Asthma stability after oral prednisone: a clinical model for comparing inhaled steroid potency

The development of AZD7624 for prevention of exacerbations in COPD: a randomized controlled trial

Background

p38 mitogen-activated protein kinase (MAPK) plays a central role in the regulation and activation of pro-inflammatory mediators. COPD patients have increased levels of activated p38 MAPK, which correlate with increased lung function impairment, alveolar wall inflammation, and COPD exacerbations.

Objectives

These studies aimed to assess the effect of p38 inhibition with AZD7624 in healthy volunteers and patients with COPD. The principal hypothesis was that decreasing lung inflammation via inhibition of p38α would reduce exacerbations and improve quality of life for COPD patients at high risk for acute exacerbations.

Methods

The p38 isoform most relevant to lung inflammation was assessed using an in situ proximity ligation assay in severe COPD patients and donor controls. Volunteers aged 18–55 years were randomized into the lipopolysaccharide (LPS) challenge study, which investigated the effect of a single dose of AZD7624 vs placebo on inflammatory biomarkers. The Proof of Principle study randomized patients aged 40–85 years with a diagnosis of COPD for >1 year to AZD7624 or placebo to assess the effect of p38 inhibition in decreasing the rate of exacerbations.

Results

The p38 isoform most relevant to lung inflammation was p38α, and AZD7624 specifically inhibited p38α and p38β isoforms in human alveolar macrophages. Thirty volunteers were randomized in the LPS challenge study. AZD7624 reduced the increase from baseline in sputum neutrophils and TNF-α by 56.6% and 85.4%, respectively (p<0.001). In the 213 patients randomized into the Proof of Principle study, there was no statistically significant difference between AZD7624 and placebo when comparing the number of days to the first moderate or severe exacerbation or early dropout.

Conclusion

Although p38α is upregulated in the lungs of COPD patients, AZD7624, an isoform-specific inhaled p38 MAPK inhibitor, failed to show any benefit in patients with COPD.

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.

Efficacy and safety of once-daily GW870086 a novel selective glucocorticoid in mild-moderate asthmatics: a randomised, two-way crossover, controlled clinical trial

OBJECTIVE

To assess the efficacy of inhaled, repeat doses (28 days) of the glucocorticoid agonist GW870086, which has been designed to inhibit gene transrepression of the glucocorticoid receptor while preserving its transactivation.

METHODS

This was a randomised, placebo-controlled, two-way crossover study, approved by the independent ethics committees of the study centres. Subjects with FEV(1) 40-85% of the predicted normal value (n = 36) received GW870086 (1 mg, once-daily) and placebo.

RESULTS

No significant change from baseline in forced expiratory volume in one second (FEV(1)) was seen following administration of GW8780086 1 mg relative to placebo; mean FEV(1) (day 28), relative to placebo, was (95% confidence intervals [CI]) -0.077 L (-0.192, 0.038). A moderate positive placebo response was observed on Days 14 and 28: Mean FEV(1) (95% CI) was 0.115 L (0.040, 0.189) and 0.115 L (0.019, 0.212), respectively. The placebo response was more notable in treatment period 1 and was larger than the response to GW870086 1 mg on day 28, irrespective of period. Peak expiratory flow rate results were consistent with FEV(1) and no difference was seen between the GW870086 and placebo for rescue medication usage.

CONCLUSION

This total lack of effect suggests that repeat-dose GW8700861 mg has suboptimal efficacy in mild to moderate asthma.

Inhaled corticosteroid dosing: double for nothing?

Two recent trials from the National Heart, Lung, and Blood Institute's asthma clinical trials networks raise a concern about using double the dose of an inhaled corticosteroid (ICS) as a positive control arm in clinical trials of add-on therapy. The literature evaluating the response to doubling the dose of an ICS is briefly reviewed. The vast majority of studies do not demonstrate a significant positive benefit from doubling the dose of an ICS but do show improvement with 4-fold increases that is equal to or greater than that of add-on long-acting bronchodilators. It is recommended that doubling the dose of an ICS no longer be considered a positive comparator arm in clinical trials, although it might be beneficial in individual patients.

FDA critical path initiatives: opportunities for generic drug development

FDA's critical path initiative documents have focused on the challenges involved in the development of new drugs. Some of the focus areas identified apply equally to the production of generic drugs. However, there are scientific challenges unique to the development of generic drugs as well. In May 2007, FDA released a document "Critical Path Opportunities for Generic Drugs" that identified some of the specific challenges in the development of generic drugs. The key steps in generic product development are usually characterization of the reference product, design of a pharmaceutically equivalent and bioequivalent product, design of a consistent manufacturing process and conduct of the pivotal bioequivalence study. There are several areas of opportunity where scientific progress could accelerate the development and approval of generic products and expand the range of products for which generic versions are available, while maintaining high standards for quality, safety, and efficacy. These areas include the use of quality by design to develop bioequivalent products, more efficient bioequivalence methods for systemically acting drugs (expansion of BCS waivers, highly variable drugs), and development of new bioequivalence methods for locally acting drugs.

