Efficacy of orally administered salbutamol and theophylline in pre-schoolchildren with asthma

Anti-inflammatory pharmacotherapy for wheezing in preschool children

Accumulating evidence indicates that there are at least two phenotypes of wheezing in preschool years with distinct natural history. Frequent wheezing in the first 3 years of life with risk factors for asthma (e.g., eczema, maternal asthma) predicts symptoms in older age, while infrequent viral-associated wheezing without risk factors for asthma has a benign prognosis. This systematic review summarizes evidence on the use of anti-inflammatory medications in preschool children with wheezing. Literature search was performed using Medline and the Cochrane Library. Retrieved articles were critically appraised. Episodic use of high-dose inhaled corticosteroids (>1,600 mcg/day of beclomethasone) may ameliorate severity of intermittent viral-associated wheezing. Maintenance inhaled corticosteroids can control symptoms in children with frequent wheezing associated with risk factors for asthma. Inhaled corticosteroids do not alter the natural history of wheezing even when started early in life and could have a negative impact on linear growth rate. Short courses of oral corticosteroids have been proposed as an effective measure to control exacerbations of symptoms although there is little evidence supporting their use. Some studies support the administration of non-steroidal anti-inflammatory medications (leukotriene pathway modifiers, cromones, methylxanthines) for mild frequent wheezing. Maintenance inhaled corticosteroids is the most effective measure for controlling frequent wheezing in preschool children, especially when accompanied by risk factors for asthma. This treatment does not affect the natural history of wheezing, although deceleration of linear growth rate is the most commonly recognized systemic adverse effect.

Oral xanthines as maintenance treatment for asthma in children

BACKGROUND

Xanthines have been used in the treatment of asthma as a bronchodilator, though they may also have anti-inflammatory effects. The current role of xanthines in the long-term treatment of childhood asthma needs to be reassessed.

OBJECTIVES

To determine the efficacy of xanthines (e.g. theophylline) in the maintenance treatment of paediatric asthma.

SEARCH STRATEGY

A search of the Cochrane Airways Group Specialised Register was undertaken with predefined search terms. Searches are current to May 2005.

SELECTION CRITERIA

Randomised controlled trials,lasting at least four weeks comparing a xanthine with placebo, regular short-acting beta-agonist (SABA), inhaled corticosteroids (ICS), cromoglycate (SCG), ketotifen (KET) or leukotriene antagonist, in children with diagnosed with chronic asthma between 18 months and 18 years old.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected each study for inclusion in the review and extracted data. Primary outcome was percentage of symptom-free days.

MAIN RESULTS

Thirty-four studies (2734 participants) of adequate quality were included. Xanthine versus placebo (17 studies): The proportion of symptom free days was larger with xanthine compared with placebo (7.97% [95% CI 3.41, 12.53]). Rescue medication usage was lower with xanthine, with no significant difference in symptom scores or hospitalisations. FEV1 , and PEF were better with xanthine. Xanthine was associated with non - specific side-effects. Data from behavioural scores were inconclusive. Xanthine versus ICS (four studies) : Exacerbations were less frequent with ICS, but no significant difference on lung function was observed. Individual studies reported significant improvements in symptom measures in favour of steroids, and one study reported a difference in growth rate in favour of xanthine. No difference was observed for study withdrawal or tremor. Xanthine was associated with more frequent headache and nausea. Xanthine versus regular SABA (10 studies): No significant difference in symptoms, rescue medication usage and spirometry. Individual studies reported improvement in PEF with beta-agonist. Beta-agonist treatment led to fewer hospitalisations and headaches. Xanthine was associated with less tremor. Xanthine versus SCG (six studies ): No significant difference in symptoms, exacerbations and rescue medication. Sodium cromoglycate was associated with fewer gastro-intestinal side-effects than xanthine. Xanthine versus KET (one study): No statistical tests of significance between xanthine and ketotifen were reported. Xanthine + ICS versus placebo + same dose ICS (three studies) : Results were conflicting due to clinical/methodological differences, and could not be aggregated.

