| Sildenafil, tezosentan and prostacyclin reduce vascular pressures in pulmonary hypertension, but may vasodilate the systemic circulation. Nebulized vasodilators allow targeted drug delivery with high local drug concentrations, less systemic hypotension and better ventilation-perfusion matching. We hypothesized that pulmonary deposition would vary with device type and drug, affecting drug dose delivered. Lung deposition was estimated by in vitro characterization of drug output and particle size distribution of nebulizers using helium-neon laser diffraction techniques. Drug output from the eFlow device was greatest and for the Pari LC Star increased with inspiratory flow. Estimated pulmonary deposition (mean, 95%CI) was 8.1 (7.2, 9.0) % of the initial drug charge for the Hudson Updraft II, 6.4 (5.8, 7.0) % for the Whisperjet, 33.0 (28.3, 37.9) % for the Pari LC Star and 56.8 (40.2, 73.4) for eFlow. All three drugs could be nebulized, but expected pulmonary deposition varied depending on the delivery device and drug. |
