Single-Dose Pharmacokinetics and Safety Pharmacodynamics of Formoterol Delivered by Two Different Dry Powder Inhalers

The Pharmacokinetics of Inhaled Drugs

The pharmacokinetic (PK) profile of a drug after inhalation may differ quite markedly from that seen after dosing by other routes of administration. Drugs may be administered to the lung to elicit a local action or as a portal for systemic delivery of the drug to its site of action elsewhere in the body. Some knowledge of PK is important for both locally- and systemically-acting drugs. For a systemically-acting drug, the plasma concentration-time profile shares some similarities with drug given by the oral or intravenous routes, since the plasma concentrations (after the distribution phase) will be in equilibrium with concentrations at the site of action. For a locally-acting drug, however, the plasma concentrations reflect its fate after it has been absorbed and removed from the airways, and not what is available to its site of action in the lung. Consequently, those typical PK parameters which are determined from plasma concentration measurements, e.g., area under the curve (AUC), Cmax, tmax and post-peak t1/2 may provide information on the deposition and absorption of drugs from the lung; however, the information from these parameters becomes more complicated to decipher for those drugs which are locally-acting in the lung. Additionally, the plasma concentration profile for both locally- and systemically-acting drugs will not only reflect drug absorbed from the lung but also that absorbed from the gastrointestinal (GI) tract from the portion of the dose which is swallowed. This absorption from the GI tract adds a further complication to the interpretation of plasma concentrations, particularly for locally-acting drugs. The influence of physiological and pathological factors needs to be considered in the absorption of some inhaled drugs. The absorption of some hydrophilic drugs is influenced by the inspiratory maneuver used during initial inhalation of the drug, and at later times after deposition. Similarly, the effects of smoking have been shown to increase lung permeability and increase the absorption of certain hydrophilic drugs. The effects of different disease states of the lung have less defined influences on absorption into the systemic circulation.

A Randomized, Crossover Trial Evaluating Patient Handling, Preference, and Ease of Use of the Fluticasone Propionate/Formoterol Breath-Triggered Inhaler

BACKGROUND

Appropriate inhaler selection is of fundamental importance in obstructive lung disease management. Key factors in device selection include a patient's capacity to operate a particular device and their preference for it.

METHODS

This randomized, open-label, two-period, crossover study (NCT01739387) compared the ability of adolescent and adult patients with obstructive lung disease to correctly handle the fluticasone propionate/formoterol fumarate (FP/FORM; Flutiform^®) pressurized metered-dose inhaler (pMDI) and FP/FORM K-haler^®, a novel breath-triggered inhaler (BTI), following a simple, standardized training regimen. The primary endpoint was the ability to perform all steps correctly at the first attempt. Secondary endpoints included the ability to perform all critical steps correctly at the first attempt, the requisite number of attempts to successfully use the inhaler, the ability to be trained within 15 minutes, and the ability to trigger the K-haler BTI to actuate at the first attempt. Ease of device use and device preference versus patients' usual maintenance inhalers were also assessed.

RESULTS AND CONCLUSIONS

At the first attempt, an identical proportion (77.2% [95% confidence interval [CI]: 72.1, 81.8]) of 307 patients performed all pMDI and K-haler BTI handling steps correctly, whereas the corresponding proportions performing all critical steps correctly were 82.4% (95% CIs: 77.7, 86.5) and 87.0% (95% CI: 82.7, 90.5), respectively. For both devices, >90% of patients required only two attempts to master device usage; >99% of patients could be trained to correctly use each device within 15 minutes. Virtually all patients (99.0% [95% CIs: 97.2, 99.8]) were able to successfully trigger the K-haler BTI's dose-release mechanism at first attempt. Ease of use and preference data for FP/FORM pMDI challenged the perceived wisdom that dry powder inhalers are necessarily simpler to use, whereas the corresponding data for FP/FORM K-haler strongly favored this novel BTI over the Turbuhaler^®, Accuhaler^®, and other pMDIs.