VISTIDE- cidofovir injection
Gilead Sciences, Inc
WARNING
RENAL IMPAIRMENT IS THE MAJOR TOXICITY OF VISTIDE. CASES OF ACUTE RENAL FAILURE RESULTING IN DIALYSIS AND/OR CONTRIBUTING TO DEATH HAVE OCCURRED WITH AS FEW AS ONE OR TWO DOSES OF VISTIDE. TO REDUCE POSSIBLE NEPHROTOXICITY, INTRAVENOUS PREHYDRATION WITH NORMAL SALINE AND ADMINISTRATION OF PROBENECID MUST BE USED WITH EACH VISTIDE INFUSION. RENAL FUNCTION (SERUM CREATININE AND URINE PROTEIN) MUST BE MONITORED WITHIN 48 HOURS PRIOR TO EACH DOSE OF VISTIDE AND THE DOSE OF VISTIDE MODIFIED FOR CHANGES IN RENAL FUNCTION AS APPROPRIATE (SEE DOSAGE AND ADMINISTRATION). VISTIDE IS CONTRAINDICATED IN PATIENTS WHO ARE RECEIVING OTHER NEPHROTOXIC AGENTS.
NEUTROPENIA HAS BEEN OBSERVED IN ASSOCIATION WITH VISTIDE TREATMENT. THEREFORE, NEUTROPHIL COUNTS SHOULD BE MONITORED DURING VISTIDE THERAPY.
VISTIDE IS INDICATED ONLY FOR THE TREATMENT OF CMV RETINITIS IN PATIENTS WITH ACQUIRED IMMUNODEFICIENCY SYNDROME.
IN ANIMAL STUDIES CIDOFOVIR WAS CARCINOGENIC, TERATOGENIC AND CAUSED HYPOSPERMIA (SEE CARCINOGENESIS, MUTAGENESIS, & IMPAIRMENT OF FERTILITY).
DESCRIPTION
VISTIDE� is the brand name for cidofovir injection. The chemical name of cidofovir is 1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine dihydrate (HPMPC), with the molecular formula of C8 H14 N3 O6 P�2H2 O and a molecular weight of 315.22 (279.19 for anhydrous).
Cidofovir is a white crystalline powder with an aqueous solubility of ≥ 170 mg/mL at pH 6�8 and a log P (octanol/aqueous buffer, pH 7.1) value of -3.3.
VISTIDE is a sterile, hypertonic aqueous solution for intravenous infusion only. The solution is clear and colorless. It is supplied in clear glass vials, each containing 375 mg of anhydrous cidofovir in 5 mL aqueous solution at a concentration of 75 mg/mL. The formulation is pH-adjusted to 7.4 with sodium hydroxide and/or hydrochloric acid and contains no preservatives. The appropriate volume of VISTIDE must be removed from the single-use vial and diluted prior to administration (see DOSAGE AND ADMINISTRATION).
MICROBIOLOGY
Mechanism of Action
Cidofovir suppresses cytomegalovirus (CMV) replication by selective inhibition of viral DNA synthesis. Biochemical data support selective inhibition of CMV DNA polymerase by cidofovir diphosphate, the active intracellular metabolite of cidofovir. Cidofovir diphosphate inhibits herpesvirus polymerases at concentrations that are 8- to 600-fold lower than those needed to inhibit human cellular DNA polymerases alpha, beta, and gamma1, 2, 3. Incorporation of cidofovir into the growing viral DNA chain results in reductions in the rate of viral DNA synthesis.
INDICATION AND USAGE
VISTIDE is indicated for the treatment of CMV retinitis in patients with acquired immunodeficiency syndrome (AIDS). THE SAFETY AND EFFICACY OF VISTIDE HAVE NOT BEEN ESTABLISHED FOR TREATMENT OF OTHER CMV INFECTIONS (SUCH AS PNEUMONITIS OR GASTROENTERITIS), CONGENITAL OR NEONATAL CMV DISEASE, OR CMV DISEASE IN NON-HIV-INFECTED INDIVIDUALS.
OVERDOSAGE
Two cases of cidofovir overdose have been reported. These patients received single doses of VISTIDE at 16.3 mg/kg and 17.4 mg/kg, respectively, with concomitant oral probenecid and intravenous hydration. In both cases, the patients were hospitalized and received oral probenecid (one gram three times daily) and vigorous intravenous hydration with normal saline for 3 to 5 days. Significant changes in renal function were not observed in either patient.
DOSAGE AND ADMINISTRATION
VISTIDE MUST NOT BE ADMINISTERED BY INTRAOCULAR INJECTION.
Dosage
THE RECOMMENDED DOSAGE, FREQUENCY, OR INFUSION RATE MUST NOT BE EXCEEDED. VISTIDE MUST BE DILUTED IN 100 MILLILITERS 0.9% (NORMAL) SALINE PRIOR TO ADMINISTRATION. TO MINIMIZE POTENTIAL NEPHROTOXICITY, PROBENECID AND INTRAVENOUS SALINE PREHYDRATION MUST BE ADMINISTERED WITH EACH VISTIDE INFUSION.
Induction Treatment
The recommended induction dose of VISTIDE for patients with a serum creatinine of ≤ 1.5 mg/dL, a calculated creatinine clearance > 55 mL/min, and a urine protein < 100 mg/dL (equivalent to < 2+ proteinuria) is 5 mg/kg body weight (given as an intravenous infusion at a constant rate over 1 hr) administered once weekly for two consecutive weeks. Because serum creatinine in patients with advanced AIDS and CMV retinitis may not provide a complete picture of the patient's underlying renal status, it is important to utilize the Cockcroft-Gault formula to more precisely estimate creatinine clearance (CrCl). As creatinine clearance is dependent on serum creatinine and patient weight, it is necessary to calculate clearance prior to initiation of VISTIDE. CrCl (mL/min) should be calculated according to the following formula:
Creatinine clearance for males = [140-age (years)] � [body wt (kg)]72 � [serum creatinine (mg/dL)]
Creatinine clearance for females = [140-age (years)] � [body wt (kg)] � 0.8572 � [serum creatinine (mg/dL)]
Maintenance Treatment
The recommended maintenance dose of VISTIDE is 5 mg/kg body weight (given as an intravenous infusion at a constant rate over 1 hr), administered once every 2 weeks.
