Which of the following drugs was most likely given to the 65-year-old woman undergoing hysterectomy to counteract tubocurarine-induced hypotension?

Correct Answer: B

Rationale: The correct answer is B: Dantrolene. Dantrolene is a muscle relaxant that acts directly on the skeletal muscle to reduce muscle tone and counteract tubocurarine-induced hypotension in the 65-year-old woman undergoing hysterectomy. Botulinum toxin is used for muscle spasticity, not hypotension. Succinylcholine is a short-acting muscle relaxant, not used for hypotension. Tubocurarine is the drug causing the hypotension, not used to counteract it.

Correct Answer: B

Rationale: The correct answer is B: Baclofen. Baclofen is a muscle relaxant commonly used to treat spasticity in conditions such as multiple sclerosis or spinal cord injuries. This drug would be appropriate for a patient experiencing muscle spasticity. Phenobarbital (A) is a barbiturate used for seizures, not muscle relaxation. Tubocurarine (C) and Succinylcholine (D) are neuromuscular blocking agents used for muscle paralysis during surgery, not for muscle spasticity. Therefore, Baclofen is the most appropriate choice for this patient.

Correct Answer: B

Rationale: The correct answer is B: Valproic acid. This drug is commonly used to treat bipolar disorder, which is characterized by mood swings. Valproic acid helps stabilize mood and prevent manic episodes. Lamotrigine (A) is used for bipolar disorder but is less effective for acute mania. Clonazepam (C) is used for anxiety and seizures, not bipolar disorder. Gabapentin (D) is primarily used for nerve pain and seizures, not bipolar disorder. Therefore, based on the context of the question, Valproic acid is the most likely drug she was taking.

Correct Answer: D

Rationale: The correct answer is D: Pancreatitis. During therapy, certain medications can cause pancreatitis due to their toxic effects on the pancreas. This can lead to inflammation of the pancreas, resulting in symptoms such as severe abdominal pain, nausea, and vomiting. Pancreatitis is a serious condition that requires immediate medical attention. Rationale: - A (Macrocytic anemia): This adverse effect is more commonly associated with deficiencies in vitamin B12 or folic acid, not typically caused by medications during therapy. - B (Hallucinations): Hallucinations are more likely to occur as a side effect of certain psychiatric medications or in cases of substance abuse, rather than during general therapy. - C (Liver cirrhosis): Liver cirrhosis is a long-term consequence of chronic liver damage, often due to alcohol abuse or viral hepatitis, not typically a direct adverse effect of therapy.

Correct Answer: D

Rationale: The correct answer is D: Na+ channels. Carbamazepine is an antiepileptic drug that works by blocking voltage-gated sodium channels, thus reducing neuronal excitability and preventing the generation of abnormal electrical discharges that lead to seizures. This mechanism of action is particularly effective in controlling partial seizures. A: Acetylcholine receptors - Carbamazepine does not directly interact with acetylcholine receptors. B: Glutamate receptors - Carbamazepine does not directly interact with glutamate receptors. C: Monoamine receptors - Carbamazepine does not directly interact with monoamine receptors. In summary, the therapeutic effect of carbamazepine in controlling seizures is mediated by its blockade of Na+ channels, which reduces neuronal excitability. Other choices are incorrect as carbamazepine does not target acetylcholine, glutamate, or monoamine receptors.