Biotransformation (Metabolism) Quiz

Study Notes

Biotransformation is the process of chemical modification of drugs in the body, facilitating their elimination through the kidneys.
The liver is the primary organ for drug metabolism, but other organs, including the kidney, gut mucosa, lungs, blood, and skin, also contribute to the process.
The goal of biotransformation is to convert drugs into more water-soluble, polar compounds that can be excreted easily.
Some drugs are excreted unchanged in the urine, such as Furosemide and atenolol.
Biotransformation can result in several outcomes:
- Inactivation: Drugs are rendered less effective or completely inactive, such as phenobarbitone, morphine, and chloramphenicol.
- Formation of active metabolites: Certain drugs are converted into active metabolites that can enhance their therapeutic effects. For example, enrofloxacin is transformed into ciprofloxacin.
- Formation of toxic metabolites: In some cases, the metabolites produced can be toxic, like paracetamol being converted into N-acetyl-p-benzoquinone imine (NAPQI), which can cause liver damage.
- Activation of inactive drugs (prodrugs): Biotransformation can transform inactive drugs into their active forms. For example, levodopa is converted into dopamine, prontosil is converted into sulfanilamide.
Biotransformation reactions are catalyzed by enzymes, which can be found in the liver microsomes (microsomal enzymes) or in the cytoplasm and mitochondria (non-microsomal enzymes).