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PubMedDate not supplied

Isolation and characterization of metaproterenol-3-O-sulfate: a conjugate of metaproterenol in human urine.

Metaproterenol (1-(3,5-dihydroxyphenyl)-2-isopropylaminoethanol) is primarily converted in humans to metaproterenol-3-O-sulfate following oral administration. Ion exchange column chromatography with a gradient of ammonium acetate buffer permitted the isolation of the ammonium salt of metaproterenol-3-O-sulfate from human urine. Treatment of aliquots of the column eluate with purified sulfatase and subsequent HPLC/fluorescence analysis confirmed the presence of metaproterenol. Comparison of the column eluate with a metaproterenol standard by 250-MHz proton-NMR revealed a pattern consistent with monosubstitution of the resorcinol ring. Negative and positive ion fast atom bombardment/mass spectrometry showed the metabolite to have a (M-H)- m/z of 290 and a (M + H)+ m/z ion of 292. These three methods support the structural assignment of metaproterenol-3-O-sulfate. Enzymatic hydrolysis of urine specimens from 29 different subjects with purified beta-glucuronidase as well as beta-glucuronidase-sulfatase mixtures yielded no significant increase in metaproterenol beyond purified sulfatase-treated urine, thus ruling out the presence of a glucuronide of metaproterenol. Approximately 40% of an oral 20-mg dose, given as either a tablet or a solution, was recovered in the urine as metaproterenol-3-O-sulfate. Approximately 5% of the dose was recovered in the unconjugated form. The majority of the dose was excreted over the first 12 hr with a biological half-life of 5-6 hr followed by a slower excretion phase with a half-life of 20 hr.

Chromatography, High Pressure Liquid↗
PubMed1985

Comparison of metaproterenol, isoetharine and salbutamol in the relief of methacholine-induced bronchospasm in dogs.

We evaluated cardiovascular effects and effectiveness of isoetharine, metaproterenol and salbutamol, when administered intratracheally to relieve methacholine-induced bronchospasm in dogs anaesthetized with 50 per cent nitrous oxide, oxygen, halothane and mechanically ventilated. Methacholine 2 micrograms X kg-1 X hour-1 was administrated first followed by halothane (1 MAC) for 30 minutes (control), then metaproterenol, isoetharine or salbutamol. Metaproterenol (15 mg) significantly decreased transpulmonary pressure to 20.1 +/- 0.5 (SE) from 22.5 +/- 1.15 cmH2O (p less than 0.025) after three min and to 15 +/- 0.5 cmH2O (p less than 0.005) after 90 min. Isoetharine (2.5 mg) decreased transpulmonary pressure after five min to 22.1 +/- 1 from 24.5 +/- 1.5 cmH2O (p less than 0.05), and to 21.75 +/- 0.55 mmH2O after 90 min. Salbutamol 25 micrograms X kg-1 decreased transpulmonary pressure to 20.7 +/- 0.75 from 24.25 +/- 1.28 after three min and to 16 +/- .5 after 90 min. The peak effects on airway pressure occurred at 15 min for metaproterenol, 25 min for salbutamol and 20 min for isoetharine. Pulmonary vascular resistance was not significantly changed during halothane anaesthesia alone but decreased significantly after metaproterenol and isoetharine infusion. Heart rate increased ten per cent after metaproterenol, three per cent after isoetharine, and five per cent after salbutamol. No arrhythmias occurred in any group. Cardiac output increased significantly to 3.25 +/- 0.2 from 1.5 +/- 0.17 L X min-1 (p less than 0.025) after metaproterenol to 3.2 +/- .025 from 1.45 +/- .009 after salbutamol and was unchanged after isoetharine. Metaproterenol and salbutamol in the presence of 1 MAC halothane anaesthesia relieved methacholine-induced bronchospasm more rapidly than did isoetharine. The onset of effect was 3 +/- 0.05 min for metaproterenol and salbutamol and 5 +/- 0.01 min for isoetharine. The effect lasted 210 +/- 10.5 min for metaproterenol, 170 +/- 12.5 min for salbutamol and 90 +/- 4.75 min for isoetharine.

