Brand Name: Fuzeon

Common Name: enfuvirtide (ENF) or T-20

Class:fusion inhibitor (type of entry inhibitor)

Standard Dose: One subcutaneous (under the skin) injection of 90 mg (1 ml) twice daily (every 12 hours) into the upper arm, thigh or abdomen. No food restrictions (take with or without food). Take missed dose as soon as possible, but do not double up on your next dose.

AWP: $2,222.78 / month for 90 mg kit

Manufacturer contact: Roche Pharmaceuticals and Trimeris, www.rocheusa.com, www.trimeris.com

AIDSInfo:1 (800) HIV–0440 (448–0440), www.aidsinfo.nih.gov

The most common are Injection Site Reactions (ISRs), which occur in virtually all patients. The severity of reactions is variable, and for most is mild to moderate. Symptoms could include itching, swelling, redness, pain or tenderness, hardened skin or bumps; others include headache and fever. Bumps termed “nodules” seem to occur more frequently and severely in areas of high muscle mass (most notably the center of the stomach—the abs—and the legs). They will hurt with movement. Allergic reactions are possible. In studies, pneumonia happened more often in the patients on Fuzeon. It is unclear if this was related to the use of Fuzeon, so report cough, fever, or trouble breathing to your healthcare provider right away.

To date none that require dose adjustment have been reported.

Fuzeon is intended for treatment of HIV in patients who are treatment-experienced. Preparing and injecting the Fuzeon can be complicated, so ask your healthcare provider how to do it. First, the drug needs to be dissolved with sterile water (provided in the kit), which may take 30 to 45 minutes. Never shake the vial with the Fuzeon. Instead, roll it gently in your hands. You can store your second dose in the refrigerator, but it must be used within 24 hours. Before injecting, it is important to make sure that the Fuzeon powder is completely dissolved. To minimize injection site reactions, inject where you can pinch an inch (upper arm, stomach, or thigh). If not, then be sure to use half the length of the needle. Inject slowly and apply a gentle massage after injection. Try using vibrating devices after injections. Careful reconstitution of drug is also helpful. The drug must be carefully reconstituted for 30–45 minutes (for the two daily doses—refrigerate the dose—after reconstitution—that will be taken later, and then allow it to warm to room temperature before using). Never shake—it will foam. Follow instructions to avoid infection. ISR may worsen when injection is repeated in the same spot or given deeper than intended, for example, into the muscle. Fuzeon can be taken at the same time as other anti-HIV drugs. Always rotate injection sites frequently. Never inject into moles, scars, bruises, nodules or the navel. New bioinjection (needleless injection device) is being studied and is available in limited distribution; however, patients report that it “hurts like hell,” but doesn’t cause as severe injection site reactions.

Fuzeon is the first and only anti-HIV compound on the market called a fusion inhibitor. Fusion inhibitors block fusion of HIV with a cell before the virus enters the cell and begins its replication process. Fusion inhibitors are a type of entry inhibitor, another one of which is expected to enter the pharmacy this year (see page 48). Because of injections, this drug will most likely be used in the heavily-treatment experienced and salvage therapy options. Two large Phase III studies showed good viral load decrease when added to an optimized antiviral combination in heavily treatment-experienced people, including those with protease inhibitor-resistant virus and those who’ve taken all three current drug classes. Participants used three to five antivirals in addition to Fuzeon, and both genotype and phenotype tests.

U.S. HIV treatment guidelines support the use of Fuzeon with an active boosted protease inhibitor in patients who are heavily treatment-experienced. The guidelines supported the approach as it resulted in better and more prolonged virologic suppression than other regimens. Evidence included several studies of new boosted protease inhibitors in treatment-experienced patients which found an enhanced virologic response when used in conjunction with Fuzeon.

The first approved entry inhibitor! Great drug for salvage, but will never be a first or second line therapy, or even third for that matter. Too expensive, too complicated with the twice daily injections, too many problems with injection site reactions (ISRs). The company has attempted to deal with the ISR problem by using a needle-free device, which has helped some people. The fact is, this drug has brought several people I know back from the edge, and that is a very good thing. Even though it is currently the “heavy hitter” on the salvage playing field, it still has the potential for resistance, so it needs to be used in combination with other active drugs, and some people have trouble scraping together a viable regimen. It’s good to know that there are options like this should I ever need it, but it also reminds me to take my little three-pill once-a-day regimen faithfully.—Cathy Olufs