Retrovir® (Zidovudine, AZT)
Who should take this?
AZT can be used to treat HIV infection in adults and children three months old or older. It is also approved for use in HIV-positive women to prevent the virus from being passed to their babies during pregnancy and delivery. It is usually given to these babies for the first six weeks of life.
AZT is sometimes used to prevent workers from getting HIV infection after they accidentally come in contact with the virus on the job.
How is it taken? / Dosage
Zidovudine comes in a capsule, a tablet and a solution that can be taken by mouth. It should be taken with plenty of water while sitting up. AZT should be taken at least 30 minutes before or an hour after a meal. It is usually taken three to four times a day. Sometimes, it may be taken five times a day.
Because it is often combined with other anti-HIV drugs such as lamivudine or abacavir and lamivudine, the combination drugs Combivir® and Trizivir® were created. This makes taking antiretroviral drugs easier.
There is also an AZT liquid that is given by injecting it into a vein.
Side Effects
The benefits of AZT come with side effects. AZT often affects the bone marrow’s ability to make red blood cells. This in turn causes anemia, making a person tired, weak and pale. To manage the anemia, it may be necessary to have transfusions.
Other side effects of AZT include:
- A build up of acid in the muscles. This is called lactic acidosis. Signs of it include muscle pain, weakness, numbness or a tingling feeling with nausea and vomiting.
- Allergic reaction. A doctor should be called immediately if a person taking AZT gets hives, swelling of the face, lips, tongue or throat or has difficulty breathing.
- Changes in where body fat collects on the body (lipodystrophy)
- Constipation
- Discolored fingernails and toenails
- Headache
- Lack of balance or dizziness
- Liver problems. Signs of this include stomach pain, nausea, vomiting, low fever, loss of appetite, dark tea-colored urine, clay-colored stools and yellowing of the eyes and skin (jaundice).
- Muscle soreness
- Nausea
- Neutropenia, an abnormally low number of a type of white blood cells known as neutrophils. This increases the risk of infections.
- Trouble sleeping
Other side effects may not be serious and may lessen or disappear with continued use of the medicine. Individuals should tell a doctor if these side effects continue or are bothersome.
Drug Interactions
Sometimes drugs taken together have effects that none has when taken alone. AZT is a powerful drug. It sometimes interacts with other drugs that a person with HIV must take.
Just because drugs interact doesn’t mean that a person shouldn’t take them. What it does mean is that a person should work with his her doctor to avoid interactions as much as possible. This means taking drugs as directed and making sure that the doctor knows all prescription and nonprescription drugs or supplement the patient is taking.
A doctor may need to change the doses or schedule of the drugs he or she prescribes to make sure that the combination is as effective as possible with the fewest side effects.
Drugs to be particularly careful about when taking AZT include:
- Pain relievers such as acetaminophen, aspirin, indomethacin (Indocin)
- Acid reflux/heartburn medications, especially Tagamet® (cimetidine)
- Anti-anxiety drugs such as Ativan® (lorazepam) and Serax® (oxazepam)
- Anti-fungus drugs such as Diflucan® (fluconazole)
- Anti-seizure drugs such as valproic acid (Depakene®, Depakote®)
- Anti-virals such as acyclovir, adefovir, cidofovir, foscarnet, ganciclovir
- Gout drugs, such as probenecid (Benemid®)
- Interferon, which is used to treat hepatitis
- Other anti-HIV drugs, especially Zerit® (stravudine)
- Vitamins and herbal supplements
Resistance
HIV can adapt and change (mutate). When this happens drugs that once were effective against HIV no longer are. The virus has found a way to grow even when the drug is taken properly. A sign of resistance is an HIV viral load that doesn’t drop. This is called drug resistance.
Sometimes when the virus develops a resistance to one drug in a category, it will become resistant to all drugs in that category. This is known as cross-resistance. A drug resistance can develop quickly. It is important that a person on antiretroviral drug therapy take all prescribed drugs as instructed and on schedule.
