Bronchodilators, inhalation devices

Ram FS, Brocklebank DM, Muers M, et al. Pressurised metered-dose inhalers versus all other handheld inhalers devices to deliver bronchodilators for chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2002 CD002170. 

Q1 The most commonly used reliever in asthma therapy is a short-acting bronchodilator, such as the beta-2-agonists (/ -agonists) salbutamol or terbutaline. These are safe and effective agents for mild to moderate symptoms and are taken directly into the respiratory tract via an inhaler device. 

Borgstrom L, Derom E, Stahl E, Wahlin-Boll E, Pauwels R. The inhalation device influences lung deposition and bronchodilating effect of terbutaline. Am J Respir Crit Care Med 1996 153 1636-1640. 

In cases of severe acute asthmatic attacks, bronchodilators and steroids for direct dehveiy to the lungs may be needed in large doses. This is achieved by direct inhalation via a nebulizer device this converts a liquid into a mist or fine spray. The dmg is diluted in small volumes of Water for Injections BP before loading into the reservoir of the machine. This vehicle must be sterile and preservative-fiee and is therefore prepared as a terminally sterilized unit dose in polyethylene nebules. 

The first commercially available DPI system appeared on the market in 1949, developed and marketed by Abbott under the name Aerohaler. Like all early pulmonary drug-delivery devices, it delivered small-molecule compoimds (bronchodilators or inhaled corticosteroids) to the airways (not necessarily the deep limg) for the treatment of asthma or chronic obstructive pulmonary disease. Table 6 lists some of the early DPI systems used for asthma and COPD the energy somces in these devices were mechanical and patient inspiration. 

In the mid-1950s the first pressurized metered dose inhaler (MDI) was developed for the administration of bronchodilator drugs locally to the lung. It was a major advance for the treatment of asthma since it made aerosol medications readily available in an inexpensive small multidose device. 

Derksen F, Olszewski M, Robinson N 1996 Use of a handheld, metered-dose aerosol delivery device to administer pirbuterol acetate to horses with heaves. Equine Veterinary Journal 28 306-310 Derksen F, Olszewski M, Robinson N 1999 Aerosolized albuterol sulfate used as a bronchodilator in horses with recurrent ainway obstruction. American Journal of Veterinary Research 60 689-693 Duvivier D, Votion D, Vandenput S et al 1997 Technical validation of a facemask adapted for dry powder inhalation in the equine species. Equine Veterinary Journal 29 471-476... 

To avoid the need for coordination in breathing and actuation of the inhaler, a breath-actuated system has been devised. Patients who inhaled at 50 L/min did not experience significantly greater bronchodilation using a breath-actuated device than those using a conventional MDI [173], The Autohaler, shown in... 

After a brief explanation of the factors governing deposition of aerosol particles in the lung, the common methods of administration of inhalation aerosols have been described. The drugs most frequently delivered by this route are bronchodilators. Correct administration and the use of inhaler accessories, such as spacer devices, enhance the efficacy of inhaled drugs. It is essential that the patient be instructed in the correct use of the devices to optimize the therapeutic effect. 

When inhaled, tiotropium is minimally absorbed into the systemic circulation and results in bronchodilation within 30 minutes, with a peak effect in 3 hours. Bronchodilation persists for at least 24 hours. In the United States, it is delivered via the HandiHaler, a single-load, dry-powder, breath-actuated device. Because it acts locally, tiotropium is well tolerated, with the most common complaint being a dry mouth. Other anticholinergic side effects that are reported include constipation, urinary retention, tachycardia, blurred vision, and precipitation of narrow-angle glaucoma symptoms. 

When working with a patient who is not man ng the drug r men correcdy, die nurse must ensure that the patient understands the drug r men. It is essential to provide written instructions. If possible, die nurse should allow the patient to administer die drug before he or she is dismissed from die liealdi care facility. The nurse should determine if adequate funds are available to obtain the drug and any necessary supplies. For example, when a bronchodilator is administered by inhalation, a spacer or extender may be required for proper administration. This device is an additional expense. A referral to the social service department of die institution may help when finances are a problem. 

The drug to be delivered determines the choice of spacer. The requirements for the delivery of bronchodilators and inhaled steroids are so different that different devices should be recommended. 

The choice of spacer depends on the drug to be delivered. The requirements for delivery of bronchodilators and steroids differ, and different devices may be advisable. Simple containers or small-volume spacers may be used for bronchodilators, whereas optimized spacers are essential for delivery of inhaled steroids. Inexpensive but ineffective spacers may cause expensive loss of drug. 

Rau JL, Restiepo RD, Deshpande V. Inhalation of single vs multiple metered-dose bronchodilator actuations from reservoir devices. Chest 1996 109 109 969-974. 

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