Drug Tolerance and Tachyphylaxis — Flashcards

Flashcard 1: Examples of drugs eliminated by zero-order elimination include _____, ethanol, and aspirin (high concentrations)

Answer: phenytoin

Flashcard 2: Which enzyme in the heme synthesis pathway is induced by barbiturates (and related drugs)?_____

Answer: $\delta$-aminolevulinic acid (ALA) synthase

Flashcard 3: Oxcarbazepine _____ cause auto-induction of metabolizing enzymes.

Answer: does not (does/does not)

Flashcard 4: Cabergoline is a _____-acting D2 agonist

Answer: longer

Flashcard 5: The loading dose of a drug is governed primarily by its _____

Answer: Vd

Flashcard 6: _____ is a phenomenon that occurs when tolerance to the effects of one drug produces tolerance to another drug

Answer: Cross-tolerance

Flashcard 7: What formula is used to calculate **loading dose**?

Answer: Loading Dose = $\frac{C_p \times V_d}{F}$

Extra: $C_p$ = target plasma concentration $V_d$ = volume of distribution $F$ = bioavailability

Flashcard 8: What is the formula for half-life (t1/2) in first-order elimination kinetics?

Answer: t1/2 = (0.693 × Vd) / CL

Extra: Where: - Vd = Volume of distribution - CL = Clearance Note: In first-order kinetics, the half-life is constant regardless of the plasma concentration.

Flashcard 9: What is the formula for Volume of Distribution (Vd)?

Answer: Vd = Amount of drug in the body / Plasma drug concentration (Cp)

Flashcard 10: What is the formula for calculating the **maintenance dose**? _____

Answer: (Cp × CL × τ) / F