Age-related changes in airway responsiveness to phosphodiesterase inhibitors and activators of adenyl cyclase and guanylyl cyclase

Tiotropium Respimat Efficacy and Safety in Asthma: Relationship to Age

BACKGROUND

Data are limited on the differential response to long-acting bronchodilators in older versus younger adults with asthma.

OBJECTIVE

To determine whether the response to tiotropium Respimat differed in older versus younger patients with asthma.

METHODS

Post hoc analyses of 4 randomized, double-blind, placebo-controlled studies in adults with asthma were carried out. Two studies compared tiotropium Respimat 5 μg once daily with placebo, both added to high-dose inhaled corticosteroid (ICS) plus long-acting β₂-agonist (ie, severe asthma). The other 2 evaluated tiotropium Respimat 2.5 or 5 μg once daily, salmeterol 50 μg twice daily, or placebo, all added to medium-dose ICS (moderate asthma). Data were analyzed in 2 pools: (1) severe and (2) moderate asthma. Efficacy end points: trough and peak FEV₁; trough forced vital capacity; Asthma Control Questionnaire total score and responder percentage, all at week 24. One set of analyses was performed with age as a continuous covariate; the second was conducted in categories less than 40, 40 to 60, and more than 60 years, with treatment-by-age subgroup interaction P values obtained. Safety was analyzed in age categories.

RESULTS

Across the age categories, treatment-by-age subgroup interaction P values for trough FEV₁ were .13 and .77 for patients with severe and moderate asthma, respectively, not indicating significant impact of age on overall treatment effect, with this observation replicated in the 2 continuum analyses. The other end points (including safety) were also not impacted by age.

CONCLUSIONS

Once-daily tiotropium Respimat add-on to ICS or ICS/long-acting β₂-agonist therapy was effective and well tolerated in patients with asthma independent of age.

The effects of aging on the functional and structural properties of the rat basilar artery

Aging leads to progressive pathophysiological changes in blood vessels of the brain and periphery. The aim of this study was to evaluate the effects of aging on cerebral vascular function and structure. Basilar arteries were isolated from male Fischer 344 cross Brown Norway (F344xBN) rats at 3, 8, and 24 months of age. The basilar arteries were cannulated in the pressurized system (90 cm H₂O). Contractile responses to KCl (30–120 mmol/L) and endothelin‐1 (10⁻¹¹–10⁻⁷ mol/L) were evaluated. Responses to acetylcholine (ACh) (10⁻¹⁰–10⁻⁴ mol/L), diethylamine (DEA)‐NONO‐ate (10⁻¹⁰–10⁻⁴ mol/L), and papaverin (10⁻¹⁰–10⁻⁴ mol/L) were assessed to determine both endothelium‐dependent and endothelium‐independent responsiveness. Advanced aging (24 months) decreased responses of the basilar artery to both the contractile and relaxing agents; whereas, DEA‐induced dilation was significantly higher in the 8‐month‐old group compared with the younger and older groups. The arterial wall‐to‐lumen ratio was significantly increased in 24‐month‐old rats. Smooth muscle cell count was also decreased in old rats. These findings indicate that aging produces dysfunction of both the endothelium and the vascular smooth muscle in the basilar artery. Aging also alters wall structure of the basilar artery, possibly through decreases in smooth muscle cell number and concomitant hypertrophy.

The purpose of this study was to determine the effects of advancing age on the structure and vasomotor responses of the basilar artery as well as the serum antioxidant capacity. Advanced aging (24 months) decreased responses of the basilar artery to both the contractile and relaxing agents, whereas, DEA‐induced dilation was significantly higher in the 8‐month‐old group compared with the younger and older rats. The arterial wall‐to‐lumen ratio was significantly increased in 24‐month‐old rats. Smooth muscle cell count was also decreased in old rats. Our findings demonstrate that aging is associated with functional impairment in endothelium‐dependent and ‐independent relaxation responses and contractility in the basilar arteries, and these diminished responses are accompanied by structural remodeling and decreased antioxidant capacity of the serum.

