The individual response to drugs is a hereditary characteristic. Variations and mutations in the genome (DNA) can result in the expression of altered proteins and thus also in altered metabolising enzymes or enzymes with altered activity. Every individual has a unique set of enzymes for metabolism.Pharmacogenetics can help making drug therapy more effective and safer.
Female patient, age 65 with pain complaints
Medication: paracetamol and codeine
The normal dose is not effective.
With increased dose there still is no improvement, although the adverse effects become worse.
Cause: the patient belongs to the small group of patients lacking the CYP2D6 enzyme and thus the patient is a poor metaboliser. Codeine needs to be converted by this CYP2D6 enzyme into morphine in order to have the palliative effect.
See how genetic status affects drug concentration here.