Cidofovir, brand name Vistide, is a topical or injectable antiviral medication primarily used as a treatment for cytomegalovirus (CMV) retinitis (an infection of the retina of the eye) in people with AIDS. Cidofovir was approved for medical use in 1996. Medical use DNA virus Its only indication that has received regulatory approval worldwide is cytomegalovirus retinitis. Cidofovir has also shown efficacy in the treatment of aciclovir-resistant HSV infections. Cidofovir has also been investigated as a treatment for progressive multifocal leukoencephalopathy with successful case reports of its use. Despite this, the drug failed to demonstrate any efficacy in controlled studies. Cidofovir might have anti-smallpox efficacy and might be used on a limited basis in the event of a bioterror incident involving smallpox cases. Brincidofovir, a cidofovir derivative with much higher activity against smallpox that can be taken orally has been developed. It has inhibitory effects on varicella-zoster virus replication in vitro although no clinical trials have been done to date, likely due to the abundance of safer alternatives such as aciclovir. Cidofovir shows anti-BK virus activity in a subgroup of transplant recipients. Cidofovir is being investigated as a complementary intralesional therapy against papillomatosis caused by HPV. It first received FDA approval on 26 June 1996, TGA approval on 30 April 1998 and EMA approval on 23 April 1997. It has been used topically to treat warts. Other It has been suggested as an antitumour agent, due to its suppression of FGF2. Administration Cidofovir is only available as an intravenous formulation. Cidofovir is to be administered with probenecid which decreases side effects to the kidney. Probenecid mitigates nephrotoxicity by inhibiting organic anion transport of the proximal tubule epithelial cells of the kidney. In addition, hydration must be administered to patients receiving cidofovir. 1 liter of normal saline is recommended in conjunction with each dose of cidofovir. Side effects The major dose-limiting side effect of cidofovir is nephrotoxicity (i.e., kidney damage). Other common side effects (occurring in >1% of people treated with the drug) include: Nausea Vomiting Neutropenia Hair loss Weakness Headache Chills Decreased intraocular pressure Uveitis Iritis Whereas uncommon side effects include: anaemia and elevated liver enzymes and rare side effects include: tachycardia and Fanconi syndrome. Probenecid (a uricosuric drug) and intravenous saline should always be administered with each cidofovir infusion to prevent this nephrotoxicity. Contraindications Hypersensitivity to cidofovir or probenecid (as probenecid needs to be given concurrently to avoid nephrotoxicity). Interactions