Table 1.

Select medications with pharmacogenetic associations.

Drug	Gene(s)	US FDA pharmacogenetic information on drug label	Pediatric data on FDA label
Codeine	CYP2D6	Summary of Pharmacogenetic Statement: ultrarapid metabolizers who have multiple copies of the CYP2D6 genotype may experience overdose symptoms at labeled doses. Guidance: “When physicians prescribe codeine-containing drugs, they should choose the lowest effective dose for the shortest period of time and inform their patients about these risks and the signs of morphine overdose”	“The safety, effectiveness and the pharmacokinetics of codeine sulfate in pediatric patients below the age of 18 have not been established”
Mercaptopurine	TPMT	Summary of Pharmacogenetic Statement: individuals homozygous for nonfunctional TPMT alleles are unusually sensitive to the myelosuppressive effects of mercaptopurine and are prone to developing rapid bone marrow suppression following the initiation of treatment. Genotype and phenotype tests are available to determine the TPMT status. Guidance: “If a patient has clinical or laboratory evidence of severe toxicity, particularly myelosuppression, TPMT testing should be considered. In patients who exhibit excessive myelosuppression due to 6-mercaptopurine, it may be possible to adjust the mercaptopurine dose and administer the usual dosage of other myelosuppressive chemotherapy as required for treatment”	Approved for “maintenance therapy of acute lymphatic (lymphocytic, lymphoblastic) leukemia as part of a combination regimen”
Warfarin	CYP2C9 VKORC1 CYP4F2	Summary of Pharmacogenetic Statement: CYP2C9 and VKORC1 genotype information, when available, can assist in selection of the initial dose of warfarin Guidance: “If the patient’s CYP2C9 and/or VKORC1 genotype are known, consider these ranges (table provided) in choosing the initial dose” Also, “consult the latest evidence-based clinical practice guidelines from the American College of Chest Physicians…”	“Adequate and well-controlled studies … have not been conducted in any pediatric population, and the optimum dosing, safety and efficacy in pediatric patients is unknown”
Simvastatin	SLCO1B1	None	“Simvastatin orally disintegrating tablets are indicated as an adjunct to diet to reduce total-C, LDL-C and apoB levels in adolescent boys and girls who are at least 1 year postmenarche, 10–17 years of age, with heterozygous familial hypercholesterolemia, if after an adequate trial of diet therapy the following findings are present: LDL cholesterol remains ≥190 mg/dl; or LDL cholesterol remains ≥160 mg/dl and there is a positive family history of premature CVD or two or more other CVD risk factors are present in the adolescent patient”

C: Cholesterol; CVD: Cardiovascular disease; LDL: Low-density lipoprotein; TPMT: Thiopurine methyltransferase.

Data taken from [104].