Timing of once-a-day theophylline dose to match peak blood level with diurnal variation in severity of asthma

The impact of reducing dose frequency on health outcomes

BACKGROUND

Dosing schedules may be one important factor determining whether patients take their prescribed medication. Schedules may influence whether a patient stays on the prescribed therapy and, if so, the degree to which the regimen is followed. Both factors are important determinants of health outcomes and health care costs.

OBJECTIVE

The goal of this study was to investigate the impact of reducing dose frequency on health outcomes and health care costs.

METHODS

Articles from peer-reviewed journals were identified from the medical literature databases MEDLINE, International Pharmaceutical Abstracts, and HealthSTAR for the years 1985 through 2002. The search included all references that reported on the impact of a change of dose frequency on chronic disease. Search terms used were combinations of dose frequency, dose schedule, and dosing and efficacy, safety, clinical effectiveness, preferences, adherence, compliance, persistence, health-related quality of life, patient satisfaction, resource use, and costs.

RESULTS

Reducing the number of daily doses through extended-release formulations or newer drugs has frequently been shown to provide the patient with better symptom control in a number of disease states. Overall improvements were seen in adherence, patient quality of life, patient satisfaction, and costs. However, results of some studies indicate that not all patients, medications, or diseases may be candidates for reduced dosing due to the potential effects on symptom control, incidence of adverse events, and overcompensation for missed doses.

CONCLUSION

Where feasible, reducing dose frequency may offer benefits for the patient in terms of health outcomes and for the health care budget holder in terms of costs.

Pathophysiology of nocturnal asthma

LEARNING OBJECTIVES

This article will focus on the pathophysiologic changes underlying the nocturnal worsening of asthma and the therapeutic approach to this disorder.

DATA SOURCES

Selected articles appearing since 1985 dealing specifically with the underlying pathologic features and therapy of nocturnal asthma.

STUDY SELECTION

Studies that aimed to elucidate the pathologic features, mechanisms, and therapeutic strategies for the treatment of nocturnal asthma are summarized.

RESULTS

Nocturnal asthma is associated with significant decline in pulmonary function and increase of airway inflammation at night. The administration of medications must be designed to achieve the maximal effect during the night in nocturnal asthma.

CONCLUSIONS

The further elucidation of the reasons underlying nocturnal asthma should lead to more specific therapeutic interventions with maximal effect at night.

Effect of once daily and twice daily sustained release theophylline formulations on daytime variation of bronchial hyperresponsiveness in asthmatic patients

BACKGROUND

Previous studies evaluating spirometric values and symptoms have shown that once daily theophylline administered in the evening produces greater stabilisation of the airway function in asthmatic patients than the prototype theophylline given twice a day. The aim of this study was to compare the effects on bronchial responsiveness to methacholine of an ultrasustained release theophylline formulation (Diffumal-24, Malesci, Florence, Italy) administered once a day, a sustained release theophylline formulation (Theo-Dur, Recordati, Milan, Italy) administered twice a day, and placebo.

METHODS

The study was performed in 12 adult patients with asthma using a randomised, double blind, three phase, cross-over design. Each phase lasted seven days and was followed or preceded by at least three days of theophylline washout. Diffumal-24 was administered once a day at 20.00 hours whereas Theo-Dur was given twice a day at 08.00 hours and 20.00 hours. In each patient the total daily dose of theophylline was the same during both phases. The dose of the two active preparations was titrated to individual needs before the beginning of the study and then given in divided or once daily doses. At 08.00, 14.00, and 20.00 hours on day 7 of each phase serum theophylline concentrations were measured and spirometric tests (FEV1) and bronchial challenge with methacholine were also performed.

