Enfuvirtide (Subcutaneous)

Overview

Enfuvirtide, which is often referred to as T-20 or Fuzeon, is part of a class of medicines known as fusion inhibitors. These medications stop the HIV virus from binding to and entering human cells. HIV must bind to glycoprotein 41 on the surface of the cell once it has attached to a receptor, and Enfuvirtide prevents it from doing so. This medicine is administered subcutaneously, and is suitable for use in patients over the age of 6.

Healthcare professionals often recommend that Enfuvirtide should be used in conjunction with at least two active antiretroviral medicines instead of being used as an addition to a failing regimen, as this reduces the chance of resistance to the medication developing. While Enfuvirtide cannot cure HIV, it can help patients with the condition to live much longer, healthier lives free from many of the symptoms associated with HIV and/or AIDS.

Enfuvirtide is the first fusion inhibitor to ever be developed and subsequently approved for treatment of the human immunodeficiency virus by the US Food & Drug Administration (FDA). It functions by disrupting HIV molecular machinery at the last state of fusion with the targeted cell. It has been specifically designed to mimic components of the virus before displacing them, and this prevents normal fusion of HIV with healthy cells.

This medication is only considered to be an effective treatment against HIV-1. Research has suggested that low activity against the isolated HIV-2 virus has only been demonstrated in vitro. While it is a relatively expensive treatment for the prevention of HIV infection, Enfuvirtide is generally regarded as a beneficial salvage treatment in patients who have developed a resistance to multiple antiretroviral medications.

Type Of Medicine

  • Fusion inhibitor

Conditions Treated

  • Human immunodeficiency virus (HIV)

Side Effects

Along with its designated effects, Enfuvirtide can also cause some unwanted side effects. Some of the most commonly experienced side effects reported by patients undergoing treatment with this medicine include the following:

  • Burning, tingling, numbness, or painful sensations/weakness in the hands, arms, legs and/or feet
  • Coughing
  • Headache
  • Awkwardness
  • Tenderness or pain around the cheekbones and eyes
  • Difficulty breathing or shortness of breath
  • Runny or stuffy nose
  • Tightness in the chest
  • Wheezing
  • Unsteadiness
  • Abnormal growths filled with semisolid material or fluid
  • Discouragement
  • Feeling empty or sad
  • Hard lumps
  • Irritability
  • Painful cold sore or blisters on the nose, lips, eyes or genitals
  • Redness of skin
  • Unusually warm skin
  • Weight loss
  • Fear

As the patient continues treatment with Enfuvirtide as prescribed by a physician, many of the previously mentioned symptoms (if not all of them) should lessen. If side effects appear to get worse or persist for a prolonged period, the patient is advised to follow this up with their healthcare provider as soon as possible. In many cases, a doctor or pharmacist may be able to advise on ways to alleviate certain side effects via over the counter remedies, supplements or other prescription medications.

Generally, the majority of patients only experience very minimal side effects when taking Enfuvirtide' if they observe any untoward effects whatsoever. The drug is designed to prevent further infection of HIV, which is a very serious condition, and most healthcare professionals agree that the benefits of taking Enfuvirtide far outweigh the risks associated with experiencing mild side effects.

Other side effects, which are experienced rarely (albeit often enough to warrant mentioning) include the following:

  • Chills
  • Bloating
  • Dark urine
  • Itching or dry eyes
  • Constipation
  • Excessive tears in the eyes
  • Quick heartbeat
  • Discharge from the eye
  • Indigestion
  • Fevers
  • Chills
  • Itching, redness, tenderness, pain, swelling or warmth at the site of injection
  • Lumps or growths on the skin
  • Loss of appetite
  • Pains in the side, stomach or abdomen
  • Nausea
  • Yellow eyes or skin
  • Swelling of the throat, face and/or tongue
  • Difficulty swallowing

Other side effects may occur, the incidence of which is not known. These can include:

