Metered dose inhaler testing connects the pressurized canister, valve, actuator, formulation, and patient-use interface to measurable aerosol performance. USP <601>, USP <1601>, and FDA MDI / DPI / nasal guidance define the core in vitro frame for emitted dose, APSD, plume behavior, and stability-linked change control. Testing supports formulation, device, and regulatory decisions when:
- APSD from NGI or Andersen impactors compares MDI formulations, propellants, and actuators under USP <601> and FDA inhalation guidance.
- Delivered dose and emitted dose series quantify actuation-to-actuation variability, priming, and end-of-life behavior under USP <601> and ISO 20072.
- Spray pattern, plume geometry, and high-speed imaging document actuator or valve changes for FDA comparability and change-control packages.
- Breathing simulation evaluates spacers, valved holding chambers, and actuation timing with USP <601> dose collection and FDA use-condition framing.
- Stability pulls track APSD, plume, dose, assay, and device function under ICH Q1A storage or ASTM D4169 distribution conditioning.
Use MDI testing when device output, patient coordination, formulation drift, or actuator changes could alter delivered performance. A defined protocol links the device setup, actuation sequence, collection method, assay, and acceptance logic before samples arrive.