Airway Resistance↗
PubMed1996

Metaproterenol responsiveness after methacholine- and histamine-induced bronchoconstriction.

We investigated whether the bronchodilator response to a beta-adrenergic agonist is influenced by the mechanism of induced bronchoconstriction. Normal subjects and asymptomatic asthmatics inhaled a dry aerosol (mass median aerodynamic diameter, 1.5 microns) with increasing concentrations of methacholine or histamine to produce a 35% decrease in specific airway conductance (SGaw), followed by a single inhalation of a metaproterenol aerosol. By studying normal subjects and asthmatics, we were able to compare metaproterenol responsiveness after widely divergent doses of the bronchoprovocative agents but the same degree of bronchoconstriction. Airway deposition of methacholine, histamine, and metaproterenol was measured using a quinine fluorescence technique. Mean baseline SGaw, metaproterenol responsiveness, and metaproterenol mass deposited were similar in normal subjects and asthmatics. Likewise, mean SGaw after completion of methacholine and histamine challenge, and the subsequently deposited metaproterenol mass were similar in the two groups. After methacholine challenge (mean +/- SD provocative drug mass causing a 35% decrease in SGaw, PM35: 8.94 +/- 5.96 mumol in normal subject and 0.30 +/- 0.29 mumol in asthmatics), metaproterenol increased mean SGaw by 89 +/- 33% in normal subjects and by 190 +/- 55% in asthmatics (p < 0.05, two-way analysis of variance). After histamine challenge (PM35, 2.92 +/- 2.49 mumol in normal subjects and 0.17 +/- 0.29 mumol in asthmatics), metaproterenol increased mean SGaw by 111 +/- 38% in normal subjects and 113 +/- 69% in asthmatics (p = not significant). Thus, for the same degree of bronchoconstriction, metaproterenol responsiveness was influenced by the dose of methacholine but not the dose of histamine. The differential metaproterenol response could be related to a functional antagonism between muscarinic and beta-adrenergic agonists.

Adrenergic beta-Agonists↗
PubMed1986

Relative bioavailability of metaproterenol in humans utilizing a single dose, stable isotope approach.

The relative bioavailability of metaproterenol (3,5-dihydroxy-alpha-[(isopropylamino)methyl]benzyl alcohol) following a single dose (10-mg metaproterenol sulfate tablet) was studied in six normal male volunteers using coadministration of a solution of a deuterated analogue (metaproterenol-d7 sulfate). The bioavailability of the tablet formulation relative to that of the oral solution was 92 +/- 9%, with excellent power at the 5% significance level. Comparison of the coadministration of the labeled and unlabeled metaproterenol sulfate solutions in two subjects after a one-week washout demonstrated the absence of an isotope effect on either absorption or elimination. A GC-MS assay for metaproterenol was developed to measure plasma concentrations resulting from oral administration. The assay was linear over the range of 0.5-8 ng/mL, corresponding to typical plasma metaproterenol concentrations obtained after a single 10-mg oral dose. Accuracy and precision data were obtained at metaproterenol concentrations of 1.0 and 2.0 ng/mL plasma to demonstrate the applicability of the assay for bioavailability studies. Following oral administration, metaproterenol showed peak plasma concentrations of 2.2 to 13 ng/mL at 0.75 to 3.0 h, with a terminal harmonic mean half-life of 2.1 h over the plasma concentration range studied. The renal clearance of 133-158 mL/min for metaproterenol slightly exceeds the glomerular filtration rate in humans.

Administration, Oral↗
PubMed1992

Electrophysiologic study of the effects of aminophylline and metaproterenol on canine myocardium.

