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

Circadian Variation in Efficacy of Medications

Although much has been learned about circadian clocks and rhythms over the past few decades, translation of this foundational science underlying the temporal regulation of physiology and behavior to clinical applications has been slow. Indeed, acceptance of the modern study of circadian rhythms has been blunted because the phenomenology of cyclic changes had to counteract the 20th century dogma of homeostasis in the biological sciences and medicine. We are providing this review of clinical data to highlight the emerging awareness of circadian variation in efficacy of medications for physicians, clinicians, and pharmacists. We are suggesting that gold-standard double-blind clinical studies should be conducted to determine the best time of day for optimal effectiveness of medications; also, we suggest that time of day should be tracked and reported as an important biological variable in ongoing clinical studies hereafter. Furthermore, we emphasize that time of day is, and should be considered, a key biological variable in research design similar to sex. In common with biomedical research data that have been historically strongly skewed toward the male sex, most pharmaceutical data have been skewed toward morning dosing without strong evidence that this is the optimal time of efficacy.

The efficacy of once-daily fluticasone furoate/vilanterol in asthma is comparable with morning or evening dosing

AIM

To investigate the effect of time of day of dosing (morning or evening) on lung function following administration of fluticasone furoate (FF)/vilanterol (VI) 100/25 mcg.

METHODS

Double-blind, placebo-controlled, randomised, three-way crossover study. Subjects with persistent asthma (N = 26) received FF/VI (morning or evening) or matching placebo once-daily for 14 (± 2 days) via dry powder inhaler (DPI). Weighted mean (0-24h) and pre-treatment FEV1 (morning and evening) were determined after the Day 14 evening dose, together with mean pre-treatment (morning and evening) peak expiratory flow (PEF) on Days 2-12.

RESULTS

FF/VI 100/25 administered morning or evening produced clinically significant increases in weighted mean FEV1: the differences [95% confidence interval (CI)] from placebo were 377 mL [293, 462] and 422 mL [337, 507], respectively; the difference between morning and evening dosing was -44 mL [-125, 36]. Day 14 pre-treatment morning FEV1 differences [95% CI] from placebo were 403 mL [272, 533] and 496 mL [369, 624] after morning and evening dosing, respectively; the morning:evening treatment difference was -94 mL [-221, 34]. Pre-treatment evening FEV1 differences [95% CI] from placebo were 275 mL [169, 380] and 309 mL [205, 413] after morning and evening dosing, respectively; the morning:evening treatment difference was -34 mL [-138, 70]. FF/VI (morning or evening) produced rapid increases in PEF with the full effect apparent after the first dose and maintained throughout the 14-day treatment period.

CONCLUSION

FF/VI 100/25 produces comparable improvements in lung function whether dosed in the morning or evening in subjects with persistent asthma.

Chronobiology and chronotherapy of allergic rhinitis and bronchial asthma

Study of the chronobiology of allergic rhinitis (AR) and bronchial asthma (BA) and the chronopharmacology and chronotherapy of the medications used in their treatment began five decades ago. AR is an inflammatory disease of the upper airway tissue with hypersensitivity to specific environmental antigens, resulting in further local inflammation, vasomotor changes, and mucus hypersecretion. Symptoms include sneezing, nasal congestion, and runny and itchy nose. Approximately 25% of children and 40% of adults in USA are affected by AR during one or more seasons of the year. The manifestation and severity of AR symptoms exhibit prominent 24-h variation; in most persons they are worse overnight or early in the morning and often comprise nighttime sleep, resulting in poor daytime quality of life, compromised school and work performance, and irritability and moodiness. BA is also an inflammatory medical condition of the lower airways characterized by hypersensitivity to specific environmental antigens, resulting in greater local inflammation as well as bronchoconstriction, vasomotor change, and mucus hypersecretion. In USA an estimated 6.5 million children and 15.7 million adults have BA. The onset and worsening of BA are signaled by chest wheeze and/or croupy cough and difficult and labored breathing. Like AR, BA is primarily a nighttime medical condition. AR is treated with H1-antagonist, decongestant, and anti-inflammatory (glucocorticoid and leukotriene receptor antagonist and modifier) medications. Only H1-antagonist AR medications have been studied for their chronopharmacology and potential chronotherapy. BA is treated with some of the same medications and also theophylline and beta2-agonists. The chronopharmacology and chronotherapy of many classes of BA medications have been explored. This article reviews the rather extensive knowledge of the chronobiology of AR and BA and the chronopharmacology and chronotherapy of the various medications used in their treatment.

