Choice of drug treatment in asthma

Inhibition of environmental estrogen-induced proliferation of human breast carcinoma MCF-7 cells by flavonoids

In the present study, we evaluated the individual and combined effects of environmental estrogens and flavonoids on the proliferation of human breast carcinoma MCF-7 cells. These compounds are as follows: (1) pharmaceutical chemicals such as diethylstilbestrol, 17alpha-ethynylestradiol (17ES), tamoxifen, mestranol, and clomiphene, (2) industrial chemicals such as bisphenol A (BisA), 4-octylphenol (OP), 4-nonylphenol (NP), and p,p'-biphenol, and (3) flavonoids such as daidzein (D), genistein (G), quercetin (Q), and luteolin (L). We found that nanomolar concentrations of 17ES, BisA, OP, and NP were sufficient to stimulate the proliferation of MCF-7 cells. Among them, 1 microM BisA exhibited cell proliferation-stimulating activity as strong as 10 nM 17beta-estradiol; and D and G exhibited cell proliferation-stimulating activity at 10 nM. On the other hand, Q and L exhibited cell proliferation-inhibiting activity. We also found that 10 nM flavonoids, such as D, G, Q, and L, were able to inhibit the proliferation-stimulating activity in MCF-7 cells by 1 microM environmental estrogens.

A comparison of regular salmeterol vs 'as required' salbutamol therapy in asthmatic children

In a multicentre, double-blind, randomized, parallel study, 426 asthmatic children aged 5-15 years old received salmeterol 50 micrograms b.i.d. or placebo b.i.d. via the Diskhaler. All patients had access to inhaled salbutamol to be used on an 'as required' (p.r.n.) basis for symptomatic relief. The study design comprised a 2-week baseline, a 12-month treatment period incorporating a 2-week 'off treatment' after 6 months, and a 2-week follow-up period at the end of the trial. At the end of 12 months of treatment with salmeterol, the adjusted change from baseline for morning and evening peak expiratory flow rate (PEF) was 56 and 47 l min-1, respectively, and this was significantly greater than placebo (P < 0.01; P < 0.05). Exacerbation rates did not differ between groups and results were not dependent upon concurrent inhaled steroid use. Neither treatment caused a change of > or = 1 doubling dose in PC20/PD20 either during or on stopping treatment. Treatment with regular salmeterol 50 micrograms b.i.d. over a 12-month treatment period provides a significant, rapid and well-maintained improvement in lung function without increasing bronchial reactivity or asthma exacerbation rates compared to p.r.n. salbutamol.

Pilgrim's progress: the effect of salmeterol in older children with chronic severe asthma

Twenty-four children aged 12-17 years entered a randomized, double-blind placebo-controlled study investigating the use of salmeterol in chronic severe asthma. In addition to their usual medication, the children were given either placebo or 100 micrograms salmeterol b.d. by dry powder inhalation. Treatment was continued throughout one term at a residential school for asthma. Symptom scores, peak expiratory flow rates, spirometry and quality-of-life scores were compared between the two treatment groups. One child withdrew during the run-in period. Twelve pupils received placebo and 11 pupils received salmeterol. There were consistent improvements in favour of salmeterol, reaching statistical significance for morning and evening peak flow rates and spirometry when measured on four occasions during the study period. There were no medication-related adverse events recorded and no pulse rate changes. Salmeterol (100 micrograms b.d.) is well tolerated and efficacious in older children with chronic severe asthma.

Twelve month comparison of salmeterol and salbutamol as dry powder formulations in asthmatic patients. European Study Group

BACKGROUND

Salmeterol is a potent selective beta 2 agonist that has been shown to have a duration of action in excess of 12 hours. In this study salmeterol and salbutamol were compared over a three month period with a further extension of nine months.

METHODS

Three hundred and eighty eight patients with mild to moderate reversible airways obstruction (forced expiratory volume in one second (FEV1) > 50% predicted) were randomised to receive salmeterol (50 micrograms) twice daily or salbutamol (400 micrograms) four times daily, both by dry powder, in a double blind parallel group study. During the first three months detailed assessment of efficacy was made with recording of morning and evening peak expiratory flow rates (PEF), asthma symptoms, and bronchodilator use when necessary for the relief of symptoms. Patients continued in the study for a further nine months with the salbutamol dose reduced to 400 micrograms twice daily. Lung function was measured at the clinic and safety data were collected during this period.

RESULTS

Salmeterol produced a significantly higher mean morning PEF (mean difference compared with salbutamol 21 (95% CI 12-31) l/min), and a significant reduction in mean diurnal variation in PEF (from 30 l/min at baseline to 11 34 l/min at baseline to 32 l/min during salbutamol treatment). Salmeterol also reduced day and night symptoms and use of rescue bronchodilator. FEV1 increased with both salmeterol and salbutamol treatment over the 12 month treatment period. For both treatments the number of patients reporting exacerbations of asthma and the frequency of these exacerbations remained constant during the study. Thirty six patients in the salmeterol and 49 in the salbutamol group withdrew during the 12 months of the study.

