/*2A	Ultrarapid	Normal	Ultrarapid: Consider alternative
				Normal: Standard starting dose
Nortriptyline (any TCA)	*2A/*4	Normal	Intermediate	Normal: Standard starting dose
				Intermediate: 25% reduction in starting dose
Nortriptyline (any TCA)	*4/*41	Poor	Intermediate	Poor: Consider alternative Intermediate: 25% reduction in starting dose
CYP2C19
Escitalopram or citalopram	*1/*17	Normal	Rapid	Normal: Standard starting dose
				Rapid: Consider alternative
Escitalopram, citalopram, or sertraline	*2/*17	Normal	Intermediate	Normal: Standard starting dose
				Intermediate: Standard starting dose

Table 2: Highlighted discrepancies in medication recommendations based on different phenotypic interpretations of CYP2D6 and CYP2C19. TCA: tricyclic antidepressant (Hicks et al., 2015; Hicks et al., 2017).