AUTHORS' CONCLUSIONS

Xanthines as first-line preventer alleviate symptoms and reduce requirement for rescue medication in children with mild to moderate asthma. When compared with ICS they were less effective in preventing exacerbations. Xanthines had similar efficacy as single preventative agent compared with regular SABA and SCG. Evidence on AEs (adverse effects) was equivocal: there was evidence for increased AEs overall, but no evidence that any specific AE (including effects on behaviour and attention) occurred more frequently than with placebo. There is insufficient evidence from available studies to make firm conclusions about the effectiveness of xanthines as add-on preventative treatment to ICS, and there are no published paediatric studies comparing xanthines with alternatives in this role. Our data suggest that xanthines are only suitable as first-line preventative asthma therapy in children when ICS are not available. They may have a role as add-on therapy in more severe asthma not controlled by ICS, but further studies are needed to examine this, and to define the risk-benefit ratio compared with other agents.

Anti-inflammatory treatment for recurrent wheezing in the first five years of life

Medications identified for the treatment of recurrent wheezing in preschool children by the Expert Panel Report of the NHLBI Guidelines for the Diagnosis and Management of Asthma include inhaled corticosteroids, chromones, theophylline, and leukotriene pathway modifiers. However, these various agents differ in their mechanism, extent of action on the airway inflammatory process, and degree of clinical efficacy. Inhaled corticosteroids can control symptoms in many young children with even severe persistent wheezing, but data on their long-term safety when administered in preschool-age children are scarce. There is some information on the uninterrupted use of inhaled corticosteroids in school-age children and the absence of an adverse effect on ultimate adult height. Despite laboratory evidence of adrenal suppression in some studies, few pediatric cases of clinical adrenal insufficiency have been reported. Low-dose inhaled corticosteroid (<400 mcg/day for beclomethasone), which is adequate for controlling mild persistent symptoms, is generally safe. Chromones have a remarkable safety profile, but they are most effective for symptoms of mild severity. Promising data have been published on the efficacy and safety of leukotriene pathway modifiers when used in young children with persistent symptoms. It is uncertain whether early introduction and long-term administration of inhaled corticosteroids prevent development of irreversible airway obstruction. Nevertheless, they may be especially useful for patients with moderate to severe disease in whom other agents (chromones or leukotriene pathway modifiers) will most likely fail to control symptoms. Pediatr Pulmonol. 2003; 35:241-252.

Treatment of recurrent acute wheezing episodes in infancy with oral salbutamol and prednisolone

The aim of this study was to investigate the role of oral salbutamol and prednisolone in the treatment of acute episodes of wheezing in infants under 15 months of age. Sixty-two acute episodes of wheezing were studied in 59 babies (age range 3-14 months; mean 7 months), who had all suffered at least one previous wheezy episode. Patients were randomised to receive either salbutamol and prednisolone, salbutamol and placebo or double placebo. Parents were requested to keep a diary card record of twice daily scoring of their baby's symptoms over the next 14 days. A significantly greater number of treatment failures occurred in the placebo group compared to babies treated with oral salbutamol (relative risk 2.51; 95% confidence intervals for relative risk 1.09-5.79). There was no difference in the number of treatment failures between babies treated with a combination of salbutamol and placebo and those treated with salbutamol and prednisolone (relative risk 0.71; 95% confidence intervals for relative risk 0.18-2.80).

CONCLUSION

This study demonstrates that oral salbutamol is beneficial in the treatment of acute episodes of wheezing in infancy. A combination of oral salbutamol and oral prednisolone appeared to have no additional benefit over treatment with oral salbutamol alone.

Is combined therapy of sympathomimetics and theophylline indicated?

