Breath-activated inhaler

B. J. Lipworth, and D. J. Clark, Lung delivery of salbutamol given by breath activated pressurized aerosol and dry powder inhaler devices, Pulm. Pharmacol. Ther. 70 211 (1997). 

New DPI designs are numerous, with the novelty often associated with the technique for achieving powder aerosolization. Some of the recent patented devices incorporate an additional energy source to supplement the inspiratory force of the patient, in order to aerosolize the drug particles into the inhaled airstream. However, unless the addition energy source is breath activated (e.g. as in Spiros), such devices will be limited by the coordination difficulties typical of the pMDIs. 

Woodman, K., Bremner, P, Burgess, C., Crane, J., Pearce, N., and Beasley, R. (1993), A comparative study of the efficacy of beclomethasone dipropionate delivered from a breath activated and conventional metered dose inhaler in asthmatic patients, Curr. Med. Res. Opin., 13, 61-69. 

Q7 Outline the advantages of using a nebulizer rather than a breath-activated or dry-powder inhaler. Would you expect this medication to fully reverse Mandy s bronchoconstriction ... 

Tiotropium is inhaled from the HandiHaler, a dry-powder, breath-activated inhaler system that delivers particles to the lung over a wide range of airflow limitations in patients with chronic obstructive pulmonary disease (COPD) it can be effectively delivered at inspiratory flow rates as low as 201/minute (2). Pharmacodynamic steady-state studies have shown that most of the bronchodUator activity is achieved with one to two doses within 48 hours, although a carryover effect on forced vital capacity was observed beyond 48 hours (3). 

The Autohaler has been devised as a breath-activated pressurised inhaler system because of the difficulty experienced by some patients in coordinating manual operation of an aerosol with inhalation. The Autohaler is activated by the negative pressure created during the inhalation phase of respiration and is specifically designed to respond to shallow inhalation in those with restricted pulmonary capacity. 

Position the inhaler in one ot the tollowing ways (A or B is optimal, but C is acceptable lor those who have dilliculty with A or B. C is required lor breath-activated inhalers) ... 

Breath-activated inhalers (BAIs), developed by Norton and 3M Healthcare, are now relatively common. Although each has a different mechanical design, both work by a trigger threshold of airflow activating the pre-loaded can, and hence firing the pMDI. This ensures that the patient is inhaling at a medium airflow when the aerosol is fired. 

Exubera (Pfizer) Dry-powder, single-dose bhster packs (1—3 mg) breath-activated inhaler... 

There are also two ways to look at compliance monitors, whether they are to help the patient to follow his or her dosing regime or whether they are for the physician to check if the patient is following this regime. In the simplest case, numerical dose counters now being fitted to breath-activated inhalers enable a patient—or perhaps more importantly a child s parent—to check if the dose has been taken. This assumes the discipline of keeping track of the previous dose number. 

Spiros (Dura Pharmaceuticals) is a reusable device containing either a disposable, prefllled plastic cassette with 30 doses or an aluminum blister disk with 16 doses. The device is breath-actuated and the inhalation flow activates a battery-driven motor, which spins an impeller that disperses the drug blend. 

Hanania NA, Wittman R, Kesten S, Chapman KR. Medical personnel s knowledge of and ability to use inhaling devices metered dose inhalers, spacing chambers, and breath-activated dry powder inhalers. Am Rev Respir Dis 1993 147 SSA983. Kelling JS, Strohl KP, Smith RL, Altose MD. Physician knowledge in use of canister nebulizers. Chest 1983 83 612-614. 

Activate the inhaler while taking a slow, deep breath for 3 to 5 seconds. 

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