Pneumocystis jirovecii, formerly carinii, pneumonia (PCP) poses a life-threatening risk to oncology patients. The use of trimethoprim-sulfamethoxazole (TMP-SMZ) or dapsone prophylaxis virtually eliminates the risk of infection; however, many patients cannot tolerate TMP-SMZ. Pentamidine is available by inhalation or IV.
The efficacy of trimethoprim-sulfamethoxazole for prophylaxis against PCP has been clearly demonstrated among pediatric cancer patients. The only reported randomized controlled trial of this drug combination for HIV-infected persons was a primary-prophylaxis study of 60 adult AIDS patients with Kaposi sarcoma, and compared the effect of no treatment with that of a regimen of 160 mg trimethoprim plus 800 mg sulfamethoxazole twice daily plus 5 mg leucovorin calcium once daily. Compared with untreated patients, those who received prophylaxis had fewer episodes of PCP and lived longer. Adverse reactions were common (50%) and included nausea, vomiting, pruritus, and rash, although these reactions also occurred commonly among patients who were not receiving trimethoprim-sulfamethoxazole.
Aerozalized pentamidine is also an acceptable means of prophylaxis. Primary prophylaxis of severely immunocompromised patients can be indicated where PCP has not yet been diagnosed. Secondary prophylaxis aims to prevent recurrent infections by PCP. For both forms of prophylaxis, an aerosolized formulation of pentamidine given by nebulizer once monthly in a dose of 300 mg is used. In primary prophylaxis, this reduces the long term likelihood of PCP by 70% when compared to no prophylaxis.
A recent review concludes that: “The use of intravenous pentamidine as PCP prophylaxis results in a breakthrough rate of 1.3%. TMP-SMZ is the first choice for PCP prophylaxis. However, when necessary, the use of intravenous pentamidine has an acceptably low failure rate, even in high-risk BMT patients. Other options should be considered for children less than 2 years of age.” It may sometimes be reasonable when TMP-SMS cannot be used and the child does not co-operate with inhalation.
Elayan, Mohammed M. et a, lMonthly Intravenous Pentamidine for the Prophylaxis of Pneumocystis Jiroveci Pneumonia in Adult Allogeneic Hematopoietic Stem Cell Transplant Recipients Biology of Blood and Marrow Transplantation , Volume 22 , Issue 3 , S163
Guidelines for Prophylaxis Against Pneumocystis carinii Pneumonia for Persons Infected with Human Immunodeficiency Virus MMWR 16, 1989 / 38(S-5);1-9current therapies and recommendations. J Pediatr Oncol Nurs. 2011 May-Jun;28(3):179-84.
Crozier F. Pneumocystis carinii pneumonia prophylaxis: