Correct statements about pamidronate include all of the following, EXCEPT:

Correct Answer: B

Rationale: The correct answer is B because pamidronate has a skeletal half-life of about 10 years, not 24 hours. A: Pamidronate is not available orally due to poor bioavailability and potential esophageal irritation. C: Fever and lymphocytopenia are reversible side effects of pamidronate. D: Pamidronate can irritate the esophagus if not washed down promptly to the stomach, leading to esophageal ulceration.

Correct Answer: D

Rationale: The correct answer is D (All of the above) because all three choices (Clavulanic acid, Sulbactam, Tazobactam) are beta-lactamase inhibitors commonly co-administered with penicillins to enhance their efficacy. Beta-lactamase inhibitors work by inhibiting bacterial enzymes that can inactivate penicillins, allowing the antibiotic to remain effective against the bacteria. Clavulanic acid, Sulbactam, and Tazobactam are specifically designed to counteract beta-lactamase enzymes produced by bacteria, making them effective choices for combination therapy with penicillins. The other choices (A, B, C) are incorrect as each of them alone is a valid beta-lactamase inhibitor used in clinical practice.

Correct Answer: B

Rationale: The correct answer is B: Metronidazole. Metronidazole is a nitroimidazole derivative commonly used as an antibacterial and antiprotozoal drug. It works by disrupting the DNA structure of bacteria and parasites, leading to their death. Clavulanic acid (A) is a beta-lactamase inhibitor, not an antibacterial drug. Nitrofurantoin (C) is a nitrofuran derivative used for urinary tract infections, not a nitroimidazole derivative. Doxycycline (D) is a tetracycline antibiotic, not a nitroimidazole derivative. Therefore, the correct choice is B as it is the only nitroimidazole derivative among the options provided.

Correct Answer: A

Rationale: The correct answer is A: Zidovudine. Zidovudine is a nucleoside reverse transcriptase inhibitor that works by inhibiting the viral reverse transcriptase enzyme, essential for viral replication in HIV-infected cells. This action helps to slow down the progression of HIV infection. Vidarabine is an antiviral drug used to treat herpes simplex and varicella-zoster viruses, not HIV. Rimantadine is an antiviral drug used to treat and prevent influenza A virus infections by inhibiting viral replication, but it does not inhibit viral reverse transcriptase. Gancyclovir is an antiviral drug used to treat cytomegalovirus infections by inhibiting viral DNA polymerase, not reverse transcriptase.

Correct Answer: B

Rationale: The correct answer is B: Postural hypotension. Nitroglycerin and isosorbide mononitrate are vasodilators that can cause a sudden drop in blood pressure when standing up, leading to postural hypotension. This is especially risky in patients with exertional angina, as it can exacerbate symptoms. A: Cough and wheezing are not common side effects of nitroglycerin or isosorbide mononitrate. C: Reflex bradycardia is unlikely as these medications primarily affect blood vessels, not the heart rate. D: Methemoglobinemia is a rare side effect associated with certain medications but is not commonly seen with nitroglycerin or isosorbide mononitrate.