Aerosol delivery to ventilated newborns is known to be poor. CFC beclomethasone dipropionate (BDP) pMDI has been reformulated as an HFA134a solution (QVAR, 3M Pharmaceuticals, London, ON) with a demonstrably lower mass median aerodynamic diameter (MMAD) of 1.1 μm and geometric standard deviation (GSD) 2.5 than the CFC aerosol. We hypothesised that an aerosol with these properties would result in increased delivery to the peripheral lung with a greater total pulmonary deposition. Aim: To investigate the total pulmonary deposition following inhalation of radiolabelled HFA 134a BDP in ventilated neonates.
Data expressed as mean(sd). Eight ventilated neonates with BPD, 40.3 (10.9) days old at time of study, with a mean corrected age of 32.2 (1.65) weeks post-gestation) were enrolled. Babies weighed 823.5 (222.7)g at birth and 1182.9 (188.3)g at time of study. Vital signs were monitored throughout the study. One dose of radiolabelled BDP (186 (57)μCi in 47 (14)μg BDP) was given via a Neonatal Ventilator Aerosol Delivery System (NVADS, Trudell Medical Inc, London, ON), a tube spacer with low dead-space connectors to interface to the ventilator circuit. Posterior images of the lungs and lateral head were obtained over 10 min using a GE Starcam gamma camera. Tissue attenuation factors for each baby were obtained using a phantom.
O2 saturation was unchanged during delivery of the aerosol (predose: 90.8 (5.2)%; dosing: 89.5 (5.1)%; post-dose: 91.6 (4.2)%). Most of the radiolabelled drug was captured in the NVADS (80.0 (13.1)%) and circuit tubing and connectors. Lung deposition was 1.27 (0.95)% of the recovered emitted dose ex-actuator or 8.63 ± 7.39% of the dose ex-spacer. These percentages translated into an average deposited lung dose of 0.6μg BDP.
These values are similar to prior work with CFC formulations of salbutamol and appear to show no advantage in the total dose of HFA134a BDP delivered to these ventilated neonates.
Clinical trials would need to be undertaken to determine if even this low deposition efficiency could provide a beneficial clinical outcome.
Myrna Dolovich, Grant monies (from industry related sources); Study funded by 3M Pharmaceuticals Canada.