Foscarnet Sodium

INDICATIONS CMV Retinitis Foscarnet sodium injection is indicated for the treatment of CMV retinitis in patients with acquired immunodeficiency syndrome (AIDS). Combination therapy with foscarnet sodium Injection and ganciclovir is indicated for patients who have relapsed after monotherapy with either drug. SAFETY AND EFFICACY OF FOSCARNET SODIUM INJECTION HAVE NOT BEEN ESTABLISHED FOR TREATMENT OF OTHER CMV INFECTIONS (e.g., PNEUMONITIS, GASTROENTERITIS); CONGENITAL OR NEONATAL CMV DISEASE; OR NONIMMUNOCOMPROMISED INDIVIDUALS. Mucocutaneous Acyclovir Resistant HSV Infections Foscarnet sodium injection is indicated for the treatment of acyclovir-resistant mucocutaneous HSV infections in immunocompromised patients. SAFETY AND EFFICACY OF FOSCARNET SODIUM INJECTION HAVE NOT BEEN ESTABLISHED FOR TREATMENT OF OTHER HSV INFECTIONS (e.g., RETINITIS, ENCEPHALITIS); CONGENITAL OR NEONATAL HSV DISEASE; OR HSV IN NONIMMUNOCOMPROMISED INDIVIDUALS.

DOSAGE AND ADMINISTRATION CAUTION - DO NOT ADMINISTER FOSCARNET SODIUM INJECTION BY RAPID OR BOLUS INTRAVENOUS INJECTION. THE TOXICITY OF FOSCARNET SODIUM INJECTION MAY BE INCREASED AS A RESULT OF EXCESSIVE PLASMA LEVELS. CARE SHOULD BE TAKEN TO AVOID UNINTENTIONAL OVERDOSE BY CAREFULLY CONTROLLING THE RATE OF INFUSION. THEREFORE, AN INFUSION PUMP MUST BE USED. IN SPITE OF THE USE OF AN INFUSION PUMP, OVERDOSES HAVE OCCURRED. ADMINISTRATION Instructions for Administration and Preparation Foscarnet sodium Injection is administered by controlled intravenous infusion, either by using a central venous line or by using a peripheral vein. The rate of infusion must be no more than 1 mg/kg/minute. An individualized dose of foscarnet sodium Injection should be calculated on the basis of body weight (mg/kg), renal function, indication of use and dosing frequency (refer to DOSAGE subsection). To reduce the risk of nephrotoxicity, creatinine clearance (mL/min/kg) should be calculated even if serum creatinine is within the normal range, and doses should be adjusted accordingly. An individualized dose at the required concentration (24 mg/mL or 12 mg/mL) for the route of administration (central line or peripheral line) needs to be aseptically prepared prior to dispensing. The standard 24 mg/mL solution may be used with or without dilution when using a central venous catheter for infusion. When a peripheral vein catheter is used, the 24 mg/mL injection must be diluted to a 12 mg/mL concentration with 5% dextrose in water or with a normal saline solution prior to administration to avoid local irritation of peripheral veins. Dilutions and/or removals of excess quantities should be accomplished under aseptic conditions. Solutions thus prepared should be used within 24 hours of first entry into infusion bag. Hydration Hydration may reduce the risk of nephrotoxicity. Clinically dehydrated patients should have their condition corrected before initiating foscarnet sodium Injection therapy. It is recommended that 750 - 1000 mL of normal saline or 5% dextrose solution should be given prior to the first infusion of foscarnet sodium Injection to establish diuresis. With subsequent infusions, 750 - 1000 mL of hydration fluid should be given with 90 - 120 mg/kg of foscarnet sodium Injection, and 500 mL with 40 - 60 mg/kg of foscarnet sodium Injection. Hydration fluid may need to be decreased if clinically warranted. Oral rehydration with similar regimens may be considered in certain patients. After the first dose, the hydration fluid should be administered concurrently with each infusion of foscarnet sodium Injection. Compatibility With Other Solutions/Drugs Other drugs and supplements can be administered to a patient receiving foscarnet sodium Injection. However, care must be taken to ensure that foscarnet sodium Injection is only administered with normal saline or 5% dextrose solution and that no other drug or supplement is administered concurrently via the same catheter. Foscarnet has been reported to be chemically incompatible with 30% dextrose, amphotericin B, and solutions containing calcium such as Ringer’s lactate and TPN. Physical incompatibility with other IV drugs has also been reported including acyclovir sodium, ganciclovir, trimetrexate glucuronate, pentamidine isethionate, vancomycin, trimethoprim/sulfamethoxazole, diazepam, midazolam, digoxin, phenytoin, leucovorin, and proclorperazine. Because of foscarnet’s chelating properties, a precipitate can potentially occur when divalent cations are administered concurrently in the same catheter. Parenteral drug products must be inspected visually for particulate matter and discoloration prior to administration whenever the solution and container permit. Solutions that are discolored or contain particulate matter should not be used. Accidental Exposure Accidental skin and eye contact with foscarnet sodium solution may cause local irritation and burning sensation. If accidental contact occurs, the …

