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Zalcitabine

Generic name: Zalcitabine
Brand names: Hivid

Why is Zalcitabine prescribed?

Zalcitabine is one of the drugs used against the human immunodeficiency virus (HIV)--the deadly cause of AIDS. HIV does its damage by slowly undermining the immune system, finally leaving the body without any defense against infection. Zalcitabine staves off collapse of the immune system by interfering with the virus"s ability to reproduce.

Zalcitabine is often combined with a protease inhibitor (Crixivan, Invirase, and Norvir) as part of the "cocktail" of drugs that has proven so effective in halting or even reversing the progress of HIV. Zalcitabine can also be combined with the HIV drug Retrovir, provided you have not already been taking Retrovir for more than 3 months. For people with advanced cases of HIV, Zalcitabine is sometimes prescribed by itself when other drugs don"t work or can"t be tolerated.

Most important fact about Zalcitabine

Although Zalcitabine can slow the progress of HIV, it is not a cure. You may continue to develop complications, including frequent infections. Even if you feel better, regular physical exams and blood counts by your doctor are highly advisable. Also be sure to notify your doctor immediately if you experience any changes in your general health.

How should you take Zalcitabine?

Zalcitabine should be taken every 8 hours, exactly as prescribed. It is important to keep levels of the drug in your body as constant as possible, so be sure to take every scheduled dose. Never take more than the prescribed dose; nerve disorders could result.

--If you miss a dose...

Take it as soon as you remember. If it is almost time for the next dose, skip the one you missed and go back to your regular schedule. Never take 2 doses at once.

--Storage instructions...

Store at room temperature in a tightly closed bottle.

What side effects may occur?

Although side effects can never be predicted, they are more likely--and more apt to be severe--in people with an advanced case of HIV. If any side effects develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue using Zalcitabine.

• More common side effects may include:
  Abdominal pain, fatigue, hives, itching, mouth sores and inflammation, nausea and vomiting, rash, tingling, burning, numbness, or pain in the hands and feet

There have been isolated reports of an extremely wide variety of additional problems occurring during Zalcitabine therapy. Whether these problems were caused by the drug remains unclear. Nevertheless, it"s wise to check with your doctor whenever any unexplained symptom develops.

Why should Zalcitabine not be prescribed?

If Zalcitabine gives you an allergic reaction, you cannot use Zalcitabine.

Special warnings about Zalcitabine

If you have an advanced case of HIV, there is a one-in-three chance that Zalcitabine will cause a serious nerve disorder called peripheral neuropathy. The first signs of this problem are numbness, tingling, and burning pain in the hands and feet. Check with your doctor as soon as any of these symptoms develop. If you continue to take Zalcitabine, they will be followed by episodes of intense, sharp, shooting pain or severe, continuous, burning pain--and the condition could become irreversible. If Zalcitabine is stopped promptly, the symptoms will gradually disappear.

Much more rarely, Zalcitabine has been known to cause a dangerous inflammation of the pancreas (pancreatitis), especially in people who have previously had the problem. The chief signs are bouts of severe abdominal pain--usually lasting for days--accompanied by nausea and vomiting. If these symptoms develop, call your doctor without delay. Zalcitabine therapy must be discontinued permanently.

Other rare but dangerous side effects to watch for include liver failure, weakening of the heart, and ulcers in the mouth and the canal to the stomach (esophagus). Kidney disease increases the risk of these side effects. If you"ve ever had kidney, liver, or heart problems, have hepatitis, or tend to abuse alcohol, be sure your doctor is aware of the situation. If you develop a liver problem, treatment with Zalcitabine may have to be stopped.

Like other HIV drugs, Zalcitabine sometimes causes a redistribution of body fat, resulting in added weight around the waist, a "buffalo hump" of fat on the upper back, breast enlargement, and wasting of the face, arms, and legs. It"s not known why this occurs, or what long-term effects it might have.

Remember that Zalcitabine does not eliminate HIV from the body. The infection can still be passed to others through sexual contact or blood contamination.

Possible food and drug interactions when taking Zalcitabine

A number of drugs can cause peripheral neuropathy and should not be taken with Zalcitabine. The list includes:

Chloramphenicol (Chloromycetin)
Cisplatin (Platinol)
Dapsone
Disulfiram (Antabuse)
Ethionamide (Trecator-SC)
Glutethimide
Gold
Hydralazine
Iodoquinol (Yodoxin)
Isoniazid (Nydrazid)
Metronidazole (Flagyl)
Nitrofurantoin (Macrodantin)
Phenytoin (Dilantin)
Ribavirin (Virazole)
Vincristine (Oncovin)

Several other drugs should be either avoided or taken with caution while on Zalcitabine therapy. Check with your doctor before taking the following:

Aminoglycoside antibiotics such as Garamycin
Amphotericin B (Fungizone)
Antacids containing magnesium and aluminum, including Maalox and Mylanta
Cimetidine (Tagamet)
Didanosine (Videx)
Foscarnet (Foscavir)
Lamivudine (Epivir)
Metoclopramide
Pentamidine (Pentam)
Probenecid

Special information if you are pregnant or breastfeeding

The safety of Zalcitabine during pregnancy has not been adequately studied. Take contraceptive measures while using Zalcitabine. If you are pregnant or plan to become pregnant, notify your doctor immediately.

Do not breastfeed your baby. HIV can be passed to an infant through breast milk.

Recommended dosage

ADULTS

The usual dose is one 0.750 milligram tablet every 8 hours. Your doctor may adjust the dosage if you have kidney problems. Zalcitabine is recommended for use in combination with other HIV medications.

CHILDREN

Safety and effectiveness have not been established for children under 13.

Overdosage

Any medication taken in excess can have serious consequences. If you suspect an overdose, seek medical attention immediately.

• Symptoms of Zalcitabine overdose may include:
  Drowsiness, vomiting, numbness, tingling, burning, and pain in the arms and legs