Amprenavir

Mechanism :

Amprenavir is an inhibitor of HIV-1 protease. Amprenavir binds to the active site of HIV-1 protease and thereby prevents the processing of viral gag and gag-pol polyprotein precursors, resulting in the formation of immature non-infectious viral particles.

Indication :

• HIV infection

Contraindications :

Coadministration is contraindicated with drugs that are highly dependent on CYP3A4 for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events. If amprenavir is coadministered with ritonavir, the antiarrhythmic agent’s flecainide and propafenone are also contraindicated. Because of the potential toxicity from the large amount of the excipient, propylene glycol, contained in the oral Solution, that formulation is contraindicated in certain patient populations and should be used with caution in others. Contraindicated in patients with previously demonstrated clinically significant hypersensitivity to any of the components of this product.

Dosing :

Adverse Effect :

Nausea, vomiting, diarrhea, and abdominal pain/discomfort.

Interaction :

Rifabutin: An increase in the plasma concentrations of rifabutin and a decrease in the plasma concentrations of amprenavir.
Ketoconazole: An increase in the plasma concentrations of amprenavir, a dosage reduction should be considered.
Rifampin: Rifampin is a potent inducer of P450 (CYP3A4) which markedly diminishes plasma concentrations of amprenavir.
Other: Should not be administered concurrently with terfenadine, astemizole, cisapride, triazolam and midazolam because coadministration with inhibitors of P450 (CYP3A4) may result in inhibition of metabolism of these drugs and create the potential for serious and/or life-threatening events (i.e., cardiac arrhythmias or prolonged sedation).
Other drugs that induce CYP3A4 less potently than rifampin, such as phenobarbital, phenytoin, carbamazepine, and dexamethasone should be used cautiously together since they could also diminish plasma concentrations of amprenavir.
Occupational Hazards: Dizziness and blurred vision have been reported. Patients should be advised to avoid driving or operating machinery if they experience these reactions.

Renal Dose :

Hepatic Dose :