Bronchoprotection with formoterol via dry powder and metered-dose inhalers in patients with asthma

Methacholine challenge testing: comparative pharmacology

Standardization of the methacholine inhalation challenge, the most common direct bronchoprovocation test, is important. One aspect of standardization is the appropriate washout period for pharmacologic agents which affect the response. This review summarizes the available data on pharmacologic inhibition of the methacholine response. Specific (anti-muscarinic) agents demonstrate marked bronchoprotection (up to 7 days for the long-acting drugs) which lasts longer than the duration of bronchodilation. The functional antagonist (beta 2 agonist class of medications) shows marked, but less, bronchoprotection which is relatively short lived and is similar to the duration of bronchodilator efficacy. Tolerance develops quickly, especially to the long-acting agents. Single doses of controller medications, such as inhaled corticosteroids (ICS) and leukotriene receptor antagonists, have no effect on the methacholine test, while regular use, at least for ICS, has a modest protective effect whose duration is uncertain and likely variable. Theophylline has a small effect and H1 blockers (all generations) have a negligible effect.

Regulatory Considerations for Approval of Generic Inhalation Drug Products in the US, EU, Brazil, China, and India

This article describes regulatory approaches for approval of "generic" orally inhaled drug products (OIDPs) in the United States, European Union, Brazil, China and India. While registration of a generic OIDP in any given market may require some documentation of the formulation and device similarity to the "original" product as well as comparative testing of in vitro characteristics and in vivo performance, the specific documentation approaches, tests and acceptance criteria vary by the country. This divergence is due to several factors, including unique cultural, historical, legal and economic circumstances of each region; the diverse healthcare and regulatory systems; the different definitions of key terms such as "generic" and "reference" drug; the acknowledged absence of in vitro in vivo correlations for OIDPs; and the scientific and statistical issues related to OIDP testing (such as how best to account for the batch-to-batch variability of the Reference product, whether to use average bioequivalence or population bioequivalence in the statistical analysis of results, whether to use healthy volunteers or patients for pharmacokinetic studies, and which pharmacodynamic or clinical end-points should be used). As a result of this discrepancy, there are ample opportunities for the regulatory and scientific communities around the world to collaborate in developing more consistent, better aligned, science-based approaches. Moving in that direction will require both further research and further open discussion of the pros and cons of various approaches.

Clinical equivalence of budesonide dry powder inhaler and pressurized metered dose inhaler

INTRODUCTION

A delivery device is the most important factor that determines the local/systemic bioavailability of inhaled corticosteroids. Dry powder inhalers (DPIs) and pressurized metered dose inhalers (pMDIs) are the most commonly used delivery devices for localized drug delivery to the airways.

OBJECTIVE

This study was to compare the clinical equivalence of budesonide delivered by the Pulmicort Turbuhaler (DPI) and the Aeronide inhaler (pMDI).

MATERIALS AND METHODS

The two inhalers were compared for their pharmaceutical equivalence and clinical equivalence. The in vitro test included the uniformity of the delivered dose and determination of the aerodynamic particle size of budesonide. The in vivo test was carried out in 36 patients with mild to moderate asthma. This was a randomized, single-blinded study conducted for a period of 3 months. This included assessment of the spirometric parameters [forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR), forced expiratory flow 25-75% (FEF25-75)], the severity of asthma symptoms, adverse events, frequency of short-acting inhaled bronchodilator usage and measurement of urinary cortisol levels.

RESULTS

The aerodynamic particle size was slightly different between the two inhalers (2.3 ± 0.2 µm for Pulmicort Turbuhaler and 2.2 ± 0.2 µm for Aeronide inhaler). Both inhalers passed the uniformity of delivered dose (95.4% and 97.4%) specified in the British Pharmacopoeia. There was no statistically significant difference observed between the two inhalers in terms of the spirometric parameters, symptom-free days, frequency of bronchodilator usage and the level of urinary cortisol.

CONCLUSION

In addition to pharmaceutical equivalence, no clinical difference observed between the two budesonide inhalers.

Methacholine challenge as a clinical bioassay of pulmonary delivery of a long-acting β₂-adrenergic agonist

STUDY OBJECTIVE

To determine whether the methacholine challenge method used for albuterol can be applied to assess long-acting β2-adrenergic agonist (LABA) bioequivalence, which would require a sufficiently steep dose-response curve.

DESIGN

Prospective, unblinded, randomized, 2-way crossover study.

SETTING

University medical center clinical research laboratory.

PATIENTS

Ten adults, aged 21-58 years, with mild asthma (forced expiratory volume in 1 sec [FEV(1)] ≥ 70% predicted) and a baseline provocational concentration of methacholine required to decrease FEV(1) by 20% (PC(20)) of 4 mg/ml or less completed the study.

INTERVENTION

Patients were randomized to receive a single dose of either 12 or 24 μg of formoterol delivered by a dry powder inhaler; 3-7 days later, at the same time of day, they received the other dose.

MEASUREMENTS AND MAIN RESULTS

The FEV(1) was measured before and 1 hour after dosing, followed by performance of a methacholine challenge. Statistical analysis was performed by the 2-sample regression method for crossover studies. The dose-response curve for bronchodilatation was flat; the mean ± SD increase in FEV(1) after formoterol 12 and 24 μg was 14 ± 5% and 14 ± 8%, respectively (p>0.05). In contrast, the geometric mean PC20 (95% confidence interval) was 7 mg/ml (2-22 mg/ml) after the 12-μg dose and 16 mg/ml (5-45 mg/ml) after the 24-μg dose (p<0.001).

CONCLUSION

Bioassay by methacholine challenge will be useful for bioequivalence studies of LABAs. A sample of at least 28 patients will be required for formoterol when methacholine challenge is performed in an optimal manner. The sample size may differ for other LABAs.

Inhalation devices for long-acting beta2-agonists: efficiency and ease of use of dry powder formoterol inhalers for use by patients with asthma and COPD

BACKGROUND

Since the long-acting beta(2)-agonist bronchodilator, formoterol, first became available for the treatment of subjects with asthma or chronic obstructive pulmonary disease (COPD), generic forms of this agent have been launched in a variety of devices. It is timely to review the characteristics of the original dry powder delivery device, the single-dose Aerolizer, its in vitro performance and its comparability with other inhaler devices that are now available for delivery of formoterol.

SCOPE

This review focuses on the performance of the formoterol Aerolizer inhaler in comparison with other inhalers. Publically available data (PubMed) on the device performance characteristics of the Aerolizer were reviewed and summarized, together with the results of comparative studies performed by the authors. Published studies (PubMed) on patient handling and inhaler technique that include the Aerolizer are described and studies comparing the clinical effect of formoterol in the Aerolizer with formoterol delivered via other devices were reviewed and are summarized.

FINDINGS

The Aerolizer performs consistently in dosing efficiency across a range of inspiratory flow rates, suggesting its suitability for use by patients with differing inspiratory flow abilities. The single-dose, capsule-based nature of the device provides patients with obvious feedback on whether the drug has been taken successfully and the Aerolizer has been shown to be one of the more easily used devices in comparative patient handling studies. Studies comparing the clinical effect of formoterol delivered by different inhalation devices show that formoterol via Aerolizer has an equivalent therapeutic effect.

CONCLUSION

Judged on the basis of dosing efficiency, ease of use and clinical equivalence, formoterol Aerolizer remains a useful option in the management of patients with asthma or COPD.