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Foscarnet is an organic analog of inorganic pyrophosphate that inhibits the replication of herpes viruses in vitro, including cytomegalovirus (CMV) and herpes simplex virus types 1 and 2 (HSV1 and HSV-2). Healthcare professionals recommend using Foscarnet to treat cytomegalovirus (CMV) retinitis in individuals with AIDS and treat certain types of herpes simplex virus (HSV) infection, named acyclovir-resistant mucocutaneous HSV infection, in individuals with weakened immune systems. This drug is sold under the trade name Foscavir. Foscarnet sodium is a white, crystalline powder, and it has the potential to chelate divalent metal ions, such as calcium and magnesium, to form stable coordination compounds. Foscavir injection is a sterile, isotonic aqueous solution for intravenous administration only. The solution is clear and colorless.

Dosage and Administration 

  • The medicine, Foscavir 24 mg/ml 250 mg, comes in a glass bottle.
  • One should not administer Foscavir by rapid or bolus intravenous injection. 

The administration of Foscavir is by controlled intravenous infusion, either by using a central venous line or by using a peripheral vein. The infusion rate must be 1 mg/kg/minute. One should calculate an individualized dose of Foscarnet based on body weight (mg/kg), renal function, an indication of use, and dosing frequency. 

One should not exceed the recommended dosage, frequency, or infusion rates. All doses must be individualized for patients’ renal function.

Induction Treatment 

The recommended initial dose of Foscavir 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 2-3 weeks depending on clinical response. For acyclovir-resistant HSV patients, 40 mg/kg (minimum one-hour infusion) either every 8 or 12 hours for 2-3 weeks or until healed. One must use an infusion pump to control the rate of infusion. Adequate hydration is recommended to establish a diuresis before and during treatment to minimize renal toxicity, provided no clinical contraindications. 
Maintenance Treatment
Following induction treatment, the recommended maintenance dose of Foscarnet 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. One might consider escalation to 120 mg/kg/day should early reinduction be required because of retinitis progression. Some patients who show excellent tolerance to Foscarnet may benefit from initiation of maintenance treatment at 120 mg/kg/day earlier in their treatment. 
Warning and Administration

Renal impairment is most likely to become clinically evident during the second week of induction therapy but may occur during Foscarnet treatment. One should monitor renal function carefully during both induction and maintenance therapy. Since Foscavir has the potential to cause renal impairment, dose adjustment based on serum creatinine is necessary.

Foscavir has been associated with changes in serum electrolytes, including hypocalcemia, hypophosphatemia, hyperphosphatemia, hypomagnesemia, and hypokalemia. Physicians should be prepared to treat the abnormalities and sequelae such as tetany, seizures, or cardiac disturbances. The rate of infusion may also affect the decrease in ionized calcium. Therefore, one must use an infusion pump for administration to prevent rapid intravenous infusion.
  • Seizures related to mineral and electrolyte abnormalities have been associated with Foscavir treatment. 
  • One must take care to infuse solutions containing Foscavir only into veins with adequate blood flow to permit rapid dilution and distribution to avoid local irritation. 
  • One should avoid Foscavir during pregnancy as this drug has the potential to harm the fetus.
Common Side Effects
The common side-effects of Foscarnet sodium injection are:
  • Loss of appetite
  • Diarrhea
  • Feeling or being sick
  • Feeling weak or tired
  • High temperature or chills
  • Feeling dizzy
  • Headache
  • Pins and needles
  • Skin rash
  • Decreased white blood cells
  • Changes to red blood cells
Price of Foscavir
Foscavir price is economical in India, and Indian Pharma Network is one of the certified pharmaceutical suppliers who can access this medication for patients via the legal procedure. 
Frequently Asked Questions
Is Foscarnet an antibiotic?
Foscarnet is an antiviral medicine that comes in 24 mg/ml in 250 ml glass bottles for intravenous infusion. 
What is the mechanism of action of Foscarnet?
Foscarnet is an organic analog of inorganic pyrophosphate that inhibits the replication of herpes viruses in vitro, including cytomegalovirus (CMV) and herpes simplex virus types 1 and 2 (HSV1 and HSV-2). 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. 
Is Foscarnet a pill?
The medicine Foscarnet comes in a glass bottle for intravenous infusion. 
How to store the medicine Foscavir?
Store the medicine Foscavir between 20° and 25°C (68° and 77°F). 
Protect from excessive heat (above 40°C) and freezing.
Nitin Goswami

Nitin Goswami joined us as an Editor in 2020. He covers all the updates in the field of Pharmaceutical, Business Healthcare, Health News, Medical News, and Pharma News.

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