Effect of tiotropium bromide on circadian variation in airflow limitation in chronic obstructive pulmonary disease

BACKGROUND

In chronic obstructive pulmonary disease (COPD), the degree of circadian variation in forced expiratory volume in 1 second (FEV1) and the influence of anticholinergic blockade is not known. Tiotropium is a long acting inhaled anticholinergic bronchodilator that increases daytime FEV1 in COPD. We hypothesised that tiotropium would modify the overnight change in FEV1, and this would be unaffected by the timing of drug administration.

METHODS

A double blind, randomised, placebo controlled trial was conducted with tiotropium 18 mg once daily in the morning (09.00 hours), evening (21.00 hours), or an identical placebo. Patients with stable COPD (n=121, FEV1=41% predicted) underwent spirometric tests every 3 hours for 24 hours at baseline and after 6 weeks of treatment.

RESULTS

There were no significant differences at baseline between the groups. Tiotropium improved mean (SE) FEV1 (over 24 hours) in the morning (1.11 (0.03) l) and evening (1.06 (0.03) l) groups compared with placebo (0.90 (0.03) l), and nocturnal FEV1 (mean of 03.00 and 06.00 hours) in the morning (1.03 (0.03) l) and evening (1.04 (0.03) l) groups compared with placebo (0.82 (0.03) l) at the 6 week visit (p<0.01). FEV1 before morning or evening dosing was similar, while the peak FEV1 moved later in the day with active treatment. The mean percentage change in FEV1 from 09.00 hours to 03.00 hours (the nocturnal decline in FEV1) was -2.8% in the morning group, -1.0% in the evening group, and -12.8% in the placebo group. The magnitude of the peak to trough change in FEV1 was not statistically different.

CONCLUSIONS

Tiotropium produced sustained bronchodilation throughout the 24 hour day without necessarily abolishing circadian variation in airway calibre.

Underdiagnosed asthma in South Australia

BACKGROUND

The prevalence of undiagnosed asthma in the general population and the clinical and demographic characteristics of these patients compared with those with diagnosed asthma are unclear.

METHODS

The North West Adelaide Health Survey (NWAHS) is a population household interview survey of adults (age>18 years) in the north western suburbs of Adelaide, South Australia (regional population 0.6 million). Data obtained were weighted to the closest census data to provide population representative estimates. Positive answers to: "Have you ever had asthma?"; "Has it been confirmed by a doctor?"; "Do you still have asthma?" determined current physician diagnosed asthma. A positive bronchodilator response on spirometric testing according to ATS criteria without a physician's diagnosis determined undiagnosed asthma. Other measures included the SF-12 health survey questionnaire, the Selim index of severity of chronic lung disease, skin allergy tests, and demographic data.

RESULTS

Of the 3422 individuals interviewed, 2523 (74%) agreed to participate in the clinical assessment. Of these, 292 (11.6%) had asthma, 236 (9.3%) with a doctor's diagnosis of asthma and 56 (2.3%) with undiagnosed asthma defined on spirometric criteria; thus, 19.2% of the total asthma group were undiagnosed. Those undiagnosed were more likely (p<0.05) to be >40 years old, on government benefits, with an income <AUD$40,000. Symptom frequency was similar in the two asthma groups, but mean spirometric values were lower in the undiagnosed group (p<0.05) while positive skin allergy tests were more common in the diagnosed group (p<0.05). SF-12 component summary scores were significantly lower in both asthma groups than in the non-asthma population. Undiagnosed asthma was frequent in men and in those aged >65 years. Health service use over the previous year was similar for both asthma groups.

CONCLUSION

Undiagnosed asthma is common among the Australian population, with a similar clinical spectrum to those with diagnosed asthma.

