Single-dose slow-release aminophylline at night prevents nocturnal asthma

Design and optimization of colon-targeted system of theophylline for chronotherapy of nocturnal asthma

The objective of the present work was to develop a delayed-onset controlled-release colon-targeted system of theophylline, and to achieve the chronotherapy of nocturnal asthma. The formulation consisted of a core tablet containing hydroxypropyl methylcellulose used for achieving controlled release of drug, and a Eudragit S100:ethyl cellulose (EC) coating capable of delaying the drug release. The system was optimized using a 3(2) full factorial design, wherein two factors [ratio of Eudragit S100:EC and the coating level (% w/w)] were evaluated for lag time, t(50) and t(80) . The optimum formulation consisted of Eudragit S100:EC in a 60:40 ratio and a coating level of 7.5% (w/w). Results showed that the tablets prepared according to the optimized values released no drug in the upper part of gastrointestinal tract; drug release was initiated at pH 6.4 (colon) after a lag time of 5 h. In vivo evaluation (pharmacokinetic studies and roentgenography) in rabbits revealed that the tablet remained intact until it reaches the colon and the drug release was initiated after a lag time of 5 h. Thus, it can be concluded that the developed system exhibited a promising colonic targeting and hence may be used for chronotherapy of nocturnal asthma.

Theophylline

Theophylline (3-methyxanthine) has been used to treat airway diseases for over 70 years. It was originally used as a bronchodilator but the relatively high doses required are associated with frequent side effects, so its use declined as inhaled β₂-agonists became more widely used. More recently it has been shown to have anti-inflammatory effects in asthma and COPD at lower concentrations. The molecular mechanism of bronchodilatation is inhibition of phosphodiesterase(PDE)3 and PDE4, but the anti-inflammatory effect may be due to histone deacetylase (HDAC) activation, resulting in switching off of activated inflammatory genes. Through this mechanism theophylline also reverses corticosteroid resistance and this may be of particular value in severe asthma and COPD where HDAC2 activity is markedly reduced. Theophylline is given systemically (orally as slow-release preparations for chronic treatment and intravenously for acute exacerbations of asthma) and blood concentrations are determined mainly by hepatic metabolism, which may be increased or decreased in several diseases and by concomitant drug therapy. Theophylline is now usually used as an add-on therapy in asthma patients not well controlled on inhaled corticosteroids and in COPD patients with severe disease not controlled by bronchodilator therapy. Side effects are related to plasma concentrations and include nausea, vomiting and headaches due to PDE inhibition and at higher concentrations to cardiac arrhythmias and seizures due to adenosine A₁-receptor antagonism.

Sleep-related hypoventilation/hypoxemic syndromes

The latest edition of The International Classification of Sleep Disorders: Diagnostic and Coding Manual subsumes a broad range of disorders under the heading "Sleep Related Hypoventilation/Hypoxemic Syndromes." Some are quite common, such as COPD with worsening gas exchange during sleep; while some are exceedingly rare, such as congenital central hypoventilation syndrome. All share the attribute of abnormal gas exchange that worsens, or may only be present, during sleep. The sleep state, the sleeping posture, and the circadian rhythm driving sleep all may affect respiration by altering control of breathing and/or pulmonary mechanics. These changes are largely inconsequential in the normal individual but interact with respiratory, neurologic, or neuromuscular disease to manifest as the sleep-related hypoventilation/hypoxemic syndromes. In addition to optimal treatment of the underlying disorder (when known and when possible), treatment usually involves nocturnal ventilatory support that is now most commonly provided by noninvasive positive pressure ventilation.

Nocturnal asthma: underlying mechanisms and treatment

Nocturnal asthma is defined by a drop in forced expiratory volume in 1 second (FEV(1)) of at least 15% between bedtime and awakening in patients with clinical and physiologic evidence of asthma. Nocturnal symptoms are a common part of the asthma clinical syndrome; up to 75% of asthmatics are awakened by asthma symptoms at least once per week, and approximately 40% experience nocturnal symptoms on a nightly basis. An extensive body of research has demonstrated that nocturnal symptoms such as cough and dyspnea are accompanied by increases in airflow limitation, airway hyperresponsiveness, and airway inflammation. Treatment strategies in nocturnal asthma are similar to those used in persistent asthma, although dosing of medications to target optimum delivery during periods of nocturnal worsening is beneficial.

History and future perspectives of treating asthma as a systemic and small airways disease

Asthma is an inflammatory disorder in which the small airways of the lung play an important role. There is also evidence for the systemic nature of asthma. No current method adequately measures small airways function alone. Therefore, a combination of functional and clinical parameters should be used to ensure that patients with asthma are adequately treated with due consideration of the small airways. Previously therapeutic strategies have focused on bronchodilation and attenuation of airway inflammation. While early oral therapies had the advantage of reaching the small airways and treating the systemic aspect of asthma, they were associated with serious side-effects. Inhaled therapies were therefore developed to limit these effects. However, inhaled therapies have the disadvantage of limited penetration into the peripheral airways and an inability to treat the systemic component of asthma. They are also associated with local and systemic side-effects. The future for asthma treatment is likely to be a systemically administered medication with few side-effects targeting disease-specific mediators. The leukotriene receptor antagonists and anti-IgE monoclonal antibodies are examples of such therapies and the emergence of other new strategies is awaited.

