Antidepressants Consider genotyping:

•In patients experiencing side effects or lack of efficacy after treatment with an adequate dose of an SSRI or SNRI. (see Table 2). Genotyping should be considered especially in patients that experienced side effects or inefficacy with multiple psychotropic drugs with a similar CYP metabolism.

•In patients experiencing side effects or unexplained high or low blood drug levels in patients using TCA (tricyclic antidepressants).

•When next to above, there are side effects and/or inefficacy with other (somatic) pharmaca with similar CYP metabolism.

Antipsychotics Consider genotyping:

•When patients experience side effects or lack of efficacy with antipsychotics other than clozapine, where medication advise is available (see Table 2). This should considered especially in patients that experienced side effects or inefficacy using other antipsychotics also with similar CYP metabolism.

•When next to above there are side effects and/or inefficacy with other (somatic) pharmaca with similar CYP metabolism.

Clozapine

When starting clozapine treatment use the blood level of the drug (TDM; therapeutic drug monitoring). Also, use TDM to optimize clozapine treatment. CYP1A2 genotyping is of limited value.

Lithium

Do not use genotyping for CYP enzymes for lithium treatment as lithium is cleared unchanged by the kidney and not by CYP enzymes.

Consider dose adjustment when starting the medication described in Table 2 for different phenotypes. Also, take into account possible interactions resulting from comedication or diet.