The nurse will instruct patients about a possible systemic effect that may occur if excessive amounts of topically applied adrenergic nasal decongestants are used. Which systemic effect may occur?

Correct Answer: D

Rationale: The correct answer is D: Palpitations. Topically applied adrenergic nasal decongestants can be absorbed systemically, leading to increased sympathetic activity. This can manifest as palpitations due to excessive stimulation of the heart. Heartburn (A) is not a systemic effect of adrenergic nasal decongestants. Bradycardia (B) is unlikely as these drugs typically cause tachycardia. Drowsiness (C) is more commonly associated with antihistamines, not adrenergic decongestants.

Correct Answer: C

Rationale: The correct term for a gradual decrease in responsiveness to a drug over days or weeks is "tolerance." Tolerance occurs due to the body adjusting to the drug's effects, requiring higher doses for the same response. Refractoriness refers to a lack of response, not a reduced response. Cumulative effect refers to increased drug effects with repeated doses. Tachyphylaxis is a rapid decrease in responsiveness, not a gradual one. Therefore, "tolerance" is the best fit for the described scenario.

Correct Answer: B

Rationale: The correct answer is B, Bupivacaine. Bupivacaine is a long-acting local anesthetic with intrinsic vasoconstrictive properties, so using additional vasoconstrictors may not significantly prolong its anesthetic effects. Procaine (A), Lidocaine (C), and Mepivacaine (D) do not have intrinsic vasoconstrictive properties, so adding vasoconstrictors can help prolong their anesthetic effects.

Correct Answer: C

Rationale: The correct answer is C - On effector cell membranes of glandular and smooth muscle cells. The M3 receptor subtype is a muscarinic acetylcholine receptor, which is primarily located on the effector cell membranes of glandular and smooth muscle cells. This receptor subtype plays a key role in mediating parasympathetic responses in these cells. A: In the myocardium - This is incorrect as the M2 receptor subtype is predominantly located in the myocardium, not the M3 subtype. B: In sympathetic postganglionic neurons - This is incorrect as muscarinic receptors are not typically found in sympathetic neurons. D: On the motor end plates - This is incorrect as nicotinic acetylcholine receptors, not muscarinic receptors, are located on motor end plates.

Correct Answer: B

Rationale: The correct answer is B: Tubocurarine. Tubocurarine has the potential to cause the greatest release of histamine among the choices. This is because tubocurarine is a non-depolarizing neuromuscular blocking agent that can directly stimulate histamine release from mast cells, leading to histamine-related adverse effects like hypotension and bronchospasm. Succinylcholine (A) mainly activates nicotinic acetylcholine receptors, while Pancuronium (C) and Rocuronium (D) are less likely to cause significant histamine release compared to Tubocurarine.