The role of theophylline in asthma management

Views on the appropriate use of theophylline in asthma management have varied substantially over the past decades. The recent emphasis on potential anti-inflammatory effects of theophylline has only added to the debate. In current guidelines, theophylline has been positioned mainly as a form of "add-on" therapy in moderate to severe persistent asthma. The purpose of this review is to analyze whether recent developments have been made that allow for a further positioning of theophylline in the treatment of asthma.

Regulation of human mast cell and basophil function by cAMP

1. Mast cells and basophils are important in mediating allergic disorders such as asthma. Activation of these cells results in the release of a wide variety of mediators that can promote inflammatory responses. 2. Receptor-mediated activators of adenylate cyclase such as the beta-adrenoceptor agonist, isoprenaline, and prostaglandin E2 (PGE2) are effective at inhibiting mediator release from human lung mast cells (HLMC) but not basophils. In HLMC, both isoprenaline and PGE2 elevate and sustain increases in cyclic adenosine 3',5'-monophosphate (cAMP) whereas in basophils, both compounds cause transient increases in cAMP. 3. Non-selective inhibitors of phosphodiesterase (PDE) such as theophylline and 3-isobutyl-1-methylxanthine are effective inhibitors of mediator release from both HLMC and basophils and both compounds cause elevations of cAMP that are sustained in both cell types. 4. Studies with selective inhibitors of PDE indicate that the cAMP-specific PDE, PDE 4, regulates the activity of basophils but not HLMC. The nature of the PDE regulating HLMC responses is uncertain. 5. These data indicate that agents that induce and sustain elevations in intracellular cAMP attenuate the stimulated release of mediators from mast cells and basophils. However, the responsiveness of HLMC and basophils to selected cAMP-active agents differs.

Effects of inhaled salmeterol and salbutamol (albuterol) on morning dips compared in intensive care patients recovering from an acute severe asthma attack

OBJECTIVE

To assess the effect of a long-acting inhaled beta 2-agonist, salmeterol (SM), compared to a short-acting inhaled beta 2-agonist, salbutamol (or albuterol, SB) on the occurrence of morning dip (MD) in patients recovering from an acute severe asthma attack (ASA).

DESIGN

Prospective study.

SETTING

18-bed, medical intensive care unit (ICU) in a university hospital.

PATIENTS

19 patients suffering from an ASA.

INTERVENTIONS

Serial measurements of the peak expiratory flow rate (PEFR), arterial blood gases, vital capacity and forced expiratory volume in one second (FEV1) were performed from admission. All patients were first treated with i.v. methyl prednisolone and i.v. SB. Once the PEFR was stable and > 35% of predicted value, i.v. SB was stopped while i.v. steroids were maintained, and patients were randomised to either inhaled SB (9 patients, 400 micrograms every 4 h) or inhaled SM (10 patients, 100 micrograms every 12 h).

RESULTS

The mean admission PEFR was 26.1 +/- 11.7% of the predicted value and was not different between the two groups. MD was more frequent with SB (6/9 patients) than with SM (4/10). The severity of MD, expressed in l/min fall in PEFR, was higher in SB than in SM (106 +/- 25 vs 55 +/- 37; p < 0.05).

DISCUSSION

MD is frequent in ASA. In ASA, SM appears to reduce the frequency and the severity of MD more than SB. The clinical implications of this observation, particularly a lowering of mortality and a shortening of the ICU stay, remain to be investigated.

A double blind cross over trial of theophylline prophylaxis for sleep hypoxaemia in Duchenne muscular dystrophy

Twelve non-ambulant patients with Duchenne muscular dystrophy underwent a double-blind cross-over clinical trial of slow-release theophylline for the treatment of asymptomatic sleep hypoxaemia. Eight channel polysomnography was carried out at home to identify patients with sleep hypoxaemia and this was repeated whilst on the theophylline and placebo limbs of the trial. The trial design was effective in maintaining blinding but theophylline adversely affected sleep quality and sleep hypoxaemia. The overnight oxygen saturation was further reduced whilst on theophylline with reduced sleep efficiency and increased sleep fragmentation. This trial lends further evidence towards the theory that the underlying aetiology of sleep hypoxaemia is upper airway obstruction.

Current therapies for asthma. Promise and limitations

Effective treatments for asthma exist, but morbidity and mortality have continued to climb. Many attempts have been made to refine rather than change therapy over the past 20 years. Drugs currently used to treat asthma include beta 2-agonists, glucocorticoids, theophylline, cromones, and anticholinergic agents. For acute, severe asthma, the inhaled beta 2-agonists are the most effective bronchodilators. Short-acting forms give rapid relief; long-acting agents provide sustained relief and help nocturnal asthma; and serious adverse effects are rare when these drugs are used properly. First-line therapy for chronic asthma is inhaled glucocorticoids, the only currently available agents that reduce airway inflammation. Their side effects can be reduced by rinsing the mouth or by using large-volume spacers. Theophylline is a bronchodilator that is useful for severe and nocturnal asthma, but recent studies suggest that it may also have an immunomodulatory effect. Although theophylline is inexpensive, monitoring its plasma concentrations is both expensive and inconvenient. Cromones work best for patients who have mild asthma: they have few adverse effects, but their activity is brief, so they must be given four times daily. The anticholinergic bronchodilators are more useful for treating COPD than for chronic asthma. These drugs have virtually no side effects, and their onset is slower and their action longer than inhaled beta 2-agonists. The new direction in treating asthma will be orally administered medication that has few side effects and is targeted specifically to the pathogenesis of asthma.

