POSITIVELY AWARE MARCH/APRIL 2011
brand name: Fuzeon
common name: enfuvirtide
class: Fusion inhibitor (a type of entry inhibitor)
manufacturer: Genentech | www.genentech.com, www.fuzeon.com,
(877) 4–FUZEON (438–9366)
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. Can be taken with or without food, with no dietary restrictions. Take missed dose as soon as possible, unless it is almost time for your next dose. Do not double up on your next dose.
AWP: $3,154.10 / month for 90 mg kit
Potential side effects and toxicity
The most common are Injection Site Reactions (ISRs), which occur in virtually all patients. The severity of reaction is variable, and for most is mild to moderate. Symptoms could include itching, swelling, redness, pain or tenderness, and hardened skin or bumps. 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 thighs). They will hurt with movement. Other side effects may include diarrhea, nausea, and fatigue. Hypersensitivity (allergic-like) 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 health care provider immediately. Immune Reconstitution Inflammatory Syndrome (IRIS) may occur as the immune system regains strength; signs and symptoms of inflammation from previous infections may occur soon after anti-HIV treatment is initiated. Report symptoms of illness, such as shingles and TB, to a medical provider.
Potential drug interactions
To date, none that are clinically significant have been found.
More information
With other powerful, newer drugs on the market, the twice-daily injectable Fuzeon has truly become a medicine of last resort. Fuzeon is intended for treatment-experienced patients. Store kit at room temperature. Preparing and injecting the Fuzeon can be complicated, so ask your health care provider how to do it. First, the drug needs to be dissolved with sterile water (provided in the kit), which may take up to 45 minutes. Never shake the vial with the Fuzeon, it will foam. Instead, roll it gently in your hands. To save time, you can prepare the two daily doses at the same time. You should store your second dose in the refrigerator, but it must be used within 24 hours (allow it to warm to room temperature before using). 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. Follow proper hygiene 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. Always rotate injection sites frequently. Never inject into moles, scars, bruises, nodules, or the navel. Switching to smaller needles, like insulin syringes, may also help with ISRs. Fuzeon can be taken at the same time as other anti-HIV drugs. Fuzeon is the 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 (see Selzentry). See package insert for more complete information on potential side effects and interactions.
Doctor’s comments
Fuzeon inhibits fusion of the virus with the CD4 cell membrane, the final stage in the entry process. It was our first true “salvage drug,” a drug to be used in people with highly resistant virus. In fact, the original TORO trials not only led to the approval of Fuzeon, but ushered in the era of salvage therapy and set the standard for clinical trial design that would later lead to the approval of drugs like Prezista, Isentress, Selzentry, and Intelence. However, Fuzeon, never a big seller, is now rarely used. For most people, even those with the most highly resistant virus, there are easier, less expensive options that don’t require twice-daily subcutaneous injections that leave long-lasting painful bumps on the skin (injection site reactions, or ISRs). But I wouldn’t dismiss Fuzeon altogether. We may be in a “honeymoon period” with respect to salvage therapy, when almost everyone can keep their viral load undetectable with a combination of other drugs. But the pipeline of drugs for treatment-experienced patients isn’t exactly gushing right now, and if we begin to see a lot of resistance to the newer drugs, especially Isentress, we may be forced to pull Fuzeon off the shelves again. —Joel Gallant, MD, MPH
Activist’s comments
Like its name suggests, it’s the first and only fusion inhibitor—so as the only drug in its class, there is no pre-existing resistance for those in desperate need of a new drug. The twice-daily injections with often painful and lingering injection site reactions mean that, despite its unique activity and efficacy, it remains a drug of last resort for those who’ve run out of options. Even when added to a failing regimen it can help maintain T-cells—buying patients time until new drugs become available to construct a new regimen. —Jeff Taylor
