Brand Name: Ziagen

Common Name: abacavir sulfate (ABC)

Class: nucleoside analog (also called nucleoside reverse transcriptase inhibitor, NRTI, or nuke)

Standard dose: Two 300 mg tablets once-a-day (or one 300 mg tablet twice-a-day), no food restrictions (may be taken with or without food). A strawberry/banana flavored liquid is available. Take missed dose as soon as possible, but do not double up on your next dose.

AWP: $445.50 / month

Manufacturer contact: GlaxoSmithKline, www.ziagen.com, 1 (800) 722–9294

AIDS Treatment Information Service: 1 (800) HIV–0440 (448–0440)

Potential side effects and toxicity: Hypersensitivity reaction (HSR, an allergic-like reaction). Approximately 5% of people (1 in 20) taking abacavir experienced HSR during clinical trials. People who think they are experiencing HSR must be evaluated by an experienced HIV provider as soon as possible before they stop taking abacavir. Be very careful, especially in the first two months of treatment. Symptoms worsen with every dose, but very slowly. If treatment is stopped by the medical provider because of this serious reaction, they can never take abacavir, Epzicom or Trizivir again (called “re-challenging”) because of life-threatening and potentially fatal reaction. (This does not apply to missed doses, when there’s no HSR, but watch for symptoms if you’ve stopped the drug for at least a few days). This reaction usually occurs during the second week of treatment, but may take as long as six weeks to appear, gets progressively worse and resolves quickly (24–48 hours) after permanent discontinuation. Symptoms usually, but not always, include some combination of sudden fever, muscle ache, severe nausea, vomiting or abdominal pain, severe tiredness, respiratory symptoms (cough, difficulty breathing and sore throat) and possibly mild rash. These symptoms are listed on the patient information sheet and warning card that you receive each time you fill your Ziagen prescription. You should always keep the warning card with you. HSR might be confused with flu during flu season, but remember that it worsens with every dose. See Epzicom tips.

More common side effects include nausea, vomiting, diarrhea, fatigue, headache, fever, rash, anorexia (loss of appetite), and potentially high blood sugar and high triglyceride levels (fat in the blood). Rare but potentially fatal toxicity with all NRTIs is pancreatitis (inflammation of the pancreas), hepatomegaly (enlarged liver) with steatosis and lactic acidosis (accumulation of lactate in the blood and abnormal acid-base balance). Lactic acidosis has been seen in patients taking NRTIs but is more severe in women, especially those overweight; and more common in people with liver disease, but can occur in people without a history of liver damage. Symptoms include persistent fatigue, abdominal pain or distension, nausea/vomiting, and difficulty breathing or shortness of breath; and enlarged, fatty liver (called hepatomegaly with steatosis). Pancreatitis can be life-threatening and may cause pain in the stomach and back, along with nausea, vomiting and blood in the urine. Check for pancreatitis by checking for increased levels of amylase and lipase in the blood. Risks for pancreatitis include: higher than recommended doses of NRTIs, advanced HIV, and alcohol use. Children should be monitored carefully for pancreatitis.

Potential drug interactions: Excessive alcohol increases abacavir levels and might increase its side effects. People with moderate to severe cirrhosis should use abacavir with caution. No clinically significant interactions between abacavir and other drugs have been observed.

Tips: Studies show that abacavir crosses the blood-brain barrier to a useful degree, which may be beneficial for patients at risk for neurological damage (such as dementia) from HIV. The pattern of viral resistance to abacavir is similar to that of other NRTIs, though abacavir can retain some activity when other NRTI’s have lost most activity.

The manufacturer recommends that people with symptoms of acute respiratory disease consider hypersensitivity even if other diagnosis such as pneumonia, bronchitis or flu is possible, but this is undoubtedly a legal issue. Be careful before you unnecessarily drop Ziagen, and burn through a potent and tolerable HIV drug. Check with your doctor if you have any side effects after taking this medicine—don’t just stop! Doctors report seeing a higher incidence of HSR in people taking abacavir as part of their first drug regimen (Studies done comparing side effects were with this group.). An analysis of 8,000 patients found a reduced risk of HSR in blacks and in men.