Conference report: Bio-International 2005

This is a summary report of the International Pharmaceutical Federation/Board of Pharmaceutical Sciences (FIP/BPS) international conference, Bio-International 2005, which was held October 24-26, 2005 at the Royal Pharmaceutical Society, in London, UK. Bioequivalence (BE) issues related to multisource locally delivered topical dosage forms, oral inhalation drug products, highly variable drug products (HVDP), and endogenously occurring drugs were discussed. The conference also focused on alternate approaches to assess BE for some of these drug products. Pharmacokinetic (PK) approaches like, dermatopharmacokinetics (DPK) for dermatological topical dosage forms, scaled average BE (s-ABE) where within-subject variability is considered for estimation of 90% confidence intervals to document BE for highly variable drugs (HVD) were recommended. In addition, issues and difficulties related to the BE assessment of oral inhalation products, role, and appropriateness of metabolites in BE assessment, importance of base line correction in BE assessment of endogenously occurring drugs, and waiver of BE study requirements for certain drugs based on a Biopharmaceutics Classification System (BCS), were also discussed.

Speed of onset of bronchodilator response to salbutamol inhaled via different devices in asthmatics: a bioassay based on functional antagonism

AIMS

To evaluate the speed of onset of bronchodilation following salbutamol administered via a metered-dose inhaler with a spacer (pMDI + Volumatic) and a dry-powder inhaler (Diskus), as well as the relative potencies of these devices in asthmatic patients with methacholine-induced bronchoconstriction.

METHODS

Eighteen patients inhaled methacholine (MCh) until FEV(1) decreased by 35% of control. Following administration of placebo, 200 microg salbutamol or 400 microg salbutamol through the pMDI + Volumatic or the Diskus, we calculated the time elapsed from drug administration and the appearance of a 90% increase in post-MCh forced vital capacity (FVC), FEV(1) and volume-adjusted mid-expiratory flow (recovery times). The salbutamol doses to be delivered by the two inhalation devices to achieve similar recovery times and the relative potencies of the devices were calculated by using the 2-by-2 Finney parallel regression method.

RESULTS

For all functional variables, recovery times were significantly (P < 0.01) shorter in pMDI + Volumatic than Diskus trials. The salbutamol doses to be delivered by the Diskus to achieve recovery times for FVC, FEV(1) and volume-adjusted mid-expiratory flow similar to those obtained with 200 microg salbutamol administered via the pMDI + Volumatic were 558 (95% CI 537, 579) microg, 395 (95% CI 388, 404) microg and 404 (95% CI 393, 415) microg, respectively, and corresponded to relative potencies of 2.79 (95% CI 2.68, 2.90), 1.98 (95% CI 1.94, 2.02), and 2.02 (95% CI 1.96, 2.07).

CONCLUSIONS

Administration of salbutamol via the pMDI + Volumatic provides faster reversal of induced bronchoconstriction than via the Diskus. The salbutamol dose targeting the lungs with the pMDI + Volumatic is approximately twice that with the Diskus.

Power to detect clinically relevant carry-over in a series of cross-over studies

The potential for carry-over effects is an important consideration in the design of any cross-over study, and can cause an investigator to abandon the design altogether. In cross-over studies, carry-over is the lingering effect of a treatment into the subsequent period. Carry-over effects are differences in the extent of the carry-over between the treatments under consideration. It is well known that the test for carry-over effects in individual studies has low power. Empirical evidence of carry-over effects, or the absence of carry-over effects, could be useful for investigators considering the design. Here we develop methods for expressing the power to detect carry-over as a function of the power to detect a clinically relevant treatment effect. Our results suggest that for two-treatment, two-period cross-over studies the power to detect clinically relevant carry-over effects is often less than 15 per cent, and the number of studies needed to differentiate this effect from the type I error rate of 10 per cent is prohibitive. For the three-treatment three-period cross-over design, the power to detect carry-over effects was larger than for the two-period study, but still approached the type I error rate in a number of cases. Unequivocal conclusions about the absence of carry-over effects based on collections of hypothesis tests appear unlikely. Similar findings are presented for bioequivalence studies. For bioequivalence studies, small carry-over effects (e.g. 12.5 per cent of the treatment effect) can seriously inflate the type I error rate, particularly when the power to detect equivalence is high.