Efficacy of salmeterol in the treatment of childhood asthma

The aim of the clinical study reported here was to investigate the efficacy of salmeterol, a new long-acting selective beta 2-agonist, in patients with bronchial asthma. Twenty-four children with moderate asthma were enrolled in the longitudinal study, consisting of a run-in period of 2 weeks followed by a treatment period of 4 weeks. Maintenance treatment consisted of inhaled corticosteroid and disodium cromoglycate, or both, at the same daily dose throughout the study. During the run-in period, the patients continued to inhale salbutamol when needed and some of them (37%) also received theophylline. They were subsequently treated with salmeterol 50 micrograms twice daily and prn salbutamol for 4 weeks. Efficacy was evaluated using symptom scores and pulmonary function tests including forced vital capacity parameters, pulmonary volumes, airway resistance and specific airway conductance that were measured sensitively by a whole body plethysmograph. As a result, salmeterol produced significant improvement in morning and evening peak expiratory flow rates, vital capacity, airway resistance, conductance and asthma symptoms versus salbutamol and theophylline. Adverse reactions were judged to be mild and few.

[Theophyllines of 12- and 24-hour sustained-release. Comparative study]

To compare 24-h and 12-h delayed-release theophylline in asthmatic patients, in terms of clinical stability and respiratory function, side effects and required dose, clinical tolerance and plasma concentrations. Patients with bronchial asthma in stable phase taking theophylline every 12 h were selected. Each patient received 12-h (treatment A) and 24-h (treatment B) theophylline formulas in a prospective, cross-over study with paired data for periods of 15 days. We evaluated theophylline doses, blood levels, clinical course, lung function and side effects. Twenty patients were enrolled. No significant differences between the two treatments were observed in mean dose of theophylline per kg body weight required to obtain therapeutic plasma concentrations (treatment A: 9.36 +/- 1.88 mg/kg/day; treatment B: 9.6 +/- 1.7 mg/kg/day). Mean blood level just before administration of a the next dose was lower with the 24-h formula, but still within therapeutic margins (treatment A: 7.31 +/- 2.27 micrograms/ml; treatment B: 10.66 +/- 2.86 micrograms/ml; p = 0.002). There were no differences in side effects after the adjustment period or in FEV1 after each treatment period. Peak expiratory flow remained stable during the study. The 24-h delayed release theophylline formula was similar to the 12-h formula in dose required by asthmatic patients and in therapeutic plasma concentrations throughout the day.

Controlled-release theophylline inhibits early morning airway obstruction and hyperresponsiveness in asthmatic subjects

BACKGROUND

Nocturnal asthma reflects the severity of the disease, and thus its pharmacologic prevention represents one on the main goals of asthma management.

SUBJECTS AND METHODS

To determine whether controlled-release theophylline inhibits the development of airway obstruction and/or airway hyperresponsiveness early in the morning, we examined 18 subjects reporting recurrent nocturnal asthma. In each subject, after five days' treatment with an 8 PM increasing dose of oral controlled-release theophylline, up to 10 +/- 1 mg/kg or placebo the night before the study day, we measured serum theophylline, FEV1 and PC20FEV1 at 6 AM, 2 PM and 10 PM.

RESULTS

At 6 AM, both FEV1 and PC20FEV1 were significantly higher on theophylline than on placebo (3.52 +/- 0.22 versus 3.17 +/- 0.25 L; P < .005 and 2.76 divided by 3.61 versus 1.55 divided by 3.73 mg/mL; P < .05, respectively). At 2 PM and 10 PM FEV1, but not PC20FEV1, was higher on theophylline than on placebo (3.73 +/- 0.21 versus 3.54 +/- 0.25 L; P < .05 and 3.40 +/- 0.22 versus 3.24 +/- 0.24 L; P < .05). Serum theophylline was 12.8 +/- 1.1 micrograms/ml, 8.9 +/- 0.77 and 9.5 +/- 0.85 at 6 AM, 2 PM and 10 PM, respectively.

CONCLUSIONS

We conclude that an evening dose of controlled-release theophyl line inhibits early morning airway obstruction and hyperresponsiveness, and that it may be helpful in the prevention of nocturnal asthma.

Clinical management of asthma in the 1990s. Current therapy and new directions

Asthma is a serious global health problem affecting nearly 100 million people worldwide. Its rising prevalence and associated morbidity and mortality are of increasing concern. Traditionally, symptomatic control of bronchoconstriction with beta 2 agonists and theophylline has been the mainstay of therapy. However, during recent years, inflammation has been recognised as the predominant cause of reversible airway obstruction and airway hyperreactivity. As a result, the emphasis in treatment has shifted to the early use of inhaled corticosteroids to control airway inflammation. beta 2 agonists are best used on an as-needed basis for the relief of acute bronchoconstriction and for the prevention of exercise-induced asthma. Sustained release theophylline or an inhaled long-acting beta 2 agonist may effectively control nocturnal symptoms. Preliminary studies involving agents active in the 5-lipoxygenase pathway as preventive therapy are encouraging. Further studies are needed to define their role in the management of asthma.