RESULTS

When the administration of Diffumal-24 was compared with that of Theo-Dur, a higher serum theophylline concentration of the former was seen in the morning whereas at 20.00 hours the reverse was true. Compared with placebo, at 08.00 hours Diffumal-24 improved FEV1 whereas Theo-Dur did not (difference between treatments 0.29 1, 95% CI 0.12 to 0.45). At 08.00 hours Diffumal-24 decreased bronchial sensitivity to methacholine, expressed as a natural logarithm of PD20, to a greater extent than Theo-Dur (difference between treatments 0.54 log units, 95% CI 0.016 to 1.08). The morning advantage observed with Diffumal-24 administration was not associated with a deterioration in the state of the airway during the daytime, the protective activity against methacholine during the 12 hours of the monitoring period being constant. Furthermore there was no difference in the mean FEV1 between the two treatments at 14.00 and 20.00 hours.

CONCLUSIONS

In adults with stable bronchial asthma treatment with a single dose of Diffumal-24 administered in the evening improved airflow obstruction and reduced bronchial hyperresponsiveness.

Treatment of nocturnal asthma by addition of oral slow-release albuterol to standard treatment in stable asthma patients

Nocturnal and early-morning complaints in asthma patients are sometimes difficult to treat. We investigated the efficacy of an oral osmotically controlled release (OR) formulation of albuterol 8 mg in 35 patients with stable asthma and nocturnal complaints and/or morning dipping of the peak expiratory flow (PEF). The mean age was 45 years (range 22-70), the FEV(1) was 61 +/- 20% of predicted, and inhaled steroids were used by 32 patients. Albuterol OR was added to their usual treatment. The use of theophyllines and oral adrenergics was not allowed. Twice-daily (b.i.d.) dosing was compared to one dose at night and to placebo. The three-period crossover study was double-blind placebo-controlled with treatment periods of 2 weeks. Responses have been analyzed by means of multiple regression analysis at a significance level of 5%. There was no significant difference of the FEV(1) or the weekly means of PEFs between the periods. During the b.i.d. treatment, the daytime and nocturnal symptom scores, used rescue medication, subjective sleep quality, and nocturnal waking tended to be better. Mental fitness was improved, but significantly only in the morning. We concluded that additional treatment with albuterol 8 mg OR once or twice daily did not lead to an overall clinical improvement in this group of patients with nocturnal asthma during standard treatment. In view of the tendency to improvement, it may be worth trying this treatment in individual patients.

Chronobiology and chronotherapy in medicine

There is a fascinating and exceedingly important area of medicine that most of us have not been exposed to at any level of our medical training. This relatively new area is termed chronobiology; that is, how time-related events shape our daily biologic responses and apply to any aspect of medicine with regard to altering pathophysiology and treatment response. For example, normally occurring circadian (daily cycles, approximately 24 hours) events, such as nadirs in epinephrine and cortisol levels that occur in the body around 10 PM to 4 AM and elevated histamine and other mediator levels that occur between midnight and 4 AM, play a major role in the worsening of asthma during the night. In fact, this nocturnal exacerbation occurs in the majority of asthmatic patients. Because all biologic functions, including those of cells, organs, and the entire body, have circadian, ultradian (less than 22 hours), or infradian (greater than 26 hours) rhythms, understanding the pathophysiology and treatment of disease needs to be viewed with these changes in mind. Biologic rhythms are ingrained, and although they can be changed over time by changing the wake-sleep cycle, these alterations occur over days. However, sleep itself can adversely affect the pathophysiology of disease. The non-light/dark influence of biologic rhythms was first described in 1729 by the French astronomer Jean-Jacques de Mairan. Previously, it was presumed that the small red flowers of the plant Kalanchoe bloss feldiuna opened in the day because of the sunlight and closed at night because of the darkness. When de Mairan placed the plant in total darkness, the opening and closing of the flowers still occurred on its intrinsic circadian basis. It is intriguing to think about how the time of day governs the pathophysiology of disease. On awakening in the morning, heart rate and blood pressure briskly increase, as do platelet aggregability and other clotting factors. This can be linked to the acrophase (peak event) of heart attacks. During the afternoon we hit our best mental and physical performance, which explains why most of us state that "I am not a morning person." Even the tolerance for alcohol varies over the 24-hour cycle, with best tolerance around 5 pm (i.e. "Doctor, I only have a couple of highballs before dinner"). Thus, all biologic functions, from those of the cell, the tissue, the organs, and the entire body, run on a cycle of altering activity and function.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Comparative pharmacokinetics of morning and evening doses of once-a-day theophylline capsules

