Salmeterol: a potent and long-acting inhibitor of inflammatory mediator release from human lung

1. The effects of salmeterol, a novel long-acting beta 2-adrenoceptor agonist, have been investigated on antigen-induced mediator release from passively sensitized fragments of human lung in vitro. 2. Salmeterol was a potent inhibitor of the release of histamine (-log IC50 = 8.54), leukotriene C4 (LTC4)/LTD4 (-log IC50 = 9.07) and prostaglandin D2 (-log IC50 = 8.81). It was slightly less potent (1-3 fold) than isoprenaline, but significantly more potent (10-35 fold) than salbutamol. 3. Propranolol competitively antagonized the inhibitory effects of salmeterol on histamine release (pA2 = 8.41) and LTC4/LTD4 release, (pA2 = 8.40) indicating an action via beta-adrenoceptors. 4. The inhibitory effects of isoprenaline (20 nM) and salbutamol (200 nM) were removed after washing the lung tissue for 2 h and 4 h respectively. In contrast, the inhibitory effects of salmeterol (40 nM) were much longer-lasting, and were still evident after 20 h. 5. Salmeterol therefore exhibits potent and persistent inhibition of anaphylactic mediator release from human lung. This anti-inflammatory effect may be important for the therapeutic potential of salmeterol in the treatment of bronchial asthma.

Interactions of flerobuterol, an antidepressant drug candidate, with beta adrenoceptors in the rat brain

Interactions of dl-flerobuterol with central beta adrenoceptors were investigated. It inhibited the binding of [3H]CGP 12177, a selective beta adrenoceptor ligand, to membranes prepared from rat cerebral cortex, cerebellum, heart and lung. The affinity of dl-flerobuterol was very close in all tissues (Ki approximately 1 microM). In cerebral cortex, binding inhibition of [3H]CGP 12177 was stereospecific, l-flerobuterol (Ki = 483 nM) being 70-fold more potent than d-flerobuterol (Ki = 34 microM). Moreover, dl-flerobuterol (Ki = 926 nM) was 7-fold less potent than isoproterenol (Ki = 140 nM) to displace [3H]CGP 12177 binding, but 5-fold more potent than salbutamol (Ki = 4600 nM). Flerobuterol did not inhibit the radioligand binding to the other receptors at the highest concentration tested, thus leading to a very high beta adrenergic selectivity. Flerobuterol increased the concentration of cyclic AMP in slices of rat cerebral cortex in a dose-dependent manner; this effect was antagonized by atenolol and propranolol. Compared to isoproterenol or norepinephrine, which produced cyclic AMP maximal increases of 380 and 460%, respectively, it showed a weaker activity with a maximal stimulation obtained at 100 microM, corresponding to a cAMP increase of 140% over basal value (100%). These data revealed that flerobuterol possessed a beta adrenergic agonist activity. Moreover, it antagonized competitively the isoproterenol- or norepinephrine-stimulated accumulation of cAMP. At low concentrations of isoproterenol or norepinephrine, the stimulation of adenylate cyclase was only due to the action of flerobuterol, but at higher concentrations, the response of isoproterenol or norepinephrine was competitively blocked by flerobuterol. At 10 microM, isoproterenol surmounted fully this antagonism.(ABSTRACT TRUNCATED AT 250 WORDS)

A single-dose comparison of inhaled albuterol and two formulations of salmeterol on airway reactivity in asthmatic subjects

Salmeterol is a new beta 2-selective agonist with a long duration of action. We compared the effect of 50 micrograms salmeterol administered by metered dose inhaler (MDI) and dry powder inhaler (DPI), with 200 micrograms albuterol (by MDI) on FEV1 and histamine-induced bronchoconstriction in 12 asthmatic subjects in a double-blind, placebo-controlled crossover study. Subjects were studied for 12 h on four occasions with a histamine challenge test at 1, 4, 8, and 12 h, the response being measured as the dose of histamine causing a 20% fall in FEV1 (PD20). There was no difference in the mean +/- standard error of the mean maximum increase in FEV1 between salmeterol MDI, salmeterol DPI, or albuterol (0.57 +/- 0.078, 0.54 +/- 0.089, and 0.49 +/- 0.081 L, respectively); the increase following placebo was 0.25 +/- 0.082 L. The area under the 12-h time-response curve for FEV1 was greater for both formulations of salmeterol (MDI and DPI) than for albuterol. The three active drugs protected against histamine-induced bronchoconstriction. The increase in PD20 at 1 and 12 h and the area under the 12-h time-response curve for PD20 were greater following both formulations of salmeterol than after albuterol. The greater change in geometric mean PD20 values at 1 h after both formulations of salmeterol (2.21 and 1.88 mumol) relative to albuterol (0.98 mumol) suggests that despite similar effects on FEV1 the doses used do not have an equivalent effect on the airways.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacological action of SN-408, a novel long-acting selective beta 2-adrenoceptor agonist]