Conversion from twice- to once-daily extended-release theophylline treatment in patients with reversible airway obstruction

This multicenter, randomized, investigator-blinded, parallel group study compared the effects of converting patients from a q12h extended-release theophylline preparation (Theo-Dur) to a q24h extended-release product (Uni-Dur). Patients (n = 133) first received open-label Theo-Dur treatment with dosage titrated to achieve peak serum theophylline concentrations of 10-20 micrograms/ml. Patients then were randomized to continue Theo-Dur (n = 64) or to convert to Uni-Dur (n = 60) with peak serum theophylline concentrations maintained in the desired range. Pulmonary function tests were performed during the open-label and blinded periods; patients maintained diaries and performed peak flow measurements before each dose of study treatment. Adverse events were recorded throughout the study. Respiratory status during blinded treatment was rated as the same or improved compared with open-label treatment by > 87% of evaluable patients and physicians, regardless of treatment group. There were no significant differences in mean peak serum theophylline concentrations at baseline, at the final evaluation, or at any point during the study. Few dosage adjustments were necessary (5/52, Uni-Dur; 9/57, Theo-Dur). There were no significant changes in pulmonary function test results or patient diary entries between the open-label and blinded periods. Headache and nausea were the most commonly reported adverse events. In conclusion, converting patients from twice- to once-daily theophylline treatment resulted in no significant changes in any measures of pulmonary function, and there were no significant differences between the groups during the blinded treatment period.

Salmeterol in two different doses in the treatment of nocturnal bronchial asthma poorly controlled by other therapies

This study compared the efficacy of inhaled salmeterol (SM) 50 micrograms twice a day with SM 100 micrograms once a day (at night) and placebo in patients with poorly controlled nocturnal asthma despite treatment with corticosteroids, oral long-acting bronchodilators, or both. This was a two-center, double-blind, randomized, crossover study with three treatment periods, each of 3 weeks' duration. The first treatment period was preceded by two 1-week run-in periods, and the last treatment period was followed by a 2-week follow-up period. In the three treatment periods, patients received either SM 50 micrograms twice a day, SM 100 micrograms nightly, or placebo, in randomized order. Salbutamol metered-dose inhaler was given as relief medication. Of the 41 randomized patients, 38 were evaluable for more than one treatment period. Efficacy and safety were determined by daily record card data: morning and evening peak expiratory flow rates (PEFR), daytime and nighttime asthma symptom scores, and rescue salbutamol use. At clinic visits, FEV1 and FVC were measured, and the physicians' and the patients' respective assessments of the study mediation were noted. The study showed that the two doses, SM 50 micrograms twice a day and SM 100 micrograms nightly, were equally effective in controlling nocturnal asthma symptoms and were significantly better than placebo. SM was well tolerated, and no unexpected problems were revealed. The adverse events reported during this study were related either to the patient's underlying disease or to an intercurrent respiratory infection.

The efficacy and tolerability of inhaled salmeterol and individually dose-titrated, sustained-release theophylline in patients with reversible airways disease

In a double-blind, double-dummy, cross-over, multicentre study, 141 patients with moderate reversible airways disease were randomized to receive either 50 micrograms salmeterol via a metered dose inhaler or individually dose-titrated oral theophylline, both twice daily for a 2-week period. Just over half (n = 77) the patients had received theophylline before, but 64 patients were new to theophylline therapy. Efficacy was based on lung function data and symptom scores. Salmeterol produced significantly higher increase in mean morning peak expiratory flow (PEF) of 161 min-1 (P < 0.001; 95% Confidence Interval (CI); 8-241 min-1) and mean evening PEF of 151 min-1 (p < 0.001; 95% CI; 7-221 min-1) compared with theophylline therapy. Further analysis of the data revealed that the increase in PEF with salmeterol compared with theophylline was highest in a sub-group of patients new to theophylline therapy. Patients on salmeterol had significantly less night-time awakenings than those on theophylline (P = 0.011) and significantly less daytime symptoms (P = 0.017). There was also a significant increase in the number of nights (P = 0.013) and days (P < 0.001) on salmeterol when no additional salbutamol was required compared with theophylline. Theophylline produced a higher incidence of adverse events compared with salmeterol. The results of this study show that inhaled salmeterol is more effective and better tolerated than individually dose-titrated oral theophylline over a 2-week study period in patients with moderate asthma.

Salmeterol compared with slow-release terbutaline in nocturnal asthma. A multicenter, randomized, double-blind, double-dummy, sequential clinical trial. French Multicenter Study Group

The aim of the multicenter, randomized, double-blind, double-dummy, parallel-group clinical trial with a 2-week treatment period was to compare the efficacy and safety of salmeterol (50 micrograms twice daily) with slow-release (SR) terbutaline (5 mg orally, twice daily) in nocturnal asthma. A total of 159 asthmatic adults (FEV, 50-90% of predicted value; sex ratio: 0.87) with at least two nocturnal awakenings during a 7-d run-in period was included in the study. Patients were centrally randomized with a national computer network (Minitel). The main variable (number of awakening-free nights during the last week of treatment) was analyzed according to a sequential method with the one-sided triangular test. The number of awakening-free nights (+/- SD) was significantly higher in the salmeterol group: 5.3 +/- 2.4 vs 4.6 +/- 2.3 (P = 0.006). Salmeterol was significantly more effective than SR-terbutaline in the following factors: number of patients without any awakening during the last week of treatment (50% vs 27%, P = 0.003), mean morning PEF (351 +/- 109 l/min-1 vs 332 +/- 105 l/min-1, P = 0.04), PEF diurnal variation 6 +/- 10% vs 11 +/- 12%, P = 0.01), overall assessment of efficacy by the patient and the investigator (P = 0.001 and 0.005, respectively), and daily rescue salbutamol intakes (P = 0.004). In the salmeterol group, significantly fewer patients reported adverse events (16% vs 29%, P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Changing strategies in the management of asthma

Mortality from asthma is apparently on the rise and, in some cases, may be due to the type and amount of medication used by the patient. As a result, the role of some commonly prescribed agents has changed in recent years. In this article, the authors review modifications in the use of currently available drugs, discuss new applications of drugs not traditionally used for asthma, and examine the rationale behind the development of entirely new classes of drugs.

