New considerations about measuring airway hyperresponsiveness

Development of drug-in-adhesive transdermal patch for α-asarone and in vivo pharmacokinetics and efficacy evaluation

A transdermal drug delivery system has been reported that can increase the bioavailability, reduce the administration duration, and maintain the concentration of drug in blood. In the present study, drug-in-adhesive transdermal patches of α-asarone using Eudragit E100 as pressure-sensitive adhesives and oleic acid plus isopropyl myristate as penetration co-enhancers were developed. In vitro permeation, in vivo pharmacokinetics in rabbits, and efficacy in asthmatic rats were evaluated. The results showed that co-enhancers could induce a synergistic effect on α-asarone permeability. In vivo study suggested that the patch can keep a relatively certain blood level of drug within 10-30 h in rabbits. Furthermore, the patch with the size of 4 cm² containing drug 3 mg/cm² showed a noticeable treating effect on asthmatic rats which is equivalent to the effect of dexamethasone, while avoiding the side-effect induced by the corticorsteroid. This suggests that the drug-in-adhesive transdermal patch is a promising delivery system containing α-asarone to be used for asthma treatment.

Asthma: are we monitoring the correct measures?

The prevalence of asthma, a common chronic inflammatory disease of the airways, has risen sharply over the past 25-30 years, with the biggest increase found in children. Currently, more than 22 million Americans have asthma. Asthma also is associated with significant morbidity and mortality worldwide. Each year, asthma is responsible for $16 billion in direct and indirect costs due to health care utilization and loss of productivity, with over 14 million missed workdays. Asthma also accounts for almost 1.8 million emergency room visits and almost 500,000 hospitalizations annually. Therefore, assessment and monitoring of disease activity is critical to improve clinical and economic outcomes for patients with asthma. To help in this endeavor, practitioners and payers rely on evidence-based guidelines to classify disease severity, to guide treatment decisions, and to assess the degree of asthma control. In August 2007, the National Asthma Education and Prevention Program (NAEPP) updated its guidelines based on greater knowledge of disease pathophysiology and the development of newer therapeutic agents. This includes an increased emphasis on the need to establish disease severity, including the components of impairment and risk, as well as on the level of asthma control. Despite the availability of the NAEPP and other guidelines, asthma control often remains suboptimal. While numerous clinical and patient-reported measures are available, it is clear that the optimal monitoring schema for patients with asthma remains undefined. To clearly establish whether asthma control is attained, multiple measures are required and should include clinical and patient-reported assessments.

Difficult-to-control asthma and obstructive sleep apnea

This study tested the hypothesis that asthma can promote obstructive sleep apnea (OSA) by looking at the prevalence of OSA among patients with difficult-to-control asthma receiving long-term oral corticosteroid (CS) therapy and examined some possible etiological factors. The study design was a prospective cohort study and was conducted in the pulmonary outpatient clinic of a tertiary care center in Haifa, Israel. Twenty-two consecutive patients with severe unstable asthma, 14 on continuous and 8 on bursts of oral CS, in addition to their standard therapy for a mean of 8.9 +/- 3.3 years, underwent a night polysomnography in a sleep laboratory regardless of sleep complaints. A standard questionnaire was completed upon attending the sleep laboratory. The OSA was defined as respiratory disturbance index (RDI) of > or = 5 and typical complaints. The correlation between RDI to asthma and morphometric parameters was tested. All but one patient had OSA [95.5% prevalence], with mean RDI of 17.7 +/- 2.5. The RDI values were significantly higher in the continuous CS therapy subgroup (21.4 +/- 3.4 vs. 11.1 +/- 1.6, p < 0.05]. The study group had above normal neck circumferences and body mass index. The former increased by 12.1% +/- 3.1% % to 29.8% +/- 1% during the oral CS therapy interval but had no significant effect on RDI as a covariant. This study showed an unexpectedly high prevalence of OSA among patients with unstable asthma receiving long-term chronic or frequent burst of oral CS therapy. It may be assumed that prolonged and especially continuous oral CS therapy in asthma increases airway collapsibility.