The objective of this study was to determine if the theophylline diurnal variation that has been observed primarily between morning and evening doses of twice-a-day products could be overcome by a once-a-day formulation. Eighteen healthy, nonsmoking, adult male subjects were given 900-mg theophylline doses as three 300-mg once-a-day theophylline capsules in the morning or evening for 5 days in a single-blind fashion. Matching placebo capsules were administered midway between each dose of active drug. Predose theophylline serum levels on day 3-6 were statistically equivalent within each treatment, indicating that approximate steady-state conditions were achieved by day 3. Mean serum level profiles over the 24-h interval following the active dose on day 5 were almost superimposable for the morning and evening treatments. All pharmacokinetic parameters were equivalent between the treatments, except for the time to peak serum level (Tmax), which was significantly shorter for the morning dose. Given the flatness of the serum level curves for both treatments, the Tmax difference was judged to be clinically unimportant. A small peak-trough level fluctuation of about 50% was seen with each treatment. We conclude that by designing a dose form in which drug release was the rate-limiting step in drug absorption, the diurnal variation commonly associated with theophylline formulations may be eliminated.

Therapeutic controversies in the treatment of asthma

OBJECTIVE

To introduce readers to the current controversial topics in the area of asthma therapy. Background is provided such that clinicians are aware of these issues and can make rational decisions.

DATA SOURCES

Pertinent articles were individually identified and reviewed from each journal.

STUDY SELECTION

Relevant studies, determined by topic and other specific criteria, e.g., testing methodology, were included.

DATA SYNTHESIS

Further investigation is required in the areas discussed. Systemic effects, specifically growth suppression (in children), adrenal suppression, and osteoporosis, have been demonstrated with high-dose inhaled glucocorticoids; however, the clinical relevance of such intravenous glucocorticoid formulations via nebulizer have not been demonstrated. Likewise, data on the equivalence of the inhaled glucocorticoids, with regard to efficacy and potential systemic effects, and the differences between metered-dose inhalers and dry powder inhalers, with regard to aerosol characteristics and drug delivery, are unclear. Theophylline, when used with inhaled beta-adrenergic agonists and systemic glucocorticoids for the treatment of acute asthma, as not been shown to provide clear benefit and may result in increased adverse effects. The use of regular (vs. "as needed" or prn) inhaled beta-adrenergic agonists, although shown in two studies to be detrimental to the control of asthma and result in an increased risk of death or near death caused by asthma, has not been conclusively demonstrated to be harmful.

CONCLUSIONS

Monitoring for adverse effects and the use of techniques to minimize systemic absorption (spacers and mouth rinsing) are recommended when high-dose inhaled glucocorticoid therapy is used. Intranasal and intravenous glucocorticoid products are not recommended for administration via nebulizer because of safety concerns. Until further data are available, inhaled glucocorticoids are thought to be equivalent on a microgram-per-microgram basis rather than an actuation-per-actuation basis. Theophylline is no longer recommended for treatment of acute exacerbations in nonhospitalized patients not already receiving the medication, and the link between deterioration of asthma control (and the risk for death) and regular inhaled beta-adrenergic agonists appears weak.

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.