CONCLUSIONS

In this study salmeterol (50 micrograms twice daily) was more effective than salbutamol (400 micrograms four times daily) in the control of asthma over three months, and more effective than salbutamol (400 micrograms twice daily) over a further nine months. Neither salmeterol nor salbutamol was associated with any worsening of control of asthma.

Inhaled salmeterol in the treatment of patients with moderate to severe reversible obstructive airways disease--a 3-month comparison of the efficacy and safety of twice-daily salmeterol (100 micrograms) with salmeterol (50 micrograms)

Three-hundred and fifty patients with moderate to severe reversible obstructive airways disease (forced expiratory volume in 1 s or peak expiratory flow rate < or = 50% predicted, a 15% reversibility to inhaled salbutamol and symptomatic) were recruited into a multi-centre, multinational, double-blind, parallel-group randomized study. Two-hundred and eighty-three patients were randomized to receive 50 micrograms salmeterol twice daily or 100 micrograms salmeterol twice daily administered from a metered-dose inhaler for 3 months. Salbutamol (100 micrograms per metered actuation) was provided for symptomatic relief. Morning and evening peak expiratory flow rate (PEFR), day-time and night-time asthma symptoms and additional bronchodilator usage were recorded by the patient on a daily basis. Lung function and patient/physician assessment of treatment efficacy were recorded at scheduled clinic visits. Safety was determined by monitoring adverse events and standard biochemical, haematological and cardiovascular parameters. Salmeterol 100 micrograms twice daily was consistently superior to salmeterol 50 micrograms twice daily in morning and evening PEFR measurements (mean differences between the treatments: 10-14 l min-1 for morning, 95% CI-0, 22 l min-1, P = 0.047; and 10-15 l min-1 for evening, 95% CI 2, 22 l min-1, P = 0.023). The improvement in PEFR was independent of concurrent steroid usage, with the most marked improvement being seen in the more severe asthmatics requiring concurrent oral corticosteroids (mean differences between the treatments: 27-31 l min-1, 95% CI: 3,55 l m-1, P = 0.027).(ABSTRACT TRUNCATED AT 250 WORDS)

Salmeterol, a novel, long-acting beta 2-adrenoceptor agonist: characterization of pharmacological activity in vitro and in vivo

1. Salmeterol, a novel, long-acting beta-adrenoceptor agonist, has been compared with isoprenaline and salbutamol for activity in vitro on a range of beta-adrenoceptor containing preparations from laboratory animals and man, and in vivo for bronchodilator activity in the conscious guinea-pig. 2. Salmeterol, like isoprenaline and salbutamol, relaxed preparations of both guinea-pig trachea (contracted by prostaglandin (PG)F2alpha or electrical stimulation) and human bronchus (contracted by PGF 2 alpha) in a concentration-related fashion. Salmeterol was of similar potency to isoprenaline and more potent than salbutamol on both airway preparations. 3. Relaxant responses of superfused guinea-pig trachea and human bronchus to isoprenaline and salbutamol declined rapidly when the agonists were washed from the tissues, with complete recovery within 10 min, whereas responses to salmeterol were more persistent. In electrically-stimulated guinea-pig trachea preparations, inhibition by salmeterol persisted for periods of up to 12h, despite continuous superfusion with agonist-free medium. However, these persistent responses were rapidly and fully reversed by the beta-adrenoceptor blocking drug, propranolol (0.1 microM). In further studies on guinea-pig trachea, propranolol caused concentration-related parallel, rightward shifts of salmeterol concentration-effect curves, yielding a pA2 of 9.0. The slope of the Schild plot was 1.02. 4. Another beta-adrenoceptor blocking drug, sotalol (10 microM), also fully and rapidly reversed established submaximal responses to salmeterol in superfused guinea-pig trachea. However, after administration of sotalol was stopped, the antagonism waned, and salmeterol responses were reasserted without the addition of further agonist. 5. In the beta 1-adrenoceptor containing preparation, rat left atria, isoprenaline exhibited potent, concentration-related, positive inotropic activity, whereas salbutamol and salmeterol were at least 2000-5000 fold less potent, and appeared to be partial agonists. At a concentration of 72 microM, salmeterol exhibited weak antagonism of isoprenaline-induced increases in atrial force of contraction. This antagonism was less marked than that caused by salbutamol (42 microM).6. On the guinea-pig isolated gastric fundus strip, a putative beta3-adrenoceptor containing preparation, salbutamol and salmeterol had only modest agonist activity, being 20-30 fold less potent than isoprenaline and the selective ,beta3-adrenoceptor agonist, BRL 35135.7. In conscious guinea-pigs, inhaled salmeterol and salbutamol were approximately equipotent in causing dose-related bronchodilatation. Whereas the duration of action of salbutamol at its threshold-effective dose was less than 90min, the responses to a similarly effective dose of salmeterol were well-maintained for at least 6 h.8. Salmeterol is therefore a potent and selective beta2-adrenoceptor agonist with a remarkably long duration of action in isolated superfused airways smooth muscle. It also causes persistent bronchodilatation in vivo, in the guinea-pig, when administered by the inhaled route.