Nα-Imidazolylalkyl and Pyridylalkyl Derivatives of Histaprodifen: Synthesis and in Vitro Evaluation of Highly Potent Histamine H1-Receptor Agonists

A novel series of N(alpha)()-imidazolylalkyl and pyridylalkyl derivatives of histaprodifen (6, 2-[2-(3,3-diphenylpropyl)imidazol-4-yl]ethanamine) was synthesized and evaluated as histamine H(1)-receptor agonists. The title compounds displayed partial agonism at contractile H(1)-receptors of guinea pig ileum and were at least equipotent with histamine. Agonist effects of the new derivatives were susceptible to blockade by the H(1)-receptor antagonist mepyramine (2-100 nM). In the imidazole series, suprahistaprodifen (51, [2-[2-(3,3-diphenylpropyl)-1H-imidazol-4-yl]ethyl]-[2-(1H-imidazol-4-yl)ethyl]amine, N(alpha)-2-[(1H-imidazol-4-yl)ethyl]histaprodifen) showed the highest H(1)-receptor agonist potency ever reported in the literature (pEC(50) 8.26, efficacy E(max) 96%). Elongation of the alkyl spacer from ethyl to butyl decreased activity from 3630% (ethyl, 51) to 163% (butyl, 53) of histamine potency. The exchange of the terminal imidazole nucleus for a pyridine ring resulted in compounds with comparably high potency. A decrease in agonist potency and efficacy was observed when the attachment of the alkyl spacer was consecutively changed from the ortho to the meta and the para position, respectively, of the pyridine ring. The pyridine series that contained a butyl chain possessed the highest potency and affinity. N(alpha)-[4-(2-pyridyl)butyl]histaprodifen (56) emerged as a strong partial agonist, being almost equipotent with 51 (pEC(50) 8.16, E(max) 89%). Compounds 51 and 56 also showed potent partial agonism at contractile H(1) receptors in guinea pig aorta and potently activated H(1)-receptor-mediated endothelium-dependent relaxation in the rat aorta. Compounds 51-65 displayed low to moderate affinity at H(2), H(3), and M(3) receptors in functional models of guinea pig. Collectively, N(alpha)-imidazolylalkyl- and N(alpha)-pyridylalkyl-substituted histaprodifens represent a novel class of potent H(1)-receptor agonists. These compounds may be useful to define the (patho)physiological role of the H(1)-receptor and refine molecular models of H(1)-receptor activation.

Relation of airway reactivity and sensitivity with bronchial pathology in asthma

Airway hyperresponsiveness in asthmatics, which may result from inflammation or remodeling, is expressed as the concentration of methacholine that causes a 20% fall in FEV1 in the concentration-response curve (PC20). A decrease in PC20 may be due to a steeper curve (hyperreactivity) and/or a curve shift to the left (hypersensitivity). Our purpose was to analyze the relation of airway sensitivity and reactivity to airway pathological changes. The PC6, as sensitivity parameter, and the slope between PC20 and PC40 as reactivity parameter, were calculated. Total and differential cell counts in the bronchoalveolar lavage fluid, and percentage of epithelial shedding, basement membrane thickness, and submucosal thickness on bronchial biopsy, were measured. The PC6 showed a correlation with the baseline FEV1%. The slope was significantly correlated with the basement membrane thickness, and also demonstrated a strong association with submucosal thickness. The PC20 showed a correlation with the baseline FEV1% and the degree of epithelial shedding. These results suggest that the airway sensitivity and reactivity measurements reflect the degree of airway caliber and remodeling, respectively.

Effects of 4-week treatment with low-dose budesonide (100 micrograms BID) from a novel inhaler Airmax and from a conventional inhaler on bronchial hyper-responsiveness, lung function and symptoms in patients with mild asthma

This study investigated the effect of low dose of budesonide 100 micrograms b.d from a new multi-dose dry powder inhaler (Airmax) and from a conventional inhaler (Turbuhaler) on bronchial hyper-responsiveness, lung function and asthma symptoms in mild stable asthmatics. Twenty-five patients were enrolled into a double-blind double-dummy crossover study with two 4-week treatment periods separated by a 4-week washout. Patients had a mean forced expiratory volume in 1 s (FEV1) of 91 +/- 13% predicted, had previously received inhaled short-acting beta 2-agonists only and had a PC20 to adenosine 5' monophosphate (AMP) < 40 mg/ml. PC20 AMP was assessed at baseline, and at the start and end of each treatment period. Patients recorded peak expiratory flow and symptoms throughout the study. There was a mean increase in PC20AMP from start to end of 3.49 doubling dilutions (DD) in the Airmax group and 2.90 DD in the Turbuhaler group. The difference was 0.60 DD (95% CI--0.47, 1.69) favouring Airmax and the upper limit exceeded the equivalence limit of +/- 1 DD. There were similar improvements in FEV1, daily PEF and symptoms in both groups. The majority of patients preferred treatment with Airmax to Turbuhaler (64 vs. 23%). Both treatments were equally well tolerated. In conclusion, 100 micrograms budesonide bid during 4 weeks from Airmax effectively attenuates the response to AMP in mild asthmatics. Overall Airmax offers equal clinical benefit to Turbuhaler.