CONTRAINDICATIONS Foscarnet sodium injection is contraindicated in patients with clinically significant hypersensitivity to foscarnet sodium.

ADVERSE REACTIONS THE MAJOR TOXICITY OF FOSCARNET SODIUM INJECTION IS RENAL IMPAIRMENT (see WARNINGS section). Approximately 33% of 189 patients with AIDS and CMV retinitis who received foscarnet sodium injection (60 mg/kg TID), without adequate hydration, developed significant impairment of renal function (serum creatinine ≥ 2.0 mg/dL). The incidence of renal impairment in subsequent clinical trials in which 1000 mL of normal saline or 5% dextrose solution was given with each infusion of foscarnet sodium injection was 12% (34/280). Foscarnet sodium injection has been associated with changes in serum electrolytes including hypocalcemia (15–30%), hypophosphatemia (8–26%) and hyperphosphatemia (6%), hypomagnesemia (15– 30%), and hypokalemia (16–48%) (see WARNINGS section). The higher percentages were derived from those patients receiving hydration. Foscarnet sodium injection treatment was associated with seizures in 18/189 (10%) AIDS patients in the initial five controlled studies (see WARNINGS section). Risk factors associated with seizures included impaired baseline renal function, low total serum calcium, and underlying CNS conditions predisposing the patient to seizures. The rate of seizures did not increase with duration of treatment. Three cases were associated with overdoses of foscarnet sodium injection (see OVERDOSAGE section). In five controlled U.S. clinical trials the most frequently reported adverse events in patients with AIDS and CMV retinitis are shown in Table 9. These figures were calculated without reference to drug relationship or severity. TABLE 9 Adverse Events Reported in Five Controlled US Clinical Trials n = 189 n = 189 Fever 65% Abnormal Renal Function 27% Nausea 47% Vomiting 26% Anemia 33% Headache 26% Diarrhea 30% Seizures 10% From the same controlled studies, adverse events categorized by investigator as “severe” are shown in Table 10. Although death was specifically attributed to foscarnet sodium injection in only one case, other complications of foscarnet sodium injection (i.e., renal impairment, electrolyte abnormalities, and seizures) may have contributed to patient deaths (see WARNINGS section). TABLE 10 Severe Adverse Events n = 189 Death 14% Abnormal Renal Function 14% Marrow Suppression 10% Anemia 9% Seizures 7% From the five initial U.S. controlled trials of foscarnet sodium injection, the following list of adverse events has been compiled regardless of causal relationship to foscarnet sodium injection. Evaluation of these reports was difficult because of the diverse manifestations of the underlying disease and because most patients received numerous concomitant medications. Incidence of 5% or Greater Body as a Whole: fever, fatigue, rigors, asthenia, malaise, pain, infection, sepsis, death Central and Peripheral Nervous System: headache, paresthesia, dizziness, involuntary muscle contractions, hypoesthesia, neuropathy, seizures including grand mal seizures (see WARNINGS) Gastrointestinal System: anorexia, nausea, diarrhea, vomiting, abdominal pain Hematologic: anemia, granulocytopenia, leukopenia, neutropenia (see PRECAUTIONS) Metabolic and Nutritional: mineral and electrolyte imbalances (see WARNINGS) including hypokalemia, hypocalcemia, hypomagnesemia, hypophosphatemia, hyperphosphatemia Psychiatric: depression, confusion, anxiety Respiratory System: coughing, dyspnea Skin and Appendages: rash, increased sweating Urinary System: alterations in renal function including increased serum creatinine, decreased creatinine clearance, and abnormal renal function (see WARNINGS) Special Senses: vision abnormalities Incidence between 1% and 5% Application Site: injection site pain, injection site inflammation Body as a Whole: back pain, chest pain (including reports of transient chest pain as part of infusion reactions), edema, influenza-like symptoms, bacterial infections, moniliasis, fungal infections, abscess Cardiovascular: hypertension, palpitations, ECG abnormalities including sinus tachycardi …

