Classifications: antiviral; Therapeutic: antiviral
Pregnancy Category: C
24 mg/mL injection
Selectively inhibits the viral-specific DNA polymerases and reverse transcriptases of susceptible viruses, thus preventing
elongation of the viral DNA chain.
Effective against cytomegalovirus (CMV), herpes simplex virus types 1 and 2 (HSV-1, HSV-2), human herpesvirus 6 (HHV-6), Epstein-Barr
virus (EBV), and varicella-zoster virus (VZV).
CMV retinitis, mucocutaneous HSV, acyclovir-resistant HSV in immunocompromised patients.
Other CMV infections, herpes zoster infections in AIDS patients.
Hypersensitivity to foscarnet; pregnancy (category C), lactation.
Kidney function impairment, cardiac disease; mineral and electrolyte imbalances, seizures, older adults. Safety and efficacy
in children are not established.
Route & Dosage
Adult: IV Induction 60 mg/kg q8h for 23 wk OR 90 mg/kg q12h for 23 wk
Recurrent CMV Retinitis
Adult: IV 90120 mg/kg/d x 2 wk
Acyclovir-Resistant HSV in Immunocompromised Patients
Adult: IV 40 mg/kg q812h for up to 3 wk or until lesions heal
See package insert.
- Note: Dose must be adjusted for renal insufficiency. See package insert for specific dosing adjustment.
PREPARE: Direct: Given undiluted (24 mg/mL) through a central line. For peripheral infusion, dilute to 12 mg/mL with D5W or NS. Do not give
other IV solution or drug through the same catheter with foscarnet.
ADMINISTER: Direct: ??Give at a constant rate not to exceed 1 mg/kg/min over the specified period of infusion with an infusion pump. Do not increase
the rate of infusion or shorten the specified interval between doses.??Use prepared IV solutions within 24 h.
INCOMPATIBILITIES Solution/additive: Ringer's lactate, acyclovir, amphotericin B, diazepam, digoxin, diphenhydramine, dobutamine, droperidol, ganciclovir, haloperidol, leucovorin, lorazepam, midazolam, pentamidine, phenytoin, prochlorperazine, promethazine, sulfamethoxazole/trimethoprim, TPN, trimetrexate, vancomycin. Y-site: Acyclovir, amphotericin B, diazepam, digoxin, diphenhydramine, dobutamine, droperidol, ganciclovir, haloperidol, leucovorin, lorazepam, midazolam, pentamidine, prochlorperazine, promethazine, sulfamethoxazole/trimethoprim, trimetrexate, vancomycin.
- Prehydrate and continue daily hydration with 2.5 L of NS to reduce nephrotoxicity.
- Store according to manufacturer's directions.
Adverse Effects (≥1%)CV:
Thrombophlebitis if infused through a peripheral vein. CNS:
Tremor, muscle twitching, headache, weakness, fatigue
, confusion, anxiety. Endocrine: Hyperphosphatemia,
hypophosphatemia, hypocalcemia. GI:
Nausea, vomiting, diarrhea
Penile ulceration. Hematologic: Anemia, leukopenia
. Renal: Nephrotoxicity
failure, tubular necrosis). Skin:
Fixed drug eruption, rash.
Diagnostic Test Interference
May cause increase or decrease in serum calcium, phosphorus, and magnesium. Decreases Hct and Hgb. Increased serum creatinine.
, amphotericin B, vancomycin
may increase risk of nephrotoxicity. Etidronate, pamidronate, pentamidine (IV)
may exacerbate hypocalcemia.
37 d. Duration:
Relapse usually occurs 34 wk after end of therapy. Distribution:
328% of dose may be deposited in bone; variable penetration into CSF; crosses placenta; distributed into breast
Not metabolized. Elimination:
7394% in urine. Half-Life:
Assessment & Drug Effects
- Monitor for cardiac arrhythmias, especially in presence of known cardiac abnormalities.
- Lab tests: Periodic CBC, serum electrolytes, serum creatinine, and creatinine clearance throughout therapy.
- Monitor serum creatinine and creatinine clearance values. Drug dose will be decreased in response to decreased clearance.
- Monitor for electrolyte imbalances.
- Monitor for seizures and take appropriate precautions.
- Question patients regarding local irritation of the penile or vulvovaginal epithelium. If either occurs, increase hydration
and better personal hygiene.
Patient & Family Education
- Report perioral tingling, numbness, and paresthesia to physician immediately.
- Understand that drug is not a cure for CMV retinitis; regular ophthalmologic exams are necessary.
- Note: Good hydration is important to maintain adequate output of urine.