title: Floating patterns of metered dose inhalers.
abstract: As long as metered dose inhalers have existed, patients have sought a reliable method to determine if a given canister was still potent. Concerning beta agonists, the answer to this question may be lifesaving. Issues of compliance have made dating canisters or counting doses impractical. Likewise, previous claims of floating characteristics are unreliable. In tap water, we float-tested 13 commonly used inhalers three times each, observing variations as they were incrementally actuated, emptying their contents. One essential pattern was observed. Almost all prescription-size canisters sink when full; all float by the time one-third of their contents is gone. Orientation of prescription-size canisters changes in a distinct pattern especially near 90% depletion. Sample-size canisters showed some variance. Results suggest that the pharmaceutical industry should include individual floating characteristics as part of the package insert as they provide a reproducible means of gauging contents.
authors.affiliation: St. Thomas Hospital, Nashville, Tennessee, USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Wolf
authors.forename: K R
authors.initials: KR
authors.lastname: Cochran
mesh_terms: D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000032:analysis / Q000627:therapeutic use; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000032:analysis / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000032:analysis / Q000627:therapeutic use; D004348:Drug Labeling; D004349:Drug Packaging; D004355:Drug Stability; D006801:Humans; D009330:Nebulizers and Vaporizers / Q000592:standards*; D013256:Steroids
chemical_list: D000318:Adrenergic beta-Agonists; D000893:Anti-Inflammatory Agents; D001993:Bronchodilator Agents; D013256:Steroids