Double-blind randomized cross-over trial of nocturnal elixir theophylline supplementation of a twice-daily sustained-release theophylline tablet formulation in asthmatic patients

Sixteen asthmatic patients with normal diurnal activity between 05:00 and 23:00 h participated in this randomized, multiple-dose, double-blind, placebo-controlled, crossover study of the pharmacokinetics and efficacy of evening supplementation of a 12-hourly sustained-release theophylline (SRT) regimen with a nonsustained-release theophylline (NSRT) formulation. The treatments were Nuelin SA (SRT) every 12 h plus, in the evening, either placebo or an additional dose of Nuelin liquid (NSRT), determined to raise the early morning (0300) plasma theophylline concentration (PTC) to 18 micrograms/ml by using the dose-concentration prediction equation established in a study conducted on healthy volunteers and reported in this journal. The 11-day trial included two 24-h inpatient periods during which PTCs and lung functions (PEF, FEV1, FEF25-75, and FVC) were determined every 2 h. The value of the prediction equation was confirmed when the early morning PTC, after evening supplementation with Nuelin Liquid, was raised nearly to the targeted 18 micrograms/ml. The nocturnal peak-to-trough fluctuation in PTC was larger during additional treatment with Nuelin liquid, but the nocturnal peak-to-trough fluctuation in lung function parameters decreased. Overall, airflow during the early morning hours (0100-0500) significantly improved during this chronotherapeutically optimized treatment of adding an NSRT product to the evening dose of a 12-hourly SRT regimen.

Current issues in the use of theophylline

Theophylline is a safe and effective medication for the management of chronic asthma. It reduces nocturnal bronchospasm and airways hyperresponsiveness, and its addition to effective doses of beta-agonists and corticosteroids leads to further improvement in symptom control. These properties are the result of actions other than simple bronchodilation, and there is a strong possibility that anti-inflammatory activity accounts for its clinical advantages. Serious side effects are uncommon and their rate can be further reduced through appropriate precautions. Recent studies have alleviated the concern over cognitive and behavioral side effects in children.

Theophylline effect on sleep in normal subjects

In an effort to isolate the effect of theophylline on sleep from the effect of asthma, we examined the impact of oral theophylline on sleep quality in normal, nonasthmatic subjects. Ten healthy, nonsmoking, male subjects ranging in age from 23 to 35 were studied. The subjects were randomly divided into two groups and studied in a double-blinded, crossover designed protocol. Each group underwent two consecutive nights in the sleep laboratory. Group one received four doses of 300 mg of sustained-release theophylline at 12-h intervals prior to the study night. Group two received a placebo. After 14 days, the patients crossed over to the other group, and the procotcol was repeated. The mean serum theophylline level on the morning following the study night was 7.85 +/- SD 2.12 micrograms/ml, with a range of 5.1 to 12.1 microns/ml. The analysis of variance for a crossover design showed no order effect. The analysis for drug effect showed that theophylline administration resulted in a statistically significant adverse effect on arousals per sleep hour (19.3 vs 15.9 for placebo, p = .006) and total sleep time (370.9 min vs 399.45 min for placebo, p = .015). Comparing the sum of ranks data, theophylline was found to have a significant adverse effect on sleep quality (p = .036). We conclude that low doses of oral theophylline result in a significant disturbance in sleep quality in normal nonasthmatic subjects.

Theophylline. Current thoughts on the risks and benefits of its use in asthma

Theophylline and its derivatives have been used in the treatment of asthma for over 50 years, but since the advent of more potent bronchodilators their use has become cloaked in controversy. Their continued existence results from their undoubted usefulness in severe acute asthma, nocturnal asthma, childhood asthma and moderate to severe chronic airflow limitation, and because of habitual use by physicians in other situations. The precise mechanism of action of theophylline remains uncertain. The role of phosphodiesterase inhibition and adenosine antagonism has been reviewed and the clinical significance of the anti-inflammatory action of theophylline discussed. Theophylline has unpredictable metabolism when first administered, and continued monitoring of drug concentrations is essential. Commonly encountered adverse effects may occur at therapeutic serum concentrations, frequently necessitating drug withdrawal. The overlapping therapeutic and toxic theophylline serum ranges can lead to life-threatening adverse effects at the upper end of the therapeutic range, especially in the elderly in whom special precaution is required.

Alternative treatments for asthma: assessing the need

Alternative treatments such as troleandomycin methotrexate, gold, and intravenous gamma globulin are sometimes considered for severe asthmatics to minimize the need for systemic corticosteroids and reduce adverse effects. These alternative therapies may also be associated with significant toxicity and expense. The ability to reduce corticosteroid use and the need for alternative treatment interventions in 125 pediatric patients at our institution were reviewed. Because corticosteroid requirements were reduced significantly, only 23 of 125 children evaluated were considered for treatment alternatives with only 10 receiving such therapy. This study emphasizes the importance of a thorough and comprehensive review of corticosteroid requirements and usage prior to initiating alternative approaches to treatment in moderate to severe asthmatics as well as in patients thought to be "steroid-dependent."