The bronchodilating effect and other related pharmacological properties of SN-408 were studied in comparison with those of isoproterenol, salbutamol and procaterol. SN-408 caused concentration-dependent relaxation of isolated guinea pig trachea via the beta 2-adrenoceptor. The order of relaxation potency was: procaterol greater than SN-408 greater than or equal to isoproterenol greater than salbutamol, but the duration of the action of SN-408 was far longer than those of other beta-agonists. Positive chronotropic and inotropic actions of SN-408 in isolated guinea pig right atria and left atria were less potent than those of other beta-agonists. In isolated guinea pig lung tissues, SN-408 increased cyclic AMP contents. Also in vivo, SN-408 showed dose-dependent bronchodilating action by i.v. administration in anesthetized guinea pigs and by inhalation in conscious guinea pigs. Bronchodilating actions of SN-408 were less potent than those of procaterol and isoproterenol, but the duration of action of SN-408 was far longer than those of other beta-agonists. SN-408 showed no evidence of the development of tolerance to the bronchodilating action. SN-408 caused small tachycardia in guinea pigs by i.v. and inhalation. SN-408 given i.v. suppressed vascular permeability in mice. These results indicate that SN-408 is a long-acting and selective beta 2-stimulant bronchodilator.

Effect of SN-408 (salmeterol hydroxynaphthoate) on passive cutaneous anaphylaxis and anaphylactic chemical mediator release in rats and guinea pigs

The influence of SN-408 (salmeterol hydroxynaphthoate), a new selective beta 2-stimulant, on homologous passive cutaneous anaphylaxis (PCA), histamine- or serotonin-induced skin reaction and anaphylactic chemical mediator release was investigated in rats and guinea pigs, and its efficacy was compared with that of salbutamol, isoproterenol or disodium cromoglycate (DSCG). Intravenous administration of SN-408 (0.1-10 micrograms/kg) 1 min before, the antigen challenge dose-dependently inhibited rat homologous PCA to a similar extent to salbutamol. The inhibitory effect of these beta-agonists was quickly attenuated along with time between the administration of the drug and the antigen challenge. SN-408, however, still showed significant inhibition at the time of administration 5 min before the antigen challenge at which other agonists did not significantly affect any more. Ten micrograms/kg of SN-408 exhibited approximately 50% inhibition of skin reaction induced by either histamine or serotonin in rats. In addition, the compound represented concentration-dependent inhibition of the anaphylactic histamine release from the isolated rat peritoneal exudate cell, indicating that the inhibitory effect of SN-408 on rat homologous PCA is due to the suppression of mediator release in addition to the antagonism to mediator(s) released. The anaphylactic release of either histamine, immunoreactive (i-) leukotriene (LT)B4 or i-LTC4 from guinea pig lung fragments was concentration-dependently inhibited by 10(-10)-10(-7) g/ml SN-408, and the inhibitory potency appeared to be enhanced by prolongation of the pretreatment interval with the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

The 1990 Lilly Prize Lecture. A way of looking at agonism and antagonism: lessons from salbutamol, salmeterol and other beta-adrenoceptor agonists

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Long-acting beta 2-adrenoceptor agonists: a new perspective in the treatment of asthma

New long-acting beta 2-adrenoceptor agonists, formoterol and salmeterol, may soon appear in several European countries for treatment of asthma. This review examines currently available information and compares the basic pharmacology and describes the clinical effects of these new drugs. The long duration of bronchodilation seen in clinical studies seems to be similar, whereas in isolated tissues there might be a difference in the binding characteristics to the beta 2-adrenoceptor. Long-acting beta 2-agonists could have an inhibitory effect on inflammatory events related to asthma, but the clinical relevance of these effects is not clear at present. Long-term studies up to one year with both new drugs have not shown any unexpected side-effects, and no tachyphylaxis to beta-adrenoceptor stimulation has been reported. Patients appear to strongly prefer the new drugs compared to the short-acting beta 2-agonists. The potential place for these drugs in the treatment of asthma is discussed and some pitfalls pointed out. It is likely that the long-acting beta 2-agonists will be beneficial to many asthmatic patients.

