FOSCARNET SODIUM

The chemical name of foscarnet sodium is phosphonoformic acid, trisodium salt. Foscarnet sodium, USP is a white to almost 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 300.04. 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, clear, colorless solution for intravenous administration only. 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. 1

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.

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 with dilution by using a peripheral vein. The rate of controlled intravenous 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 a sealed bottle or 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 to 1,000 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 to 1,000 mL of hydration fluid should be given with 90 mg/kg to 120 mg/kg of foscarnet sodium injection, and 500 mL with 40 mg/kg to 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 intravenous 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 exposed area should be flushed with water. DOSAGE THE RECOMMENDED DOSAGE, FREQUENCY, OR INFUSION RATES SHOULD NOT BE EXCEEDED. ALL DOSES MUST BE INDIVIDUALIZED FOR PATIENTS’ RENAL FUNCTION. Induction Treatment The recommended initial dose of foscarnet sodium injection for patients with normal renal function is: For CMV retinitis patients, either 90 mg/kg (1-1/2 to 2 hour infusion) every twelve hours or 60 mg/kg (minimum one hour infusion) every eight hours over 2 to 3 weeks depending on clinical response. For acyclovir-resistant HSV patients, 40 mg/kg (minimum one hour infusion) either every 8 or 12 hours for 2 to 3 weeks or until healed. An infusion pump must be used to control the rate of infusion. Adequate hydration is recommended to establish a diuresis (see Hydration for recommendation ), both prior to and during treatment to minimize renal toxicity (see WARNINGS ), provided there are no clinical contraindications. Maintenance Treatment Following induction treatment the recommended maintenance dose of foscarnet sodium injection for CMV retinitis is 90 mg/kg/day to 120 mg/kg/day (individualized for renal function) given as an intravenous infusion over 2 hours. Because the superiority of the 120 mg/kg/day has not been established in controlled trials, and given the likely relationship of higher plasma foscarnet levels to toxicity, it is recommended that most patients be started on maintenance treatment with a dose of 90 mg/kg/day. Escalation to 120 mg/kg/day may be considered should early re-induction be required because of retinitis progression. Some patients who show excellent tolerance to foscarnet sodium injection may benefit from initiation of maintenance treatment at 120 mg/kg/day earlier in their treatment. An infusion pump must be used to control the rate of infusion with all doses. Again, hydration to establish diuresis both prior to and during treatment is recommended to minimize renal toxicity, provided there are no clinical contraindications (see WARNINGS ). Patients who experience progression of retinitis while receiving foscarnet sodium injection maintenance therapy may be retreated with the induction and maintenance regimens given above or with a combination of foscarnet sodium injection and ganciclovir (see CLINICAL TRIALS section ). Because of physical incompatibility, foscarnet sodium injection and ganciclovir must NOT be mixed. Use in Patients with Abnormal Renal Function Foscarnet sodium injection should be used with caution in patients with abnormal renal function because reduced plasma clearance of foscarnet will result in elevated plasma levels (see CLINICAL PHARMACOLOGY ). In addition, foscarnet sodium injection has the potential to further impair renal function (see WARNINGS ). Safety and efficacy data for patients with baseline serum creatinine levels greater than 2.8 mg/dL or measured 24-hour creatinine clearances < 50 mL/min are limited. Renal function must be monitored carefully at baseline and during induction and maintenance therapy with appropriate dose adjustments for foscarnet sodium injection