Preventing perinatal HIV transmission: zidovudine use during pregnancy

Preventing perinatal HIV transmission: zidovudine use during pregnancy – includes patient information sheet

Cynthia Carmichael

The incidence of acquired immunodeficiency syndrome in the United States is increasing more rapidly among women than among men, with heterosexual transmission being the most rapidly increasing transmission category.[1] In 1994, human immunodeficiency virus (HIV) infection became the third leading cause of death for American women between the ages of 25 to 44.[2] The implications of these statistics are multiple and profound. In the 1990s, some 125,000 to 150,000 children will become motherless because of HIV/AIDS.[3] According to the Centers for Disease Control and Prevention, approximately 7,000 infants are born every year to HIV-infected women, and about 25 percent of these infants acquire HIV infection from their mothers., About 90 percent of pediatric HIV infections are caused by perinatal HIV transmission.[4] HIV is now among the leading causes of death for children between birth and four years of age.[5]

Perinatal HIV transmission can occur during pregnancy, during delivery or through breast feeding. It is thought that most cases of perinatal HIV transmission occur during labor and delivery. Factors that influence perinatal HIV transmission include maternal viral burden (a viral load more than 20,000 RNA copies per mL is more likely to be associated with HIV transmission, although perinatal transmission does occur in some instances even when the mother has a low viral load), rupture of the membranes more than four hours before delivery,[6] low maternal CD4 count, premature delivery and symptomatic maternal HIV disease.[7]

Mode of delivery has not been conclusively shown to affect perinatal HIV transmission, although results of the European Collaborative Study[8] did suggest that some protection is conferred by cesarean delivery.

In February 1994, an interim analysis of a breakthrough AIDS clinical trial, the AIDS Clinical Trials Group Protocol 076 (ACTG 076), revealed that the administration of zidovudine (Retrovir) to HIV-infected pregnant women and their newborns reduced the rate of perinatal HIV transmission from mother to infant by two-thirds (67 percent).[9] The data provided compelling evidence that perinatal HIV transmission could be interrupted through a specific intervention (Table 1). Incidentally, the results of ACTG 076 and a more recent retrospective analysis by the CDC showing that health care workers with a “significant exposure” to HIV had a 79 percent decreased risk of HIV infection if they used postexposure zidovudine prophylaxis lend support to a theory expounded by several HIV researchers[10]–that the most effective time to affect HIV replication is early in infection, when the viral population is most homogeneous and before the inevitable HIV mutations become too numerous.[11]

TABLE 1

Recommended Zidovudine Dosages

to Reduce Perinatal HIV Transmission

Antepartum therapy

Begin after 14 weeks’ gestation:

Zidovudine (Retrovir), 100 mg orally five time per day

Intrapartum therapy

Intravenous zidovudine, 2 mg per kg loading dose over 30 to 60

minutes,

followed by 1 mg per kg per hour drip until cord is clamped

Zidovudine may be mixed in normal saline, 5% dextrose in normal

saline,

lactated Ringers, or 5% dextrose in lactated Ringers (may be

piggybacked)

If delivery is anticipated within 30 minutes of time of arrival, a

diluted

bolus of zidovudine can be given (maximum concentration: 4 mg per

mL)

If intravenous zidovudine is unavailable, an oral loading dose of

400 mg

followed by 200 mg every two hours may be considered, although

efficacy has not been studied

In patients undergoing induction of labor, zidovudine should be

given

when induction begins

In patients undergoing elective cesarean section, zidovudine

should be started four hours before surgery

Newborn therapy

Zidovudine syrup, 2 mg per kg per dose four times daily for six

weeks,

begun within eight to 12 hours of birth

It is unlikely that any benefit will be gained if therapy is

delayed until after

the first 48 hours of life

If the infant’s status is NPO, intravenous zidovudine should be

given,

1.5 mg per kg over 30 minutes, every six hours

Dosages for premature infants are as yet unknown

HIV = human immunodeficiency virus; NPO = nothing through the

mouth.

Adapted from Recommendations of the U.S. Public Health Service on

the use of

zidovudine to reduce perinatal transmission of human

immunodeficiency virus.

MMWR Morb dine to reduce perinatal transmission of human

immunodeficiency

virus. MMWR Morb Mortal Weekly Rep 1994;43(RR-11):1-20; and New

York State

Department of Health AIDS Institute. Clinical guidelines for the

use of

zidovudine therapy to reduce perinatal transmission of HIV, New

York State

Department of Health, 1994.

Counseling Strategies

Implementing effective HIV counseling and testing for patients involves the following steps:

* Making patients aware of HIV infection by having literature available in the physician’s office (Table 2).

TABLE 2

Resources for AIDS Information

Antiretroviral Pregnancy Registry (800-722-9292, ext. 58465).

Monitors toxicity/teratogenicity of zidovudine (Retrovir),

didanosine (Videx) and zalcitabine (Hivid).

National AIDS Education and Training Centers (301-443-6364).

Provides didactic and clinical HIV/AIDS education to family

physicians and other health care professionals.

National HIV Telephone Consultation Service (800-933-3413).

“Warmline,” supported in part by the American Academy of

Family Physicians.

CDC HIV/AIDS Treatment Information Service (800-448-0440).

AIDS Clinical Trials Information Service (800-TRIALS-A).

National Pediatric and Family HIV/AIDS Resource Center

(800-362-0071).

CDC National AIDS Clearinghouse (800-458-5231).

AHCPR Clinical Practice Guidelines (800-358-9295).

AIDS = acquired immunodeficiency syndrome; HIV = human

immunodeficiency

virus; CDC = Centers for Disease Control and Prevention; AHCPR =

Agency

for Health Care Policy and Research.

COPYRIGHT 1997 American Academy of Family Physicians

COPYRIGHT 2004 Gale Group