Circadian rhythm in peak expiratory flow: alteration with nocturnal asthma and theophylline chronotherapy

Theophylline for the management of respiratory disorders in adults in the 21st century: A scoping review from the American College of Clinical Pharmacy Pulmonary Practice and Research Network

Theophylline is an oral methylxanthine bronchodilator recommended as alternate therapy for the treatment of asthma and chronic obstructive pulmonary disease (COPD). However, it is not generally recommended for the treatment of other respiratory disorders such as obstructive sleep apnea (OSA) or hypoxia. Most clinical practice guidelines rely on evidence published prior to the year 2000 to make these recommendations. This scoping review aimed to gather and characterize evidence describing theophylline for the management of respiratory disorders in adults between January 1, 2000 and December 31, 2020. Databases searched included Ovid MEDLINE, Embase, CINAHL Complete, Scopus, and International Pharmaceutical Abstracts. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews. Studies were included if they were published in English, theophylline was used for any respiratory disorder, and the study outcomes were disease- or patient-oriented. After removal of duplicates, 841 studies were screened and 55 studies were included. Results aligned with current clinical guideline recommendations relegating theophylline as an alternative therapy for the treatment of respiratory disorders, in favor of inhaled corticosteroids and inhaled bronchodilators. This scoping review identified the need for future research including: theophylline versus other medications deemed alternative therapies for asthma and COPD, meta-analyses of low-dose theophylline, and studies evaluating evidence-based patient-oriented outcomes for OSA, hypoxia, ventilator-induced diaphragmatic dysfunction, and spinal cord injury-related pulmonary function.

Asthma diagnosis: into the fourth dimension

Asthma is the most common chronic respiratory disease in the UK; however, the misdiagnosis rate is substantial. The lack of consistency in national guidelines and the paucity of data on the performance of diagnostic algorithms compound the challenges in asthma diagnosis. Asthma is a highly rhythmic disease, characterised by diurnal variability in clinical symptoms and pathogenesis. Asthma also varies day to day, seasonally and from year to year. As much as it is a hallmark for asthma, this variability also poses significant challenges to asthma diagnosis. Almost all established asthma diagnostic tools demonstrate diurnal variation, yet few are performed with standardised timing of measurements. The dichotomous interpretation of diagnostic outcomes using fixed cut-off values may further limit the accuracy of the tests, particularly when diurnal variability straddles cut-off values within a day, and careful interpretation beyond the 'positive' and 'negative' outcome is needed. The day-to-day and more long-term variations are less predictable and it is unclear whether performing asthma diagnostic tests during asymptomatic periods may influence diagnostic sensitivities. With the evolution of asthma diagnostic tools, home monitoring and digital apps, novel strategies are needed to bridge these gaps in knowledge, and circadian variability should be considered during the standardisation process. This review summarises the biological mechanisms of circadian rhythms in asthma and highlights novel data on the significance of time (the fourth dimension) in asthma diagnosis.

Asthma: Chronopharmacotherapy and the molecular clock

Bronchial asthma is characterized by chronic airways inflammation and reversible airflow limitation. In patients with asthma, symptoms generally worsen during the early hours of the morning, and pulmonary function often deteriorates at the same time, suggesting a role for chronopharmacotherapy. Several drugs for asthma have been developed based on chronopharmacology. Most medications employed for the chronotherapy of asthma are administered once at night with the goal of preventing chronic airway inflammation or development of airflow limitation. In addition to bronchodilators, the inhaled glucocorticosteroid ciclesonide is now available with once-daily dosing, which also improves patients' compliance. Numerous investigations have demonstrated the usefulness of chronotherapy for asthma, especially for patients with nocturnal asthma. This review focuses on chronotherapy of asthma, and also provides a molecular biological explanation for the influence of asthma medications on the clock genes.

A controlled porosity osmotic pump system with biphasic release of theophylline: influence of weight gain on its in vivo pharmacokinetics

In our previous work, a controlled porosity osmotic pump system with biphasic release of theophylline, a system composed of a tablet-in-tablet (TNT) core and a controlled porosity coating membrane, was developed for the nocturnal therapy of asthma. Sodium phosphate and sodium chloride were selected as the osmotic agents in inner and outer layer of the TNT core respectively, and CA-PEG400-DEP (54.5%-36.4%-9.1%, w/w) was chosen as coating solution. Formulations with weight gain of 19 mg/T (mg per tablet), 9 mg/T and 6 mg/T were prepared respectively and their pharmacokinetics in beagle dogs were also studied to examine the influence of weight gain on their in vivo pharmacokinetics. Sustained release tablet of theophylline (SRT) was selected as reference to evaluate the in vitro and in vivo difference between conventional sustained release tablets and the developed formulation. T(max) and mean residence time (MRT) of the developed formulations were prolonged compared to that of SRT and a satisfying bioavailability was achieved at weight gain of 6 mg/T. If applied to the chronotherapy of asthma at night, the developed formulation with a weight gain of 6 mg/T might help to reduce the inconvenience brought by too later administration of conventional dosage forms and maintain a relatively high blood drug concentration 7 h after administration.

