A new method to evaluate plume characteristics of hydrofluoroalkane and chlorofluorocarbon metered dose inhalers.

Two concerns raised when comparing metered dose inhalers (MDIs) to other inhalation devices are their relatively high throat deposition and the 'cold-Freon' effect seen in a small number of patients. The cold-Freon effect is presumed to be a result of the cold, forceful MDI plume impacting on the back of a patient's throat. This in vitro study uses a new plume characterization method to determine the spray force and plume temperature of various MDIs. Spray force measurements were made for 28 marketed products consisting of bronchodilators, steroids, press-and-breathe, breath-actuated and nasal inhalers. Results show that chlorofluorocarbon (CFC)-containing MDIs produce extremely forceful and cold plumes. Several hydrofluoralkane (HFA)-containing MDIs produced much softer and warmer plumes, but two HFA products had spray forces similar to the CFC products. Although the type of propellant used can affect spray force, actuator orifice diameter is the most important factor. Data obtained from marketed products and experimental inhalers show that MDIs that have a low spray force also have low throat deposition.

Advances in metered dose inhaler technology with the development of a chlorofluorocarbon-free drug delivery system.

The impending phaseout of chlorofluorocarbon (CFC)-containing metered dose inhalers (MDIs) has challenged the pharmaceutical industry to rethink and redesign many components of the technology involved in delivering asthma medication to the lungs. Along with the emergence of the first formulation using the nonozone-depleting propellant, hydrofluoroalkane (HFA) 134a to replace CFC propellants, advances in drug delivery technology have improved the performance characteristics of the MDI itself. Although MDIs have remained the mainstay of asthma therapy for 40 years, MDI technology still presents challenges. Some of the shortcomings of existing CFC MDIs affect the reliability of dosing. These challenges have been addressed in the development of the first CFC-free beta-agonist for the treatment of asthma. Airomir CFC-free (salbutamol sulfate; 3M Pharmaceuticals, St. Paul, MN), which is currently available in over 30 countries and was recently approved in the United States (Proventil HFA; Schering-Plough, Madison, NJ), incorporates numerous design and technological improvements which together with the introduction of CFC-free propellants mark the beginning of the next generation of asthma therapy. Although the new generation of CFC-free MDIs incorporates several improvements in dose reproducibility, these changes should be virtually transparent to the patient switching from a CFC MDI to a CFC-free MDI. What may be noticeable is a "softer puff," which is the result of valve and actuator redesign. The taste of the new CFC-free product may also be a little different yet totally acceptable to users.