Circadian rhythms in the pharmacokinetics and clinical effects of beta-agonist, theophylline, and anticholinergic medications in the treatment of nocturnal asthma

Published asthma consensus reports now acknowledge that asthma is a nocturnal disease in as many as 75% of those afflicted by this medical condition. Nonetheless, the treatment of this chronic obstructive pulmonary disease in the clinic continues to be based primarily on homeostatic considerations in that it relies on long-acting bronchodilator and other therapies formulated and scheduled to ensure constant or near-constant levels of medication during the 24h. The need of asthma patients prone to nighttime attacks is not the same during the day and night; the therapeutic requirements of patients who experience nocturnal asthma, especially ones with the more severe forms of the disease, are often not satisfied by conventional medications. The therapeutic response and patient tolerance to bronchodilator medications can be improved markedly when the medications are proportioned during the 24h as a chronotherapy, that is, when more medication is delivered during nighttime sleep than daytime activity, as verified by numerous studies. This article reviews how the body's circadian rhythms influence the pharmacokinetics and effects of commonly prescribed asthma therapies and addresses why and how they must be taken into consideration to increase the effectiveness of asthma treatment.

Drug-induced sleep disturbances. Focus on nonpsychotropic medications

Different medications can have significant effects on sleep quality and/or quantity. When prescribing medications it is important to be aware of these possible adverse effects of drugs. Disturbances of the sleep/wake cycle caused by medications can vary and include insomnia, daytime sleepiness, nightmares and changes in the sleep architecture. Psychotropic drugs are well known to have an effect on the sleep/wake cycle, but there is only limited information about the sleep effects of nonpsychotropic medications. Cardiovascular drugs, especially beta-blockers, which are widely used drugs, often change the sleep architecture and cause nightmares and insomnia. Both of these effects can be a potential source of noncompliance. Because of the complicated relationship between sleep, nocturnal asthma and antiasthmatic agents, the appropriate dosage and timing of medications should always be considered. Patients with Parkinson's disease often experience disrupted sleep due to their disorder and the adverse effects of anti-parkinsonian medications.

Bambuterol in the treatment of asthma. A placebo-controlled comparison of once-daily morning vs evening administration

Once-daily morning (7 AM) vs evening (10 PM) administration of the terbutaline prodrug bambuterol (20-mg tablet dose) was investigated in a double-blind, cross-over, randomized, and placebo-controlled study involving 29 diurnally active patients with asthma. Terbutaline plasma concentration, spirometry, and drug tolerance were assessed during 39-h inpatient studies. A 7-day washout period separated each treatment. Mean 24-h plasma concentration was comparable for morning and evening bambuterol (13.2 vs 14.0 nmol/L). The Cmax for evening vs morning dosing was 17.2 vs 15.5 nmol/L (p < 0.02). The 24-h mean FEV1 was greater (p < 0.001) for bambuterol (morning: 3.2 L; evening: 3.4 L) vs placebo (2.9 L) as it was for FVC, FEF25-75%, and peak expiratory flow rate (PEFR), with the maximum effect at 4 AM independent of medication time. Evening dosing, however, resulted in greatest 7 AM (awakening) FEV1, FEV25-75, and PEFR (p < 0.03). With reference to corresponding-in-time placebo values, improvement in FEV1 at the end of the 24-h dosing intervals amounted to 0.34 L (13.5%) (p < 0.0004) and 0.35 L (15.9%) (p < 0.0012) with evening and morning bambuterol dosing, respectively. Side effects were greater for bambuterol than placebo, but not significantly so. Once-daily bambuterol therapy proved to be an effective treatment for asthma, whether administered in the evening or morning. Evening dosing seems best for nocturnal asthma since airway patency overnight and on awakening at 7 AM is most improved.

