Which of the following local anesthetics would be most appropriate for a pregnant woman with a history of anaphylactic reaction to para-aminobenzoic acid (PABA)?

Correct Answer: C

Rationale: The correct answer is C: Lidocaine. Lidocaine is an amide-type local anesthetic that does not contain PABA, making it suitable for a patient with a history of anaphylactic reaction to PABA. Procaine (A) is an ester-type local anesthetic that metabolizes into PABA. Tetracaine (B) is also an ester-type local anesthetic that may cross-react with PABA. Benzocaine (D) is a para-aminobenzoic acid derivative and should be avoided in patients with a history of anaphylaxis to PABA.

Correct Answer: A

Rationale: The correct answer is A: Tubocurarine. Tubocurarine is a non-depolarizing muscle relaxant that works by blocking the action of acetylcholine at the neuromuscular junction. In a patient with Tubocurarine deficiency of plasma cholinesterase, using Tubocurarine as a muscle relaxant would be contraindicated because it would exacerbate the deficiency and lead to prolonged effects. Summary of other choices: B: Cisatracurium - Not contraindicated in a patient with Tubocurarine deficiency of plasma cholinesterase. C: Baclofen - Acts on spinal cord neurons, not related to neuromuscular junction function. D: Mivacurium - A short-acting non-depolarizing muscle relaxant, not contraindicated in this scenario.

Correct Answer: D

Rationale: The correct answer is D: Inhibition of acetylcholine exocytosis from cholinergic terminals. Botulinum toxin works by blocking the release of acetylcholine at the neuromuscular junction, leading to muscle paralysis. This inhibition prevents the communication between nerve cells and muscles, resulting in the therapeutic effect. Choices A, B, and C are incorrect as they do not directly relate to the mechanism of action of botulinum toxin in blocking acetylcholine release.

Correct Answer: C

Rationale: The correct answer is C: Propofol induction. Cisatracurium is preferred over tubocurarine for patients undergoing propofol induction due to its faster onset and shorter duration of action, aligning with propofol's rapid onset and short duration. This minimizes the risk of prolonged muscle paralysis and respiratory depression. Liver insufficiency (A) and renal insufficiency (D) would not affect the choice between cisatracurium and tubocurarine. Advanced age (B) alone is not a primary factor for choosing cisatracurium over tubocurarine.

Correct Answer: B

Rationale: The correct answer is B: Carbamazepine. The patient most likely took Carbamazepine because it is commonly used to treat trigeminal neuralgia, a condition characterized by severe facial pain. Valproic acid is used for seizures and mood disorders, not typically for facial pain. Lamotrigine is primarily used for seizures and bipolar disorder. Ethosuximide is used for absence seizures, not trigeminal neuralgia. Therefore, based on the patient's symptoms and common drug indications, Carbamazepine is the most likely drug taken.