key term - Cytochrome P450

Definition

Cytochrome P450 refers to a large family of enzymes that play a crucial role in the biotransformation and metabolism of various substances in the body, including drugs, toxins, and endogenous compounds. These enzymes are primarily found in the liver and are responsible for oxidative reactions that modify chemical structures, making them more water-soluble and easier to excrete. This process is vital for detoxifying harmful substances and can also influence the efficacy and safety of medications.

5 Must Know Facts For Your Next Test

1. Cytochrome P450 enzymes are named for their absorption spectrum; they absorb light at a wavelength of 450 nm when bound to carbon monoxide.
2. There are over 50 different cytochrome P450 genes identified in humans, with CYP3A4 being the most abundant and responsible for metabolizing approximately 50% of all clinically used drugs.
3. These enzymes can be induced or inhibited by various substances, including other drugs, leading to significant variations in drug metabolism and responses among individuals.
4. Cytochrome P450 plays a role not only in drug metabolism but also in the metabolism of endogenous compounds like steroids and fatty acids.
5. Genetic polymorphisms in cytochrome P450 genes can lead to differences in drug metabolism rates among individuals, affecting therapeutic outcomes and risk of adverse effects.

Review Questions

• How do cytochrome P450 enzymes influence the metabolism of drugs within the body?
  • Cytochrome P450 enzymes influence drug metabolism by catalyzing oxidative reactions that transform lipophilic drug compounds into more hydrophilic metabolites. This transformation enhances the solubility of drugs, facilitating their excretion through urine or bile. The activity of these enzymes can significantly affect how quickly or effectively a drug is metabolized, which can impact its therapeutic efficacy and safety.
• What role does genetic variability in cytochrome P450 enzymes play in personalized medicine?
  • Genetic variability in cytochrome P450 enzymes is critical for personalized medicine as it leads to differences in individual responses to medications. Some patients may have polymorphisms that cause them to metabolize certain drugs too quickly or too slowly. Understanding these genetic differences allows healthcare providers to tailor drug choices and dosages for optimal effectiveness while minimizing adverse effects, thus enhancing individualized treatment plans.
• Evaluate the impact of cytochrome P450 enzyme interactions on polypharmacy in elderly patients.
  • In elderly patients who often take multiple medications (polypharmacy), interactions involving cytochrome P450 enzymes can significantly impact drug therapy. The altered metabolism due to enzyme induction or inhibition can lead to increased toxicity or reduced effectiveness of medications. Therefore, understanding these interactions is essential for clinicians to avoid adverse drug events and ensure safe prescribing practices, especially as aging can also lead to changes in liver function and enzyme activity.

Related terms

Biotransformation:

The chemical modification made by an organism on a chemical compound, typically referring to the metabolic conversion of drugs into more polar and readily excretable forms.

Hepatic Metabolism: The process by which the liver chemically alters drugs and other substances, often involving cytochrome P450 enzymes to facilitate their elimination from the body.

Drug Interactions: The effects that occur when two or more drugs affect each other's pharmacokinetics or pharmacodynamics, often mediated by cytochrome P450 enzymes which can alter drug metabolism.