Background. Pentamidine isethionate has been reported as 80% effective in treatment of Pneumocystis carinii pneumonia (PCP) in patients with AIDS. Pentamidine is usually administered parenterally by intravenous or intramuscular injection. There is a 50% incidence of toxicity requiring change of therapy with the administration of pentamidine via these routes. A study comparing single dose aerosol and parenteral administration of pentamidine to AIDS patients with diffuse interstitial infiltrates showed that aerosolization resulted in higher alveolar concentrations of pentamidine. No systemic side effect were observed in the patients who received aerosolized pentamidine.

Another recent study has indicated that aerosolizing 600 mg of pentamidine for a 21 day treatment course has been successful in 13 of 15 patients with PCP. This study also reported no systemic side effects. Adverse reactions of coughing was noted in adverse reactions were successfully treated by administration of an aerosolized bronchodilator prior to aerosolization of pentamidine or by lowering the gas flow rate to the pentamidine aerosol delivery device.

In general, the procedure for aerosolization calls for 600 mg of lypholized pentamidine to be reconstituted with 6 ml of sterile water. The solution is then placed in the Respirgard II Nebulizer^® System. The solution is nebulized for approximately 30 minutes. The Respirgard II Nebulizer System is specifically designed for the aerosolization of pentamidine. It consists of a Wright type nebulizer and a series of one way valves, that act both as baffle to trap large particles and direct exhalation to a bacterial filter. The elimination of large (>4 micron) particles is essential to prevent severe airway reactions in aerosolized pentamidine from being dispersed in the surrounding environment.

Upon the advice of the Infectious Disease Department, it may be recommended to administer the treatment in a negative pressure isolation room. If not available, one may consider using an isolation HEPA filter device, e.g. Demistifier canopy.

AEROSOLIZATION OF PENTAMIDINE

Verify Physician's order

Aerosolize pentamidine 600 mg in 6 ml of sterile water for twenty-one(21) days.

Equipment Needed

1. Oxygen Flowmeter with nipple adapter.

2. Respirgard II Nebulizer System.

3. Micronebulizer.

4. Unit dose Albuterol.

5. Two vials of 300 mg each Pentamidine.

6. One 10 ml vial sterile water for injection, PCP.

7. 50 psi dry gas source.

8. Protective mask.

9. Nose clips.

10. Demistifier canopy

Procedure

1. Gather all necessary equipment. If an isolation canopy, refer specifically to the canopy Set-up section for the Demistifier .

• oxygen flowmeter with nipple adapter, Respirgard II Nebulizer System and Micronebulizer can be procured from respiratory care stocking areas.

• Pentamidine and Albuterol is procured from Pharmacy. It will be kept in the medication room in the general care areas.

• 10 ml vial sterile water and 10 ml syringe with 18 gauge needle are kept on the medication cart in the general care areas.

2. Explain procedure to patient.

3. Assemble the equipment in patient's room. See diagrams.

4. If using the Demistifier canopy, turn on prior to enclosing the patient-assure patient's comfort and tolerance to the canopy enclosure.

5. Reconstitute Pentamidine.

• Draw up sterile water in the syringe and inject 3 ml into each of the 300 mg Pentamidine vials.

• Shake Pentamidine vials until all solute dissolves in solvent.

• Withdraw the solution from each Pentamidine vial and place in nebulizer of the Respirgard II Nebulizer System.

6. Have the patient put the mouth piece in their mouth and adjust gas flow for a good mist - approximately 7 L/min. Apply nose clips to the patient.

7. Instruct patient to breath normally and inhale and exhale through their mouth. Encourage the patient to take slow deep breaths with inspiratory pauses.

8. Run the nebulizer at 7 L/M for 30 minutes. If the patient becomes tired treatment can be stopped and then restarted.

9. Visitors as well as hospital personnel should refrain from entering the patients room while the pentamidine is being administered. The Department of Epidemiology has recommended that no other patients should be in the room during the treatment.

10. Therapists must wear protective eye wear as well as an approved mask while the pentamidine is being aerosolized.

11. At the end of the treatment the disposable equipment and tent should be considered hazardous waste. Discard nebulizing device and canopy in appropriate container.

Special Notes

1. It is not necessary for the therapist to remain in the room throughout the treatment. Once the therapists complete their initial patient evaluation, they should remain on the patient floor/unit and periodically check and re-evaluate the patient. If the patient should want to take a break or the patient starts coughing, the therapist is to turn off the gas flow to the nebulizer. There have not been any studies on the effect of aerosolized pentamidine on normal human lungs. However, high dose aerosolized pentamidine in rats showed no ill effects and no histopathologic evidence of airway inflammation or damage. No adverse effects are expected but in order to be on the safe side pentamidine is not to be aerosolized in an open environment.

2. Clinical experience has shown that the extra time it takes to nebulize the last 2 ml of pentamidine is poorly tolerated by the patient due to fatigue.

3. A recent study has documented that after 21 days of aerosol therapy serum pentamidine levels are negligible. Therefore, the systemic side effects of pentamidine as seen in parenteral administration has not been found.

Complications

1. Aerosolization of pentamidine may induce bronchospasm. This has been noted in some patients who have a history of bronchospasm or smoking. If this occurs, stop therapy and administer bronchodilator such as Albuterol. Then continue with therapy. The next time therapy is due, pretreat patient with a bronchodilator before administering pentamidine.

2. Coughing. This has also been noted for the same population of patients as described above. If this occurs treat as above. In some instances slowing the gas flow-rate to 4-5 L/min has helped.

3. Fatigue. Some patients experience fatigue from concentrating on breathing through the device or due to their disease. Allow the patient to take a rest during the therapy. During rest breaks the gas flow is to be

4. Some patients experience a burning sensation in the back of their throat during the latter part of the therapy. Stop the therapy and have the patient drink some liquid then resume aerosolization. The burning sensation should stop.

5. Notify the physician if any complications occurred during treatment and note it in the patient's chart.

House Formula

Active PCP:

600 mg pentamidine diluted with 6 ml of sterile water. Aerosolized for 30 minutes once a day for 21 days.

Prophylactic:

300 mg pentamidine diluted with 6 ml of sterile water. Aerosolize for 30 minutes. Treatment regime is 1 time per month.

Charting

Chart in the progress note section of the patient's chart. Chart "Aerosolized Pentamidine Day # ____ Nebulized 600 mg Pentamidine, estimated absorbed dose 45-60 mg. Treatment time ____ minutes".

Chart time and initial section of nursing medication book. Notify the RN when the treatment is completed.

Also note any adverse reaction and if the patient required pretreatment with aerosolized Albuterol.

Submitted by Joseph Previtera, RRT