TABLE 5.
Suggested dose adjustments based on CYP2D6 phenotype
| PERCENT OF STANDARD DOSE
| ||||
|---|---|---|---|---|
| DRUG | POOR METABOLIZERS | INTERMEDIATE METABOLIZERS | EXTENSIVE METABOLIZERS | ULTRA-RAPID METABOLIZERS |
| Imipramine (Tofranil) | 30 | 80 | 130 | 180 |
| Doxepin (Sinequan) | 35 | 80 | 130 | 175 |
| Trimipramine (Surmontil) | 35 | 90 | 130 | 180 |
| Despramine (Norpramin) | 40 | 80 | 125 | 170 |
| Nortriptyline (Pamelor) | 55 | 95 | 120 | 150 |
| Clomipramine (Anafranil) | 60 | 90 | 110 | 145 |
| Paroxetine (Paxil) | 65 | 85 | 115 | 135 |
| Venlafaxine (Effexor) | 70 | 80 | 105 | 130 |
| Amitriptyline (Elavil) | 75 | 90 | 105 | 130 |
| Bupropion (Wellbutrin) | 90 | 95 | 105 | 110 |
| Perphenazine (Trilafon) | 30 | 80 | 125 | 175 |
| Haloperidol (Haldol) | 75 | 95 | 100 | 115 |
| Olanzapine (Zyprexa) | 60 | 105 | 120 | 150 |
| Risperidone (Risperdal) | 85 | 90 | 100 | 110 |
Dose-adjustment values were determined by comparing drug concentration, clearance, or exposure data across phenotypes. Values have been approximated to the nearest 5%.
ADAPTED FROM INFORMATION IN KIRCHHEINER J, NICKCHEN K, BAUER M, ET AL. PHARMACOGENETICS OF ANTIDEPRESSANTS AND ANTIPSYCHOTICS: THE CONTRIBUTION OF ALLELIC VARIATIONS TO THE PHENOTYPE OF DRUG RESPONSE. MOL PSYCHIATRY 2004; 9:442–473.