Plasma theophylline concentrations and airway function in asthmatic children receiving standard and modified RTC therapy

The effects of three different dosage schedules for sustained-release theophylline (Theolong) were investigated in children with asthma. With regimen II (unequal doses at 0800 h and 2000 h), the maximum plasma theophylline concentration following the evening dose was significantly higher than that following the morning dose, and also was larger than that following the evening dose with regimen I (equal doses at 0800 and 2000 h). With regimen III (equal doses at 0600 h and 2100 h), the mean theophylline concentration-time curve showed a single large peak at 1100 h, whereas with regimen I, there were two peaks at 2300 and at 1400 h. Knowledge that a change of the dosage schedule can affect the pharmacokinetics of theophylline in this way should aid physicians in its safe and effective use.

Conversion of COPD patients from multiple to single dose theophylline. Serum levels and symptom comparison

The objective of the present study was to determine if patients with COPD who were taking Theo-Dur bid or tid (total dose 400 to 900 mg per day) could be safely switched to Uni-Dur, 800 mg given qd at bedtime. Twenty-eight patients were enrolled in the study, and 23 completed the study. The mean daily dose of theophylline prior to the study was 828 mg, while the mean dose after three weeks of Uni-Dur therapy was 783 mg. The mean serum theophylline level 10.5 +/- 3.6h after the last Theo-Dur dose was 10.5 mg/L. After three weeks of Uni-Dur therapy, the mean theophylline level at 8:00 AM was 14.6 mg/L, while the mean theophylline level at 8:00 PM was 9.9 mg/L. This latter level did not differ significantly from that obtained at the start of the study 10.5 +/- 3.6 h after the last dose of Theo-Dur. After three weeks of Uni-Dur therapy, the peak expiratory flow rate, the FEV1, and the FVC were not significantly changed from those at the initial evaluation. Twenty-one of the 23 patients ended up receiving 800 mg Uni-Dur qd. From this study, we conclude that once daily theophylline dosing with Uni-Dur compared with bid or tid dosing with Theo-Dur produces similar theophylline levels and pulmonary function, and most COPD patients who are taking 400 to 900 mg Theo-Dur daily can be managed with 800 mg Uni-Dur once daily at bedtime.

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.

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.

Circadian variations in theophylline concentrations and the treatment of nocturnal asthma

The nocturnal worsening of asthma is a common problem that can be difficult to treat. Two different sustained-release theophylline preparations were used to determine (1) if the serum theophylline concentrations (STC) depend on the type and dosing schedule of the preparation, (2) the relationship between STC and the circadian variations in asthma, and (3) the effect of STC on sleep quality and respiratory patterns during the night. In 16 subjects with nocturnal asthma, the STC were significantly higher during the daytime on twice-daily versus once-daily theophylline preparations given at 7 P.M., but the FEV1 values were similar. During the night, the STC were significantly higher with the once-daily regimen, and the awakening FEV1 value was also improved (p less than 0.05). All polysomnographic variables were similar between the two preparations, except that with the once-daily preparation there was a decreased number of hypopneas (p less than 0.05) and fewer minutes below an oxygen saturation of 90% (p less than 0.05). We conclude that patients with nocturnal asthma need their treatment focused on the nocturnal portion of the circadian cycle and that higher STC during this critical time period are beneficial without interfering with sleep quality.

Safety and efficacy of once-daily Uniphyl tablets compared with twice-daily Theo-Dur tablets in elderly patients with chronic airflow obstruction

