Foscarnet sodium

CLINICAL USE

Antiviral agent:Treatment and maintenance therapy of cytomegalovirus retinitis (CMV)Mucocutaneous herpes simplex infection (HSI)

DOSE IN NORMAL RENAL FUNCTION

CMV: 60 mg/kg every 8 hours induction dose for 2–3 weeks, then 60 mg/kg daily, increase to 90–120 mg/kg if toleratedMucocutaneous herpes simplex infection: 40 mg/kg every 8 hours

PHARMACOKINETICS

Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :300

%Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :14–17

%Excreted unchanged in urine &nbsp &nbsp : 85

Volume of distribution (L/kg) &nbsp &nbsp &nbsp :0.4–0.6

half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp :2–4/>100

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 &nbsp &nbsp : 28 mg/kg every 8 hours

10 to 20 &nbsp &nbsp : 15 mg/kg every 8 hours

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : 6 mg/kg every 8 hours

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp:Dialysed. Dose as in GFR

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/min. See ‘Other Information’

HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :Dialysed. Dose as in GFR

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/min. See ‘Other Information’

HDF/high flux &nbsp :Dialysed. Dose as in GFR

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/min. See ‘Other Information’

CAV/VVHD &nbsp &nbsp &nbsp:Dialysed. Dose as in GFR=10–20 mL/min.

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Antivirals: avoid with lamivudine

Ciclosporin: may cause acute renal failure in combination

ADMINISTRATION

Reconstition

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Route

Centrally (undiluted); peripherally (diluted)

Rate of Administration

Continuous infusion over 24 hours, or intermittent infusion over at least 60 minutes

Comments

If given peripherally dilute with glucose 5% or sodium chloride 0.9% to a concentration of 12 mg/mL or lessAlternatively, piggy-back the undiluted foscarnet dose to 1 litre of a glucose 5% or sodium chloride 0.9% infusionIf given centrally, can be administered undiluted but additional fluids should be given to reduce the risk of nephrotoxicity

OTHER INFORMATION

Maintain adequate hydration to prevent renal toxicityMonitor serum calcium and magnesium Some units use full-dose ganciclovir and half-dose foscarnet concomitantly for treatment of resistant CMV disease

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