Enfuvirtide resistance appears to develop through substitutions in viral DNA, leading to some changes in the enfuvirtide HR1 domain of gp41.
Primarily, this drug has a lower extent of binding to alpha-1 acid glycoprotein with an absolute bioavailability of 84.3% ± 15.5%, and is 92% bound to plasma proteins. The catabolism of this drug is believed to be through amino acid breakdown and also through recycling. This drug is hydrolyzed to a deamidated metabolite that is indicated in some experiments.
Injection site reactions are the most common side effects, including erythema, induration, edema, hemorrhage, nodules, and cysts on the injection area. In some studies, hypersensitivity, as well as other immune-mediated reactions were also distinguished, but the increased rate of pneumonia was observed in the treatment group of this drug, as compared to the control group. Rashes, fever, nausea, vomiting, chills, rigors, hypotension, and/or elevated serum liver transaminase are included in the systemic hypersensitivity reactions observed. This drug must not be restarted following a hypersensitivity reaction, or else these reactions may recur on re-challenge.
This drug must be injected subcutaneously and should not be administered intramuscularly or intravenously. Varying the injection sites like the abdomen, upper thighs, upper arms can minimize the complications. This drug has no documented drug interactions nor evidence of risk in humans but studies are still inadequate.
In phase 3 clinical trials, there is an increased risk of bacterial pneumonia, but the infection’s association with the drug is not yet clear. Patients should be carefully monitored if ever signs and symptoms of pneumonia occur.