Oxygen desaturation and subclinical coronary artery disease may predispose older patients with chronic airflow obstruction to cardiac arrhythmias, especially when high concentrations of theophylline are present in the blood. To assess the safety and efficacy of Uniphyl tablets, an oral theophylline preparation formulated for once-daily dosing, in elderly patients with chronic airflow obstruction, we conducted a randomized, three-phase, double-blind crossover study comparing evening dosing with Uniphyl tablets, Theo-Dur tablets administered twice daily, and placebo. The patients in the study were scheduled to receive each treatment for two weeks. Each day, symptoms, side effects, peak expiratory flow rates, and use of metered-dose inhalers were recorded. Near the end of each phase, serum theophylline concentrations were measured every two hours between 8:00 A.M. and 8:00 P.M. on two consecutive days. The patients underwent ambulatory Holter monitoring during the final 48 hours of each phase. Twelve patients completed the active-drug phases of the study, but seven of the 12 were removed from the placebo phase because of increasing symptom severity. The difference between the number of patients completing the active-drug and placebo phases was statistically significant (p less than 0.001). Treatment with Uniphyl tablets resulted in a significantly (p less than 0.05) greater increase in peak expiratory flow rate than Theo-Dur tablet therapy, and both active drugs increased peak expiratory flow rate more than placebo. Circadian variation in peak expiratory flow rate was seen during the placebo and Theo-Dur tablet phases but not during the Uniphyl tablet phase. Symptoms and side effects were similar during the two active-drug phases. Cardiac ectopy was observed in most of the patients, but it was not significantly greater during the theophylline phases than during the placebo phase. Furthermore, ectopic activity was not directly related to the times of maximal serum theophylline concentration.

Review of the North American experience with evening administration of Uniphyl tablets, a once-daily theophylline preparation, in the treatment of nocturnal asthma

Increasing awareness of the exaggerated circadian rhythm in bronchomotor tone that causes most asthmatic patients to have increased respiratory symptoms in the early morning has resulted in a search for dosing strategies that will provide maximal bronchodilatory activity at the time of reduced bronchial patency. The purpose of this paper is to review briefly the published data on the North American experience with evening administration of the once-daily theophylline preparation, Uniphyl tablets. An increasing body of data demonstrates that this regimen produces peak concentrations of theophylline in the blood during the early morning hours, the time of maximal benefit for patients with nocturnal asthma. These data also show that once-daily Uniphyl administered in the evening is superior to both a once-daily morning Uniphyl schedule and to a conventional twice-daily sustained-release theophylline preparation in reducing early morning bronchoconstriction and associated symptoms.

How much theophylline is enough?

Theophylline not only is a bronchodilator but also has other effects (inhibition of mediator release, enhancement of mucociliary clearance, enhancement of diaphragmatic contractility) that are potentially beneficial to asthmatic patients. Recent studies suggest that theophylline pharmacodynamics vary among asthmatic patients. However, on average, most of the total bronchodilatory response occurs at serum theophylline concentrations of 0 to 10 mg/liter. Additional (but less) bronchodilatation occurs at serum theophylline levels between 10 and 20 mg/liter. Pharmacodynamic relationships are not well established for other therapeutic effects of theophylline, such as attenuation of pharmacologically induced bronchoconstriction. An important feature of oral controlled-release theophylline therapy is timing of drug administration. Because airway reactivity increases and airway caliber decreases at night, it has been suggested that the greatest benefit is derived from theophylline when peak serum concentration is reached during the night or the early morning.

Multicenter comparison of once-daily Uniphyl tablets administered in the morning or evening with baseline twice-daily theophylline therapy in patients with nocturnal asthma

Ninety-six patients with reversible airways disease and a history of nocturnal asthma completed a four-week open-label study that compared the effectiveness of Uniphyl tablets (The Purdue Frederick Company, Norwalk, Connecticut) administered once daily in the morning or the evening with twice-daily baseline theophylline therapy. All patients transferred easily from their previous twice-daily theophylline regimen to once-daily Uniphyl therapy. Predose serum theophylline levels and pulmonary function values were similar for the twice-daily and once-daily theophylline regimens. However, both the morning and evening once-daily Uniphyl regimens were judged by the investigators to control the asthmatic symptoms of more patients than did the prestudy twice-daily theophylline. In addition, patient acceptance of the two once-daily Uniphyl regimens was significantly (p less than 0.01) greater than that of the previous twice-daily theophylline therapy. During the fourth week of the study, the evening Uniphyl dosing schedule resulted in significantly (p less than 0.01) higher home-monitored morning peak expiratory flow rates and fewer nighttime awakenings than the pre-study twice-daily theophylline regimen. The morning regimen was not associated with such an improvement. The results of the study suggest that a once-daily evening dosage regimen with Uniphyl tablets provides greater control of nocturnal asthma.

