What is Ziagen

• Ziagen is an anti-HIV medication. It is in a category of HIV medications called nucleoside reverse transcriptase inhibitors (NRTIs). Ziagen prevents HIV from altering the genetic material of healthy T-cells. This prevents the cells from producing new virus and decreases the amount of virus in the body.

• Ziagen, manufactured by GlaxoSmithKline, was approved for the treatment of HIV by the U.S. Food and Drug Administration (FDA) in 1998.

• Ziagen is available in pharmacies as a single drug, which is always combined with at least two other anti-HIV drugs, or in combination tablets: Trizivir and Epzicom.

What about side effects

• Approximately 5 percent of people who take Ziagen are allergic to it and can experience a "hypersensitivity reaction." This can be serious and may require that Ziagen therapy be stopped. A hypersensitivity reaction usually appears during the second week of therapy, but it can take as long as six weeks to notice any symptoms. The most common symptoms are fever and rash, followed by headaches, stomach upset, feeling tired, sore throat, cough, and shortness of breath. These symptoms usually get worse over time and it is important that you report them to your doctor immediately.

• An inexpensive laboratory test is available to look for an inherited gene, called HLA-B*5701, that has been linked to the hypersensitivity reaction in HIV-positive people taking Ziagen. While not all people with this gene experience an allergic reaction while taking Ziagen, most do. In turn, if you are tested and found to have this gene, Ziagen (or other medications containing abacavir) should either be avoided or used with caution. If you and your doctor are thinking about starting Ziagen or another abacavir-containing medication for the first time, be sure to discuss this genetic test.

• If your doctor tells you that you are allergic or are having a hypersensitivity reaction, you will be told to stop the drug. If you stop taking Ziagen because of these symptoms, you must not start the drug again, or start any drug that contains Ziagen (e.g. Trizivir or Epzicom). Some people who were allergic to the drug and restarted therapy saw their symptoms return immediately and became very ill.

• Lactic acidosis, which can be fatal, and severe liver problems have been reported in people taking NRTIs including Ziagen. Contact your doctor immediately if you experience nausea, vomiting, or unusual or unexpected stomach discomfort; weakness and tiredness; shortness of breath; weakness in the arms and legs; yellowing of the skin or eyes; or pain in the upper stomach area.

• Some of the more common side effects include appetite loss, headaches, feeling crummy (malaise), nausea, vomiting, and diarrhea. Very often, these side effects improve within a few months/weeks of starting Ziagen.

• Anti-HIV drug regimens containing NRTIs, including Ziagen, can cause increased fat levels (cholesterol and triglycerides) in the blood, abnormal body-shape changes (lipodystrophy; including increased fat around the abdomen, breasts, and back of the neck, as well as decreased fat in the face, arms, and legs), and diabetes. These side effects of anti-HIV drug therapy are reviewed in our lessons on Lipodystrophy, Facial Lipoatrophy, and Risks To Your Heart (Hyperlipidemia).

How does it work?

• As with all the NRTI (nucleoside reverse transcriptase inhibitor) drugs, Ziagen works by terminating the growing DNA (gene) chain of HIV as it is trying to reproduce itself. This results in defective HIV particles that are unable to infect new cells.

• When taken regularly as prescribed, Ziagen combination therapy usually leads to a decrease in HIV viral load (RNA) in the blood and an increase in the CD4 cell count.

• In other studies, these benefits have been associated with decreased rates of AIDS opportunistic infections, improved quality of life and increased survival.

What about drug interactions?

• Ziagen can increase the amount of the protease inhibitor Agenerase (amprenavir), and probably Lexiva (fosamprenavir) in the body. However, it is not necessary to change the doses of either Ziagen or Agenerase/Lexiva.

• Ziagen can increase the rate at which methadone, a drug often used to help manage symptoms of heroin withdrawal, is cleared from the body. If you are taking methadone and Ziagen at the same time, it might be necessary to increase your methadone dose.