Aminophylline and beta-adrenergic agonists are widely used in the treatment of obstructive lung diseases. It has been suggested that combined aminophylline and beta-agonist therapy may promote the development of atrial and ventricular arrhythmias. The effects of these agents in combination on myocardial conduction and tissue refractoriness have not been documented. We evaluated the electrophysiologic effects of intravenous aminophylline and inhaled metaproterenol on canine myocardium. Aminophylline produced significant decreases from baseline in the AH interval (85 +/- 6.5 [SD] to 63 +/- 4.1 ms [p less than 0.02]), Wenckebach cycle length (WCL) (226 +/- 8.7 to 182 +/- 5.8 ms [p less than 0.02]), and ventricular effective refractory period (VERP) (166 +/- 6.0 to 148 +/- 4.9 ms [p less than 0.01]). Metaproterenol produced similar results, except metaproterenol significantly decreased the atrial effective refractory period (AERP) from 152 +/- 6.6 to 130 +/- 3.2 ms (p less than 0.02), an effect not seen with aminophylline alone. Metaproterenol also produced significantly greater reductions in AH interval and WCL, as well as a greater increase in heart rate than aminophylline did. When compared with aminophylline alone, combined metaproterenol and aminophylline therapy produced significantly greater reductions in the AH interval (63 +/- 4.1 versus 48 +/- 1.2 ms for combined therapy [p less than 0.01]), HV interval (32 +/- 1.2 versus 28 +/- 2.0 ms for combined therapy [p less than 0.02]), WCL (182 +/- 5.8 versus 150 +/- 7.1 ms for combined therapy [p less than 0.02]), and VERP (148 +/- 4.9 versus 132 +/- 2.0 ms for combined therapy [p less than 0.02]). We conclude that both aminophylline and metaproterenol significantly enhance AV nodal and His-Purkinje conduction. Metaproterenol produced significant changes in both atrial and ventricular tissue refractoriness. Metaproterenol produced significantly greater changes than aminophylline alone, and inhaled metaproterenol combined with intravenous aminophylline produced greater changes in AV nodal and His-Purkinje conduction and ventricular refractoriness than did aminophylline alone in a canine model.

Administration, Inhalation↗
PubMed1982

Comparison of orally administered metaproterenol and theophylline in the control of chronic asthma.

The efficacy of metaproterenol (orciprenaline) and theophylline given orally at currently recommended doses was examined in 34 children with chronic asthma using a randomized double-blind cross-over evaluation of four weeks' duration for each active regimen. No serious adverse effects were seen with either medication, but tremor occurred more frequently with metaproterenol (P less than 0.01). No significant differences were observed in the frequency of nausea, vomiting, headache, or insomnia (P greater than 0.05). Symptoms of wheezing, coughing, exercise intolerance, and interference with sleep were more frequently associated with the oral metaproterenol regimen; completely asymptomatic days occurred 50% more frequently in association with theophylline therapy (P less than 0.01). Mean peak flows, performed twice daily during each of the four-week study periods, were 86 and 92% of predicted for metaproterenol and theophylline, respectively (P less than 0.05). Pulmonary function decreased significantly less with theophylline than with metaproterenol among those who completed six minutes of treadmill exercise during both regimens (P less than 0.05). Corticosteroids, used for acute symptoms that failed to respond to the addition of inhaled metaproterenol, were required in four patients during both regimens, in ten patients only during the metaproterenol regimen, and in one patient only during the theophylline regimen (P less than 0.02). Thus, theophylline therapy was associated with fewer adverse effects, fewer symptoms of asthma, better pulmonary function, better exercise tolerance, and less requirements for corticosteroids than was treatment with metaproterenol.

Administration, Oral↗
PubMed1992

The efficacy of nebulized metaproterenol in wheezing infants and young children.

