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Aerosol administration of fenoterol hydrobromide (Th 1165a) in subjects with reversible obstructive airway disease.

Bronchodilatory and side effects of fenoterol hydrobromide (Th1165a; hydroxyphenylorciprenaline; Berotec) and isoproterenol given by inhalation were compared in a double-blind crossover study involving 20 volunteer subjects with reversible obstructive disease of the airways. Subjects inhaled medications from aerosol canisters containing fenoterol hydrobromide (0.1 mg, 0.2 mg, or 0.4 mg) or isoproterenol (0.15 mg) or an inert placebo propellant in a random sequence of five testing days. All active drugs substantially increased the forced expiratory volume in one second, the mean forced expiratory flow during the middle half of the forced vital capacity, and the specific conductance. The onset of bronchodilation after both fenoterol and isoproterenol was rapid, but the effect from fenoterol lasted much longer, up to eight hours. None of the medications cuased significant tachycardia or hypertension. After inhalation of 0.1 mg of fenoterol hydrobromide, none of the subjects reported nervousness, headache, tremor, or nausea, incontrast with results reported for isoproterenol, higher aerosol doses fo fenoterol, or oral administration of fenoterol. No additional therapeutic benefit was found in the administration of higher doses of fenoterol.

Adolescent

Aerosol fenoterol by intermittent positive pressure breathing in asthmatic patients.

Ten subjects with mild to moderately severe asthma participated in a study of the bronchodilator activity and incidence of side effects of fenoterol aerosol administered by intermittent positive pressure breathing (IPPB). The doses of fenoterol used in the Bird micronebulizer were 0, 0.25 mg, 0.5 mg, 1.0 mg, and 2.5 mg, and these were administered in a randomized, double-blind fashion. The bronchodilator response, assessed by the area under the FEV1 curve, showed mean (+/- SE) values of 1.44 +/- 0.53 1 hr for 0.25 mg of fenoterol to 1.66 +/- 0.56 1 hr for 2.5 mg of fenoterol (p greater than 0.05), longer (p less than 0.01) than the mean placebo response of 0.06 +/- 0.38 1 hr. A dose-dependent increase in tremor was observed for each of the doses of fenoterol. The 0.25-mg dose of fenoterol solution is an appropriate starting dose for the treatment of moderately severe asthma.

Adult

Evidence that the efficacy (intrinsic activity) of fenoterol is higher than that of salbutamol on beta-adrenoceptors in guinea-pig trachea.

The functional antagonism of carbachol by fenoterol and salbutamol (beta-adrenoceptor agonists) has been used to demonstrate that the efficacy (intrinsic activity) of fenoterol was about twice that of salbutamol on guinea-pig trachea. The mean maximum shifts of the carbachol concentration--response lines by fenoterol and salbutamol were (log units) 1.07 +/- 0.07 (n = 5) and 0.64 +/- 0.07 (n = 5) respectively. This difference in their efficacies could be demonstrated as differences in maximum relaxation on tracheal preparations contracted with carbachol, although this was dependent on the concentration of carbachol used. beta-Adrenoceptor blocking properties of salbutamol (1 mM) but not fenoterol (1 mM) could be demonstrated on trachea in that salbutamol, but not fenoterol, antagonised the shift in the carbachol concentration--response line produced by isoprenaline. The implications of these findings in relation to the use of fenoterol and salbutamol as bronchodilators is discussed.

Adrenergic beta-Antagonists

Comparison of the bronchodilator effects of aerosol fenoterol and isoproterenol.

Aerosolized fenoterol in a dosage of 400 microgram was compared to isoproterenol 150 microgram in 31 asthmatic subjects during the course of a double-blind parallel 90-day study. Bronchodilator activities of the two drugs were evaluated for up to 6 hours on days 1, 45 and 90. Analysis of the data revealed that fenoterol consistently produced a significantly greater increase in FEV1, FEF25-75% and Gaw/VL. Specific airway conductance increased on each test day 25 percent or more above baseline for over three hours after use of fenoterol and for only one hour after use of isoproterenol. Fenoterol has less effect upon the cardiovascular and central nervous systems, but produced a greater incidence of shaking compared to isoproterenol. Patients used fenoterol less frequently than isoproterenol which can be attributed to the former having a greater peak effect and time course of bronchodilation. The therapeutic efficacy of fenoterol was sustained throughout this three-month study, and suggests that this relatively selective beta2 adrenergic drug will provide a well tolerated, alternative aerosol for chronic use in asthma.

