Fosamprenavir

CLINICAL USE

Protease inhibitor:For HIV infection, in combination with other antiretroviral drugs

DOSE IN NORMAL RENAL FUNCTION

700 mg twice daily with ritonavir 100 mg twice daily

PHARMACOKINETICS

Molecular weight :625.7 (as calcium salt)

%Protein binding :90 (amprenavir)

%Excreted unchanged in urine : <1 (amprenavir)

Volume of distribution (L/kg) :6 (amprenavir)

half-life – normal/ESRD (hrs) :7.7/Unchanged (amprenavir)

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Unlikely to be dialysed. Dose as in normal renal function

HD :Unlikely to be dialysed. Dose as in normal renal function

HDF/high flux :Unlikely to be dialysed. Dose as in normal renal function

CAV/VVHD :Unknown dialysability. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Anti-arrhythmics: possibly increased concentration of amiodarone, flecainide, lidocaine and propafenone (increased risk of ventricular arrhythmias) – avoid concomitant use

Antibacterials: concentration of both drugs increased with erythromycin; increases concentration of rifabutin – reduce rifabutin dose; concentration significantly reduced by rifampicin – avoid concomitant use; possibly increases dapsone concentration; avoid concomitant use with telithromycin in severe renal and hepatic impairment

Antidepressants: concentration reduced by St John’s wort – avoid concomitant use; possibly increases side effects of tricyclics; possibly reduces paroxetine concentration

Antimalarials: avoid concomitant administration with artemether/lumefantrine

Antipsychotics: possibly inhibits aripiprazole metabolism – reduce aripiprazole dose; possibly increases clozapine concentration; possibly increases pimozide and sertindole concentration (increased risk of ventricular arrhythmias) – avoid concomitant use

Antivirals: concentration reduced by efavirenz, lopinavir and tipranavir; concentration possibly reduced by nevirapine; concentration increased by ritonavirAnxiolytics and hypnotics: increased risk of prolonged sedation and respiratory depression with alprazolam, clonazepam, diazepam, flurazepam and midazolamCilostazol: possibly increases cilostazol concentration – avoid concomitant use

Ergot alkaloids: increased risk of ergotism – avoid concomitant useImmunosuppressants: monitor ciclosporin, tacrolimus and sirolimus levelsStatins: possibly increased risk of myopathy with atorvastatin; possibly increased myopathy with simvastatin – avoid concomitant use

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

Prodrug of amprenavir, 700 mg of fosamprenavir is equivalent to 600 mg amprenavir.

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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