Pentamidine for PJP Prophylaxis
Both inhaled (aerosolized) and intravenous pentamidine are effective second-line options for Pneumocystis jirovecii pneumonia (PJP) prophylaxis in hematopoietic stem cell transplant (HSCT) patients, particularly when trimethoprim-sulfethoxazole (TMP-SMX) is contraindicated due to allergies or cytopenias. However, their use depends on specific clinical and logistical considerations.
Tolerability
Inhaled pentamidine is associated with fewer systemic adverse effects (e.g., lip tingling, neuropathy) but may cause localized respiratory symptoms like bronchospasm. A retrospective study of pediatric HSCT patients reported a 10% reaction rate to pentamidine, with 9/10 reactions occurring with IV administration and only 1 with inhaled [1][4].
IV pentamidine has higher rates of systemic reactions, including hypotension, pancreatitis, and tachycardia, leading to discontinuation in 6% of pediatric transplant patients[3]. However, prospective studies in adults show high patient satisfaction (86%) and no severe (grade 3/4) adverse events [2].
Logistical Considerations
Inhaled pentamidine requires specialized nebulization equipment and may be impractical for young children or those unable to cooperate with inhalation [1][4]. Teratogenicity concerns also complicate administration logistics [4].
IV pentamidine is easier to administer but requires monitoring for infusion-related reactions. Bimonthly dosing (4 mg/kg, max 300 mg) has been shown to be safe and effective in pediatric HSCT patients [5].
Efficacy
Both routes demonstrate comparable efficacy, with breakthrough PJP rates of 0–1.3% [3][6]. No cases of PJP were reported in studies of IV pentamidine in HSCT patients [2][5], and inhaled pentamidine showed similar protection [6][7].
Recommendations
Inhaled pentamidine may be preferred for patients at higher risk of systemic toxicity (e.g., those with preexisting neuropathy or hypotension) [1][4].
IV pentamidine is a practical alternative for younger children or those unable to tolerate inhalation, with close monitoring for adverse effects [3][5].
Citations:
[1] https://jppt.kglmeridian.com/view/journals/jppt/25/2/article-p111.xml
[2] https://pubmed.ncbi.nlm.nih.gov/29269796/
[3] https://onlinelibrary.wiley.com/doi/10.1111/petr.12441
[4] https://pmc.ncbi.nlm.nih.gov/articles/PMC7025749/
[5] https://escholarship.org/content/qt28m2248v/qt28m2248v.pdf?t=ohrksv
[6] https://pmc.ncbi.nlm.nih.gov/articles/PMC6105857/
[7] https://ascopubs.org/doi/10.1200/jco.2006.24.18_suppl.9043
[8] https://pubmed.ncbi.nlm.nih.gov/36214573/
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