PTCB Pharmacology #1 3 Flashcards

Which enzyme does warfarin inhibit to produce its anticoagulant effect?

Answer: Vitamin K epoxide reductase

Warfarin inhibits vitamin K epoxide reductase, preventing the recycling of vitamin K. This depletes vitamin K-dependent clotting factors (II, VII, IX, X) and proteins C and S.

Statins reduce LDL cholesterol primarily by:

Answer: Inhibiting HMG-CoA reductase in the liver

Statins competitively inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis, reducing intracellular cholesterol and upregulating LDL receptors on hepatocytes.

A drug with a narrow therapeutic index (NTI) is best described as:

Answer: A drug where there is little difference between the effective and toxic dose

Narrow therapeutic index drugs (e.g., warfarin, digoxin, lithium, phenytoin) have a small window between therapeutic and toxic concentrations, requiring close monitoring and dose adjustments.

Omeprazole (Prilosec) is an example of which type of drug?

Answer: Proton pump inhibitor

Omeprazole is a PPI (proton pump inhibitor) that irreversibly inhibits the H+/K+ ATPase. H2 blockers (ranitidine, famotidine) reversibly block histamine H2 receptors on parietal cells.

Which of the following neurotransmitters is primarily affected by SSRI antidepressants?

Answer: Serotonin

SSRIs (selective serotonin reuptake inhibitors) block the serotonin transporter (SERT), increasing synaptic serotonin levels. SNRIs affect both serotonin and norepinephrine.

What is a prodrug?

Answer: A drug administered in an inactive form that is converted to the active form in the body

A prodrug is pharmacologically inactive until metabolized (usually hepatically) into its active form. Examples include clopidogrel (active metabolite via CYP2C19), enalapril (→enalaprilat), and codeine (→ morphine).