What role does priming play in the effectiveness of an MDI?

Priming an MDI (Metered-Dose Inhaler) is an essential step to ensure that the inhaler delivers the correct dose of medication effectively, especially after it has not been used for a while. Priming involves releasing a specific number of actuations (or sprays) into the air before using the inhaler for inhalation. This process clears any potential blockages and ensures that the medication is adequately mixed and positioned within the device.

When an MDI has been inactive for some time, the propellant may not flow correctly, and the medication may settle or become trapped in the nozzle. Priming helps to re-establish the proper flow and dispersal of medication, ensuring that each actuation provides the intended dose when the patient uses the inhaler.

Thus, this step is crucial in maintaining the efficacy of the inhaler, particularly after long periods of non-use, as it helps to prevent suboptimal drug delivery and ensures that the patient receives the full therapeutic benefit of the medication with each inhalation.