Table 2.
Changes in the cytochrome P450 activity with ageing.
| CYP Enzyme | Change with ageing | Probe drug used | Confounding factors |
|---|---|---|---|
| CYP1 | ↓ | Theophylline | Ethnic polymorphisms, sex differences, lifestyle, and disease |
|
| |||
| CYP2CYP2C9CYP2C19 | ↓ (~25%) | PhenytoinWarfarinOmeprazole | Age-related effects, and unrecognised environmental effects, and pharmacogenetic variation |
|
| |||
| CYP2D6 | ↓ Older women↓ Older Japanese men | DextromethorphanHaloperidol | Genetic polymorphisms |
|
| |||
| CYP2E1 | ↓ Aged rats↔ Aged mice↓ Activity in human liver microsomes↔ Human hepatocytes | Chlorzoxazone | ? Gender-conflicting results Polymorphisms |
|
| |||
| CYP3ACYP3A4 | ↓ Aged rodents↔ Humans↑ CL in women, no age effects | Cyclosporine, Erythromycin, Verapamil, Midazolam | InducersInducers |
| Multiple | ↓ | Antipyrine | Metabolised by CYP3A4, 1A2 and 2C8/9 |