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Accuracy of float testing for metered-dose inhaler canisters
Tina Penick Brock1, Andrea M Wessell, Dennis M Williams
1School of Pharmacy, University of North Carolina-Chapel Hill, 27599-7560, USA. tbrock@unc.edu
Journal of the American Pharmaceutical Association (Washington, D.C. : 1996)
|August 2, 2002
Summary
Metered-dose inhaler (MDI) float tests are unreliable for determining remaining medication. Canister floating patterns vary by product and are not a consistent indicator of inhaler contents.
Area of Science:
- Pharmaceutical Technology
- Respiratory Medicine
Background:
- Metered-dose inhalers (MDIs) are crucial for delivering respiratory medications.
- Accurate assessment of remaining medication in MDIs is essential for effective asthma management.
- Current methods for assessing MDI contents may lack reliability.
Purpose of the Study:
- To characterize and evaluate the floating patterns of commercially available metered-dose inhaler (MDI) canisters.
- To determine if MDI canister floating behavior can reliably indicate the amount of medication remaining.
Main Methods:
- Four canisters each of three different asthma medications were tested.
- Canisters were actuated and weighed to determine remaining medication levels (100% down to 0%).
- Canister positions and submersion percentages were recorded while floating in water.
Main Results:
- Significant differences in floating behavior were observed among MDI products.
- Canisters were fully submerged nozzle-up when two-thirds full or more.
- Canisters inverted to float nozzle-down when less than half full, with variable positions.
Conclusions:
- MDI canister float characteristics are product-specific, influenced by canister size, design, and contents.
- The float test is not a reliable method for patients or clinicians to assess remaining MDI medication.
- The National Asthma Education and Prevention Program recommends tracking used actuations for accurate dose counting.