Effects of inhaled ciclesonide and fluticasone propionate on cortisol secretion and airway responsiveness to adenosine 5'monophosphate in asthmatic patients

The efficacy and systemic effects of ciclesonide, a novel glucocorticosteroid, inhaled via pressurized metered-dose inhaler (pMDI) were compared with fluticasone propionate pMDI in 26 patients with asthma, using a randomized, double blind, placebo-controlled, double dummy, 6-period crossover study design. Treatments were placebo, ciclesonide 320 microg (ex-actuator dose) once daily (o.d.), ciclesonide 640 microg o.d., ciclesonide 640 microg twice daily (b.i.d.), fluticasone propionate 440 microg (ex-actuator dose) b.i.d., and fluticasone propionate 880 microg b.i.d. The primary variable was area under the plasma cortisol concentration-time curve over 24 h (plasma cortisol AUC(0-24), relative to placebo) derived from samples taken every 2 h, on the 9th day of treatment. Secondary variables were 24-h urinary cortisol excretion and PC20 for adenosine 5'-monophosphate (AMP) (relative to placebo and expressed in doubling concentrations). Ciclesonide did not affect 24-h cortisol secretion. Fluticasone propionate suppressed cortisol secretion as demonstrated by a decrease in plasma cortisol AUC(0-24), relative to placebo, by 29% (95% CI 15-41) and 59% (95% CI 51-66) with 440 and 880 microg b.i.d., respectively. PC20 more than doubled with each active treatment, but no statistically significant dose-response effect could be established. It was concluded that moderate to high doses of fluticasone propionate suppressed cortisol secretion, that ciclesonide did not suppress cortisol secretion, and that all active treatments decreased hyperresponsiveness to AMP.

Is a two-week trial of oral prednisolone predictive of target lung function in pediatric asthma?

We used a 2-week trial of prednisolone to determine "target" lung function for subsequent asthma therapy. The aim of this study was to evaluate whether some children exceed their "target" forced expired volume in 1 sec (FEV1) on subsequent visits in the following year, and whether this is associated with particular clinical or pathological features. Children (aged 6-16 years) with difficult asthma underwent spirometry and exhaled nitric oxide (FE(NO)) measurements before and after 2 weeks of prednisolone 40 mg/day. At the end of the course, subepithelial eosinophils and reticular basement membrane thickness were assessed. The highest FEV1 obtained in a 1-year follow-up was compared with the poststeroid postbronchodilator ("target") FEV1. Four of 22 children (18%) demonstrated an increase of > 9% above their "target" FEV1 during follow-up. None of these children had been prescribed additional asthma medications. Three of 7 children with persistent airflow limitation (PAL; poststeroid postbronchodilator FEV1 < 80% predicted) recorded an FEV1 > 80% predicted during follow-up. The median (interquartile range) number of subepithelial eosinophils was significantly higher in children who exceeded their target FEV1 than in children who did not (12.4 (8.5-39.9) vs. 1.4 (0.0-4.8) cells/mm2, P = 0.018). In conclusion, a 2-week course of prednisolone is not necessarily predictive of "target" lung function. Definitions such as PAL should be regularly reviewed on individual basis.

Pharmaceutical characteristics that influence the clinical efficacy of inhaled corticosteroids

BACKGROUND

Inhaled corticosteroids (ICSs) are the most effective therapy for the management of persistent asthma. The aim of ICS therapy is to achieve a high anti-inflammatory effect in the airways with a concomitant low risk of unwanted local and systemic effects. Direct estimates of clinical efficacy and potency based on studies in humans are difficult to interpret.

OBJECTIVE

To examine the challenges of using alternative estimates of ICS efficacy and potency, including pharmaceutical characteristics.

DATA SOURCES AND STUDY SELECTION

Articles published from 1990 to 2002 on the potency, efficacy, and tolerability of ICSs were identified using MEDLINE and in-house databases and were then reviewed. Search terms included inhaled corticosteroid, budesonide, fluticasone, beclomethasone, mometasone, and potency.

RESULTS

Differences among ICSs can be readily shown using preclinical measures, such as glucocorticoid receptor binding or skin blanching tests. However, pharmaceutical (delivery and pharmacokinetic) differences of ICSs can have a greater impact on clinical efficacy than in vitro potency differences. For example, the unique esterification of budesonide in the airways prolongs its local activity and may contribute positively to its efficacy and therapeutic index. Although comparative clinical trials suggest 6-fold differences in potencies among ICSs, there is currently no evidence to support differences in efficacy when they are administered at equipotent dosages.

CONCLUSIONS

Greater preclinical potency of an ICS does not imply greater clinical efficacy. Pharmacokinetic factors can have a significant impact on relative clinical efficacy.

Dose response and therapeutic index of inhaled corticosteroids in asthma

Inhaled glucocorticoids play an indispensable role in the therapy of asthma. Development of new compounds was initially directed to increase the potency of the individual corticosteroid; thereafter, pharmacokinetic characteristics were modified to reduce unwanted systemic effects. Target of the present development is to attain compounds with the most favorable risk-to-benefit ratios. Since then, there has been substantial discussion about how to rank and weigh the different glucocorticoids. This article provides an evaluation of the relevant clinical studies published between May 2001 and June 2002, identifying the main determinants of the therapeutic value of inhaled glucocorticoids.