Drug Interactions A possible drug interaction of foscarnet sodium injection and intravenous pentamidine has been described. Concomitant treatment of four patients in the United Kingdom with foscarnet sodium injection and intravenous pentamidine may have caused hypocalcemia; one patient died with severe hypocalcemia. Toxicity associated with concomitant use of aerosolized pentamidine has not been reported. Because foscarnet sodium injection can reduce serum levels of ionized calcium, extreme caution is advised when used concurrently with other drugs known to influence serum calcium levels (e.g., intravenous pentamidine). Renal impairment and symptomatic hypocalcemia have been observed during concurrent treatment with foscarnet sodium injection and intravenous pentamidine. Because of foscarnet's tendency to cause renal impairment, the use of foscarnet sodium injection should be avoided in combination with potentially nephrotoxic drugs such as aminoglycosides, amphotericin B, cyclosporine, acyclovir, methotrexate, tacrolimus and intravenous pentamidine (see above) unless the potential benefits outweigh the risks to the patient. When diuretics are indicated, thiazides are recommended over loop diuretics because the latter inhibit renal tubular secretion, and may impair elimination of foscarnet sodium injection, potentially leading to toxicity. Abnormal renal function has been observed in clinical practice during the use of foscarnet sodium injection and ritonavir, or foscarnet sodium injection, ritonavir, and saquinavir. (See DOSAGE AND ADMINISTRATION .) Because of the risk of QT prolongation and the potential for torsades de pointes, the use of foscarnet sodium injection should be avoided in combination with agents known to prolong the QT interval including Class IA (e.g., quinidine or procainamide) or Class III (e.g., dofetilide, amiodarone, sotalol) antiarrhythmic agents, phenothiazines, tricyclic antidepressants, and certain macrolides and fluoroquinolones.

Mechanism of Action Foscarnet exerts its antiviral activity by a selective inhibition at the pyrophosphate binding site on virus-specific DNA polymerases at concentrations that do not affect cellular DNA polymerases. Foscarnet does not require activation (phosphorylation) by thymidine kinase or other kinases.

DESCRIPTION The chemical name of foscarnet sodium is phosphonoformic acid, trisodium salt. Foscarnet sodium is a white, crystalline powder containing 6 equivalents of water of hydration with an empirical formula of Na 3 CO 5 P·6H 2 O and a molecular weight of 300.1. The structural formula is: Foscarnet sodium Injection has the potential to chelate divalent metal ions, such as calcium and magnesium, to form stable coordination compounds. Foscarnet sodium Injection is a sterile, isotonic aqueous solution for intravenous administration only. The solution is clear and colorless. Each milliliter of foscarnet sodium Injection contains 24 mg of foscarnet sodium hexahydrate in Water for Injection, USP. Hydrochloric acid may have been added to adjust the pH of the solution to 7.4. Foscarnet sodium Injection contains no preservatives. VIROLOGY Mechanism of Action Foscarnet exerts its antiviral activity by a selective inhibition at the pyrophosphate binding site on virus-specific DNA polymerases at concentrations that do not affect cellular DNA polymerases. Foscarnet does not require activation (phosphorylation) by thymidine kinase or other kinases. Antiviral Activity in Cell Culture The quantitative relationship between the cell culture susceptibility of human cytomegalovirus (CMV) or herpes simplex virus 1 and 2 (HSV-1 and HSV-2) to foscarnet and clinical response to therapy has not been established and virus sensitivity testing has not been standardized. Sensitivity test results, expressed as the concentration of drug required to inhibit by 50% the growth of virus in cell culture (EC 50 ), vary greatly depending on the assay method used, cell type employed and the laboratory performing the test. A number of sensitive viruses and their EC 50 values are listed below (Table 1). The combination antiviral activity of foscarnet and ganciclovir or acyclovir are not antagonistic in cell culture. TABLE 1 Foscarnet Inhibition of Virus Replication in Cell Culture Virus EC 50 value (μM) CMV Ganciclovir resistant CMV HSV-1, HSV-2 HSV-TK negative mutant HSV-DNA polymerase mutants 50 - 800* 190 10 -130 67 5 - 443 *Mean = 269 μM Antiviral Activity in vivo Statistically significant decreases in positive CMV cultures from blood and urine have been demonstrated in two studies (FOS-03 and ACTG-015/915) of subjects treated with foscarnet sodium Injection. Although median time to progression of CMV retinitis was increased in subjects treated with foscarnet sodium Injection, reductions in positive blood or urine cultures have not been shown to correlate with clinical efficacy in individual subjects (Table 2). TABLE 2 Blood and Urine Culture Results from CMV Retinitis Patients* Blood +CMV -CMV Baseline End of Induction† 27 1 34 60 Urine +CMV -CMV Baseline End of Induction† 52 21 6 37 *A total of 77 subjects were treated with foscarnet sodium Injection in two clinical trials (FOS-03 and ACTG-015/915). Not all subjects had blood or urine cultures done and some subjects had results from both cultures. †(60 mg/kg foscarnet sodium Injection TID for 2-3 weeks). Resistance Cell culture: CMV and HSV isolates with reduced susceptibility to foscarnet have been selected in cell culture by passage of wild type virus in the presence of increasing concentrations of the drug. All foscarnet resistant isolates are known to be generated through amino acid substitutions in the viral DNA polymerase pUL54 (CMV) or pUL30 (HSV) (Table 3). TABLE 3 Summary of Foscarnet Resistance-associated DNA Polymerase Amino Acid Substitutions in Cell Culture CMV pUL54 T419M, T552N, S585A, F595I, Q807A, M844T/V, V946L HSV-1 pUL30 Y577H, E597D, A605V, L702H, V714M, L774F, L788M, D780N, L782I, P797T, L802F, V813M, V817M, Y818C, T821M, R842S, S889A, F891C, V892M, D907V, A910V, SRA914-916LCV, V958L, R959H HSV-2 pUL30 _ In vivo: Limited clinical data are available on the development of clinical resistance to foscarnet and many pathways to resistance likely exist. Substitutions documented in the litera …

