Drug Efficacy and Potency — Flashcards

Flashcard 1: When the rate of drug **administration** equals the rate of drug **elimination**, the drug has reached _____ concentration.

Answer: Steady-state concentration (Css)

Extra: Steady-state is achieved when the rate of drug administration (input) equals the rate of drug elimination (output). It typically takes 4–5 half-lives (t½) to reach steady-state. Formula for IV infusion: $Css = \frac{Rate\ of\ infusion}{Clearance}$

Flashcard 2: _____ and ofloxacin have the maximum bioavailability among fluoroquinolones.

Answer: Levofloxacin

Flashcard 3: Time for peak plasma concentration (Tmax) of a drug indicates the rate of _____ from the administered site.

Answer: absorption

Flashcard 4: The half-life of letrozole is _____ hours.

Answer: 45

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

Answer: Vd

Flashcard 6: 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 7: 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 8: What is the formula for Volume of Distribution (Vd)?

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

Flashcard 9: What is the formula for calculating the **maintenance dose**? _____

Answer: (Cp × CL × τ) / F

Flashcard 10: Sketchy Pharmacology: Neuro/Psych Does the blue curve represent an inhaled anesthetic with a high or low blood solubility? _____

Answer: Low (quickly saturated, e.g. N2O)