Lecture 5

The Drug Metabolizing Microsome System (DMMS) utilizes cytochrome P450 enzymes, which transform drugs into metabolites through oxidation and reduction reactions.

Drug metabolism can lead to enzyme induction or inhibition, affecting drug duration of action.

Drug Metabolism: Phase I (R-OH) primarily involves oxidation and reduction, yielding slightly polar metabolites that can still be active.

Drug Metabolism: Phase II (conjugation) involves methylation, glucuronidation, acetylation, and sulfation, producing highly polar, inactive metabolites for renal excretion.

Cytochrome P-450 Enzymes (3A4) are found in the liver, gut lumen, enterocytes, and systemic circulation.

Neonates/Infants have a reduced drug metabolism capacity, resulting in slower elimination and prolonged drug duration of action. Conversely, aging causes a decrease in drug metabolism rate due to reduced liver blood flow and increased body fat.

Renal elimination involves glomerular filtration, proximal tubular secretion, and distal tubular reabsorption.

Elimination kinetics include zero order and first order elimination, where zero-order elimination results in constant elimination rates and first-order elimination follows an exponential decay.

Half-life is the time required for the plasma drug concentration to decrease to half of its initial level and is essential for determining drug administration frequency.

Half-life is influenced by factors like liver and kidney function, volume of distribution, and clearance, making these essential in calculating drug half-life.

In a practice scenario, given a drug's half-life (5 hours) and initial plasma drug concentration (24 mg/L), the time it takes to reach a plasma concentration of 3 mg/L can be calculated. The answer is C. 15 hours.

The Drug Metabolizing Microsome System (DMMS) utilizes cytochrome P450 enzymes, which transform drugs into metabolites through oxidation and reduction reactions.

Drug metabolism can lead to enzyme induction or inhibition, affecting drug duration of action.

Drug Metabolism: Phase I (R-OH) primarily involves oxidation and reduction, yielding slightly polar metabolites that can still be active.

Drug Metabolism: Phase II (conjugation) involves methylation, glucuronidation, acetylation, and sulfation, producing highly polar, inactive metabolites for renal excretion.

Cytochrome P-450 Enzymes (3A4) are found in the liver, gut lumen, enterocytes, and systemic circulation.

Neonates/Infants have a reduced drug metabolism capacity, resulting in slower elimination and prolonged drug duration of action. Conversely, aging causes a decrease in drug metabolism rate due to reduced liver blood flow and increased body fat.

Renal elimination involves glomerular filtration, proximal tubular secretion, and distal tubular reabsorption.

Elimination kinetics include zero order and first order elimination, where zero-order elimination results in constant elimination rates and first-order elimination follows an exponential decay.

Half-life is the time required for the plasma drug concentration to decrease to half of its initial level and is essential for determining drug administration frequency.

Half-life is influenced by factors like liver and kidney function, volume of distribution, and clearance, making these essential in calculating drug half-life.

In a practice scenario, given a drug's half-life (5 hours) and initial plasma drug concentration (24 mg/L), the time it takes to reach a plasma concentration of 3 mg/L can be calculated. The answer is C. 15 hours.