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.

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