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Lexiva - fosamprenavir

General Information This drug is almost always used as one component of a multidrug combination to suppress the human immunodeficiency (HIV) viral load.
Specifics Fosamprenavir is one of the newest antiviral drugs against HIV, but it is rapidly establishing itself as a potent, convenient, and very well-tolerated option.

Fosamprenavir works by inhibiting the production of HIV's proteins.  It is classified as a protease inhibitor (PI).

Dosing Generally fosamprenavir is taken as one of the 700 mg pills twice a day with or without food.  Usually it is taken with 100 mg of ritonavir (Norvir) twice a day.

Occasionally fosamprenavir may be taken as a single daily dose of two 700 mg pills with two 100 mg ritonavir (Norvir) gel caps.

This combination of ritonavir and fosamprenavir is termed "boosted fosamprenavir" because ritonavir increases the levels of fosamprenavir in the bloodstream. 

(this refers to your willingness, ability, and actual performance in taking your medications)

For further information and tips on adherence, go to the Adherence section of this site.

As with any antiviral drug or antibiotic, try not to ever miss a dose.  If you miss a dose and notice that you have done so within a few hours of its scheduled time, you may take the dose as usual and take the next dose at its regular time. 

It is very important that you do not alter the dosing of fosamprenavir or ritonavir without advice from your healthcare provider.

If you miss more than one dose, look at the reasons why you missed them and come up with a plan to avoid it in the future.  For example, if you fell asleep too early, take the medicine earlier in the evening, with your later meal, set an alarm, or have someone appointed to wake you up for your medicine.  

It is strongly recommended that you consider using weekly pill boxes and arrange all of your doses a week in advance.  Buy a small pill box so that you can carry a dose or two of your medicines with you in case you are away from home.

Possible Side Effects
The package insert for most drugs including fosamprenavir is often overwhelming and scary with perhaps an overemphasis on side effects.  We have summarized the important and more common problems here.

Most people take fosamprenavir without many side effects. 

Possible side effects include stomach upset, diarrhea, nausea, liver problems, increased fat (cholesterol and triglycerides) in the blood, and possibly diabetes.  Usually you will have blood tests done in the first month to look for the beneficial effects of fosamprenavir and any side effects. 

Many minor side effects will either stay constant or get better with time.  It is mainly the side effects that are severe or get worse that may cause significant health risks for you.

All drugs of this type can cause or contribute to abnormal fat redistribution characterized by an enlarged belly and/or thinning of the face, arms, or legs.  In most cases this would be also accompanied by elevated cholesterol levels, elevated triglyceride levels, and perhaps a tendency to develop diabetes.   Fosamprenavir may have less effect on these problems than other protease inhibitors.

This refers to the way that fosamprenavir affects other medications and how other medications affect fosamprenavir
Fosamprenavir levels in the bloodstream are affected by the following drugs and should be used cautiously if at all:
Efavirenz (Sustiva)
Lopinavir/ritonavir (Kaletra)
Delavirdine (Rescriptor)

Fosamprenavir affects the levels of certain drugs in the bloodstream and these drugs should be used cautiously - usually with dose adjustments:
Atorvastatin (Lipitor)
Methadone (Dolophine and others)
Rifabutin (Mycobutin)

The following drugs should not be taken with fosamprenavir:
Ergot derivatives: dihydroergotamin, ergonovine, ergotamine, methylergonovine
GI motility agent: cisapride
Neuroleptic: pimozide
Sedatives/sleeping pills: midazolam, triazolam
Anti-TB drug: rifampin
Report to you healthcare provider or go to an Emergency Room if you have severe side effects, increasing side effects, shortness of breath, uncontrollable diarrhea, fever, weakness, jaundice (eyes and skin turn yellow,) muscle pain, nausea and vomiting so that you cannot hold down your food and liquids.
You can download this handout in PDF format by clicking HERE.