Breath-actuated inhalers

Zanamivir has a bioavailability of less than 5% when absorbed through the gastrointestinal tract. It is administered using a breath-actuated inhaler device (Diskhaler)... 

O Hagan AH, Corbett JR. Contact allergy to budesonide 200. in a breath-actuated inhaler. Contact Dermatitis 1999 41(1) 53. 

Another very elegant and highly portable device that aids patient coordination is the breath-actuated inhaler, originally developed by Riker Laboratories (3M) [47] and further enhanced by Ivax-Norton (EasiBreathe). In this type of device, a mechanical release mechanism is used, firing the MDI when a certain threshold inspiratory flowrate is reached. Once the dose has been dispensed, the device is then reprimed, ready for use. This type of device has gained wide acceptance in Europe and has been introduced for several MDI products. 

Children of any age older than six years who have difficulty using pMDIs should use a pMDI with a spacer, breath-actuated inhaler, DPI, or nebulizer. DPIs require an inspiratory effort that may be difficult to achieve during severe attacks. 

AIR [Alkermes (Eh Lilly)] Dry-powder phospholipid matrix small mechanical and breath-actuated inhaler... 

It is now widely accepted that pMDIs should not be used alone by children 6 years of age or less. Even children older than this should probably avoid using a pMDI unless in the form of a breath-actuated inhaler or via a spacer device. 

It is uncertain whether the use of breath-actuated inhalers offer an advantage over the pMDI for patients with neurological deficits or other conditions that cause decreased hand strength. However, Chapman et al. (55) found that pMDI-familiar and pMDI-naive elderly subjects preferred a breath-actuated device over the pMDI. 

Wallace WAH, Lenny J, Cooksey E, Greening AP, Crompton GK. Ability of patients with severe air flow limitation to trigger a new breath actuated inhaler. Thorax 1989 44 318. 

Baum EA, Design, development and testing of a new breath actuated inhaler. Inspiration, development in inhalational therapy meeting proceedings. Medicine Publishing Foundation, 1988 20-30. 

Ruggins, NR, Milner AD, Swarbiick A. An assessment of a new breath actuated inhaler device in acutely wheezy children. Arch Dis Child 1993 68 477-480. 

Dry powder inhalers are generally described as breath actuated devices, because the inspiratory airstream releases the dose from the dose system and supplies the energy for the generation of fine drug particles from the powder formulation. Because the efficiency of dose release and powder disintegration increases with increasing inspiratory flow rate for most DPIs, these devices would be better described as breath controlled devices. In Section 3.9, the effect of resistance and clinical conditions on the flow curve and relevant flow parameters for DPIs are discussed. 

Aerosolized medications are available as pressurized or breath-actuated metered-dose inhalers (MDIs), dry powder inhalers (DPIs), and nebulized or wet aerosols. Most inhaled medications currently used are available as metered-dose inhalers (Table 3). For the patient who has difficulty to coordinate activation of a MDI, a spacer improves delivery. Spacers reduce deposition of the drug in the... 

MDI, breath actuated >5 years Slow (30 1/min or 3-5 s) inhalation Indicated for patients unable to... 

An alternative approach to achieving patient coordination between actuation and inhalation is a breath actuated device such as the Autohaler. This device uses a mechanical vane to detect the appropriate inhalation rate for automatic firing of the pMDI. 

Breath-actuated metered dose inhalers - evohalers... 

Newman, S. P., Weisz, A. W., Talaee, N., and Clarke, S. W. (1991), Improvement of drug delivery with a breath actuated pressurised aerosol for patients with poor inhaler technique, Thorax, 46, 712-716. 

The inhaler should be simple to use, require little patient coordination and preferably should be breath-actuate. 

The AERx, developed by Aradigm (Hayward, CA), is a metered dose liquid inhaler designed to deliver various pharmaceutical compounds to the peripheral lungs. The system, as shown in Fig. 10, consists of a unit dose disposable container equipped with a nozzle array, a piston assembly, and electronics associated with breath actuation and compliance monitoring functions. ... 

Larsen, J.S. Hahn, M. Kochevar, J.W. Morris, R.J. Kasier, H.B. Weisberg, S.C. Halverson, P.C. Quessey, S.N. Administration errors with a conventional metered dose inhaler versus a novel breath actuated device. Ann. All. 1993, 71, 103-106. 

Very young children and older people have significant difficulty coordinating their actuation of the device with breathing in Ref.. Patients who have this coordination difficulty can either be supplied with a dry powder inhaler (where the inspiration through the device is also responsible for the release and aero-solization of the powdered drug so that coordination is no longer an issue), or they may be be prescribed a Breath Operated Inhaler (BOI). 

Figure 9.47 Dispersion of Ventodisk or Becodisk contents by breath actuation a cross-section of a Diskhaler is shown with a disc located on the support wheel, (a) A disc is located beneath an aperture in the body of the Diskhaler through which a piercing needle enters, (b) The needle penetrates the upper and lower surfaces of the blister, (c) The patient inhales through the device and pierced blister, entraining the blister contents into the airstream.

Timing of the aerosol entry at a particular point in the breathing cycle can have a profound effect on deposition. With the metered-dose inhaler without a spacer, poor synchronization of inspiration with the firing of the valve can result in a substantial loss of the aerosol bolus. For this reason, breath-actuated valves have been developed [91-93]. 

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... 

Figure 10 Photograph of a breath-actuated metered-dose pressurized-pack inhaler (Autohaler).

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