• Hadeer S Harb, Ahmed A Elberry, Hoda Rabea, Maha Fathy, and Mohamed Ea Abdelrahim.
• Clinical Pharmacy Department, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt.
• Respir Care. 2018 Nov 1; 63 (11): 1360-1369.

BackgroundPredosing patients with COPD with salbutamol by using a pressurized metered-dose-inhaler (pMDI) as a bronchodilator was hypothesized to improve the distribution of the subsequent nebulized dose. This study determined the effect of a pMDI preliminary bronchodilator dose on the aerosol delivered by a mesh nebulizer during single-limb noninvasive ventilation.MethodsTwelve subjects with COPD who received noninvasive ventilation were enrolled in a randomized, open-label, urinary pharmacokinetic study. A bi-level ventilator with a dry single-limb circuit and the fixed expiratory port was set in the spontaneous mode, with initial inspiratory and expiratory pressures of 20 and 5 cm H2O respectively, a 1:3 inspiratory-expiratory ratio, and 15 breaths/min. Salbutamol was administered via a mesh nebulizer with a large spacer or T-piece placed between the fixed-orifice expiratory valve and the oronasal mask. In vivo dosing methods were randomized for days 1, 3, and 5 of the study. On each day, a 1-mL respirable solution that contained 5,000 μg salbutamol was nebulized by using a mesh nebulizer with 3 setting: (1) T-piece, (2) large spacer, and (3) large spacer plus pMDI. Only with the large spacer plus pMDI setting, 2 pMDI doses, which contained 100 μg salbutamol each, were actuated before nebulization. Urine samples were collected at 0.5 h (as an index of pulmonary bioavailability) and pooled up to 24 h after dosing (as an index of systemic absorption). On day 2, ex vivo studies were performed for the 3 setting with salbutamol collected onto filters placed before the mask. The drug was eluted from the filters and analyzed to determine the inhaled dose.ResultsA large spacer plus pMDI showed a trend to deliver a higher fraction (percentage of nominal dose) of both ex vivo filters and 0.5-h urinary salbutamol. The 0.5-h urinary salbutamol excreted with a large spacer plus pMDI (1.99%) was larger than with the T-piece (1.73%) and large spacer (1.78%). This trend did not extend to the 24-h levels, in which bioavailability with the large spacer plus pMDI (49.9%) was lower than with the T-piece (52.8%) and with the large spacer (54.3%). However, no differences were significant.ConclusionsThe T-piece and large spacer were equally efficient for salbutamol delivery from the mesh nebulizer in patients with COPD and on single-limb noninvasive ventilation. Adding a preliminary bronchodilator dose by pMDI prenebulization showed a trend toward greater pulmonary bioavailability of nebulized salbutamol and may be worth considering to maximize delivery of salbutamol to patients who are severely ill.Copyright © 2018 by Daedalus Enterprises.

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