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Drug Elimination
Irreversible removal of drug from the body.
Excretion
Removal of intact drug from the body.
Biotransformation
Chemical conversion of drug to metabolite.
First-pass effect
Metabolism in liver reduces active drug availability.
Phase I Metabolism
Involves oxidation, reduction, or hydrolysis reactions.
Phase II Metabolism
Conjugation of metabolites to enhance water solubility.
Cytochrome P450
Key enzyme family in drug metabolism.
CYP450 Enzymes
Over 50 enzymes metabolizing 90% of drugs.
Hydrophilic Molecules
More polar molecules for easier elimination.
Prodrugs
Inactive drugs converted to active forms post-metabolism.
Oxidation
Addition of oxygen or removal of hydrogen.
Reduction
Removal of oxygen or addition of hydrogen.
Hydrolysis
Addition of water to break down compounds.
Enzyme Induction
Increases P450 enzyme activity and drug metabolism.
Enzyme Inhibition
Decreases P450 enzyme activity and increases drug effects.
Grapefruit Juice
Causes suicide inhibition of CYP3A4 enzymes.
Renal Excretion
Primary route for drug elimination via urine.
Clinical Relevance
Understanding metabolism impacts drug efficacy and safety.
Liver Activity
Primary site for drug metabolism (100% activity).
Tissue Distribution
Metabolism occurs in liver, lungs, kidneys, etc.
NAPQI
Toxic metabolite of paracetamol causing liver damage.
Glucuronidation
Phase II process making drugs more water-soluble.
Gray Baby Syndrome
Toxicity in neonates due to glucuronyl transferase deficiency.
Active Metabolite
Converted active drug prolonging therapeutic effects.
Inactive Metabolite
Converted active drug resulting in termination of action.
Microsomal Enzymes
Located in endoplasmic reticulum, involved in metabolism.
Non-microsomal Enzymes
Present outside endoplasmic reticulum, catalyze various reactions.
Factors Affecting Metabolism
Include enzyme induction, inhibition, and genetic factors.
