Class
- Antiprotozoal agent
- Aromatic diamidine compound
Mechanism of Action
- Exact mechanism not fully understood.
- Interferes with protozoal DNA, RNA, phospholipid, and protein synthesis.
- Has activity against Pneumocystis jirovecii, Trypanosoma brucei, and Leishmania species.
Indications
- Pneumocystis jirovecii pneumonia (PJP/PCP)
- Treatment in patients intolerant to TMP-SMX.
- Prophylaxis in immunocompromised patients (HIV/AIDS, transplant, oncology patients).
- African trypanosomiasis (early hemolymphatic stage of T. brucei gambiense)
- Not effective in CNS disease.
- Leishmaniasis (off-label, less common).
Dosing
1. PJP Treatment
- IV: 4 mg/kg once daily infused over ≥60 minutes for 14–21 days.
- IM: 4 mg/kg once daily for 14–21 days (less preferred).
2. PJP Prophylaxis
- Inhalation (via nebulizer): 300 mg every 4 weeks (most common).
- IV alternative: 4 mg/kg every 2–4 weeks (rarely used).
- IV or IM: 4 mg/kg once daily or on alternate days for 7–10 doses.
Adverse Effects
Systemic (IV/IM)
- Renal: nephrotoxicity, azotemia, acute tubular necrosis.
- Metabolic: hypo/hyperglycemia, pancreatitis, hypocalcemia, hypokalemia, hypomagnesemia.
- Hematologic: leukopenia, thrombocytopenia, anemia.
- Cardiac: QT prolongation, arrhythmias, hypotension.
- Hepatic: elevated transaminases.
- Others: rash, fever, nausea, vomiting.
Inhaled
- Cough, bronchospasm, wheezing, metallic taste.
Contraindications
- Hypersensitivity to pentamidine.
- Use cautiously in patients with renal impairment, diabetes, electrolyte imbalances, or cardiac disease.
Monitoring
- Renal function: BUN, serum creatinine.
- Electrolytes: glucose, potassium, calcium, magnesium.
- Liver function tests.
- ECG if prolonged therapy (risk of QT prolongation).
- CBC for cytopenias.
- Clinical: cough/bronchospasm for inhaled use.
Formulations
- IV/IM injection.
- Nebulized inhalation solution (for prophylaxis).
Key Points for Oncology/Immunocompromised Patients
- Alternative to TMP-SMX for PJP prophylaxis/treatment in patients with sulfa allergy, renal dysfunction, or severe cytopenias.
- Inhaled pentamidine is often chosen for prophylaxis in stem cell transplant recipients or HIV patients unable to tolerate TMP-SMX.
- Requires close monitoring for metabolic and renal toxicity.