Salmeterol in nocturnal asthma: a double blind, placebo controlled trial of a long acting inhaled beta 2 agonist

OBJECTIVE

To determine whether inhaled salmeterol, a new long acting inhaled beta adrenergic agonist, reduces nocturnal bronchoconstriction and improves sleep quality in patients with nocturnal asthma.

DESIGN

Randomised, double blind, placebo controlled crossover study.

SETTING

Hospital outpatient clinics in Edinburgh.

SUBJECTS

Twenty clinically stable patients (13 women, seven men) with nocturnal asthma, median age 39 (range 18-60) years.

INTERVENTIONS

Salmeterol 50 micrograms and 100 micrograms and placebo taken each morning and evening by metered dose inhaler. Rescue salbutamol inhalers were provided throughout the run in and study periods.

MAIN OUTCOME MEASURES

Improvement in nocturnal asthma as measured by peak expiratory flow rates and change in sleep quality as measured by electroencephalography.

RESULTS

Salmeterol improved the lowest overnight peak flow rate at both 50 micrograms (difference in median values (95% confidence interval for difference in medians) 69 (18 to 88) l/min) and 100 micrograms (72 (23 to 61) l/min) doses twice daily. While taking salmeterol 50 micrograms twice daily patients had an objective improvement in sleep quality, spending less time awake or in light sleep (-9 (-4 to -44) min) and more time in stage 4 sleep (26 (6-34) min).

CONCLUSIONS

Salmeterol is an effective long acting inhaled bronchodilator for patients with nocturnal asthma and at a dose of 50 micrograms twice daily improves objective sleep quality.

Protection against allergen-induced asthma by salmeterol

The effects of the long-acting beta 2-agonist salmeterol on early and late phase airways events provoked by inhaled allergen were assessed in a group of atopic asthmatic patients. In a placebo-controlled study, salmeterol 50 micrograms inhaled before allergen challenge ablated both the early and late phase of allergen-induced bronchoconstriction over a 34 h time period. Salmeterol also completely inhibited the allergen-induced rise in non-specific bronchial responsiveness over the same time period. These effects were shown to be unrelated to prolonged bronchodilatation or functional antagonism. These data suggest novel actions for topically active long-acting beta 2-agonists in asthma that extend beyond their protective action on airways smooth muscle.

Liquid chromatographic methods for the determination of albuterol (salbutamol), albuterol sulphate and related compounds in drug raw materials, tablets and inhalers

Liquid chromatographic methods for the determination of albuterol (salbutamol), albuterol sulphate and related compounds in drug raw materials, tablets and inhalers are described. The methods resolve five known related compounds from the drug and, in the case of inhalers, several compounds not related to the drug. Two of these were identified as 2,6-di-t-butyl-4-methylphenol, a common antioxidant, and 2,2'-methylene bis(6-t-butyl-4-methylphenol). Related compounds are detectable at levels of about 0.03%. Eleven albuterol and 12 albuterol sulphate raw materials and eight tablet formulations were found to contain related compounds ranging from 0.03 to 0.54%, 0.09 to 0.50% and 0.32 to 0.95%, respectively. Non-drug compounds in three inhaler samples ranged from 4.6 to 12% of the drug delivered through the valve. Some of the non-drug compounds may be excipients.

Salmeterol, a new long acting inhaled beta 2 adrenoceptor agonist: comparison with salbutamol in adult asthmatic patients

Salmeterol is a new inhaled beta 2 adrenoceptor agonist, which has been shown in animal experiments to produce a more prolonged bronchodilator effect than currently available beta 2 adrenoceptor agonists. It was studied in eight adult asthmatic patients. Each patient received on separate test days salbutamol 200 micrograms and salmeterol 50, 100, and 200 micrograms according to a randomised, double blind, crossover design. FEV1, peak expiratory flow (PEF), heart rate, blood pressure, and tremor were recorded in the clinic for six hours after drug inhalation; PEF was recorded for a further six hours at home. All three doses of salmeterol produced peak increases in FEV1 (mean 0.5-0.8 l) and PEF (71-100 l/min) similar to those produced by salbutamol 200 micrograms (0.5 l and 74 l/min). After salbutamol FEV1 and PEF had returned to baseline within six hours, but after all three doses of salmeterol more than half of the maximum bronchodilator effect remained after 12 hours. The effects of salbutamol and the two lower doses of salmeterol (50 and 100 micrograms) on cardiovascular measurements and on tremor were similar, whereas after salmeterol 200 micrograms there was a small decrease in diastolic blood pressure and an increase in heart rate and tremor. Thus inhaled salmeterol has a long acting bronchodilator action in asthmatic patients. This effect may be of value in the treatment of asthma, particularly in patients with nocturnal symptoms.