Dry Powder Inhalers: From Bench to Bedside.

Dry powder inhalers (DPIs) are now widely prescribed and preferred by the majority of patients. These devices have many advantages over the traditional pressurized metered-dose inhaler (pMDI) but they do have disadvantages. The characteristics of the dose emitted from a DPI are affected by the inhalation manoeuvre used by a patient.

Can all patients with COPD use the correct inhalation flow with all inhalers and does training help?

The inhalation rate is important when patients use an inhaler. Dry powder inhalers (DPIs) require an inhalation rate >30 L min(-1) whereas metered dose inhalers (MDIs) should be used at <90 L min(-1). Within the setting of a routine clinic, we have measured peak inhalation flows (PIF) of COPD patients when they used a Diskus (SDSK), Turbuhaler (STBH), Handihaler (SHAND) and MDI.

Emitted dose estimates from Seretide Diskus and Symbicort Turbuhaler following inhalation by severe asthmatics.

The dose emitted from dry powder inhalers may be inhalation flow-dependent. Using an ex vivo method, the Electronic Lung, we have measured the aerodynamic characteristics of the emitted dose for both active constituents from Seretide Diskus (salmeterol xinafoate 50 mcg; fluticasone propionate 500 mcg) and Symbicort Turbuhaler (formoterol 6 mcg; budesonide 200 mcg). Electronic inhalation profiles were collected from 20 severe asthmatics (mean PEFR 53% predicted) when they inhaled using a placebo Seretide Diskus and a placebo Symbicort Turbuhaler.