Compatibility of common respiratory therapy drug combinations

Respiratory therapists are being asked to take care of sicker patients and in many cases this requires the administration of multiple inhalation drugs. In an effort to reduce the workload, therapists are combining drugs in the same nebulizer. Pharmacists also are being asked to prepare unit dose preparations of combined inhalation drugs without physical compatibility data. It is theorized that some drug combinations precipitate and that these particulates are ultimately inhaled into the patient's lungs. These particulates can cause locally high concentrations of drug resulting in tissue irritation or actual occlusion of the airway. This study tested the physical compatibility of 22 common combinations used in our hospital and found 19 of these combinations incompatible. Due to the potential of precipitaion, we recommend that inhalation drugs not be routinely combined without specific compatibiltiy data.