as outlined below (see Dose Adjustment and PATIENT MONITORING ). During foscarnet sodium injection therapy if creatinine clearance falls below the limits of the dosing nomograms (0.4 mL/min/kg), foscarnet sodium injection should be discontinued, the patient hydrated, and monitored daily until resolution of renal impairment is ensured. Foscarnet sodium injection is not recommended in patients undergoing hemodialysis because dosage guidelines have not been established. Dose Adjustment Foscarnet sodium injection dosing must be individualized according to the patient’s renal function status. Refer to Table 13 below for recommended doses and adjust the dose as indicated. Even patients with serum creatinine in the normal range may require dose adjustment; therefore, the dose should be calculated at baseline and frequently thereafter. To use this dosing guide, actual 24-hour creatinine clearance (mL/min) must be divided by body weight (kg), or the estimated creatinine clearance in mL/min/kg can be calculated from serum creatinine (mg/dL) using the following formula (modified Cockcroft and Gault equation): TABLE 13: Foscarnet sodium injection Dosage Guide Induction CrCI (mL/min/kg) HSV: Equivalent to CMV: Equivalent to 80 mg/kg/day total (40 mg/kg Q12h) 120 mg/kg/day total (40 mg/kg Q8h) 180 mg/kg/day total (60 mg/kg Q8h) (90 mg/kg Q12h) > 1.4 > 1.0 to 1.4 > 0.8 to 1.0 > 0.6 to 0.8 > 0.5 to 0.6 > 0.4 to 0.5 < 0.4 40 Q12h 30 Q12h 20 Q12h 35 Q24h 25 Q24h 20 Q24h Not recommended 40 Q8h 30 Q8h 35 Q12h 25 Q12h 40 Q24h 35 Q24h Not recommended 60 Q8h 45 Q8h 50 Q12h 40 Q12h 60 Q24h 50 Q24h Not recommended 90 Q12h 70 Q12h 50 Q12h 80 Q24h 60 Q24h 50 Q24h Not recommended Maintenance CrCI (mL/min/kg) CMV: Equivalent to 90 mg/kg/day (once daily) 120 mg/kg/day (once daily) > * 1.4 > * 1.0 to 1.4 > * 0.8 to 1.0 > * 0.6 to 0.8 > * 0.5 to 0.6 > † 0.4 to 0.5 < ‡ 0.4 90 Q24h 70 Q24h 50 Q24h 80 Q48h 60 Q48h 50 Q48h Not recommended 120 Q24h 90 Q24h 65 Q24h 105 Q48h 80 Q48h 65 Q48h Not recommended * > means “greater than”. † > means “greater than or equal to”. ‡ < means “less than”. PATIENT MONITORING The majority of patients will experience some decrease in renal function due to foscarnet sodium injection administration. Therefore, it is recommended that creatinine clearance, either measured or estimated using the modified Cockcroft and Gault equation based on serum creatinine, be determined at baseline, 2 to 3 times per week during induction therapy and once weekly during maintenance therapy, with foscarnet sodium injection dose adjusted accordingly (see Dose Adjustment ). More frequent monitoring may be required for some patients. It is also recommended that a 24-hour creatinine clearance be determined at baseline and periodically thereafter to ensure correct dosing (assuming verification of an adequate collection using creatinine index). Foscarnet sodium injection should be discontinued if creatinine clearance drops below 0.4 mL/min/kg. Due to foscarnet sodium injection’s propensity to chelate divalent metal ions and alter levels of serum electrolytes, patients must be monitored closely for such changes. It is recommended that a schedule similar to that recommended for serum creatinine (see above) be used to monitor serum calcium, magnesium, potassium and phosphorus. Particular caution is advised in patients with decreased total serum calcium or other electrolyte levels before treatment, as well as in patients with neurologic or cardiac abnormalities, and in patients receiving other drugs known to influence serum calcium levels. Any clinically significant metabolic changes should be corrected. Also, patients who experience mild (e.g., perioral numbness or paresthesias) or severe (e.g., seizures) symptoms of electrolyte abnormalities should have serum electrolyte and mineral levels assessed as close in time to the event as possible. Careful monitoring and appropriate management of electrolytes, calcium, magnesium and creatinine are of particular importance in patients with conditions that may predispose them to seizures (see WARNINGS ). 12