Adult

Fenoterol: a review of its pharmacological properties and therapeutic efficacy in asthma.

Fenoterol, the 4-hydroxyphenyl derivative of orciprenaline, is a resorcinol derivative with relatively high selectivity for beta2-adrenoceptors. It is active in man after inhalation or oral administration and is indicated in the treatment of bronchospasm associated with asthma, bronchitis and other obstructive airway diseases. Clinical experience has shown that fenoterol is an effective bronchodilator with negligible effects on the cardiovascular system following aerosol administration of usual therapeutic doses. In children, inhaled fenoterol is effective in preventing exercise-induced asthma and administration of the aerosol in young children has been successfully used to terminate acute asthma attacks. In trials in adults, inhaled fenoterol was superior to placebo. In other controlled studies, it showed a tendency to cause a slightly greater maximum improvement in airway function as assessed spirometrically, and to have a longer duration of action than inhaled orciprenaline, salbutamol or terbutaline, although in these trials statistically significant differences were often not found. The onset of maximum effect is less rapid than with isoprenaline but is longer lasting. About 60% of the eventual maximum response to fenoterol is reached in the first few minutes after inhalation. Oral fenoterol is more effective than placebo, ephedrine or orciprenaline, and probably similar to salbutamol and terbutaline. Following usual aerosol doses, side-effects are minimal. Oral administration is associated with a higher incidence of side-effects than inhalation, including fine muscle tremor and tachycardia.

Adolescent

Response of asthmatic patients to fenoterol inhalation: a method of quantifying the airway bronchodilator dose.

A radiotracer technique is described which enables direct measurement of the dose and distribution of inhaled aerosol bronchodilator in man. The mean (+/-SD) amounts of the B2-adrenergic agonist, fenoterol, administered to a group of 12 asthmatic subjects in a double-blind randomized fashion were: placebo, 0 microgram; low dose, 5.6 (+/-1.2) microgram; medium dose, 32.7 (+/-7.3) microgram; and high dose, 127.5 (+/-29.2) microgram, with a mean of 86.3% of the total subject dose being deposited in the lungs. The medium and high doses of fenoterol produced similar increases above baseline in forced expired volume in 1 sec (FEV1), maximum flow at 50% of vital capacity (V max 50), and maximum flow at 25% of vital capacity (V max 25). These increases were greater than those with placebo for the entire 4-hr study (p less than 0.01). The low dose of fenoterol was more effective than placebo in increasing FEV1, V max 50, and V max 25 above baseline values (p less than 0.05), but not for the entire 4-hr study. The high-dose fenoterol caused palpitations and tremor in 3 of the 12 subjects, and the medium-dose fenoterol caused palpitations in one of these subjects.

Adult

Comparison of four weeks' treatment with fenoterol and terbutaline aerosols in adult asthmatics. A double-blind crossover study.

Fenoterol and terbutaline, two long-acting beta 2-adrenoceptor agonists in aerosol form, were compared in an 8-wk randomized double-blind crossover study in 22 mild to moderately severe asthmatics. Patients completed diary cards, recorded peak expiratory flow rate (PEFR) twice daily, and attended a clinic for measurement of PEFR, 1-sec forced expiratory volume (FEV1), and forced vital capacity (FVC) twice during each treatment period. Fifteen patients completed the study; 5 dropped out while using fenoterol, and 2 while using terbutaline. At clinic attendances, the patients had a significantly higher mean PEFR after 4 wk on terbutaline (385 L/min) than after fenoterol (316 L/min) (p less than 0.001). Similar results were found on analysis of the morning and evening PEFR recordings. On comparing each individual's PEFR recordings during the 2 treatments, it was found that there was no significant difference among the treatments in 3 patients, while 9 patients had a better response to terbutaline, and 3 patients had a better response to fenoterol. While similar number expressed a subjective preference for each treatment, the lung function data suggested that the effectiveness of fenoterol appeared to decline during the trial period.