The benefit of beta-adrenergic agonists in the treatment of acutely wheezing infants and young children has not been well documented in the outpatient setting. To determine the efficacy of nebulized metaproterenol sulfate, 74 children aged 36 months or younger with acute wheezing participated in a double-masked, randomized, placebo-controlled clinical trial. Children received nebulized metaproterenol, either as an initial treatment or after a control treatment with normal saline solution. At baseline and 20 minutes after each treatment, an assessment was made that included measurements of heart rate, respiratory rate, oxygen saturation, and clinical variables related to respiratory compromise with the use of a standardized respiratory distress index (RDI). Children who received saline solution as initial therapy had no significant differences from baseline in any of the assessment measures. After metaproterenol therapy, children demonstrated an increase in heart rate ([mean +/- SD] 147 +/- 14 beats per minute vs 153 +/- 16 beats per minute), a decrease in respirations (50/min +/- 5/min vs 45/min +/- 7/min), improvement (lower scores) on the RDI (24 +/- 4 vs 15 +/- 2), and an increase in oxygen saturation (94.1% +/- 2.7% vs 95.3% +/- 3.0%). Patients aged 12 months or younger (n = 37) benefited from metaproterenol treatment (improvement in respiratory rate and RDI) but not to the same degree as children aged 24 months or older (n = 23) (improvement in respiratory rate, RDI, and oxygen saturation). Compared with assessments made before metaproterenol treatment, patients with respiratory syncytial virus infection (n = 21) had improvement in respirations (52/min +/- 7/min vs 45/min +/- 6/min) and RDI scores (22 +/- 4 vs 14 +/- 3). Based on a priori criteria (reduction in a premedication respiratory rate of 20% and an RDI score of 50%), responders to metaproterenol therapy included 45% of the entire sample and, respectively, 40% of those aged 12 months or younger, 52% of those aged 24 months or older, and 48% of patients who tested positive for respiratory syncytial virus. Although there appears to be an age-dependent degree of response, metaproterenol is effective in relieving the respiratory distress of young acutely wheezing children, including those with documented respiratory syncytial virus bronchiolitis.

Administration, Inhalation↗
PubMed1991

A randomized comparison of atropine and metaproterenol inhalational therapies for refractory status asthmaticus.

STUDY OBJECTIVE: To compare the forced expiratory volume in one second (FEV1) response to inhaled anticholinergic with the response to beta-adrenergic solutions in adults with refractory status asthmaticus. DESIGN: After the decision was made to hospitalize, 40 patients were prospectively randomized in a double-blind trial to receive either atropine sulfate or metaproterenol by nebulizer. SETTING: A county teaching hospital emergency department. TYPE OF PARTICIPANTS: Adults requiring hospitalization for refractory status asthmaticus. INTERVENTIONS: Standard therapies for acute bronchospasm, followed by either 1.5 mg atropine or 15 mg metaproterenol by nebulizer. MEASUREMENTS AND MAIN RESULTS: The two groups were similar on entry into the study, including mean FEV1 measurements (0.70 L atropine/0.60 L metaproterenol, P greater than .05). Compared with baseline, The FEV1 improvement for the metaproterenol group was statistically significant (+ 0.18 L, P = .05; + 31%, P less than .05), whereas the improvement with atropine did not reach significance (+0.09 L or +10%, P greater than .05). Comparing the two groups, statistically significant differences favoring metaproterenol were found in the percent improvement in the FEV1 (+10% atropine/+31% metaproterenol, P less than .05) and in the percentage of patients experiencing at least a 15% decrease in their FEV1 below baseline (35% atropine/10% metaproterenol, P less than .05). No patient suffered adverse side effects. CONCLUSION: For the majority of adults with refractory status asthmaticus, an additional beta-adrenergic inhalation treatment results in greater FEV1 improvement than that resulting from the addition of an atropine inhalation.

Administration, Inhalation↗
PubMed1990

Prehospital administration of inhaled metaproterenol.

STUDY OBJECTIVES: We conducted a study of the prehospital use of inhaled metaproterenol. DESIGN, SETTING, TYPE OF PARTICIPANTS, AND INTERVENTIONS: Advanced life support (ALS) providers were trained with a standardized curriculum to identify patients likely to benefit from prehospital inhaled metaproterenol administration. Unit doses of metaproterenol were used in a small-volume nebulizer. We prospectively included 122 patients in an initial study (71 men; age, 63 +/- 19 years) to evaluate the safety and effectiveness of metaproterenol in the field, and 150 patients (including the original 122) in an additional study to evaluate patient selection criteria. MEASUREMENTS AND MAIN RESULTS: The treatments resulted in an increase in peak flows, a decrease in respiratory rates, and no change in heart rates. In 62% of patients, the increase in peak flow exceeded 15%. Wheezing improved in 59% of the patients, worsened in 4%, and did not change in the remainder. Air entry by auscultation improved subjectively in 59% of patients. Mild tremor occurred in 8% of patients, moderate tremor occurred in 1%, and no tremor occurred in the remainder. Significant dysrhythmias did not occur. CONCLUSIONS: ALS providers correctly identified patients for this therapy. No technical problems were encountered in the field with this treatment approach. We conclude that ALS providers can be taught to identify patients likely to benefit from inhaled metaproterenol, that inhaled metaproterenol can be administered in the field, and that metaproterenol is both safe and effective when used in the prehospital setting.