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

THE MAJOR TOXICITY OF FOSCARNET SODIUM IS RENAL IMPAIRMENT (see WARNINGS section ). Approximately 33% of 189 patients with AIDS and CMV retinitis who received foscarnet sodium (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 1,000 mL of normal saline or 5% dextrose solution was given with each infusion of foscarnet sodium was 12% (34/280). Foscarnet sodium has been associated with changes in serum electrolytes including hypocalcemia (15% to 30%), hypophosphatemia (8% to 26%) and hyperphosphatemia (6%), hypomagnesemia (15% to 30%), and hypokalemia (16% to 48%) (see WARNINGS section ). The higher percentages were derived from those patients receiving hydration. Foscarnet sodium 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 (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 in only one case, other complications of foscarnet sodium (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, the following list of adverse events has been compiled regardless of causal relationship to foscarnet sodium. 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 tachycardia, first degree AV block and non-specific ST-T segment changes, hypotension, flushing, cerebrovascular disorder (see WARNINGS ) Central and Peripheral Nervous System: tremor, ataxia, dementia, stupor, generalized spasms, sensory disturbances, meningitis, aphasia, abnormal coordination, leg cramps, EEG abnormalities (see WARNINGS ) Gastrointestinal: constipation, dysphagia, dyspepsia, rectal hemorrhage, dry mouth, melena, flatulence, ulcerative stomatitis, pancreatitis Hematologic: thrombocytopenia, platelet abnormalities, thrombosis, white blood cell abnormalities, lymphadenopathy Liver and Biliary: abnormal A-G ratio, abnormal hepatic function, increased SGPT, increased SGOT Metabolic and Nutritional: hyponatremia, decreased weight, increased alkaline phosphatase, increased LDH, increased BUN, acidosis, cachexia, thirst Musculo-Skeletal: arthralgia, myalgia Neoplasms: lymphoma-like disorder, sarcoma Psychiatric: insomnia, somnolence, nervousness, amnesia, agitation, aggressive reaction, hallucination Respiratory System: pneumonia, sinusitis, pharyngitis, rhinitis, respiratory disorders, respiratory insufficiency, pulmonary infiltration, stridor, pneumothorax, hemoptysis, bronchospasm Skin and Appendages: pruritus, skin ulceration, seborrhea, erythematous rash, maculo-papular rash, skin discoloration Special Senses: taste perversions, eye abnormalities, eye pain, conjunctivitis Urinary System: albuminuria, dysuria, polyuria, urethral disorder, urinary retention, urinary tract infections, acute renal failure, nocturia, facial edema Selected adverse events occurring at a rate of less than 1% in the five initial U.S. controlled clinical trials of foscarnet sodium include: syndrome of inappropriate antidiuretic hormone secretion, pancytopenia, hematuria, dehydration, hypoproteinemia, increases in amylase and creatinine phosphokinase, cardiac arrest, coma, and other cardiovascular and neurologic complications. Selected adverse event data from the Foscarnet vs. Ganciclovir CMV Retinitis Trial (FGCRT), performed by the Studies of the Ocular Complications of AIDS (SOCA) Research Group, are shown in Table 11 (see CLINICAL TRIALS section ). TABLE 11: FGCRT: Selected Adverse Events * EVENT GANCICLOVIR FOSCARNET No. of Events No. of Patients Rates† No. of Events No. of Patients Rates † Absolute neutrophil count decreasing to < 0.50 x 10 9 per liter 63 41 1.30 31 17 0.72 Serum creatinine increasing to > 260 μmol per liter (> 2.9 mg/dL) 6 4 0.12 13 9 0.30 Seizure ‡ 21 13 0.37 19 13 0.37 Catheterization-related infection 49 27 1.26 51 28 1.46 Hospitalization 209 91 4.74 202 75 5.03 * Values for the treatment groups refer only to patients who completed at least one follow-up visit – i.e. 133 to 119 patients in the ganciclovir group and 93 to 100 in the foscarnet group. “Events” denotes all events observed and “patients” the number of patients with one or more of the indicated events. † Per person-year at risk. ‡ Final frozen SOCA I database dated October 1991. Selected adverse events from ACTG Study 228 (CRRT) comparing combination therapy with foscarnet sodium or ganciclovir monotherapy are shown in Table 12. The most common reason for a treatment change in patients assigned to either foscarnet sodium or ganciclovir was retinitis progression. The most frequent reason for a treatment change in the combination treatment group was toxicity. TABLE 12: CRRT: Selected Adverse Events Foscarnet Sodium N=88 Ganciclovir N=93 Combination N=93 No. Events No. Pts. * Rate † No. Events No. Pts. * Rate † No. Events No. Pts. * Rate † Anemia (Hgb < 70g/L) 11 7 0.20 9 7 0.14 19 15 0.33 Neutropenia ‡ ANC < 0.75 x 10 9 cells/L ANC < 0.50 x 10 9 cells/L 86 50 32 25 1.53 0.91 95 49 41 28 1.51 0.80 107 50 51 28 1.91 0.85 Thrombocytopenia Platelets < 50 x 10 9 /L Platelets < 20 x 10 9 /L 28 1 14 1 0.50 0.01 19 6 8 2 0.43 0.05 40 7 15 6 0.56 0.18 Nephrotoxicity Creatinine > 260 μmol/L (> 2.9 mg/dL) 9 7 0.15 10 7 0.17 11 10 0.20 Seizures 6 6 0.17 7 6 0.15 10 5 0.18 Hospitalizations 86 53 1.86 111 59 2.36 118 64 2.36 * Pts. = patients with event. † Rate = events/person/year. ‡ ANC = absolute neutrophil count. Adverse events that have been reported in post-marketing surveillance include: administration site extravasation, localized edema, hypersensitivity reactions (including anaphylactic shock, urticaria and angioedema) (see WARNINGS section ), gastrointestinal hemorrhage, increased lipase, glomerulonephritis, nephrotic syndrome, proteinuria, status epilepticus, ventricular arrhythmia, prolongation of QT interval, torsade de pointes (see WARNINGS section ), gamma GT increased, diabetes insipidus (usually nephrogenic), renal calculus, Fanconi syndrome acquired, renal tubular acidosis, renal tubular necrosis, crystal-induced nephropathy, hypercalcemia, hypernatremia, esophageal ulceration and muscle disorders including myopathy, myositis, muscle weakness and rare cases of rhabdomyolysis. Cases of vesiculobullous eruptions including erythema multiforme, toxic epidermal necrolysis, and Stevens-Johnson syndrome have been reported. In most cases, patients were taking other medications that have been associated with toxic epidermal necrolysis or Stevens-Johnson syndrome.

A possible drug interaction of foscarnet sodium and intravenous pentamidine has been described. Concomitant treatment of four patients in the United Kingdom with foscarnet sodium 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 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 and intravenous pentamidine. Because of foscarnet’s tendency to cause renal impairment, the use of foscarnet sodium 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, potentially leading to toxicity. Abnormal renal function has been observed in clinical practice during the use of foscarnet sodium and ritonavir, or foscarnet sodium, 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 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.