  • Tarry or black stools
  • Blood in stools
  • Bleeding gums
  • Pain in the chest
  • Decreased frequency of urine
  • Decreased amount of urine
  • Inability to move legs or arms
  • Difficult or painful urination
  • Increased thirst
  • Pale skin
  • Sore throat
  • Sudden weakness or numbness in the legs and arms
  • Unusual bruising or bleeding
  • Unusual weakness or tiredness
  • Sores, ulcers or white spots in the mouth
  • Bad or unusual taste or aftertaste
  • Changes in taste
  • Diarrhea
  • Pus or grease at roots of the hair
  • Swollen, tender or painful lymph glands in the armpit, neck or groin

Because the psychology of the patient can be affected by Enfuvirtide use, he or she should be prepared to experience mood swings, confusion, memory issues, depression and/or hallucinations. Caution should therefore be taken when prescribing this medicine to patients with a history of mental health issues, such as schizophrenia, bipolar disorder (mania) or depression.

Not all side effects may have been reported. Patients who experience side effects which are not currently listed are advised to inform their doctor and to notify the FDA of their findings.

Dosage

As with all medicines, it is imperative that the patient administers Enfuvirtide only as prescribed by a qualified doctor. This means that patients must avoid taking any more Enfuvirtide than advised, either in terms of dose size or frequency of use. In addition to this, patients should be prepared to stop using Enfuvirtide if advised to do so by their doctor, even if they still have a supply of the medication remaining.

  • The usual adult dose for HIV is 90mg of Enfuvirtide, administered subcutaneously.
  • The usual pediatric dose for those between 6 and 16 years of age is 2mg per kg of weight, administered subcutaneously.

Subcutaneous administration information:

While many patients will receive their doses of Enfuvirtide administered by a healthcare professional in a clinical setting, some people who undergo treatment with this medicine may elect to self-administer, or may have no choice but to self-administer (such as those living in a rural area, without reasonable access to a clinic or hospital).

Subcutaneous injections are shots which are administered via a syringe directly into the fat situated between the skin and muscle. Patients who elect to self-administer Enfuvirtide subcutaneously should do so only when their healthcare provider is completely satisfied that they have the ability to do so without posing a risk of injury to themselves.

There are four areas of the body where subcutaneous injections are typically administered:

  • Thigh' entire leg should be uncovered before patient locates the area between the hip and knee, and to the side. Patient should be able to grasp 1-2 inches of skin before administering the injection.
  • Abdomen' injections may be administered below the waist, slightly above the hip bone and/or at least two inches away from the bellybutton. Patients must not inject into the belly button.
  • Upper arm' patients may find it difficult to inject into their own upper arm, although this information may be beneficial for a third-party who administers the injection.
  • Lower back' the back should be uncovered from the waist down to the top of the buttocks. The patient should imagine a line which runs across the back just above the crack between buttocks. Injections may be given below the waist, but above this line. Injections should be administered halfway between the side and the spine.

Patients are advised to keep a diary of where each injection has been given, in order to keep track of the sites available for use. This diary should make note of the time, date and site administration location every time a subcutaneous injection of Enfuvirtide is administered.

Subcutaneous injections can either be administered straight in at a 90-degree angle, or at a 45-degree angle. If two inches of skin can be gripped between the thumb and forefinger, the injection may be administered directly-in at 90 degrees. If less than two inches of skin can be grasped between forefinger and thumb, the injection should be given at a 45-degree angle. Patients can also use these further recommendations to successfully administer a subcutaneous injection of Enfuvirtide:

  • An alcohol wipe should be opened and used to clean the area of skin which the patient intends to inject in. This area should be allowed to sufficiently dry prior to injection.
  • The needle should be prepared. The Patient should hold the syringe with their strongest hand and remove the cover with their other hand. The syringe should then be placed between forefinger and thumb, with the barrel of the syringe allowed to rest on the second finger.
  • The patient should then use their free hand to grab the area of skin they intend to inject into.
  • The needle should be inserted into the skin. The barrel of the syringe should be held tightly, and the wrist used to inject. Once the needle has sufficiently penetrated, the plunger should be pushed down to inject the Enfuvirtide.
  • The needle should be removed at the same angle it entered after administration, and the injected area should be wiped with a gauze or pad to prevent infection.

It is important for injection sites to be rotated to help prevent scarring and/or changes to the skin. When re-using an injection site, the medicine should be administered at least an inch away from any previous areas of injection. For further advice on how best to choose an injection site, patients are advised to contact their healthcare provider.