Pathogenesis of asthma: therapeutic implications

The current knowledge of asthma, specifically an appreciation of the contributing mechanisms leading to its development as well as its clinical features, has increased vastly in recent years. A better understanding of asthma's inflammatory nature has resulted in wider use of antiinflammatory agents. Specific effects of available antiasthma medications have been better elucidated, thereby helping to focus the development of newer drugs and improve the use of currently available therapeutic agents. The purpose of this article is to further understanding of asthma by providing the pathologic and physiologic basis of this disease. This is vitally important information as it is shaping the directions of the therapeutic approach to asthma care.

Chronotherapy of reversible airways disease with once-daily evening doses of a controlled-release theophylline preparation

1. Asthma and COPD worsen at night and in the early morning, due to various circadian influences. 2. Uninterrupted sleep, stable lung function over 24 h, and reduced and stable airways responsiveness are primary therapeutic goals in asthma and COPD. 3. Once-daily evening theophylline chronotherapy meets these goals, providing rising blood levels at night and in the early morning, when most needed. 4. This regimen is now indicated for morning and evening dosing for reversible airway obstruction, in the United States and Canada, and marks the first available treatment for these diseases to include dosing time in the therapeutic strategy. It reflects increasing recognition by the medical community of the need to consider the individual patient's timing of symptoms in relation to the kinetics of the drug. 5. Theophylline chronotherapy is as well tolerated as more frequently administered methylxanthine preparations despite the relatively large single doses required by the prolonged dosing interval. The convenience of once-daily administration favors drug-taking compliance. 6. Theophylline chronotherapy does not provide constant blood levels over the 24-h day. Indeed, by improving lung function by means of a larger peak-to-trough difference than associated with twice-daily theophylline, once-daily chronotherapy has altered our thinking about theophylline pharmacodynamics.

Theophylline analysis at the chest clinic--comparison of a portable versus conventional system

The running cost and clinical application of a new, portable, direct-injection, high-performance, liquid chromatograph for the measurement of theophylline was compared with conventional laboratory-based analysis by studying the two methods in two parallel chest clinics. Thirty-six patients were managed with the portable method and 33 by the conventional system. They were already receiving theophylline preparations for treatment of their asthma or chronic airflow limitation. Over the 12-week period of study, the percentage of patients with levels in the therapeutic range rose from 33% to approximately 87% in both clinics, but this change was achieved in only 6 weeks using the portable system. Patients whose theophylline levels were increased into the therapeutic range had improved symptom scores as measured by visual analogue scales but we were unable to demonstrate any significant change in spirometry. The cost of the portable system compared favourably with laboratory analysis, and had the additional benefit of quicker detection of non-compliance and facility for discussion with the patients at the time of consultation.

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.

Long-term management of reversible obstructive airways disease in adults

The goals of the long-term management of reversible obstructive airways disease (ROAD) are to find the minimum treatment that controls symptoms, allows resumption of normal life, prevents severe attack and death, and controls airflow obstruction. ROADs include asthma, chronic bronchitis, and emphysema. Although the differential diagnosis between these different entities may be difficult, they share the same possibilities of pharmacotherapy, including bronchodilator and antiinflammatory drugs. beta 2-agonists administered via inhaled route produce the best bronchodilator/side effects ratio, provided that the drugs reach the bronchi. This underlines the importance of a proper inhalation technique when using a metered-dose inhaler. In patients with hand-breath coordination problems, powder inhalers or spacer devices are useful to ameliorate the therapeutic efficacy of inhaled drugs. Anticholinergic agents are usually less potent bronchodilators than inhaled beta 2 agonists in asthma, but they may have additive effects when associated with beta 2 agonists. Only a therapeutic trial with peak-flow monitoring can demonstrate the efficacy of anticholinergic drugs in individuals. Theophylline's kinetics are characterized by a narrow therapeutic index with high inter- and intraindividual variabilities. Sodium cromoglycate and nedocromil sodium are antiallergic drugs, the efficacy of which has been demonstrated in controlled studies. Corticosteroids are the most efficient anti-asthma drugs. Inhaled corticosteroid dosing should be tailored to each individual. If inhaled corticosteroid therapy is used in an oral corticosparing attempt, patients should be followed-up during several months. The management of ROAD includes the diagnostic procedures, the identification of triggers and inducers of airways obstruction, the assessment of severity of the disease, and then the treatment and education of the patient. Strategy design to achieve proper use of drugs by patients is discussed.

