AGACNP Pharmacology Practice Questions (130 Flashcards)

Aging is associated with an increase in total body fat and a decrease in lean muscle mass. For lipid-soluble drugs like diazepam, this results in an increased Volume of Distribution (Vd). Clinical Pearl: An increased Vd leads to a significantly prolonged elimination half-life (t1/2), meaning the drug stays in the system longer, increasing the risk for accumulation and toxicity (sedation, falls). ANCC Tip: Distinguish between lipid-soluble (increased Vd) and water-soluble (decreased Vd) drugs in the elderly.

Tachyphylaxis. This is a rapid decrease in response to a drug after repeated administration (acute tolerance). In the case of Nitroglycerin, it is thought to be due to the depletion of free sulfhydryl groups needed for conversion to nitric oxide. AGACNP Tip: Differentiate Tachyphylaxis (rapid, hours) from Tolerance (gradual, days/weeks). Common ICU examples include Nitrates and Beta-2 agonists (Albuterol). Management often involves drug-free intervals to restore sensitivity.

This patient has neurogenic shock (loss of sympathetic tone + bradycardia). Phenylephrine is a pure alpha-1 agonist; while it increases SVR, it can cause reflex bradycardia, worsening the patient's existing bradycardia. The preferred agent is Norepinephrine or Dopamine because they provide both alpha-1 (vasoconstriction) and beta-1 (inotropic/chronotropic) support. ANCC Tip: Neurogenic shock requires an agent that addresses both the tank (vasodilation) and the pump (bradycardia). Phenylephrine is typically reserved for anesthesia-induced hypotension.

Administer Dantrolene (2.5 mg/kg IV). The patient is experiencing Malignant Hyperthermia (MH), a rare, hypermetabolic state triggered by volatile anesthetics or Succinylcholine. Dantrolene works by binding to the ryanodine receptor (RyR1), inhibiting the release of calcium from the sarcoplasmic reticulum into the cytosol, which halts the uncontrolled muscle contractions. Key 2026 update: Ryanodex (concentrated dantrolene) allows for faster reconstitution and administration than older formulations.

1. Faster INR correction (minutes vs hours). 2. Lower volume (avoids TACO/volume overload). 3. No need for blood typing or thawing. 4. Contains Factors II, VII, IX, X, and Proteins C/S. Exam Tip: FFP is only used if PCC is unavailable. Always co-administer Vitamin K for sustained effect.