Improved control of asthma in the office setting. A large-scale study of once-daily evening doses of theophylline

A large-scale, multi-investigator open evaluation compared a once-daily regimen of controlled-release theophylline (Uniphyl tablets) with previous twice- or thrice-daily methylxanthine regimens. Three hundred asthmatic patients, 78 percent prone to nocturnal episodes during prior therapy, completed the investigation. Eighty-two percent of the patients were treated for moderate or severe disease. After a one-week evaluation of baseline theophylline therapy (with adjunctive medication), the patients substituted evening doses of the once-daily drug in approximate milligram-for-milligram equivalent doses. Concomitant medications were allowed as before. Nighttime and morning asthma control improved significantly without deterioration in the evening, and without increased side effects. Once-daily therapy resulted in markedly fewer night awakenings involving inhaler use (p less than 0.01), and near 60 percent reductions in the number of patients with nighttime or early morning exacerbations (p less than 0.01). Control of morning chest tightness, wheeze, and dyspnea improved significantly (p less than 0.01), and patients' as well as investigators' global evaluations favored once-daily treatment (p less than 0.01). Morning peak expiratory flow rates improved both at home (p less than 0.01) and at the office (p = 0.05). The forced expiratory volume in one second at the office increased modestly in the entire group. It is concluded that Uniphyl is effective and well tolerated when administered in once-daily evening doses.

Relationship between rate and extent of absorption of oral theophylline from Uniphyl brand of slow-release theophylline and resulting serum concentrations during multiple dosing

The relationship between a standardized assessment of rate and extent of absorption of slow-release theophylline and serum concentrations during multiple dosing was examined in eight healthy adult volunteers. Each subject received single doses of a reference theophylline solution in addition to single and multiple doses of Uniphyl, a "once-a-day" theophylline formulation, administered after an overnight fast and after a large breakfast. Extent of absorption was similar during single and multiple dosing but was significantly greater when dose was taken after breakfast; 68 +/- 7% (mean +/- SEM) and 61 +/- 4% of administered doses were absorbed during single and multiple dosing, respectively, when breakfast was withheld, whereas 83 +/- 4% and 86 +/- 4% of administered doses were absorbed when single and multiple doses, respectively, followed breakfast. Observed mean serum concentrations during multiple dosing approximated values predicted from the single-dose study; mean peak serum concentrations averaged more than twice the tough for both predicted and observed values after both fasting and postprandial administration. These data demonstrate incomplete absorption of theophylline from Uniphyl with greater extent of absorption when Uniphyl is taken after food. The study also provides further documentation that characterization of rate and extent of absorption from single doses permit prediction of the mean serum concentration-time profile during multiple dosing at defined rates of theophylline elimination. This provides the potential to anticipate fluctuations in serum concentrations at clinically relevant elimination rates that deviate from the mean of samples typically used for study.

Comparison of 12-hour and 24-hour sustained-release theophylline in outpatient management of asthma

A once-daily sustained-release preparation of theophylline (Theo-24) was compared to a twice-daily (bid) preparation (Theo-Dur). Fourteen subjects with asthma requiring daily therapy with theophylline were evaluated in a 30-day prospective study. Pulmonary function and serum levels of theophylline were measured. With the twice-daily preparation the mean variation over 12 hours between the maximum concentration (Cmax) and minimum concentration (Cmin) for theophylline was 3.0 micrograms/ml +/- 0.3 microgram/ml, and there was no significant change in tests of pulmonary function. With the once-daily preparation the mean variation over twenty four hours between Cmax and Cmin was 7.4 micrograms/ml +/- 1.1 micrograms/ml, with a small but significant associated change in the forced expiratory volume in one second (84.1 vs 79.6 percent of predicted). Several of the subjects had large differences between Cmax and Cmin with the once-daily preparation. For some, Cmin was quite low while at the same time Cmax was high enough so that further increases in the dose of the once-daily preparation would not have been possible. Thus, consideration of the variation from Cmax to Cmin is necessary in adjusting a patient's dose of the once-daily preparation and may present problems in changeover from the twice-daily preparation if the mean blood level of theophylline is already high.