Concepts of circadian chronopharmacology

Circadian and other rhythmic changes in biological susceptibility and response of organisms to a large variety of physical as well as chemical agents including medications and foods are rather common phenomena. Modern chronopharmacology investigates drug effects (a) as a function of biological timing and (b) upon parameters characterizing the endogenous bioperiodicities. A better understanding of periodic and thus predictable changes in drug effects can be attained through consideration of complementary concepts: (1) the chronokinetics of a drug--dosing time-dependent and predictable (rhythmic) changes in parameters used to characterize the pharmacokinetics (or the bioavailability) of a drug, e.g., maximum concentration (Cmax), span of time to reach Cmax (tmax), area under the concentration-time curve (AUC), half-life (t1/2), etc.; (2) the chronesthesy (rhythmic changes in susceptibility of a target biosystem to this drug); and (3) the chronergy (the drug-integrated overall effects). One of the aims of chronopharmacology is solving problems of drug optimization. Chronotherapy refers to the use of a chronopharmacologic approach to clinical treatment so as to enhance both effectiveness and tolerance of a drug by determining the best biological time for its dosing.

Biologic rhythms and medicine

Medical practice and research in the United States and other countries are pervaded by the traditional concepts of homeostasis. As a result, the time of day or year when a diagnostic or therapeutic procedure is performed or a drug is administered is not considered important. However, during the last three decades, the science of chronobiology has revealed the importance to medicine of the rhythms that exist in the biologic functions and processes of humans. This article reviews the basic concepts of human chronobiology and discusses the rhythm dependence of certain disease states and the pharmacodynamics of medications frequently prescribed for their treatment. Special reference is made to the nocturnal exacerbation of asthma and the use of chronobiologic principles in its treatment.

Chronobiology and asthma. III. Timing corticotherapy to biological rhythms to optimize treatment goals

Synthetic corticosteroids are frequently used to manage asthma and other inflammatory diseases. The timing of such drugs (whether ingested, inhaled, or infused) in relation to body rhythms influences the magnitude of both desired and undesired effects. It is crucial that corticotherapy be correctly scheduled to the circadian system of the hypothalamic-pituitary-adrenocortical (HPA) system. The secretion of cortisol from the adrenal cortex is not constant during each 24-hour period. Instead, production of this hormone varies as a high-amplitude circadian rhythm, with most of the secretion taking place during the initial hours of the activity span and very little late in the evening and during the first half of the sleep span. Results of laboratory and human studies indicate that the timing of exogenous corticosteroids, in relation to the circadian rhythm in HPA activity, is a critical factor. For example, the optimization of corticosteroid therapy for asthmatics entails daily (or alternate-day) administrations in the morning and, if necessary, early afternoon. By timing exogenous corticosteroids early during the activity span, the risk of adrenal suppression is minimized or avoided while bronchial patency is optimally enhanced, i.e., increasing the 24-hour average forced expiratory volume in 1 second (FEV1) and reducing its nocturnal dip. Clinical findings indicate that these results are obtainable with both acute and chronic corticosteroid therapies. In contrast, splitting the daily dose of corticosteroids into several small administrations, such as at mealtimes and before bedtime, markedly increases the likelihood of adrenal suppression without achieving the desired therapeutic effect. The dosing of synthetic corticosteroids late in the afternoon or evening, whatever the route of delivery, suppresses pituitary adrenocorticotropic hormone (ACTH) production during subsequent 24-hour spans, resulting in adrenocortical inhibition. Also, morning dosing of corticosteroids over many years seems to induce less--if any--osteopenia compared to dosing at other times. The adrenal response to exogenous administration of ACTH also is circadian-rhythmic. ACTH dosing in the morning results in greatest adrenal response in terms of cortisol secretion, while dosing in the evening results in least response. Knowledge of the circadian organization of the HPA axis is necessary to optimize the effect of synthetic corticosteroids, whether they be used to treat asthma, rheumatoid arthritis or other cortico-dependent diseases, or as a substitution therapy for Addison's disease.

