by
David F. Kisor, Pharm.D., FCP
| Oct 17, 2017
Pharmacogene: CYP2C19
Type of pharmacogene: Pharmacokinetic
CYP2C19 codes for the drug-metabolizing enzyme CYP2C19. This enzyme is responsible for metabolizing approximately eight percent (8%) of medications. Variants of this pharmacogene may affect drug metabolism of substrate drugs.
Pharmacogene Variant of the Week (PVOW 10_15_2017): CYP2C19*2
Reference single nucleotide polymorphism number: rs4244285
DNA base change: c.681G>A
Pharmacogene function as compared to normal function: No function
Pharmacogene product: CYP2C19 drug metabolizing enzyme
Pharmacogene product activity as compared to normal activity: None
General Conceptual Pharmacogene Variant Information
CYP2C19*2 Imparts:
Increased drug exposure
- Higher maximum concentration
- Increased area under the curve (AUC)
- Longer half-life
Note: For a prodrug, less of the active drug will be formed.
Drug Exposure Plot
Note: "No" or "decreased" function/activity shown in relative terms.
Conceptual statement 1: Notwithstanding other variables, individuals with one (heterozygous) or two (homozygous) copies of this pharmacogene variant will likely have decreased drug metabolism of an administered active drug, with increased exposure and potential increased risk of an adverse drug reaction.
Conceptual statement 2: Notwithstanding other variables, individuals with one (heterozygous) or two (homozygous) copies of this pharmacogene variant will likely have decreased drug metabolism of an administered prodrug, with decreased exposure to the active drug and potential increased risk of drug inefficacy.
The reader is directed to https://www.pharmgkb.org/haplotype/PA166128325/guideline