A single oral dose method for predicting steady state theophylline concentrations in clinical practice

A single dose, single point method of predicting patients' oral maintenance theophylline dosage has been compared with a noninvasive method. Twenty patients with obstructive lung disease received an oral dose (6 mg kg-1) of micro-crystalline theophylline. The plasma theophylline concentration after 8-10 h was then used to calculate the optimum maintenance dose of sustained release aminophylline required to achieve steady state concentrations between 55 and 110 mumols l-1. The mean steady state plasma theophylline concentration for this dosage schedule was also predicted by a method using population average pharmacokinetic parameters (assumed clearance method). These predictions were then compared with observed concentration-time profiles at steady state. The mean difference between the observed values and those predicted from a morning test dose was -0.11 mumol l-1 (95% CI -7.0 to +7.2). A larger difference (-7.4 mumol l-1 95% CI -18.2 to +3.4) was found for the assumed clearance method. Since the confidence intervals contain zero, these differences are not significantly different from zero at the 5% level, although the morning test dose method allowed prediction of the whole concentration-time profile and was more precise. An evening test dose was also used in the study, but the mean difference between the observed values and those predicted from this method was larger at -24.8 mumol l-1 (95% CI -32.89 to -17.21) and was significantly different from zero. This study indicates that a morning test dose followed by a single blood sample can be used to establish maintenance theophylline therapy quickly and safely in selected patients.

Once-daily theophylline in the treatment of nocturnal asthma

The efficacy and side-effects of individually adjusted doses of controlled-release theophylline given once daily in the evening (average dose 650 mg) were compared with those of standard treatment with controlled-release terbutaline 7.5 mg b.d. Thirty-six asthmatics with regular morning obstruction ("morning dipping") were studied over two treatment periods each of two weeks, according to a crossover, randomized, double blind design. Morning peak expiratory flow (PEF) was slightly but significantly higher with theophylline (363 l.min-1) than terbutaline (342 l.min-1). Feelings of dyspnoea on waking in the morning were also less pronounced with theophylline. There were no other differences between the treatment periods during the day or night, with respect to dyspnoea or any the other symptoms. Side-effects were mild and were reported with similar frequencies during both treatments. It is concluded than an individually adjusted dose of once-daily theophylline administered in the evening is at least as effective as conventional therapy with controlled-release terbutaline in preventing nocturnal and early morning asthma, when both drugs are added to regular medication with inhaled sympathomimetics and steroids.

Predictability and intraindividual variability of serum theophylline concentrations in patients with obstructive lung disease: 12-h versus 24-h dosing

The predictability and intraindividual variability of serum theophylline concentrations (STC) after different dosing schedules were investigated in 24 patients with chronic obstructive lung disease (COLD). Three oral regimens were compared in 3 groups of 8 randomly assigned patients. Group I:Drug A once daily in the evening; Group II: Drug A b.d.; Group III: Drug B b.d. The doses for each patient were estimated by Bayesian forecasting aiming at an STC of 10-15 mg/l. STC and FEV1 were measured on two consecutive days at steady-state. The day-to-day variability of STC was less than 20% in all three groups. The within-day fluctuation in Group I amounted to 259% (median) compared to 57% and 38% in Groups II and III, respectively. Dose adjustment by Bayesian forecasting resulted in a therapeutic STC in most patients with a b.d. regimen, whereas for the once daily dose the prediction was not satisfactory. No difference in lung function was found between the 24-h and 12-h dosing, probably because of the large intersubject variability in FEV1. Therefore, the question whether the differences in STC profile are of clinical importance in COLD can only be investigated in a larger group of patients.

Nocturnal oxygen saturation and body movement in asthmatics treated with controlled-release preparations of theophylline or terbutaline

Nine adult asthmatics with a history of nocturnal symptoms and with morning dips in peak expiratory flow (PEF) were treated for 10-14 days with 24-h controlled-release preparation of theophylline (Th), or a controlled-release preparation of terbutaline (Te), in a double-blind cross-over experiment. During treatment with 450-900 mg Th in the evening morning, plasma drug levels ranged from 53-95 (mean 73) mumol/l. The Te dose was 7.5 mg twice daily. Morning PEF values during Th (mean 338 l.min-1) and Te (316 l.min-1) were not significantly different. There were no significant differences between the treatments in average nocturnal oximetric O2 saturation (91.9% during Th and 91.0% during Te), or the amount of nocturnal body movement, recorded with a static charge sensitive bed (total number of movements 146 during Th and 120 during Te). No difference between the treatments was seen with respect to assessment by the subjects of sleep quality, which was considered fair or good. The findings suggest that in moderately severe asthma, nocturnal oxygenation and sleep quality were similar during the two treatments.

Management of asthma and chronic airflow limitation. Are methylxanthines obsolete?

After almost 50 years as first-line drugs in the management of asthma and COPD, methylxanthines have been largely superceded by inhaled adrenoceptor agonist and anticholinergic bronchodilators which are more potent and far less toxic. Accumulating evidence indicates that intravenous theophylline contributes side effects, but is rarely of benefit in acute exacerbations of asthma or COPD. In the maintenance therapy of asthma, first-line therapy is dose-optimized inhaled steroids, reducing the need for bronchodilators. Inhaled adrenoceptor agonists are second line medications, anticholinergic aerosols third line, and theophylline, if needed at all, may fulfill a minor systemic steroid-sparing function in severe asthmatics on maximum doses of the inhaled medications. In the maintenance therapy of some patients with COPD, theophylline sometimes may be useful but these responders should be identified by objectively establishing therapeutic benefit. Since many patients have side effects from the methylxanthines, while their therapeutic benefit over and above dose-optimized inhaled therapy is marginal, their continued almost routine use in the management of reversible airflow obstruction is hard to justify, although this class of drugs may be useful in selected patients in whom both subjective and objective benefit can be demonstrated. In COPD, theophylline may improve exercise capacity in some patients by still incompletely understood mechanisms probably unrelated to bronchodilation.

