Question

The main advantage of valacyclovir compared to acyclovir is a. a very short half life b. better oral bioavailability c. less renal toxicity d. it is useful for the treatment of HIV infection e. it has fewer drug interactions

Short answer

Answer: The main advantage of valacyclovir compared to acyclovir is better oral bioavailability.

Step-by-step solution

Analyze option A

Examine whether valacyclovir has a very short half-life compared to acyclovir. Valacyclovir actually has a longer half-life of about 2.5 – 3.6 hours compared to acyclovir, which has a half-life of approximately 2.5 hours. Therefore, a very short half-life is not the main advantage of valacyclovir compared to acyclovir. We can eliminate option A.

Analyze option B

Examine whether valacyclovir has better oral bioavailability compared to acyclovir. Valacyclovir has an oral bioavailability of around 54% compared to only 15-30% for acyclovir, which allows for fewer doses per day and improved patient adherence. This is a significant advantage of valacyclovir compared to acyclovir. We can keep option B as a possible correct answer.

Analyze option C

Examine whether valacyclovir has less renal toxicity compared to acyclovir. Both valacyclovir and acyclovir have similar renal toxicity profiles, as they are both primarily excreted through the kidneys. There is no significant difference in renal toxicity between these two drugs. We can eliminate option C.

Analyze option D

Examine whether valacyclovir is useful for the treatment of HIV infection. Valacyclovir and acyclovir are both used primarily for the treatment of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections, not HIV infection. They do not have significant activity against HIV. We can eliminate option D.

Analyze option E

Examine whether valacyclovir has fewer drug interactions compared to acyclovir. Both valacyclovir and acyclovir have similar drug interaction profiles. There is no significant difference in drug interactions between these two drugs. We can eliminate option E.

Determine the correct answer

After eliminating options A, C, D, and E, we are left with option B: better oral bioavailability. This is the main advantage of valacyclovir compared to acyclovir. The correct answer is B.