Tests for drug-metabolizing enzymes that are relevant or potentially relevant clinically
| Grade of Usefulness | Drug | Score (Table 2) | Enzyme | Phenotype or Genotype Preferred | Comment/Recommendation |
|---|---|---|---|---|---|
| Definite | Azathioprine, 6-MP | 14 | TPMT | Phenotype | Prospective testing should be routine |
| Suxamethonium, mivacurium | a | BChE | Phenotype or genotype | Retrospective in cases; prospective in family studies | |
| Probable | Warfarin (acenocoumarol) | 12 | CYP2C9 | Genotype | Prospective testing may help |
| Phenytoin | 10 | CYP2C9 (CYP2C19) | Genotype | Prospective testing may help | |
| Perhexiline | 10 | CYP2D6 | Phenotype (parent to metabolite ratio) | Prospective genotyping may be also helpful | |
| Omeprazole, lansoprazole | 9 | CYP2C19 | Genotype | Retrospective testing may help in nonresponse | |
| Possible | Codeine | 8 | CYP2D6 | Genotype | Retrospective testing may help in nonresponse |
| Nortriptyline | 8 | CYP2D6 | Genotype | Prospective testing may help | |
| Metoprolol | 7 | CYP2D6 | Genotype | Unlikely in practice | |
| Atomoxetine | 6 | CYP2D6 | Genotype | Prospective testing may help | |
| Propafenone | 6 | CYP2D6 | Genotype | Unlikely in practice | |
| 5-Fluorouracil | 6 | DPD | Depends on local expertise | Prospective testing may help | |
| Tolbutamide | 6 | CYP2C9 | Genotype | Prospective testing may help | |
| Efavirenz | 5 | CYP2B6 | Genotype | Prospective testing may help | |
| Hydralazine | 5 | NAT2 | Genotype | Retrospective testing may help in nonresponse | |
| Irinotecan | 5 | UGT1A1 | Genotype | Prospective testing may help | |
| Tropisetron | 5 | CYP2D6 | Genotype | Unlikely in practice | |
| Losartan | 4 | CYP2C9 | Genotype | Unlikely in practice |
↵ a The suxamethonium-BChE combination did not work well with our algorithm and already has a definite place in therapeutics