Aerosolized pentamidine and pregnancy

Estimation of fetal risk from aerosolized pentamidine in pregnant healthcare workers

Inhaled pentamidine is used to treat Pneumocystis carinii pneumonia. Its potential effects on DNA have raised concerns about its safety for pregnant healthcare workers. We used a pharmacokinetic approach to estimate the fetal risks, based on the published data of pentamidine renal clearance and of urinary pentamidine concentrations in healthcare workers exposed to aerosolized pentamidine. The maximum pentamidine doses (intravenous equivalent) that healthcare workers were exposed to were calculated to be 9.8 micrograms/kg/d and 1.7 microgram/kg/d at the two different institutions reported. In parallel, based on animal data, we derived the intravenous-equivalent reference doses for embryolethality and for teratogenicity, the doses that can be viewed as tentative safe exposure levels. These analyses reveal that the exposure levels of a healthcare worker to aerosolized pentamidine are estimated to be in the vicinity of the teratogenic reference dose (4 micrograms/kg/d) and greater than the embryolethal reference dose (0.08 microgram/kg/d). Further improvement of the pentamidine administration technique and of environmental management in hospitals is warranted.

Embryofetal effects of pentamidine isethionate administered to pregnant Sprague-Dawley rats

The effects of pentamidine isethionate on the developing embryo and fetus have not been previously published. Pregnant Sprague-Dawley rats were given various doses of pentamidine during the period of embryogenesis. Animals were killed on days 18 to 20 of pregnancy and their fetuses were removed by hysterectomy. Autopsies were performed on all fetuses. There were significant differences among groups with regard to maternal weight gain and pregnancy resorption. More pregnancy resorptions were noted in the group that received normal human doses (4 mg/kg/day) of pentamidine than in the control group (p less than 0.05). One structural anomaly consisting of unilateral renal agenesis was noted in the 711 fetuses examined. Skeletal survey of fetal rats was unremarkable. Pentamidine was without teratogenic effects in rats when administered in doses similar to those recommended for adult humans; however, it appears to have an embryocidal effect when given in those same doses during embryogenesis.

Occupational exposure to aerosolized pentamidine

Occupational exposure to aerosolized pentamidine has raised questions regarding transmission of tuberculosis and the effect of the drug itself. To estimate the exposure of a health care worker, we measured the ambient concentration of aerosolized pentamidine in field conditions in 36 m3 unventilated treatment room. The amount of pentamidine averaged in three different environmental air samples over a four-hour period was 4.5 +/- 3.6 x 10(-5) mg/m3. This amount is very small compared to the doses received by the patients in whom long-term adverse effects are few. The greater risk to health care workers is probably transmission of tuberculosis from undiagnosed cases, especially in populations with an increased incidence of tuberculosis. Tuberculosis control measures such as improved ventilation and masks should also decrease exposure to ambient air pentamidine until toxicity studies determine long-term adverse effects, if any, of aerosolized pentamidine.

Aerosolized pentamidine in HIV. Promising new treatment for Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia is the most common life-threatening disease diagnosed in patients infected with the human immunodeficiency virus (HIV). Patients treated for their initial episode are at risk for recurrence of the disease. HIV-positive patients with low T4 lymphocyte counts are also at risk. Conventional treatment regimens with parenteral pentamidine isethionate (Pentam 300) or trimethoprim-sulfamethoxazole have a 50% to 60% incidence of serious adverse effects and a 20% to 40% rate of failure. Aerosolized pentamidine represents a promising new therapy for HIV-infected patients. Major adverse reactions have not been reported with its use. The Food and Drug Administration's (FDA's) recent approval of aerosolized pentamidine may also have a positive effect on healthcare costs by preventing episodes of P carinii pneumonia. In addition, FDA approval may result in reimbursement of patients for this new therapy by more insurance companies.