Administration, Inhalation↗
PubMed1988

Effect of inhaled metaproterenol on exercise performance in patients with stable "fixed" airway obstruction.

We studied the effect of inhaled metaproterenol on exercise performance in ten patients with moderate to severe nonreversible chronic obstructive pulmonary disease (COPD), defined as a FEV1/FVC ratio below 60%, and less than 15% improvement in FEV1 and FVC after both one-time administration of inhaled metaproterenol and a 10-day therapeutic trial with oral theophylline, inhaled metaproterenol, and oral prednisone. After baseline evaluation, on two separate days all selected patients had spirometry and a self-paced 12-min treadmill walking test performed (in double-blind crossover fashion) before and after random administration of five puffs of inhaled metaproterenol or placebo. A few weeks later, testing was repeated single-blind before and after inhaled metaproterenol, but this time the 12-min walk was done in an enclosed hall. Pretreatment spirometry values were similar on all study days, and none of the subjects had a significant change (greater than 15% from baseline) in FEV1 or FVC after the administration of placebo or metaproterenol. The postmetaproterenol treadmill and hall walking distances improved by a mean (+/- SD) of 112 +/- 56 m (p less than 0.001) and 82 +/- 46 m (p less than 0.01), respectively. Individual improvements in exercise performance did not correlate with the corresponding changes in FEV1 or FVC, or with the baseline DLCO measurement. We conclude that an objective improvement in physical performance after administration of a relatively high dose of inhaled metaproterenol can be seen in some patients with moderate to severe "fixed" airway obstruction, despite a lack of significant response as judged by conventional spirometry criteria.

Administration, Inhalation↗
PubMedDate not supplied

Aerosolized metaproterenol compared to subcutaneous epinephrine in the emergency treatment of acute childhood asthma.

In a double-blind, randomized trial, we compared the effects of aerosolized metaproterenol to subcutaneous epinephrine in 35 episodes of acute asthma in children between 6 and 19 years of age. Patients were randomized to two parallel groups and then received both a placebo medication and an active medication to a maximum of three treatments. Repeated treatments were given to 15 patients on metaproterenol and 12 patients on epinephrine. Initial improvement in PEFR and FEV1 were statistically significant and comparable in both groups. Patients receiving a second metaproterenol treatment had more improvement in respiratory rate and clinical score compared with those in the epinephrine group. There were fewer treatment failures in the metaproterenol group. Followup at 24 to 48 hours showed significant treatment failure differences between the two groups (metaproterenol = 0, epinephrine = 5; p less than 0.05). Side effects were similar in both groups; in all instances they were mild, and their frequency did not increase in patients receiving repeated doses of medications. In conclusion, aerosolized metaproterenol was well tolerated in acute childhood asthma in repeated doses, and it appeared to be associated with prolonged bronchodilation and improved outcome.

Acute Disease↗
PubMed1989

Effects of inhaled metaproterenol and atropine on the pulmonary mechanics of infants with bronchopulmonary dysplasia.

We evaluated the individual and combined effects of an inhaled beta-adrenergic agent (metaproterenol) and an inhaled anticholinergic agent (atropine) on the pulmonary function of infants with bronchopulmonary dysplasia. In this randomized, double-blind study we studied 15 infants at a mean postnatal age of 15.8 weeks (range 4-28 weeks). On 4 successive days, pulmonary function tests were measured before and after a single treatment with one of the following four aerosols: placebo, metaproterenol, atropine, and combined metaproterenol and atropine. Following treatment with metaproterenol, atropine, and combined metaproterenol and atropine, airway resistance and maximal expiratory flow at functional residual capacity improved significantly when compared with baseline. Pulmonary function values returned toward baseline by 3 hours after the treatments. We found no significant differences between the effects of metaproterenol and atropine and were unable to show any synergy of the two agents.