Controlled-release theophylline in the treatment of nocturnal asthma

A total of 104 asthmatic patients with symptoms of asthma and/or a 'morning dip' in the peak expiratory flow rate (PEFR) who were receiving multiple therapies, including inhaled or oral steroids, were treated in addition once nightly with controlled-release theophylline in an 8-week double-blind, placebo-controlled cross-over study. Theophylline produced an improvement in symptoms of cough, wheeze, sleep disturbance and PEFR in the 73 completing patients compared to run-in and placebo treatment. Theophylline also produced an improvement in the forced expiratory volume in 1 s and forced vital capacity relative to baseline, and in the difference between actual and predicted PEFR values. Nausea was the most frequent side-effect but both patients' and investigator's global impressions of the effect of study medication were in favour of theophylline.

Theophylline in the management of airflow obstruction. 2. Difficult drugs to use, few clinical indications

The narrow therapeutic index, potential toxicity, and need to monitor plasma concentrations make theophyllines difficult to use. Other drugs provide comparable or better bronchodilator and prophylactic efficacy. In asthma theophyllines should be considered for chronic stable asthma when treatment with optimal doses of inhaled steroids and bronchodilators fails to provide adequate control; for nocturnal asthma; and for prophylaxis and relief of symptoms in children and adults when inhaled treatment cannot be given. In general, theophyllines cannot be recommended for chronic airflow obstruction. A trial of theophylline is reasonable in individual patients whose symptoms remain troublesome despite a trial of steroids and optimal doses of inhaled bronchodilators.

Formoterol, a new long acting beta 2 agonist for inhalation twice daily, compared with salbutamol in the treatment of asthma

Sixteen patients with stable chronic asthma participated in a double blind crossover study comparing the new inhaled long acting beta 2 agonist formoterol with salbutamol. Inhaled (n = 15) and oral steroid (n = 1) treatment were maintained at the same daily dose throughout the study. For four weeks the patients received either formoterol 24 micrograms twice daily or salbutamol 400 micrograms twice daily, plus additional puffs (with the same drug) when needed. Asthma symptoms, additional puffs of beta 2 agonist, peak expiratory flow (PEF), and side effects were recorded daily. During treatment with formoterol the patients used fewer additional puffs of beta 2 agonist, had better symptom scores, less disturbed sleep, more days without additional aerosol, and higher PEF both morning and evening than during salbutamol treatment. Thus formoterol 24 micrograms twice daily gave long lasting bronchodilatation and asthma symptoms were well controlled with regular twice daily administration.

Sleep disturbances in patients with asthma

The prevalence of sleep complaints and sleep disturbances was studied prospectively in 98 consecutive adult asthmatic patients (mean age 45 years, 46% men) attending an out-patient clinic by means of questionnaires and sleep diaries. The results were compared with those from an age- and sex-matched group of 226 healthy individuals. The most common sleep disturbances among the asthmatic patients were early morning awakening (51%), difficulty in maintaining sleep (DMS; 44%) and daytime sleepiness (44%). With decreasing asthma control (i.e. increased number of acute asthmatic attacks) there was an increase of DMS, nocturnal wakefulness, nocturnal breathing problems and bronchodilator inhalations at night. A decrease in estimated sleep time (P less than 0.05) and increase in nocturnal wakefulness (P less than 0.05) was seen with decreasing daytime FEV1--measured as percentage of the predicted value (%FEV1). There was also significant correlation between increasing age and decreasing %FEV1 (P less than 0.01). Among the 26 patients who were only taking one oral bronchodilator, no definite difference regarding sleep quality was found between those treated with theophylline and those taking an oral beta 2-agonist. The prevalence rates of DIS, DMS and daytime sleepiness were about twice as high among the asthmatic patients than in the healthy population. It is concluded that impaired quality of sleep, with disturbed sleep during the night, early morning awakenings and daytime sleepiness, is common among patients with bronchial asthma.

A new approach to the treatment of asthma

Asthma is a chronic inflammatory condition. The previous emphasis on bronchodilator therapy, which does not treat the underlying inflammation, may be misplaced. Earlier introduction of antiinflammatory agents, such as corticosteroids or cromolyn sodium, is strongly recommended. Effective suppression of airway inflammation reduces the need for bronchodilator therapy and may reduce the morbidity and, perhaps, mortality of asthma.

Theophylline disturbs sleep mainly in caffeine-sensitive persons

In order to study effects of theophylline on sleep, a randomised double-blind cross-over study with slow release theophylline vs. placebo was performed on 13 healthy male volunteers (mean age 24 years), eight of whom were considered caffeine-sensitive and five caffeine-insensitive. A sleep diary was filled in during the entire period. At the end of each 2 week study period a sleep questionnaire was filled in and a sleep recording was conducted. Seven of the eight caffeine-sensitive persons reported that their sleep was disturbed during the theophylline period, while none of the five caffeine-insensitive experienced any difference between the periods. Analysis of the sleep diaries (mean +/- SD) revealed a significant increase in sleep latency (16 +/- 11 vs 4 +/- 7 min) and decrease in sleep efficiency (95 +/- 3 vs 98 +/- 3%) among the caffeine-sensitive persons during the theophylline period compared with the placebo period, while no such difference was found among the caffeine-insensitive. We conclude that theophylline seems to disturb sleep mainly in caffeine-sensitive persons.