foscarnet (foss-kar-net) Foscavir

 Indications

Treatment of cytomegalovirus (CMV) retinitis in HIV-infected

patients (alone or with ganciclovir). Treatment

of acyclovir-resistant mucocutaneous herpes simplex

virus (HSV) infections in immunocompromised patients.

Action

Prevents viral replication by inhibiting viral DNA-polymerase

and reverse transcriptase. Therapeutic Effects:

Virustatic action against susceptible viruses including

CMV.

Pharmacokinetics

Absorption: IV administration results in complete

bioavailability.

Distribution: Variable penetration into CSF. May

concentrate in and be slowly released from bone.

Metabolism and Excretion: 80–90% excreted

unchanged in urine.

Half-life: 3 hr (in patients with normal renal function);

longer half-life of 90 hr may reflect release of

drug from bone.

TIME/ACTION PROFILE

ROUTE ONSET PEAK DURATION

IV rapid end of infusion

8–24 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity; HF (due to

sodium content); Patients on sodium-restricted diets;

Hemodialysis; Lactation: Avoid breast feeding.

Use Cautiously in: Renal impairment (doseprequired

if CCr 1.4–1.6 mL/min/kg; see product information);

History of seizures; History of QT interval prolongation

or cardiovascular disease; Concurrent use of

other QT interval prolonging medications; Hypokalemia

or hypomagnesemia (must be corrected prior to therapy);

OB, Pedi: Safety not established.

Adverse Reactions/Side Effects

CNS: SEIZURES, headache, anxiety, confusion, dizziness,

fatigue, malaise, mental depression, weakness.

EENT: conjunctivitis, eye pain, vision abnormalities.

Resp: coughing, dyspnea. CV: TORSADE DE POINTES,

chest pain, edema, palpitations, QT interval prolongation.

GI: diarrhea, nausea, vomiting, abdominal pain,

abnormal taste sensation, anorexia, constipation, dyspepsia.

GU: renal failure, albuminuria, dysuria, nocturia,

polyuria, urinary retention. Derm:qsweating,

pruritus, rash, skin ulceration. F and E: hypocalcemia,

hypokalemia, hypomagnesemia, hyperphosphatemia,

hypophosphatemia. Hemat: anemia, granulocytopenia,

leukopenia, neutropenia. Local: pain/

inflammation at injection site. MS: arthralgia, myalgia,

back pain, involuntary muscle contraction. Neuro:

ataxia, hypoesthesia, neuropathy, paresthesia, tremor.

Misc: HYPERSENSITIVITY REACTIONS (including anaphylaxis,

urticaria, and angioedema), fever, chills, flu-like

syndrome, lymphoma, sarcoma.

Interactions

Drug-Drug: Avoid use of drugs known to prolong

the QTc interval including quinidine, procainamide,

amiodarone, sotalol, chlorpromazine, thioridazine,

moxifloxacin, pentamidine, and methadone.

Concurrent use with parenteral pentamidine may result

in severe, life-threatening hypocalcemia. Risk of nephrotoxicity may beqby concurrent use of other nephrotoxic

agents (amphotericin B, aminoglycosides,

cyclosporine, acyclovir, methotrexate, tacrolimus,

pentamidine (IV)).

Route/Dosage

IV (Adults): CMV retinitis—60mg/kg q 8 hr or 90

mg/kg q 12 hr for 2–3 wk, then 90–120 mg/kg/day as

a single dose. Doseprequired for any degree of renal

impairment; HSV—40 mg/kg q 8–12 hr for 2–3 wk

or until healing occurs.

Availability (generic available)

Solution for injection: 24 mg/mL.