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
Drug of choice for cytomegalovirus retinitis in HIV patients is:- 
Select and explain. 
A. Acyclovir, B. Ganciclovir, C. Amantadine, D. Foscarnet
B: Ganciclovir
Answer: B: Ganciclovir 
Explanation: Ganciclovir is an analogue of acyclovir which is the most active drugs against CMV. It is activated intracellularly by virus specific thymidine kinase and its triphosphate nucleotide inhibits viral DNA polymerase. CMV retinitis is treated by i.v. infusion of ganciclovir 10 mg/kg/day. This can prevent blindness in AIDS patients. Systemic therapy can be supplemented by intravitreal injection of ganciclovir.