Bronchodilator effect and toxicity of theophylline 300 mg twice a day (R1), salbutamol 4 mg tid (R2), their combination in higher (200/4mg, R3), and lower doses (100/2mg R4), and placebo (calcium lactate 300 mg) tid (R5) were compared in 25 patients with bronchial asthma in a randomized crossover trial. Statistically significant improvement in forced expiratory volume in one second (FEV1) was observed in all the active treatment groups (R1 to R4) compared with placebo (R5). The mean improvement in FEV1 was 29.0%, 22.0%, 28.0%, 30.0%, and 0.73% in regimen R1, R2, R3, R4, and R5, respectively day 1, and corresponding improvement was 30.0%, 24.0%, 29.0%, 34.0%, and 4.4% on completion of one week therapy. On intergroup statistical comparison, mean improvement in pulmonary function test values were statistically significant or highly significant in regimens R1 to R4, as compared with placebo. However, improvement between any two regimens was not statistically significant in any of the regimens (R1-R4). Almost all the regimens were tolerated well and no patient showed major adverse reactions or cardiotoxicity necessitating withdrawal of the drug. On the other hand, minor adverse reactions were common and the high dose combination (R3) was found to have more adverse reactions than the low dose combination and either drug used alone.

Response to bronchodilators assessed by lung mechanics

Abnormalities of compliance and functional residual capacity were shown in eight young children aged 2-8 years with asthma during an acute attack. In a randomised, placebo controlled study treatment with bronchodilator (salbutamol) was associated with a significant improvement in compliance and lessening of hyperinflation as shown by a reduction in functional residual capacity.

The use of anti-asthmatic drugs. Do they affect sports performance?

Recent major advances in pharmacological management have provided asthmatics with a satisfactory range of drugs to control asthma. These include sodium cromoglycate (cromolyn sodium), H1-antagonists, belladonna alkaloids, methyl xanthines, glucocorticoids and beta 2-adrenoceptor stimulants. Despite the tendency for most asthmatics to develop bronchoconstriction after exercise, sport and physical activity are now accepted as valuable in the overall management of patients with asthma. Thus, control of exercise-induced asthma (EIA) is essential, if asthmatics are to participate safely in physical activity and without respiratory disadvantage in competitive sport. Fortunately, inhibition or minimization of exercise-induced asthma may be achieved in most asthmatics by pre-exercise aerosol beta 2-agonists supplemented if necessary by sodium cromoglycate and/or theophylline. Regular medication as required to attain and maintain normal ventilatory function throughout each day is the objective in all patients with asthma and appears to be a prerequisiste to control exercise-induced asthma. The introduction of anti-doping controls into high performance sport has presented added difficulties for the asthmatic athlete. Although not always so, currently all of the classes of drugs previously noted are acceptable for the treatment of asthma and exercise-induced asthma. Anomalies may exist in the banning of 2 beta 2-adrenoceptor agonists, fenoterol and orciprenaline (metaproterenol). All sympathomimetic amines with alpha- or predominantly beta-stimulation are banned. The perpetuation of the need to report the use of beta 2-agonists prior to competition appears unnecessary. Although relatively little specific research has been undertaken, there is minimal evidence to suggest that asthmatics can derive any additional ergogenic advantage from medication to control asthma and exercise-induced asthma. beta 2-agonists, sodium cromoglycate and glucocorticoids administered by the aerosol route are not considered to be ergogenic. Some doubts have been raised concerning theophylline and its enhancement of both cardiac and respiratory muscle function. Investigations as to the validity of the suggestion that theophylline could augment physical performance appear warranted. It is reported that some athletes may be unnecessarily taking oral and perhaps parenteral glucocorticoids to obtain certain side effects. Any decision to ban these agents except for aerosol or local use could be supported.

Content of reports on clinical trials: a critical review

A 10% sample of English language papers, published in 1980, listed in Index Medicus, and classified under the heading, Clinical Trials, was used to assess the state of trials and reports from them. Tabulations are presented concerning the design of the trials represented by the papers in the sample. The manuscript concludes with a discussion of reporting responsibilities for investigators involved in trials and of methods for meeting those responsibilities.

