#foscarnet

HSV enters Freiburg in the Cup Final

The Penalty areaAs the second half approaches, SC Freiburg has a chance to score an early goal, but the hosts manage to hold off the Hamburg attack. A strong run through Freiburg’s defense is broken by the impressive performance of Heuer Fernandes. The striker throws in the ball and runs into the penalty area. His long-range effort is deflected by Schlotterbeck. But Freiburg’s defensive line…

Common Brand Names: Foscavir

Therapeutic Class: Antiviral agent

Common Injectable Dosage Forms:

Solution for Injection: 24 mg/mL (250 mL, 500 mL)

Dosage Ranges:

Induction in cytomegalovirus (CMV) retinitis: 60 mg/kg/dose every 8 hours or 90 mg/kg every 12 hours for 14-21 days. Maintenance dose is 90-120 mg/kg/day as a single infusion.

Herpes Simplex (Acyclovir-resistant): 40 mg/kg/dose every 12 hours for 14-21 days.

Administration and Stability: Rate of infusion should not exceed 1 mg/kg/minute. Hydration with 750-1000 mL of NS or D5W prior to infusion is recommended. Peripheral line infusion requires dilution to maximum concentration of 12 mg/mL in NS or D5W. Central line infusion require no further dilution for infusion. Foscarnet is a hazardous agent and required appropriate precautions for handling and disposal. pH 7.4

Pharmacology/Pharmacokinetics: Foscarnet is a pyrophosphate analogue that acts as a noncompetitive inhibitor of many viral RNA and DNA polymerases, as well as HIV reverse transcriptase. Foscarnet is considered to a virostatic agent. Elimination half-life is 3 hours. Up to 28% of drug may be deposited in bone.

Drug and Lab Interactions: Concurrent use of fluoroquinolones with foscarnet increases seizure potential. Nephrotoxic drugs (amphotericin B, aminoglycosides, etc.) should be avoided. Protease inhibitors are associated with increased renal impairment when used concurrently. QT prolonging agents may enhance the adverse/toxic effects of foscarnet.

Contraindications/Precautions: Contraindicated in patients with a hypersensitivity to foscarnet. Discontinue therapy in patients with CrCl <0.4 mL/min/kg. Pregnancy Category C.

Monitoring Parameters: CrCl, CBC, electrolytes, hydration status

Adverse Effects: Possible side effects include fever, headache, hypokalemia, hypocalcemia, hypomagnesemia, hypophosphatemia, nausea, vomiting, diarrhea, anemia, and granulocytopenia. Foscarnet may also alter creatinine clearance/renal function.

by. Franchesca Mandapat

Brand name: Foscavir

Chemical name: phosphonoformic acid, trisodium salt

Appearance: white, crystalline powder

IUPAC name: Phosphonoformic acid

Half life: 3.3-6.8 hours

Toxicity: Oral, rat LD50: >2,000 mg/kg. Signs of overdose include renal impairment.

1. What is Foscavir/Foscarnet?

An antiviral drug which is utilized for the treatment of infections caused by cytomegalovirus or CMV. Foscarnet is also used as prevention in case a relapse of CMV occurs after the initial treatment of an infection.

2. How should Foscavir be taken?

One method is intravenously (I.V.).  The dose may be administered once or thrice a day as a slow infusion for over one to two hours. The process of calculating the exact dose is based on the patient’s weight. Foscavir is given for at least two to four weeks or indefinitely. In most cases, doctors will prescribe a normal saline infusion for one to two hours prior to each dose of foscarnet.

3. What are the adverse effects this drug can cause?

Foscarnet has a great negative impact on the kidneys which indicates that patients should consistently drink water. A normal saline administered intravenously protects the kidneys.

The most common adverse effects of foscarnet therapy include headache, diarrhea, and fatigue.

When the drug is stopped, tremor and muscle twitching may occur. The patient must contact his or her doctor in this occasion.

Uncommon adverse effects include penile, mouth, and vaginal ulcers.

4. How should foscarnet be stored?

At room temperature, specifically 15-30°C. It is recommended that the drug should be used within 24 hours of dilution.

Sources:

Foscarnet. (2009). Retrieved May 16, 2019, from https://hivclinic.ca/main/drugs_fact_files/foscarnet.pdf