Comparison of sustained-release theophylline scheduled conventionally (twice-daily, equal interval in equal amount) versus once-daily mornings or evenings on circadian pattern of bronchial patency in asthmatics

The effects of differently timed, but equivalent TheoDur (Key Pharmaceutical Co.) dosage schedules--twice-daily equally divided 12 hr (BID), once-daily evening (OD-PM) and once-daily morning (OD-AM)--were compared under steady-state conditions in 10 adult asthmatics with a documented history of nocturnal dyspnea. Assessments of airways function by spirometry were done every 3-hr over one complete 24-hr dosing interval for each dosage schedule under carefully controlled conditions. The different TheoDur regimens did not affect the 24-hr group average FEV1.0, PEF, MMEF or FVC. However, statistically significant circadian variation in airways function existed irrespective of the drug dosing schedule. Airways patency and FVC were least overnight (0200-0500 hr) and best during the morning or afternoon. With regard to FEV1.0 and PEF, which evidenced group circadian change for BID and OD-PM regimen by Cosinor analysis, the peak-to-trough (double amplitude) difference expressed as a percentage of the 24-hr average was rather large, being greatest for the OD-PM schedule (20.5% for FEV1.0 and 24.3% for PEF). The data for the 10 participants revealed individual differences in the effectiveness of the 3 studied theophylline dosing regimens when assessed in terms of the mean level and stability of airways function over the 24 hr. Based on the findings, neither the BID, OD-PM nor the OD-AM regimen effectively moderated the nocturnal deterioration of pulmonary function suggesting theophylline as dosed and timed may not be as efficacious as desired for patients with a history of strictly nighttime dyspnea. Thus, the schedule and prescription of TheoDur must take into account differences between patients, including the time when asthma symptoms are most likely to be experienced by each.

Administration-time-dependency of the pharmacokinetic behavior and therapeutic effect of a once-a-day theophylline in asthmatic children

Using a double-blind, placebo-control, crossover study design, 8 asthmatic children (8-15 years) were evaluated for temporal patterns in airways function throughout separate study periods when treatment was placebo or Theo-24 once-daily on separate occasions at 0600, 1500 or 2100 hr. During 39-hr in-hospital observations, pulmonary function and serum theophylline concentrations (STC) were assessed every 3 hr under all treatments. The pharmacokinetics of Theo-24 varied greatly depending on the dosing time. For the afternoon and evening dosings, the Cmax, Tmax, AUC, % swing, % fluctuation, % AUC fluctuation, % nocturnal excess and Cav(2-6 hr) were all statistically significantly greater than for the morning dosing. Compared with the placebo regimen, dosing patients with Theo-24 at 1500 hr disrupted circadian patterns of airways function, especially airways patency, while dosing at 2100 hr, reduced the amplitude and shifted the acrophase of several spirometric measures to a slightly earlier time. Theo-24 treatment irrespective of dosing time resulted in comparable enhancement of the group 24-hr mean, minimum and maximum values of airways patency with reference to placebo baselines. Theo-24 dosing at 1500 or 2100 hr, however, resulted in the best effect on the airways as assessed by the 24-hr mean FEV 1.0 level in 7 of the 8 asthmatic children. When the drug was given at 1500 hr, the time of lowest FEV 1.0 was shifted from the nighttime hours in 5 of 8 patients. These findings suggest that clinicians need to individualize the theophylline dosing schedule of patients to best control the symptoms of asthma.

Day-night patterns in bronchial patency and dyspnea: basis for once-daily and unequally divided twice-daily theophylline dosing schedules

Asthma typically worsens overnight. Although 24-hr variation in environmental conditions may contribute to the worsening of dyspnea at night, this does not fully explain day-night patterns of this disease. Circadian (about 24-hr) rhythms in bioprocesses which influence airways patency constitute major contributory factors. The nighttime exacerbation of asthma may represent the influence of circadian bioperiodicities in bronchial patency, airways hyperreactivity to acetylcholine, histamine and house dust, and altered levels of several plasma constituents such as cortisol, epinephrine, histamine and cyclic AMP.

Sustained-release theophylline and nocturnal asthma, once-daily and unequal dosing schedules

Many asthmatic patients experience aggravation of symptoms overnight resulting in disruption of their sleep. Sustained-release theophylline represents at this time a major bronchodilator medication which possesses a sufficient duration of activity to avert the nocturnal breathing distress of asthma. Circadian rhythm-adapted theophylline schedules consisting of unequal dosing--more or all the drug taken in the evening--have proven efficacious in clinical investigations for certain patients. Although the kinetic behavior of some formulations is affected by food, the circadian rhythm-adapted schedules represent a significant step forward toward the goal of optimizating sustained-release theophyllines for patients who experience nighttime symptoms.