OVERDOSAGE In controlled clinical trials performed in the United States, overdosage with foscarnet sodium Injection was reported in 10 out of 189 patients. All 10 patients experienced adverse events and all except one made a complete recovery. One patient died after receiving a total daily dose of 12.5 g for three days instead of the intended 10.9 g. The patient suffered a grand mal seizure and became comatose. Three days later the patient expired with the cause of death listed as respiratory/cardiac arrest. The other nine patients received doses ranging from 1.14 times to 8 times their recommended doses with an average of 4 times their recommended doses. Overall, three patients had seizures, three patients had renal function impairment, four patients had paresthesias either in limbs or periorally, and five patients had documented electrolyte disturbances primarily involving calcium and phosphate. Overdose (up to 20 times the recommended dose) has been reported in post-marketing use of foscarnet sodium Injection. Some of these post-marketing reports were relative overdoses in that the dose of foscarnet sodium Injection had not been adjusted in patients with a reduced renal function. The pattern of adverse events associated with a foscarnet sodium Injection overdose is consistent with the known adverse event profile of the drug. There is no specific antidote for foscarnet sodium Injection overdose. Hemodialysis and hydration may be of benefit in reducing drug plasma levels in patients who receive an overdosage of foscarnet sodium Injection, but the effectiveness of these interventions has not been evaluated. The patient should be observed for signs and symptoms of renal impairment and electrolyte imbalance. Medical treatment should be instituted if clinically warranted.

HOW SUPPLIED Foscarnet sodium injection is supplied as follows: NDC Foscarnet Sodium Injection (24 mg per mL) Package Factor 25021-189-84 6,000 mg per 250 mL 10 bags per carton Single-Dose Flexible Container Bag Foscarnet sodium injection 24 mg per mL for intravenous infusion, is supplied in 250 mL dual port infusion bag. Storage Conditions Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.] For Single Dose Only. Discard unused portion. Protect from excessive heat (above 40°C) and from freezing. If refrigerated or exposed to temperatures below the freezing point, precipitation may occur. By keeping the infusion bag at room temperature with repeated shaking, the precipitate can be brought into solution again. Foscarnet sodium injection should be used only if the infusion bag and twist off port stopper are intact, a vacuum is present, and the solution is clear and colorless. Do not remove the infusion bag from the overwrap until ready for use. Sterile, Nonpyrogenic, Preservative-free, PVC-free, DEHP-free. The container and container closure are not made with natural rubber latex. SAGENT ® Mfd. for SAGENT Pharmaceuticals Schaumburg, IL 60195 (USA) Made in India ©2021 Sagent Pharmaceuticals, Inc. February 2021 SAGENT Pharmaceuticals ®