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(zīdō`vyo͞odēn'), drug used to treat patients infected with the human immunodeficiency virus (HIVHIV,
human immunodeficiency virus, either of two closely related retroviruses that invade T-helper lymphocytes and are responsible for AIDS. There are two types of HIV: HIV-1 and HIV-2. HIV-1 is responsible for the vast majority of AIDS in the United States.
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), which causes AIDSAIDS
or acquired immunodeficiency syndrome,
fatal disease caused by a rapidly mutating retrovirus that attacks the immune system and leaves the victim vulnerable to infections, malignancies, and neurological disorders. It was first recognized as a disease in 1981.
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; also called azidothymidine. Originally developed in 1964 as an anticancer drug, AZT was never approved for that purpose. In 1984, Burroughs-Wellcome Company, which owned the rights to the drug, reexamined it as part of a search for any antiviral drugantiviral drug,
any of several drugs used to treat viral infections. The drugs act by interfering with a virus's ability to enter a host cell and replicate itself with the host cell's DNA.
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 that might be effective against the AIDS virus. It was approved by the FDA in 20 months, rather than the usual 8 to 10 years, in part for humanitarian reasons; thousands of people were dying of AIDS, no other treatment was forthcoming, and AIDS activists were lobbying heavily for approval.

AZT affects HIV's ability to reproduce by inhibiting the transcription of RNA to DNA. Although AZT can be helpful in the short term by promoting weight gain, decreasing the number of opportunistic infections, and improving T4 (CD4) lymphocyte counts (see immunityimmunity,
ability of an organism to resist disease by identifying and destroying foreign substances or organisms. Although all animals have some immune capabilities, little is known about nonmammalian immunity.
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), some researcher believe studies of its effectiveness to be flawed and regard the drug as too toxic for long-term use. There is also a question of whether it is helpful in HIV-positive, asymptomatic people. AZT does not cure or prevent AIDS, nor does it keep one from transmitting the virus to others, although some studies show that it does lessen the possibility that an HIV-infected mother will transmit the virus to her fetus.

Adverse effects include bone marrow depression, headache, nausea, muscle pain, and a reduction in the number of certain white blood cells. The risk of side effects increases when certain other drugs, including acetaminophenacetaminophen
, an analgesic and fever-reducing medicine. It is an active ingredient in many over-the-counter medicines, including Tylenol and Midol. Introduced in the early 1900s, acetaminophen is a coal tar derivative that acts by interfering with the synthesis of
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, are taken at the same time.

References in periodicals archive ?
He] declined a second course of AZT, but the ill effects of the first course failed to resolve.
But a study headed by Louise Kuhn of Columbia University, reported in the July issue of the Journal of Infectious Diseases, found that AZT exposure was associated with increased risk of death among infants.
Approved September 6, 1996 for the treatment of pediatrics with HIV infection who have undergone prolonged prior AZT therapy.
Even if prenatal HIV testing were available, drugs like AZT are unaffordable or not available to reduce mother-to-child transmission.
Second, according to Lurie and Wolfe, a subgroup analysis within the 076 protocol indicates that short course AZT (treatment no longer than twelve weeks) is as effective as long course AZT (treatment longer than twelve weeks), suggesting an affirmative answer to the research question implied by the placebo-controlled design--"Is the shorter regimen better than nothing?
Of the mothers who took AZT before delivery and also elected to have a Caesarean section, only 0.
The "preventable deaths can be averted if you simply require all women in these experiments to be offered some regimen of AZT," the doctors noted.
In the study, known as ACTG 076, AZT therapy was initiated in the second or third trimester and continued during labor, and infants were treated for six weeks following birth.
Existing studies suggest that women are less likely than men to receive AZT (zidovudine) even after controlling for a variety of factors (e.
This clinical trial named, like the aircraft, because of the joint French and British participation, found that AZT neither prolongs life nor delays the onset of AIDS in people who are infected with HIV but otherwise are well.
WASHINGTON - The exclusive patent for AZT, a drug for AIDS treatment made by Burroughs Wellcome Corp.