Which of the following drugs would be contraindicated for a patient undergoing major surgery to remove a breast carcinoma who has chronic obstructive pulmonary disease and is a heavy smoker?

Correct Answer: A

Rationale: The correct answer is A: Tubocurarine. Tubocurarine is a non-depolarizing neuromuscular blocking agent that can cause histamine release, leading to bronchoconstriction, which is dangerous for a patient with chronic obstructive pulmonary disease (COPD) and a heavy smoker undergoing major surgery. Glycopyrrolate (B) is a muscarinic antagonist that can be used to reduce secretions during surgery. Clonidine (C) is an alpha-2 adrenergic agonist that can help with perioperative hypertension. Vecuronium (D) is a non-depolarizing neuromuscular blocking agent, like tubocurarine, but it does not cause histamine release, making it a safer option 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.

Correct Answer: A

Rationale: The correct answer is A: Carbamazepine. This is because carbamazepine is commonly used as an alternative to valproic acid due to its similar efficacy in treating certain types of seizures. Carbamazepine is also effective in treating bipolar disorder, which may be a reason for switching from valproic acid. Clonazepam (B) and phenytoin (C) are not appropriate substitutes for valproic acid as they have different mechanisms of action and are used for different types of seizures. Ethosuximide (D) is primarily used for absence seizures and would not be a suitable substitute for valproic acid in this case.