Adult

Comparison of the bronchodilator effects of oral therapy with fenoterol hydrobromide and ephedrine.

Fenoterol hydrobromide (Berotec; formerly Th 1165a) is a sympathomimetic bronchodilator drug. Twenty subjects with mild to moderate reversible bronchospasm completed a double-blind multiple crossover study of single doses of 5 mg, 7.5 mg, and 10 mg of fenoterol hydrobromide, 24 mg of ephedrine, and placebo. Spirometric and body-plethysmographic measurements were performed sequentially prior to administration of drug or placebo and each hour up to eight hours afterwards. No significant drug-response relationship was noted for pulse rate or blood pressures, and side effects (eg, shakiness, nervousness) were minimal. Administration of fenoterol resulted in bronchodilation; a peak effect was noted at two to three hours after administration, and the duration of action was up to eight hours. A statistically significant dose-response relationship was observed; therapy with 5 mg of fenoterol hydrobromide was superior to placebo and equal to ephedrine, and doses of 7.5 mg and 10 mg of fenoterol hydrobromide were significantly better than placebo or ephedrine.

Administration, Oral

Carbuterol, fenoterol, orciprenaline, salbutamol and terbutaline per os in reversible obstructive chronic bronchitis.

The effects of tablets of carbuterol, orciprenaline, salbutemol, terbutaline and fenoterol at two dosages were studied using FEV1 and specific airway conductance as parameters. A placebo was used as a reference. Carbuterol and fenoterol proved to be more potent than the other sympathomimetic competitors. Fenoterol 5 mg was on the average somewhat less potent than 3 mg carbuterol. This differnce was not statistically significant for FEV1; it was significant three hours after intake for airway conductance. None of the drugs produced significant changes of the blood pressure. Carbuterol and 12 mg fenoterol caused a statistically significant increase in heart rate. ECG changes were observed in eight patients with the different beta-sympathomimetics, with the exception of 5 mg fenoterol.

Administration, Oral

[Influence of fenoterol of cAMP levels and motility on the rat uterus in vitro (author's transl)].

CAMP levels of isolated rat uteri (2nmol/g wwt) were increased by Fenoterol (10(-4)--1 mug/ml) in a dose dependent manner reaching concentrations of more than 10nmol/g withing 2--5 min. AT 2 TIMES 10(-3) MUG/ML Fenoterol inhibited spontaneous contractions of the rat uterus in vitro. A 10,000 fold higher dosis of Fenoterol was needed to elicit a similar degree of inhibition, when contractions were induced by 0.6 mU/ml Oxytocin. However cAMP levels were elevated by Fenoterol in presence of Oxytocin, uterine contractions were not inhibited, i.e. the elevation of cAMP after administration of Fenoterol is correlated with a relaxant effect only in uteri contracting spontaneously.

Animals

Comparison of the bronchodilating action and of the tolerance of fenoterol and isoproterenol aerosols.

Fenoterol aerosol (400 micrograms) and isoproterenol aerosol (200 micrograms) were compared in a double blind cross-over trial in 59 patients with reversible broncho-obstruction. Measurements of VC, FEV1, respiratory impedance (ZR), blood pressure and pulse rate as records of subjective symptoms, râles and side effects, were made over a period of 180 minutes. After fenoterol FEV1 increased significantly from the 15th minute till the first hour. After isoproterenol an increase of this parameter was obtained only at the 15th minute. The decrease in ZR was always larger with fenoterol than with isoproterenol. This difference was significant at the 2nd hour (P < .05) and at the 3rd hour (P < .01). In a group with severe obstruction the airway obstruction improved more with fenoterol than with isoproterenol (P < .01). The functional improvement induced by 400 micrograms fenoterol appeared to be more potent and of longer duration than the improvement caused by 200 micrograms isoproterenol. Moreover it appeared more rapidly after administration.

