Which of the following MDIs does NOT require shaking before use?

The QVAR Redihaler does not require shaking before use because it utilizes a different formulation compared to traditional metered-dose inhalers (MDIs). Unlike MDIs that contain a propellant and rely on shaking to evenly distribute the medication within the canister, the QVAR Redihaler is a breath-activated aerosol that contains a stable suspension of the medication, ensuring consistent delivery without the need for prior agitation.

In contrast, other inhalers like ProAir HFA, Symbicort, and Albuterol are traditional MDIs that contain propellants and require shaking to ensure homogeneity of the medication. Shaking these devices mixes the medication and the propellant effectively, which is crucial for delivering the correct dose with each actuation.