| 3A4 |
It is the most abundant form among the CYP3A subfamily.
It
has low substrate specificity. Chemical properties of a drug critical
to CYP3A4 inactivation include the formation of reactive metabolites
by CYP isoenzymes, preponderance of CYP inducers and P-gp substrates/inhibitors,
and occurrence of clinically significant PK interactions with coadministered
drugs. Mechanism-based inhibition of CYP3A4 causes PK-PD drug–drug
interactions that may lead to adverse drug effects |
(33) |
| 1A2 |
It is an important metabolizing enzyme in the liver,
comprising
approximately 13% of all CYP proteins. There are more than 100 substrates
reported for CYP1A2 |
(34) |
| 2C19 |
It is a clinically important enzyme responsible for the metabolism
of several drugs. CYP2C19 is also known to be involved in the detoxification
of potential carcinogens or the bioactivation of some environmental
procarcinogen(s) to reactive DNA binding metabolites |
(29) |
| 2C9 |
It is abundantly expressed and contributes
to drug metabolism
to the greatest extent. It is the major enzyme responsible for the
metabolic clearance of several drugs with a narrow therapeutic index.
Thus, interindividual variability in CYP2C9 protein expression and
activity may impact the efficacy and safety of drug treatment. CYP2C9
substrates used therapeutically, especially those where drug interactions
and effects of genetic polymorphisms may affect treatment outcomes |
(35) |
| 2D6 |
It is involved in the hepatic metabolism
of many clinically
used medications. The CYP2D6 gene is highly polymorphic, and its function
is highly variable. People with decreased or no CYP2D6 enzyme activity
may be at risk of reduced efficacy and/or adverse effects when taking
medications metabolized by CYP2D6 |
(36) |