Adolescent

Effect of fenoterol and isoxsuprine on myometrial and intervillous blood flow during late pregnancy.

The use of beta-adrenergic agonists in high-risk pregnancies has shown evidence of favorable effects on the fetus. Intravenous injections of 133Xe were given to evaluate the effects of short-term administration of fenoterol (3 microgram/min) and isoxsuprine (150 migrogram/min) on the intervillous and myometrial blood flow in a series of 48 women during the last trimester of pregnancy. Both fenoterol and isoxsuprine treatment increased the maternal heart rate significantly. There was a significant rise in myometrial blood flow when fenoterol was given, but the intervillous blood flow did not change significantly during the administration of either isoxsuprine or fenoterol. Previous oral isoxsuprine treatment did not diminish the cardiac effect of intravenous fenoterol, but the improvement in myometrial blood flow was eliminated. This result indicates that beta-adrenergic agonists may have a specific dilatational effect on the myometrial blood vessels. From the hemodynamic point of view, the beta-adrenergic agonists have a limited value in the treatment of chronic fetal asphyxia or intrauterine fetal growth retardation.

Ethanolamines

Actions of the uterine relaxant, fenoterol, on uteroplacental hemodynamics in human subjects.

The action of fenoterol, a uterine relaxant of the adrenergic beta-mimetic group of drugs, has been investigated on placental, myometrial, and cardiac blood pools. 113mIndium was injected intravenously and the blood pools were measured by recording gamma activity externally. In eight cases with oxytocin-induced labor, fenoterol inhibited the typical blood pool changes of labor, i.e., contraction-synchronized decrease of placental and myometrial blood pools with increase in cardiac blood pool. Furthermore, fenoterol produced an increase in placental and myometrial pools with corresponding decrease of cardiac blood pool. These changes were observed consistently. In four other cases, of which three had spontaneous labor, similar effects were observed. The possible mechanisms of hemodynamic action of fenoterol, with reference to uterine relaxation, are discussed.

Adult

Effect of fenoterol (Th1165a) infusion on uterine and umbilical blood flow in pregnant sheep.

The effect of fenoterol (Th1165a) upon uterine artery blood flow (UtBF) and umbilical vein blood flow (UmBF) was investigated in near-term, nonlaboring chronic sheep preparations. During intravenous fenoterol infusions to the ewe in either incremental doses from 0.025 to 0.200 microng per kilogram per minute or constant infusions of 0.025 microng per kilogram per minute for 120 minutes. UtBF and UmBF did not change significantly. Dose-related maternal tachycardia, hyperglycemia, and relative acidemia occurred, but there were no significant changes in mean maternal and fetal arterial pressures or fetal heart rate. The simultaneous infusion of propranolol (2 microng per kilogram per minute) with fenoterol (0.200 microng per kilogram per minute) blocked the maternal tachycardia but resulted in a significant decrease in UmBF and a significant increase in UtBF. In all of the maternal infusions. UtBF significantly rose and plateaued up to 14 per cent above the control level during the 120 minute recovery period after infusion. A non-beta-adrenergic effect of fenoterol is suggested as the cause of this UtBF increase.

Animals

Clinical comparison of fenoterol and albuterol administered by inhalation. A double-blind study.

The effects of inhaling 0.4 mg of fenoterol hydrobromide (Berotec), 0.2 mg of albuterol (salbutamol), or placebo were compared in a double-blind three-way crossover study in a group of 12 asthmatic patients. After inhalation of fenoterol, the maximum increase in the forced expiratory volume in the first second (FEV1) was 0.76 L (48 percent) and in the peak expiratory flow (PEF) was 100 L/min (47 percent). The corresponding figures after inhalation of albuterol were 0.68 L (46 percent) and 98 L/min (48 percent), respectively. In comparison with administration of placebo, the FEV1 was significantly increased until six hours after inhalation of either drug. From three to six hours after inhalation, the effect of administration of fenoterol (as measured by FEV1 or PEF) significantly exceeded that of albuterol. Administration of either drug resulted in approximately equal bronchodilation (as measured by the increase in FEV1 or PEF), the effect of inhalation of fenoterol being of longer duration.

