Side-effects

As fosamprenavir (Telzir) is converted into amprenavir in the body, its side-effects are very similar to those of amprenavir. The commonest side-effects are headache, nausea, rash, diarrhoea, vomiting and fatigue. These are usually mild .

As a class, protease inhibitors have been associated with a syndrome of fat and metabolic irregularities. This syndrome includes fat redistribution, high blood fat levels, diabetes, increased levels of blood sugar and increased bleeding in haemophiliacs. The cause and long-term health implications of the syndrome are unknown at this stage. GlaxoSmithKline has presented test tube and animal studies that support its claim that amprenavir may not cause body fat changes, but further long-term data are required before this claim can be substantiated.^{1 2}

Amprenavir is a sulfonamide drug, so people who have experienced adverse reactions to cotrimoxazole (Septrin) or other drugs of this type may experience reactions to fosamprenavir.

The US product label for fosamprenavir cautions of a possible connection between fosamprenavir treatment and heart attack, based on French study findings that each year of therapy with the drug increased the risk of heart attack by 54%. There is also a caution that fosamprenavir therapy can cause increases in cholesterol.

Less than 1% of people who have taken fosamprenavir have experienced severe and life-threatening skin reactions, including Stevens-Johnson syndrome.