All of the following agents are beta receptor agonists EXCEPT:

Correct Answer: C

Rationale: The correct answer is C: Methoxamine. Beta receptor agonists stimulate beta receptors, leading to various effects like increased heart rate and bronchodilation. Methoxamine is an alpha-1 adrenergic agonist, not a beta receptor agonist. Epinephrine, Isoproterenol, and Dobutamine are all beta receptor agonists, so they are incorrect choices. Epinephrine acts on both alpha and beta receptors, Isoproterenol is a non-selective beta agonist, and Dobutamine primarily targets beta-1 receptors.

Correct Answer: A

Rationale: Phenobarbital is the correct answer because it is a known inducer of hepatic drug-metabolizing enzyme systems, such as cytochrome P450 enzymes. This increase in enzyme activity can lead to faster metabolism and clearance of drugs, resulting in potential drug interactions. Zolpidem, Flurazepam, and Zaleplon are not known to significantly increase the activity of hepatic drug-metabolizing enzymes, making them incorrect choices.

Correct Answer: C

Rationale: Rationale: Carbamazepine is the correct answer because it is a first-line treatment for trigeminal neuralgia due to its mechanism of action in inhibiting voltage-gated sodium channels. This helps reduce neuronal firing and alleviate nerve pain. Primidone and Lamotrigine are not typically used for trigeminal neuralgia. Topiramate may have some efficacy, but it is not as effective as Carbamazepine, which is the drug of choice for treating this condition.

Correct Answer: A

Rationale: The correct answer is A: Pyridoxine. Pyridoxine (Vitamin B6) accelerates the metabolism of levodopa outside the brain, reducing its effectiveness. This leads to decreased levodopa levels in the brain, diminishing its beneficial effects in treating Parkinson's disease. Thiamine (B1), Tocopherol (E), and Riboflavin (B2) do not have this effect on levodopa metabolism.

Correct Answer: B

Rationale: Step 1: Buprenorphine is a partial mu receptor agonist with 20-60 times the analgesic potency of morphine. This is due to its high affinity for the mu receptor, resulting in potent analgesic effects. Step 2: Buprenorphine also has a longer duration of action compared to morphine, making it suitable for sustained pain management. Summary: A: Pentazocine is a mixed opioid receptor agonist/antagonist, not a partial mu receptor agonist like buprenorphine. C: Nalbuphine is a kappa receptor agonist and mu receptor antagonist, not a partial mu receptor agonist like buprenorphine. D: Naltrexone is a pure opioid receptor antagonist, not a partial mu receptor agonist like buprenorphine.