Reports on HIV/AIDS: 1990

JANUARY 26, 1990, MMWR, Vol. 39, RR-1: [inclusive page numbers]
was culture-positive for HIV 4 months after completing 6 weeks of chemotherapy. The
second person was exposed to a high concentration of HIV on abraded skin in a
research laboratory, was started on zidovudine within 24 hours postexposure, and
remains HIV-seronegative after 11 months. The risk of seroconversion after this type
of laboratory exposure is unknown. The third person was exposed to a high
concentration of HIV on broken skin in a research laboratory, was started on
zidovudine within 24 hours after the exposure, and is HIV-seronegative 3 months after
the exposure. The risk of seroconversion after this type of laboratory exposure also is
unknown. All individuals were able to complete a 6-week course of therapy (200 mg
orally every 4 hours) without clinically significant adverse effects. Information
regarding enrollment in this study can be obtained by calling the NIAID study
coordinator at [phone].
Prophylaxis Schedules Currently Used After Occupational Exposure
Various regimens have been prescribed for zidovudine prophylaxis after occupational exposure. No data are available to enable investigators to determine the
efficacy or compare the toxicity of these or other regimens. At the National Institutes
of Health Clinical Center, workers who elect to receive zidovudine are treated with 200
mg every 4 hours (six times daily) for 6 weeks (6). At San Francisco General Hospital,
workers who elect to receive zidovudine are treated with 200 mg every 4 hours (five
times daily; no dose is given at 4:00 a.m.) for 4 weeks (6). Some clinicians have used
an initial dose of 400 mg, and others have prescribed treatment courses ranging from
4 days to 4 months. At several institutions, attempts are made to begin prophylaxis
within 1 hour after exposure for workers who elect to receive the drug.
DISCUSSION
Data from animal and human studies are inadequate to establish the efficacy or
safety of zidovudine for prophylaxis after occupational exposure to HIV. However,
some physicians believe that zidovudine should be offered as prophylaxis to persons
after certain occupational exposures for the following reasons: the severity of the
illness that may result from HIV infection, the documented antiviral effect of
zidovudine in the treatment of persons with established HIV infection, the apparent
reversibility of acute toxicity in persons taking zidovudine for a brief period, and the
suggestion that in some animal studies, zidovudine postexposure may modify the
course of some retroviral infections. Other physicians believe that zidovudine should
not be recommended for uninfected persons after occupational exposures because of
the lack of data demonstrating efficacy in postexposure prophylaxis, the limited data
on toxicity in uninfected individuals, and the fact that zidovudine has been shown to
be carcinogenic in rats and mice.
At this time, prophylaxis with zidovudine cannot be considered a necessary
component of postexposure management. However, workers who might be at risk of
occupational exposure to HIV should be informed, as part of job orientation and
ongoing job training, of the considerations pertaining to the use of zidovudine for
postexposure prophylaxis. The PHS recommends that if a physician decides to offer
zidovudine to a worker after an exposure incident, that decision by the physician and
the decision by the worker to take zidovudine should take into account the following
considerations.

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