Side-effects

The most common side-effect associated with T-20 (enfuvirtide, Fuzeon) is the development of reactions around the injection site. In the TORO studies, 98% of patients who took T-20 had a site reaction. In the two studies, 46 to 53% of T-20 users reported mild tenderness at the injection site at any clinic visit, 15 to 19% reported moderate pain, and 1 to 3% reported severe pain, but only 4% stopped treatment because of the reaction.¹

There seems to be less risk of injection site reaction when administration is via injection into the arm.² However, the reactions are more severe in patients with less fat under the skin: this may be problematic for people with lipoatrophy following extensive antiretroviral therapy.³

Site reactions follow a number of patterns:

• Itchy rash
• Red swollen or puffy skin
• Hardened skin
• Cysts or nodules forming at the injection site. These may be more common if injection occurs in the legs.

More rarely, several individuals have developed abscesses at the injection site. Patients usually experience only one type of site reaction over time. The rashes and reactions may occasionally require treatment with antihistamines or painkillers.

Biojector 2000 avoids the use of needles. It is a needle-less device that is placed against the skin and T-20 is pushed under the skin using high pressure.⁴ The FDA updated product labelling for T-20 after Biojector 2000 was found to cause long-term nerve pain, bruising, and bleeding below the skin in some patients. There is also concern that patients taking blood-thinning medications or those with bleeding disorders may be at an increased risk of bleeding or bruising if using Biojector 2000 to administer T-20.

FDA product labelling now advises against injecting T-20 at sites where large nerves - such as the elbow, knee, groin, and parts of the buttocks - are close to the skin. Patients are also cautioned not to inject T-20 near to moles, scars, burns, tattoos, above blood vessels or near the belly button. Recommended injection sites are the abdomen, upper arm, and outer thigh.

Other side-effects that may be due to T-20 include headache, insomnia, peripheral neuropathy, and eosinophilia (an increase in the number of immune cells known as eosinophils).

Bacterial pneumonia and lymphadenopathy (swollen glands) also occur more frequently in T-20 users.¹ T-20’s manufacturer, Roche has promised to explore these effects further in post-marketing studies. Bacterial pneumonia occurred in 7% of T-20 recipients in the TORO studies, compared to 1% of the control arm. Lymphadenopathy may be a result of the large amount of foreign protein injected by T-20 users over time, since T-20 is a peptide.