PharmacologyGenetics Enzymes mediate how drugs are metabolized, or broken down, and either enter the bloodstream or are excreted. The primary enzyme class consists of the Cytochrome P450 (CYP450) enzymes. Each isozyme has a unique identifier (over 50 types). Each isozyme has genetic variations, called Alleles (think genetic variation that causes differing eye color). The varying alleles for a CYP450 isozyme causes variation in function (slow vs fast vs no metabolism). Changes in metabolism can have dramatic effect on the effectiveness and toxicity of a drug. This is an example of genetic variation, and how pharmacogenomics influences pharmacokinetics (what the body does to a drug). We could use an individuals specific genome in order to prescribe the correct amount: i.e. pharmacogenomics for personalized/precision medicine.
Example: Codeine is a poor opioid receptor agonist (weak psychoactive effects), but ~10% of codeine is demethylated (remove
The largest barrier in this field is relating genes to outcomes! Most drugs have a complex metabolic pathway, involving multiple enyzmes: i.e. a complex, dynamical system! In addition, a person’s end effect is influenced by many other genetic, environmental, or biological factors.