Pharmacokinetics- Metabolism Flashcards
What is Metabolism?
A process that renders lipid-soluble and non-polar compounds to water-soluble and polar compounds, so that they are excreted by various processes.
What happens to lipid soluble substances in metabolism?
Are passively reabsorbed from renal or extrarenal excretory sites into the blood.
Define Biotransformation
Chemical transformation of xenobiotics in living organisms.
Biotransformation is needed for:
a. Detoxification
b. Protect the body from injected toxins.
c. Both
C. Both
Xenobiotics are….
Chemical substances found in living organisms that aren’t naturally produced
The 4 Functions of Biotransformation are:
Hint: PPLT
- Pharmacological inactivation
- Pharmacological activation
- Lethal synthesis
- Toxicological activation or Bioactivation.
Difference between Pharmacological inactivation (PI) and Pharmacological activation (PA).
PI - Conversion of an active drug to inactive or less active metabolite.
PA - Conversion of an inactive drug (pro-drugs) to active metabolite.
What is a Pro-drug?
Inactive drug that undergoes metabolism to become an active metabolite.
Difference between Toxicological activation and Lethal synthesis.
Toxicological activation - Conversion of an active drug to more active metabolite.
Lethal synthesis - conversion of an inactive to more active metabolite.
Pharmacological inactivation example
Phenobarbitone to pHydroxyphenobarbitone
Toxicological activation example
Codeine to Morphine
Pharmacological activation example
Phenacetin to Paracetamol
Explain ‘No change in pharmacological activity’
Conversion of an active drug to equally active metabolite.
Explain ‘Change in pharmacological activity’
Conversion of an active drug to active metabolite, but different pharmacological activity.
Major site of drug metabolism is the….
Liver
What happens in Phase I of Metabolism?
A functional group is generated.
A parent drug is converted to a more polar metabolite by introducing or unmasking small polar functional groups of molecules.
Name some Phase I reactions.
Oxidation
Reduction
Hydrolysis
Phase I results in…
Activation, Change or Inactivation of drug.
What happens in Phase II of Metabolism?
An endogenous radical is conjugated.
Attachment of polar endogenous molecules to the functional group of unchanged drugs
Example of endogenous molecule
Glucuronic acid
Amino acids