Combination bronchodilator therapy

Bronchodilators may be classified into 3 groups: anticholinergics, beta-adrenoceptor agonists and methylxanthines. These drugs act through related biochemical pathways and there are theoretical reasons for expecting beneficial additive or synergistic interactions between them. While there is in vitro evidence of synergistic interactions producing bronchodilatation, in vivo studies indicate that the interactions are additive rather than synergistic but still of therapeutic value. There have been no clinical studies on methylxanthines combined with anticholinergic drugs, but there is an extensive and growing literature on the other combinations. The majority show clear evidence of an additive bronchodilator effect when anticholinergics are combined with beta 2-adrenoceptor agonists, although atropine sulphate is less effective in this regard than atropine methylnitrate or ipratropium bromide. This type of combination has only been tested by inhalation and, because of the slower onset of action of the anticholinergic group, it is preferable that the beta 2-adrenoceptor agonist be inhaled first. There is no evidence for an additive interaction of the side effects of these drugs. In general, bronchitics respond better than asthmatics to anticholinergic drugs. Studies on methylxanthines (usually theophylline) and adrenoceptor agonists may be divided into 2 groups: those using ephedrine and those using more selective beta-adrenoceptor agonists. Ephedrine is a relatively ineffective bronchodilator and often fails to add any useful bronchodilatation to theophylline. Also, there does seem to be a synergistic increase in side effects of the two drugs and this combination is therefore undesirable. Ephedrine has now been superseded by the more selective beta 2-adrenoceptor agonist drugs all of which, whether given orally, intravenously or by inhalation, appear to have an additive effect with the methylxanthines. It is often possible to achieve the same therapeutic effect with half doses of drugs from 2 different groups as with a full dose of 1 drug. This may sometimes, but not always, reduce side effects. There is evidence that giving 2 drugs by different routes is a useful therapeutic procedure; for example, the addition of an inhaled beta 2-adrenoceptor agonist may improve upon the maximal bronchodilatation achieved with intravenous theophylline. When theophylline is administered plasma levels of the drug should be monitored and it is possible that, when used in combination with a beta 2-adrenoceptor agonist, a therapeutic range lower than that normally recommended may apply. There is no longer any place for fixed combination bronchodilators and, in spite of recent suggestions, there is no evidence that bronchodilator combinations are responsible for an increase in asthma mortality. Further studies to clarify some aspects of bronchodilator combinations are needed. The therapeutic use of various combinations is briefly discussed.

Effects of oral theophylline and oral salbutamol in the treatment of asthma

A double-blind randomised controlled trial was conducted to study the effects of oral theophylline alone compared with oral theophylline and salbutamol in a sample of asthmatic children. Each treatment was administered at maximum recommended dosage. Children treated with the theophylline and salbutamol combination had higher pulse rates, lower peak flow measurements, and depressed blood theophylline levels. These results suggest that when given at maximum oral dosage, theophylline and salbutamol in combination, tend to interact negatively producing tachycardia and reduced therapeutic function.

Does theophylline potentiate inhaled beta 2-agonists?

The influence of pretreatment with equipment bronchodilating doses of intravenous theophyllamine and inhaled terbutaline on the effect of five terbutaline inhalations was investigated in a cross-over study in six adult asthmatics with stable and reproducible bronchoconstriction. Theophylline in a dose giving a maximal mean plasma concentration of 16.7 +/- 1.21 micrograms/ml (92 mumol/l) gave far from maximal acute bronchodilation as the following five terbutaline inhalations gave the same further bronchodilation. Pretreatment with five terbutaline inhalations induced almost equal bronchodilation compared with theophyllamine but the following five inhalations now gave only about one-fourth of the effects recorded after theophyllamine pretreatment. This potentiation could, however, be due to the different routes of administration of the pretreatments. In a randomized, double-blind, cross-over study in eight asthmatic, pretreatment with equipotent oral bronchodilating doses of theophylline and terbutaline was shown to give the same potentiation of the following five terbutaline inhalations. Theoyphylline orally as such thus did not potentiate the effect of inhaled beta 2-stimulants. It had only the same effect as oral terbutaline, but induced less tremor. This means that the potentiation after intravenous and oral pretreatment was not due to theophylline but to the different routes of administrations. Systemic administration probably gave a better distribution and thus better effect of the inhaled terbutaline.

