Pentamidine


Aerosolized pentamidine is widely used for pneumocystis carinii pneumonitis in AIDS patients. Conversely, theintravenous form of the drug is seldom used, for reasons of efficacy and toxicity.
 
Incidence
Bronchospasm: 10 to 29%.
 
Cutaneous reactions: morbilliform eruptions 15%.
 
Clinical manifestations
Cutaneous: morbilliform eruptions, erythroderma; generalized urticaria, contact urticaria (nurses), facial rash.
 
Respiratory: bronchospasm (aerosolized pentamidine), laryngeal edema, tongue swelling, hypersensitivity pneumonitis.
 
Other: conjunctivitis.
 
Diagnostic methods
Cutaneous testing.
 
Skin-prick tests positive with 3 mg/ ml pentamidine isethionate in contact urticaria and some cases of bronchospasm.
 
Intradermal skin-tests: false positive with 0.015 and 0.15 mg/ ml pentamidine.
 
Intravenous test dose is dangerous (2 deaths reported).
 
Mechanisms
Non specific histamine release (documented with intravenous pentamidine).
 
IgE-mediated hypersensitivity (contact urticaria, some cases of bronchospasm).
 
Irritative effect (bronchospasm).
 
Management
Use premedication with nebulized albuterol and/ or cromolyn sodium prior to aerosolized pentamidine.
 
Slow intravenous administration (decreases non specific histamine release).
 
In patients with hypersensitivity to systemic pentamidine; cautious administration of aerosolized pentamidine is safe when the following protocol is applied:
 
Dilution of 300 mg of pentamidine isethionate in 20 ml of sterile water (15 mg/ ml).
 
 
Dilution

Volume inhaled

Pentamidine (mg)

1/10 000

4

0.006

1/1 000

4

0.06

1/100

4

0.6

1/10

4

6

Full strength

20

300

References

  1. Carr A, Cooper D.A, "Pathogenesis and management of HIV-associated drug hypersensitivity", AIDS. Clin. Rev., 1995 - 96: 65-97
  2. Belsito D.V, "Contact urticaria from pentamidine isethionate", Contact. Dermatitis., 1993 ; 29 (3): 158-9
  3. Pradalier A, Vincent D, Bouée S, Girard P.M, "Bronchospasme de mécanisme allergique a l’isethionate de pentamidine en aérosol", Presse. Med., 1993 ; 22 (11): 554
  4. Baum C.G, Sonnabend J.A, O’Sullivan M, "Prophylaxis of AIDS-related Pneumocystis carinii pneumonia with aerosolized pentamidine in a patient with hypersensitivity to systemic pentamidine", J. Allergy. Clin. Immunol, 1992 ; 90 (2): 268-9
  5. Gordin F.M, Simon G.L, Wofsy C.B, Mills J, "Adverse reactions to trimethoprim-sulphamethoxazole in patients with the acquired immunodefiency syndrome", Ann. Intern. Med., 1984 ; 100: 495-9

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.