Treatment of asthma by a controlled-release theophylline tablet formulation: a review of the North American experience with nocturnal dosing

As many as 80 percent of asthmatics experience nighttime or early-morning episodes, which are difficult to treat and potentially fatal. The greater-than-normal amplitude of circadian airflow variation in many asthmatics contributes heavily to the genesis of the early 'morning dip'. Beta-agonists and corticosteroids are of limited usefulness in nocturnal asthma, and slow-release theophylline drugs, while potentially effective, vary in 24-hr blood profile and hence their influence on nocturnal episodes. Traditional 12-hr 'symmetric' theophylline regimens, instead of meeting increased nocturnal demands, may actually produce lower night- than daytime blood levels. On the other hand, appropriately timed administration of a once-daily theophylline drug might provide maximum blood levels when needed and help stabilize 24-hr airflow. Accumulated data, summarized in this review, demonstrate the chronotherapeutic potential of single-daily evening doses of a controlled-release theophylline preparation (Uniphyl 400-mg tablets) in nocturnal and early morning asthma. Nighttime blood concentrations with this regimen were higher than were those with Theo-Dur tablets, B.I.D., in the same total daily doses, or with once-daily morning Uniphyl administration. In fed and fasted subjects, evening administration of Uniphyl 400-mg tablets was well tolerated and did not lead to 'dose dumping.' Clinically, this treatment demonstrated advantages over B.I.D. theophylline, over single-daily morning regimens, and over prior theophylline therapy. Advantages of the evening regimen included better early-morning airflow (without significant decline later in the day), more effective symptom control, better patient acceptance, fewer night awakenings, and the obvious convenience of once-daily dosing. In addition, lung function showed greater stability, throughout the day, with once-daily evening therapy than with traditional 12 hr dosing. Uniphyl 400-mg tablets may be administered once daily to provide maximum blood levels at the time of peak bronchoconstriction, whether at night or during the day.

Chronobiology and asthma. II. Body-time-dependent differences in the kinetics and effects of bronchodilator medications

Several bronchodilator medications exhibit body-time (i.e., biological rhythm)-dependent changes in their pharmacokinetics and effects. Epinephrine (Adrenalin), metaproterenol (orciprenaline), aminophylline, and ipratropium bromide all have a better effect on the tone of the airways during the night and/or morning, when bronchial patency is low, than during the day, when it is high. The pharmacokinetics of sustained-release theophyllines (SRTs) exhibit administration-time differences. Day-night dosing-time differences in the kinetics of theophylline are especially prominent in children. Generally, in day-active asthmatic children the absorption of SRT is more rapid after a morning than an evening dosing. The administration-time effect on the kinetics of SRTs also is apparent in adult patients, but the magnitude of difference between the day versus evening administrations apparently is more moderate. Initial findings from studies of unequal (morning versus evening) BID dosing schedules--more theophylline or terbutaline before bed-time than arising--reveal a better therapeutic advantage relative to equal BID dosing schedules for those patients with predominantly nocturnal symptoms. Once-daily (OD) SRTs intended for delivery of the entire daily dose at a single time also differ quantitatively in their chronokinetics. Since asthma is mainly a nocturnal disease in many patients, it has been recommended by many that ODSRTs be taken in the evening. If taken in the morning, as is the current practice in the United States, they may not ensure therapeutic theophylline blood levels during the night when most needed. Moreover, not all ODSRTs appear suitable for once-nightly administration because of unacceptable kinetics.