Effects of oral theophylline combined with oral and inhaled beta-2-adrenostimulants in asthmatics

The acute ventilatory, cardiovascular and tremorogenic effect of a high oral dose of terbutaline (5 mg) was compared with that of half the dose (2.5 mg) combined with 280 mg anhydrous theophylline orally in the randomized, double-blind, cross-over study in eight asthmatics. After 120 min, when steady-state bronchodilation was achieved, five terbutaline inhalations (1.25 mg terbutaline sulphate) were added to both treatment regimens. The mean maximum plasma concentration of theophylline was then 7 micrograms/ml (39 mumol/l). Inhalation of a beta 2-adrenostimulant had a very good additional effect without increasing side effects in these patients with good inhalation technique. The oral low-dose combination gave significantly better bronchodilation than the high dose of terbutaline alone and caused significantly less tremor. Although the combination only had an additive bronchodilating effect, it may offer important clinical advantages. If the patient cannot use the metered dose aerosol, an oral low dose combination should be preferred to a single high dose of either theophylline or beta 2-adrenostimulants. In patients with good inhalation technique but not controlled by inhalation from a metered dose aerosol alone, a combination of oral theophylline and terbutaline in "sub-optimal" dose and an inhaled beta 2-agonist in individually titrated optimal dose gave a maximal bronchodilating effect with minimum side effects.

Bronchodilator effects of clemastine, ipratropium, bromide, and salbutamol in preschool children with asthma

The bronchodilator activity in nebulised salbutamol, ipratropium bromide, clemastine, and a placebo was studied in 14 asthmatic children aged between 3 and 5 years. Changes in lung function were monitored by measuring peak expiratory flow rate and total respiratory resistance using a modification of the forced oscillation technique. Ipratropium bromide produced a degree of bronchodilation similar to that of salbutamol, but the bronchodilatory activity of clemastine was not appreciably better than for the placebo.

Combined treatment with sustained-release theophylline and beta2-adrenoceptor-stimulating agents in chronic childhood asthma

The effect of adding theophylline to treatment with a beta2-adrenoceptor stimulant was studied in 18 asthmatic children in a double-blind cross-over trial. Most patients were taking cromolyn sodium (cromoglycic acid) or beclomethasone aerosol, or both. A sustained-release preparation of theophylline was administered in individually titrated doses, producing a mean plasma theophylline concentration of about 8 micrograms/ml. Statistically significant improvements were found during the theophylline treatment in symptom score, consumption of beta2 stimulants in aerosol form, and morning peak expiratory flow rate and forced expiratory volume in one second. There was also a reduced need for emergency-room treatment during the theophylline period. Reported side effects were few and mild and were similar during the theophylline and placebo periods. Of the 17 patients who completed the trial, 14 preferred theophylline and three expressed no preference between theophylline and placebo. Adding submaximal doses of sustained-release theophylline to treatment with a beta2 stimulant gave further relief of asthmatic symptoms without appreciable side effects, suggesting that the drug combination has a favourable therapeutic index.

Salbutamol: tablets, inhalational powder, or nebuliser?

A study was carried out to ascertain the most effective method of giving salbutamol. Seventeen children with severe asthma received active salbutamol (4 mg via a nebuliser, 400 micrograms as an inhalational powder, or a 4 mg tablet) together with complementary placebos on a double-blind, triple-dummy randomly allocated basis. The bronchodilatation effect was assessed by measuring the peak expiratory flow rate. The bronchodilatation effect was greatest when patients received nebulised salbutamol (p less than 0.05) but lasted longest when they received the tablet (p less than 0.0001); the onset of the effect was rapid with all forms of administration. These results indicate that nebulised salbutamol gives the best relief in severe asthma; in less severe cases, however, a regimen combining the inhalational powder and tablets is sufficient and more convenient.