This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Viral Drugs, Subject name: Pharmacology
More than 90% of this drug is excreted in the urine in intact form. Because its urinary solubility is low, patients should be well hydrated to prevent nephrotoxicity. The drug is: 
Select and explain. 
A. Indinavir, B. Zidovudine, C. Acyclovir, D. Amantadine
C: Acyclovir
Answer: C: Acyclovir 
Explanation: - Both indinavir and acyclovir can cause nephrotoxicity and renal stone formation. - But indinavir is metabolized mainly in the liver and acyclovir is excreted unchanged in the urine. - Therefore patients should be well hydrated to prevent nephrotoxicity of acyclovir.