While the manufacturer of Enfuvirtide provides general dosage instructions, it should be reiterated that these are simply guidelines which can be altered by the patient's doctor. A doctor will consider a number of factors when determining dose size, including the age, height, weight and condition of the patient, along with their current HIV treatment schedule.

Patients are advised against taking double doses. If a patient misses a dose, they should take the missed dose as soon as they realise, unless it is closer to the time to take the next scheduled dose. In this case, the patient should simply omit the missed dose and continue with the next scheduled dose as standard.

If a patient experiences signs of overdose (fast or slow heartbeat, difficult or labored breathing, loss of consciousness, loss of co-ordination, seizures or flushed skin) they may require immediate medical attention, and should call their local poison control center on 1800-222-1222 or emergency services on 911 as soon as possible.

Interactions

All drugs have the potential to interact with other medicines within the body, and these interactions can cause the effects of one or more medications to change, resulting in them becoming ineffective at treating the condition they were prescribed for. In rare cases interactions can even cause dangerous or potentially fatal side effects. Because of these risks, it is important for the patient to keep a detailed list of all medications they are currently taking. This extends to complementary therapies, over the counter remedies, herbal supplements and vitamins along with prescription drugs.

The following is a list of medicines known to interact with Enfuvirtide. Patients who are currently undergoing treatment with one or more of these drugs should inform their doctor prior to starting treatment with Enfuvirtide:

  • Atazanavir
  • Cobicistat
  • Darunavir

Warnings

Enfuvirtide must not be used as a monotherapy. The HIV virus can potentially become resistant to Enfuvirtide if it is not combined with other medications or treatments, such as antiretroviral therapy.

Patients with a history of blood clotting or bleeding disorders, or breathing problems, should inform their doctor prior to undergoing treatment with Enfuvirtide. It may not be a suitable medication for certain patients who experience recurrences of one or more of these conditions.

While the majority of patients will experience skin reactions at the site where this medicine is injected, in rare instances further complications can arise. If skin reactions get worse or last for more than a week, the patient should inform their doctor.

HIV increases the propensity for the patient to get other infections, and in some cases Enfuvirtide users have developed pneumonia. It is not clear whether Enfuvirtide is the direct cause of pneumonia, however its use may exacerbate or increase the potential for developing the condition, particularly in patients who smoke.

While Enfuvirtide is not expected to cause any harm to an unborn baby, pregnant mothers should be aware that HIV can be passed to an unborn baby if they do not take the correct medication during the pregnancy. All prescribed HIV medicines should be taken to control the infection. In addition to this, HIV-positive mothers of newborn babies should avoid breastfeeding, as they may pass the virus to their offspring via breast milk.

Storage

Unmixed Enfuvirtide vials should be stored at room temperature. In some tropical areas, the medication may require refrigeration between 2C and 8C. This medicine should be kept out of the reach of children and animals, away from excess moisture and heat sources.

Sterile water vials used to dilute Enfuvirtide should also be stored at room temperature. When the medication has been mixed to create an injectable solution, the solution should be kept refrigerated and used within 24 hours of preparation.

For advice on how to dispose of unwanted, unused or expired Enfuvirtide, the patient should consult FDA guidelines and state laws on the correct disposal of medications.

Summary

While Enfuvirtide is greatly beneficial in terms of stopping HIV from affecting healthy cells, it also poses a risk to patients who fail to effectively communicate with their healthcare providers or physicians. While Enfuvirtide is effective at stopping HIV from replicating, it must not be used on its own as HIV can become resistant to it. Patients are therefore advised to take the advice of their doctor and ensure that they continue to take a full and varied regimen of anti-HIV medications.

Enfuvirtide can also cause a number of unwanted side effects, as well as potentially interacting with a number of different medicines. Patients should make themselves aware of the risks of using Enfuvirtide prior to taking their first dose.

When taken correctly, Enfuvirtide functions to prevent symptoms associated with HIV and can prevent the patient from developing AIDS, providing them with a much greater quality of life. To achieve these results, patient and doctor must work together in order to develop a satisfactory dosage schedule in conjunction with antiretroviral medications and other HIV drugs.