The Choice of Inhalers in Adults and Children over Six

Publisher Website
Google Scholar
Abstract
Available delivery systems for ambulatory use include the conventional suspension pressurized metered dose inhaler (MDI), the conventional MDI with add-on devices such as spacing chambers and several powder delivery systems. Gas-driven or ultrasonic nebulizers are also available but are generally reserved for in-hospital use or for the treatment of the most severely obstructed patients. It is difficult to select one best system for use in older children, adolescents and adults; all available systems have their deficiencies and these are outlined here. The most widely prescribed device, the MDI, is misused by some patients with claims of up to one-third of clinic patients showing inadequate inhaler technique. In the 1990s, the MDI has also been criticized for liberating chlorofluorocarbons (CFCs). On occasion, the adjuvants are said to precipitate cough. In some countries, the production of generic or second entry inhalers has been accompanied by vexing concerns over the bioequivalence of therapeutic aerosols. The problem of patient coordination with the inhaler is meant to be dealt with by a variety of add-on devices. Spacing chambers and reservoir systems improve drug delivery and treatment efficacy for some patients. Unfortunately, there are relatively few data on patient spacer technique or optimal teaching methods. There is considerable potential for patient misuse of these superficially simple devices. One common problem is that the devices become dirty and worn but are seldom replaced by patients. A more subtle problem is electrostatic drug adherence to the spacing chamber thereby reducing drug delivery. This is particularly likely to happen after the device is washed if it is rubbed dry with a cloth rather than air-dried. The most obvious problems, however, concern patient compliance. Spacing chambers reduce the patient's perception of aerosol delivery; although this may minimize the unpleasant taste of some drugs, many patients confuse this with decreased efficacy unless they are warned about it. This factor and the bulkiness of some devices would tend to reduce compliance. Dry powder systems are available in several formats but may offer uncertain drug delivery in the presence of low flow or high humidity conditions. The need to load powder inhalers may be cumbersome. With some powder delivery systems such as the TurbuhalerTM, the patient's failure to perceive drug delivery is sometimes a cause for poor compliance. There are fewer data describing patient use of powder inhalers than for the MDIs that have been in longer use. With these various shortcomings for each of the available delivery systems, it is fair to say that no single system is suitable for all patients. The MDI is probably suitable with good efficacy in 80–90% of adult patients if appropriate teaching is offered. For the minority of patients unable to use the conventional MDI adequately, an add-on device or powder delivery system is available as an alternative. With no single delivery system to be recommended universally, it is incumbent upon the physician or caregiver to assess the patient's ability to use various inhalers effectively and to determine patient preference. Regrettably, academic medicine has generally failed in its duty to train medical professionals in this essential task.