All of the following statements regarding verapamil are true EXCEPT:

Correct Answer: B

Rationale: Verapamil is a calcium channel blocker that slows down the heart rate by blocking L-type calcium channels. This action helps in reducing blood pressure and controlling heart rhythm. Therefore, statement B stating that verapamil increases heart rate is incorrect. Choices A, C, and D are true as verapamil blocks L-type calcium channels, relaxes coronary artery smooth muscle, and depresses cardiac contractility, respectively.

Correct Answer: D

Rationale: The correct answer is D because the statement that the half-life of glucagon is between 6 and 8 hours is FALSE. Glucagon's half-life is actually very short, around 5-10 minutes. This is due to rapid degradation by enzymes in the liver and kidneys. Glucagon is not stable in the bloodstream for long periods. A: Statement A is true as glucagon is indeed synthesized in the A cells of the pancreatic islets of Langerhans. B: Statement B is true as glucagon is a peptide consisting of a single chain of 29 amino acids, which is conserved across mammals. C: Statement C is true as glucagon is extensively degraded in the liver, kidneys, plasma, and at tissue receptor sites.

Correct Answer: C

Rationale: The correct answer is C: Celecoxib. Celecoxib is a selective COX-2 inhibitor, meaning it primarily targets the COX-2 enzyme, reducing inflammation and pain without affecting the protective COX-1 enzyme. This selective action reduces the risk of gastrointestinal side effects associated with traditional NSAIDs that inhibit both COX-1 and COX-2. Piroxicam (A), Indomethacin (B), and Diclofenac (D) are non-selective NSAIDs that inhibit both COX-1 and COX-2, leading to a higher risk of gastrointestinal complications.

Correct Answer: B

Rationale: The correct answer is B: Cyclosporine. Cyclosporine is an immunosuppressant medication used to prevent organ rejection after transplantation. It is not considered a cytotoxic agent because it does not directly target and kill rapidly dividing cells. Azathioprine, Leflunomide, and Cyclophosphamide are cytotoxic agents commonly used in chemotherapy to kill rapidly dividing cells, making them incorrect choices.

Correct Answer: A

Rationale: The correct answer is A: Vitamin C. Mega doses of Vitamin C can be beneficial for viral respiratory infections due to its antioxidant properties and ability to support the immune system. Vitamin A is important for immune function but is not specifically known for its effectiveness against viral infections. Vitamin K is involved in blood clotting and bone health, not directly related to viral respiratory infections. Vitamin PP refers to Vitamin B3 (niacin), which plays a role in energy production and skin health, but is not typically associated with combating viral infections. In summary, Vitamin C is the most suitable choice for supporting the immune response against viral respiratory infections.