Likely Phenotype Example CYP2C19 Diplotypes Implication for Citalopram Metabolism Therapeutic Recommendations
Ultra-rapid *17/*17
*1/*17
Increased metabolism will lower drug levels Consider alternative drug
Extensive *1/*1 Normal metabolism Initiate therapy with recommended starting dose
Intermediate *1/*2
*1/*3
*2/*17
Reduced metabolism compared to extensive Initiate therapy with recommended starting dose
Poor *2/*2
*2/*3
*3/*3
Greatly reduced metabolism will increase drug levels Consider 50% reduction of starting dose or alternative drug