Potential adverse effects of bronchodilators in the treatment of airways obstruction in older people: recommendations for prescribing

Asthma and chronic obstructive pulmonary disease (COPD) are common disorders that are associated with increasing morbidity and mortality in older people. Bronchodilators are used widely in patients with these conditions, but even when used in inhaled form can have systemic as well as local effects. Older people experience more adverse drug effects because of pharmacodynamic and pharmacokinetic changes and particularly drug-drug and drug-disease interactions. Cardiovascular disease is common in older people and beta-adrenoceptor agonists (beta-agonists) have inotropic and chronotropic effects that can increase arrhythmias and cardiomyopathy. They can also worsen or induce myocardial ischaemia and cause electrolyte disturbances that contribute to arrhythmias. Tremor is a well known distressing adverse effect of beta-agonist administration. Long-term beta-agonist use can be associated with tolerance, poor disease control, sudden life-threatening exacerbations and asthma-related deaths. Functional beta2-adrenoceptors are present in osteoblasts, and chronic use of beta-agonists has been implicated in osteoporosis. Inhaled anticholinergics are usually well tolerated but may cause dry mouth, which can be troublesome in older people. Pupillary dilatation, blurred vision and acute glaucoma can occur from escape of droplets from loosely fitting nebulizer masks. Although ECG changes have not been seen in randomized controlled trials of long-acting inhaled anticholinergics, supraventricular tachycardias have been observed in a 5-year randomized controlled trial of ipratropium bromide. Paradoxical bronchoconstriction can occur with inhaled anticholinergics as well as with beta-agonists, but tolerance has not been reported with anticholinergics. Anticholinergic drugs also cause central effects, most notably impairment of cognitive function, and these effects have been noted with inhaled agents. Use of theophylline is limited by its adverse effects, which range from commonly occurring gastrointestinal symptoms to palpitations, arrhythmias and reports of myocardial infarction. Seizures have been reported, but are rare. Theophylline is metabolized primarily by the liver, and commonly interacts with other medications. Its concentration in plasma should be monitored closely, especially in older people. Although many clinical trials have been conducted on bronchodilators in obstructive airways disease, the results of these clinical trials need to be interpreted with caution as older people are often under-represented and subjects with co-morbidities actively excluded from these trials.

The use of bronchodilators in the treatment of airway obstruction in elderly patients

Ageing is associated with important anatomical, physiological and psychosocial changes that may have an impact on the management of obstructive airway diseases (asthma and chronic obstructive pulmonary disease (COPD)) and on their optimal therapy. Ageing-related modifications might be responsible for a different effectiveness of bronchodilators in the elderly patients as compared to younger subjects. Furthermore, the physiological involution of organs and the frequent comorbidity, often interfere with pharmacokinetics of bronchodilator drugs used in asthma and COPD. This review will focus on the use of bronchodilators in the elderly, with particular attention to the achievable goals and to rationale, utility and pitfalls in using the inhalation therapy in this age group. beta(2)-agonists, anticholinergics and methylxanthines will be discussed and their side effects in the elderly will be considered.

Phosphodiesterase activity in neutrophils from horses with chronic obstructive pulmonary disease

Neutrophils are recruited to the lungs of horses with chronic obstructive pulmonary disease (COPD) and exhibit increased activity after antigen challenge. Phosphodiesterase type4 (PDE4) inhibitors have been shown to attenuate human neutrophil activation. The aim of this study was to establish the PDE isoenzyme profile of equine neutrophils using isoenzyme selective inhibitors to determine if these compounds should be evaluated in horses with COPD. Total cAMP and cGMP dependent PDE activity was no different in neutrophils from normal (156.2+/-7.1 and 6.8+/-0.6 pmol/min/mg for cAMP and cGMP, respectively) and COPD susceptible horses (146.0+/-10.2 and 5.5+/-0.6 pmol/min/mg for cAMP and cGMP, respectively). The PDE4 inhibitors, CDP840 and rolipram, caused significant, concentration related and almost complete inhibition of PDE activity (IC(50) values=8.8+/-0.1 x 10(-9) and 7.3+/-0.2 x 10(-9)M for CDP840; 1.2+/-0.1 x 10(-6) and 1.1+/-0.1 x 10(-6)M for rolipram in normal and COPD susceptible horses, respectively). The inhibitory effects of the mixed PDE3/ PDE4 inhibitor, zardaverine were of similar magnitude and potency to rolipram. However, the limited inhibitory effects of the PDE3 inhibitor, siguazodan, suggest that zardaverine is acting primarily via PDE4 inhibition. These results indicate that PDE4 is the predominant isoenzyme present in the equine neutrophil and inhibition of PDE activity using selective PDE4 inhibitors may, therefore, modulate equine neutrophil activation in horses with COPD.