A respiratory system includes a nebulizer pneumatically connected to a breathing unit. A pressure sensitive mechanism detects negative pressure at the breathing unit due to inspiration and initiates nebulization. The nebulizer is configured to cease nebulization prior to the end of inspiration. Residual medicament disposed in the system is cleared from the system and delivered to the patient during the remainder of the inspiration cycle. A compressor provides positive pressure to aid delivery of medicaments to the patient.