Pharmacology Flashcards

A patient is taking a monoamine oxidase inhibitor (MAOI). Which sedation-related drug combination poses the greatest risk of a life-threatening interaction?

Answer: Meperidine and an MAOI

Meperidine combined with MAOIs can cause a serotonin syndrome or excitatory reaction that may be fatal; this combination is absolutely contraindicated.

Which property of nitrous oxide makes it unsuitable for prolonged use (>6 hours) or use in patients with vitamin B12 deficiency?

Answer: It irreversibly inhibits methionine synthase

Nitrous oxide irreversibly oxidizes the cobalt atom in vitamin B12, inhibiting methionine synthase and impairing DNA synthesis, which is especially harmful with prolonged exposure.

The vasopressor of choice for treating hypotension caused by anaphylaxis during dental sedation is:

Answer: Epinephrine 1:1,000 IM

Epinephrine 1:1,000 (0.3-0.5 mg) administered IM into the lateral thigh is the first-line treatment for anaphylaxis due to its rapid bronchodilatory and vasopressor effects.

Propofol's rapid emergence from sedation is primarily due to which pharmacokinetic property?

Answer: High lipid solubility enabling rapid redistribution

Propofol's high lipid solubility allows rapid redistribution from the brain to peripheral tissues, explaining the quick recovery even though its terminal half-life is several hours.

Which of the following describes the mechanism of action of succinylcholine (a depolarizing neuromuscular blocker)?

Answer: Binds and activates nicotinic receptors, causing persistent depolarization

Succinylcholine mimics acetylcholine at nicotinic receptors, causing depolarization and initial fasciculations, then sustained depolarization prevents repolarization and produces flaccid paralysis.

A patient on chronic opioid therapy requires IV sedation. Compared to an opioid-naive patient, this patient will likely need:

Answer: Higher doses of opioids due to tolerance, but same benzodiazepine doses

Chronic opioid use leads to pharmacodynamic tolerance at mu receptors, requiring higher opioid doses for the same effect, while benzodiazepine requirements are generally unchanged.

Which statement about atropine use in dental anesthesia is CORRECT?

Answer: It reduces secretions and treats bradycardia by blocking muscarinic receptors

Atropine is an anticholinergic (antimuscarinic) agent that reduces salivary and airway secretions and increases heart rate, making it useful for treating sedation-related bradycardia.