Hivid® (Zalcitabine, Dideoxycytidine or ddC)

Who should take this?

Hivid is usually not given to people when they first begin antiretroviral drugs. This is because if the virus became resistant to Hivid, it might resist other more powerful anti-HIV drugs such as Videx®.

People who have had pancreatitis or nerve pain in the past should take zalcitabine only when other drugs cannot be used.

How is it taken? / Dosage

Zalcitabine is given as a tablet. It should be taken on an empty stomach at least one hour before or two hours after a meal. It is taken every eight hours (three times a day). Studies are being done to find out if it could successfully be given only twice a day. 

People with kidney disease may need to take less zalcitabine or take it less often.

Hivid should always be taken exactly as prescribed by the doctor. This increases its effectiveness. This will also help prevent HIV from becoming resistant to the drug.

Side Effects

Zalcitabine can cause severe side effects. These include:

• Lactic acidosis
• Liver damage that can lead to liver failure
• Pancreatitis or inflammation of the pancreas. This may be fatal. A doctor should be called right away if a person taking Hivid has stomach pain, nausea and vomiting.
• Peripheral neuropathy, a serious nerve disorder. Signs of this include burning, numbness, or tingling in the hands, arms, fee, or legs. This usually starts a few months after taking zalcitabine. It gets worse over time. The nerve damage may be permanent if zalcitabine is continued.

A doctor should be called right away of any of these symptoms occur:

• Breathing irregularities
• Dark urine
• Loss of appetite
• Numbness, tingling, burning, or pain in the fingers or toes
• Pale stools
• Upset stomach or stomach pain
• Vomiting
• Yellowing of the skin

Your doctor may have you stop taking your medicine. Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to zalcitabine.

Other less severe side effects include:

• Fatigue
• Fever
• Headache
• Skin rash
• Sores in the mouth or throat
• Tiredness

Some side effects go away in time as the body gets used to the medicine. Side effects with Hivid are common. A doctor should be consulted if any of the symptoms don’t go away or are severe.

Because of the side effects, it’s important to keep all appointments with the doctor and lab.

Drug Interactions

Sometimes when two drugs are taken together, the effects are different than if each is taken alone. Sometimes drugs should never be mixed. In other cases, it is possible to take the two drugs but steps need to be taken to balance the effects they have on each other.

People taking zalcitabine should consult their doctor if they are also taking drugs to treat:

• Acid reflux/heartburn medications, such as Mylanta® or cimetidine (Tagamet®)
• Antibiotics such as interferon
• Cancer such as cisplatin (Platinol®) or doxorubicin (Adriamycin® or Rubex®)
• Drugs to treat alcohol abuse such as disulfiram (Antabuse®)
• Fungus infections such as amphotericin
• Gout, such as probenecid (Benemid®)
• High blood pressure, such as hydralazine (Apresoline®)
• Kaposi’s sarcoma, Hodgkin’s disease and non-Hodgkin’s lymphomas, such as vincristine (Oncovin®)
• Other anti-HIV drugs such as didanosine (ddI or Videx®) or foscarnet (Foscavir®)
• Parasites, such as metronidazole (Flagyl®) or iodoquinol (Yodoxin)
• Pneumocystis carinii pneumonia, such as Pentamidine (Pentam® or NebuPent®) Pentamidine and zalcitabine should not be taken together
• Rheumatoid arthritis, such as gold compounds
• Seizures, such as phenytoin (Dilantin®)
• Skin infections such as dapsone
• Stomach problems, such as metoclopramide (Reglan®)
• Tuberculosis such as ethionamide (Trecator-SC®) or isoniazid (INH)
• Tumors of the adrenal glands, such as glutethimide (Doriden®)
• Urinary tract infections, such as nitrofurantoin (Macrodantin®)
• Viral pneumonia, such as ribavirin (Virazole®)
• Vitamins and herbal supplements

Resistance

Sometimes HIV changes (mutates). Drugs that once worked to keep viral loads down, no longer do. This is known as drug resistance. It can happen because the levels of the anti-HIV drugs weren’t high enough in the blood or they weren’t taken properly or the body didn’t absorb them. Resistance to one drug in a class may affect any or all the drugs in that class. This is called cross-resistance. Drug resistance and cross-resistance can limit the options available to a person to treat HIV. Using combinations of drugs at the same time is helpful in preventing drug resistance.