Administration, Inhalation↗
PubMed1981

Comparison of oral aminophylline and aerosol metaproterenol in asthma.

The bronchodilator efficacy of oral aminophylline and aerosol metaproterenol was compared in 18 asthmatic patients in a stable clinical condition. Treatment consisted of four regimens in a double-blind random sequence on four different days after withholding bronchodilators: (1) the administration of aminophylline tablets, 0.4 to 0.6 g, orally, (2) 3 puffs of aerosol metaproterenol administered in a sequential manner, (3) a combination of both, (4) placebos. Both oral aminophylline and aerosol metaproterenol produced significant bronchodilatation measured by forced expiratory volume in 1 second (FEV1). After the administration of aerosol metaproterenol, there was a more prompt and larger improvement in FEV1 than after the administration of aminophylline (p less than 0.01). The combined therapy produced a response which was larger, but not significantly, than the effect of metaproterenol. Side effects were frequent after the administration of aminophylline but absent after aerosol metaproterenol. The advantages of the aerosol adrenergic agonists are the prompt onset of action and efficacy, small dosage preferentially delivered to the bronchial tree and lack of side effects.

Administration, Oral↗
PubMed1990

Frequency of inhaled metaproterenol in the treatment of acute asthma exacerbation.

Acute asthma exacerbations are common complaints in patients who present to the emergency department. A prospective, double-blinded study was designed to evaluate how frequency of dosing of an inhaled beta-agonist, metaproterenol (Alupent inhalation solution) would affect patient response, length of stay in the ED, and admission rates. Forty-one patients initially received a 0.3-mL dose of nebulized metaproterenol followed by two additional doses of either metaproterenol or saline every 20 minutes. While there was no difference in response (forced expiratory volume in one second) in patients at 30 minutes after their arrival, there was an improved response in the metaproterenol group at 60 and 120 minutes. The length of stay in the ED was approximately the same for both groups. There was no significant difference in admission rates. No increase in undesirable side effects (eg, nausea, tremor, palpitations) was seen in the metaproterenol-treated group. Frequent dosing of metaproterenol is useful in asthmatics having acute exacerbations and leads to rapid improvement without an increase in toxicity.

Acute Disease↗
PubMedDate not supplied

Comparison of inhaled metaproterenol via metered-dose and hand-held nebulization in prehospital treatment of bronchospasm.

INTRODUCTION: Although the efficacy of the administration of beta-adrenergic bronchodilators has been demonstrated, the best method available for the delivery of these drugs in the prehospital setting has not been defined. This paper compares the effects of administration of metaproterenol when administered by paramedics using either a metered-dose inhaler (MDI) or a hand-held nebulizer (HHN). HYPOTHESIS: There is no difference in the effects produced in patients suffering from smooth bronchiolar muscle spasm by metaproterenol when delivered either by a standard metered-dose inhaler or with a hand-held nebulizer. PARTICIPANTS: Consecutive prehospital patients complaining of difficulty breathing with clinical evidence of bronchospasm and with a history of asthma, chronic obstructive pulmonary disease, or emphysema who were not in extremis. METHODS: Prior to the administration of metaproterenol, a peak expiratory flow rate (PEFR) was obtained. This measurement was repeated five minutes following the conclusion of the administration of metaproterenol. Patients in Burbank, California, received the treatment using a standard metered-dose inhaler, and those in Madison, Wisconsin, received the drug using a hand-held nebulizer. Peak expiratory flow rates were compared using Student's t-tests with Bonferroni's correction. Statistical significance was set at p < 0.05. RESULTS: Data were collected from 36 consecutive patients by the paramedics of the Burbank Fire Department and from 32 consecutive patients by the paramedics of the Madison Fire Department. For the metered-dose inhaler group, the mean value for peak expiratory flow rate for the pre-treatment test was 95.4 +/- 88.1 l/min, and after treatment was 109.4 +/- 89.3 l/min (p < 0.001). For the hand-held nebulizer group, the mean value for peak expiratory flow rate before the administration of the metaproterenol was 96.1 +/- 76.3 l/min and following the treatment was 149.1 +/- 92.9 l/min (p < 0.001). The mean values for the differences between the control peak expiratory flow rate and the post-treatment peak expiratory flow rate for the metered-dose inhaler group was + 140.0 +/- 27.4 l/min, and for the hand-held nebulizer group was + 53.0 +/- 69.1 l/min (p < 0.003). CONCLUSIONS: In the prehospital setting, the administration of metaproterenol using a hand-held nebulizer is more effective than delivering the drug using a metered-dose inhaler. The hand-held nebulizer is easier to use and delivers a higher dose of the drug than is convenient using the metered-dose inhaler.