Adolescent

The bronchodilator effect of fenoterol (Berotec).

The efficacy of the selective beta 2 sympathomimetic fenoterol (Berotec) in aerosol and tablet forms was studied in 15 subjects with reversible airways obstruction. The maximal bronchodilator effect of fenoterol by aerosol (0.4mg) was found to equal that of isoprenaline, and to be maintained at that level over the three hour period studied. When given orally, neither one tablet (2.5 mg) nor two tablets (5 mg) of fenoterol increased the FEV1 to the same extent as isoprenaline, and the larger oral dose (5 mg) produced troublesome side effects in several subjects. It is concluded that fenoterol by aerosol is an effective bronchodilator with a duration of action of at least three hours, without significant side effects.

Adolescent

[Cardiovascular action, placental passage, pharmakokinetics and metabolism of fenoterol in pregnant guinea pigs (authors transl)].

Cardiovascular action, placental passage and metabolism of fenoterol was studied in pregnant guinea pigs following either a single intravenous injection of 4.5 mug/kg or an infusion of 0.45 mug/kg per min. for 1 hour. After a single injection maternal heart rate increased from 212 to 248 beats/min. within the first minute retruning to basal levels after 35 min. Blood pressure decreased from 70 to 63 mm Hg within 6 min. Fetal heart rate remained unchanged during the first 15 min. but decreased lateron. Fenoterol was rapidly eliminated (t 1/2 = 36 min.) and metabolished. Metabolism consisted of a fast (t 1/2 =2,5 min.) and a slow (t 1/2 = 58 min.) component. Little radioactivity was found in fetal plasma following a single injection. Infusion of 0.45 mug/kg min. for 1 hour increased maternal heart rate from 208 to 234 beats/min. and decreased maternal blood pressure from 76 to 66 mg Hg within the first 10 min. Fetal heart rate remained unchanged for the first 15 min., but decreased from 249 to 219 beats/min. the second 15 min. Little radioactivity was found in fetal plasma also following infusion. Only 2 to 6 percent of the radioactivity (0.0lng/ml) were identified as unchanged fenoterol. The low lipophilic property of fenoterol may be responsible for the low permeability of the placental barrier.

Animals

[Acute bronchodilator effect of chinoxaline, prednisolone, ipratropium bromide and fenoterol tested by whole-body plethysmography (author's transl)].

The acute bronchodilator effect of chinoxaline, prednisolone and ipratropium bromide was tested by whole-body plethysmography in 18 patients with chronic obstructive airway disease over a period of 60 min. The subsequent administration of fenoterol by a metered dose inhaler demonstrated the possibility of further bronchodilation. Chinoxaline (80 mg i.v.) was followed by a statistically-significant decrease in airway resistance to 82.66% of the baseline value after 5 min. (maximum reduction) and to 87.11% after 60 min.; fenoterol (0.4 mg = 2 puffs) caused a further marked decrease to 49.61% after 20 min. Prednisolone (250 mg i.v.) did not produce statistically-significant acute bronchodilation. Airway resistance decreased to a minimum level of 89.16% after 20 min. and to 90.77% after 60 min.; however, following fenoterol (0.4 mg = 2 puffs) the airway resistance was reduced to 45.72%. Ipratropium bromide inhalation (0.08 mg = 4 puffs) resulted in the greatest bronchodilatory response, with a statistically-significant effect from the 5th to the 60th min. Airway resistance was 64.66% after 5 min., 63.22% after 10 min., 58.94% after 20 min., 57.72% after 30 min. and 51.22% after 60 min. (maximum reduction); fenoterol (0.4 mg = 2 puffs) caused only a slight further decrease to 48.32%.

Adult