Drug delivery apparatus

An apparatus comprising:

• a drug delivery device for selectively delivering drug-laden air or air not laden with the drug;
• a sensor for monitoring the breathing pattern of a patient;
• a controller arranged to control the drug delivery device to deliver drug-laden air in pulses which begin when the patient is monitored by the sensor to begin inhalation;
• a feedback indicator which indicates to a patient whether the monitored breathing pattern is effective for inhaling drug-laden air or not;
• a dose calculator which calculates the dose delivered to the patient, wherein the dose calculator includes a formulation input through which the formulation of the drug being delivered is entered for use in the calculations made by the dose calculator;
• and
• an indicator which indicates to the patient when a desired dose has been delivered, wherein the controller includes a pulse length generator which determines the duration of each pulse on the basis of the monitored breathing pattern of the patient, and wherein the pulse length generator includes a breathing pattern analyser which analyses the breathing pattern of a patient in order to determine the time at which a patient begins to inhale an end volume, the end volume being the volume of the upper airways of the patient which, at the end of the inhalation, contains the end volume of air which does not reach the lungs.