Administration, Inhalation↗
PubMed1981

Comparison of oral and inhaled metaproterenol for prevention of exercise-induced asthma.

The effectiveness of inhaled versus oral metaproterenol in preventing exercise-induced asthma (EIA) was studied. Inhaled metaproterenol given 10 min before the exercise significantly reduced the degree of EIA in a group of twenty-four patients, and in 75% of them completely prevented it. The mean percentage decrease in FEV1 was 6.5% with the inhaler and 30.1% with placebo. When inhaled 1 hr before the exercise, metaproterenol was still better than placebo but its effectiveness was considerably lower. Metaproterenol tablets had a slight protective effect given 1 hr before, and none when administered 2 hr before exercise. There was no correlation between the protective effect against EIA and the bronchodilating effect obtained before exercise. Metaproterenol administered by metered-dose inhaler is a very effective prophylactic medication against clinically troublesome EIA, while metaproterenol tablets should not be recommended for this purpose.

Administration, Intranasal↗
PubMed1977

Long-term effects of metaproterenol in asthmatic children.

Oral metaproterenol was administered daily for 3 months to asthmatic children. The study was designed to determine whether chronic tolerance developed to this drug. Initial and final crossovers on the first 2 and the last 2 days of the investigation to a test dose of metaproterenol and placebo failed to show tolerance as indicated by improvement in lung volumes and dynamic mechanics of breathing after metaproterenol. Forced expiratory volume in 1 sec was the test most consistent in demonstrating bronchodilation; the action of metaproterenol. Forced expiratory volume in 1 sec was the test most consistent in demonstrating bronchodilation; the action of metaproterenol appeared to last at least 5 hours as measured by this test. T of distribution of ventilation, e.g., single- and multiple-breath nitrogen washout tests, were not consistently altered by metaproterenol. These tests did not appear to be sufficiently sensitive to detect improvement even when airway resistance decreased and forced expiratory volume in 1 sec increased toward the normal range.

Asthma↗
PubMed1987

Comparison of inhaled metaproterenol, inhaled atropine sulfate, and their combination in treatment of children with acute asthma.

The separate and combined effects of inhaled metaproterenol and atropine sulfate were evaluated in the treatment of 44 episodes of acute asthma occurring in 35 children ranging in age from 13 months to 13 years. Peak expiratory flow rate and pulmonary index were measured before and after each of up to three inhalation treatments. Significant improvement in peak flow rate (P less than .04) was noted after the second inhalation of metaproterenol both with and without the combination of atropine sulfate compared with the effects of atropine alone. Patients treated with metaproterenol and metaproterenol combined with atropine also experienced fewer therapeutic failures (2/15 and 2/16, respectively) compared with those treated with atropine (6/13, P less than .02). Pulmonary index scores did not differ among the treatment groups. Inhaled metaproterenol appears to be more effective than inhaled atropine sulfate in the treatment of children with acute asthma. The addition of inhaled atropine sulfate appears to offer no advantage over treatment with inhaled metaproterenol alone.

Acute Disease↗