Treatment with beta2-adrenoceptor agonist in vivo induces human clock gene, Per1, mRNA expression in peripheral blood

This study examined whether in vivo exposure to a beta2-adrenoceptor agonist, tulobuterol, induces human Period1 (hPer1) mRNA expression in cells from peripheral whole blood. In one experiment, oral tulobuterol was administered to five healthy volunteers at 22:00 h, while in another, a transdermally tulobuterol patch was applied to the same five subjects at 20:00 h. In each experiment, serum tulobuterol concentrations were measured at four time points, and total RNA was isolated from peripheral blood cells for determinations of hPer1 mRNA expression by real-time polymerase chain reaction. Both the tulobuterol tablet and the transdermal patch increased hPer1 mRNA expression, suggesting that analyses of human peripheral blood cells could reliably represent peripheral clock gene mRNA expression in vivo.

Circadian rhythms in the CNS and peripheral clock disorders: function of clock genes: influence of medication for bronchial asthma on circadian gene

Bronchial asthma is a chronic inflammatory disorder of the airways, in which inflammation causes bronchial hyper-responsiveness and flow limitation in the presence of various stimuli. Pulmonary function in asthmatic patients frequently deteriorates between midnight and early morning, which has suggested a role for chronotherapy. Although relationships between bronchial asthma and the function of clock genes remain unclear, some medications given for asthma such as glucocorticoids or beta(2)-adrenoceptor agonists may influence clock genes in vivo. In our studies of clock gene mRNA expressions in human bronchial epithelial cells in vitro and peripheral blood cells in vivo, we demonstrated that glucocorticoid or beta(2)-adrenoceptor agonist treatment strongly induced human Per1 mRNA expression both in vitro and in vivo. Human peripheral blood cells provide a useful indication of peripheral clock gene mRNA expression in vivo.

Regulation and modulation of electric waveforms in gymnotiform electric fish

Weakly electric gymnotiform fish specialize in the regulation and modulation of the action potentials that make up their multi-purpose electric signals. To produce communication signals, gymnotiform fish modulate the waveforms of their electric organ discharges (EODs) over timescales spanning ten orders of magnitude within the animal's life cycle: developmental, reproductive, circadian, and behavioral. Rapid changes lasting milliseconds to seconds are the result of direct neural control of action potential firing in the electric organ. Intermediate-term changes taking minutes to hours result from the action of melanocortin peptides, the pituitary hormones that induce skin darkening and cortisol release in many vertebrates. Long-term changes in the EOD waveform taking days to weeks result from the action of sex steroids on the electrocytes in the electric organ as well as changes in the neural control structures in the brain. These long-term changes in the electric organ seem to be associated with changes in the expression of voltage-gated ion channels in two gene families. Electric organs express multiple voltage-gated sodium channel genes, at least one of which seems to be regulated by androgens. Electric organs also express multiple subunits of the shaker (Kv1) family of voltage-gated potassium channels. Expression of the Kv1 subtype has been found to vary with the duration of the waveform in the electric signal. Our increasing understanding of the mechanisms underlying precise control of electric communication signals may yield significant insights into the diversity of natural mechanisms available for modifying the performance of ion channels in excitable membranes. These mechanisms may lead to better understanding of normal function in a wide range of physiological systems and future application in treatment of disease states involving pathology of excitable membranes.

Beta2-adrenoceptor agonists induce the mammalian clock gene, hPer1, mRNA in cultured human bronchial epithelium cells in vitro

The mammalian Per1 gene is one of the most important components of circadian clock function of the suprachiasmatic nucleus and peripheral tissues. We examined whether the beta2-adrenoceptor agonists, procaterol and fenoterol, induce human Per1 mRNA expression in human bronchial epithelium. The in vitro stimulation of beta2-adrenoceptor agonists in BEAS-2B cells led to a remarkable increase in the level of hPer1 mRNA. Moreover, fenoterol or procaterol induced the phosphorylation of CREB in BEAS-2B cells as verified by immunoblot analysis. beta2-adrenoceptor agonists induced human Per1 mRNA expression by the signaling pathways of cAMP-CREB in BEAS-2B cells.

Dexamethasone influences human clock gene expression in bronchial epithelium and peripheral blood mononuclear cells in vitro

We determined whether human peripheral blood mononuclear cells (PBMCs) could be used to analyze clock genes by studying their mRNA expressions in human bronchial epithelium (BEAS-2B) and PBMCs following stimulation by the glucocorticoid homologue dexamethasone (DEX) in vitro. PBMCs were obtained at 10:00 h from two diurnally active (approximately 07:00 to 23:00 h) healthy volunteers and were evaluated for hPer1 mRNA expression following DEX stimulation in vitro using real time-PCR analysis. DEX stimulation of human BEAS-2B cells and PBMCs in vitro led to a remarkable increase of hPer1 mRNA. The glucocorticoid rapidly affected the expression of hPer1 mRNA in PBMCs, suggesting that human PBMCs may be a useful surrogate marker for the investigation of drug effects on clock genes.

Alteration of the circadian rhythm in peak expiratory flow of nocturnal asthma following nighttime transdermal beta2-adrenoceptor agonist tulobuterol chronotherapy

We investigated the efficacy of nighttime transdermal tulobuterol (beta2-adrenoceptor agonist) chronotherapy for nocturnal asthma by assessing changes both in the frequency of symptoms and features of the circadian rhythm in peak expiratory flow (PEF), a measure of airway caliber. Thirteen patients with nocturnal asthma were evaluated before and during tulobuterol patch chronotherapy, applied once daily in the evening for 6 consecutive days. Patients were asked to record their PEF every 4h between 03:00 and 23:00 h for one day. Circadian rhythms in PEF were examined by group-mean cosinor analysis. The group average PEF at 03:00 h, the time during the 24 h when PEF is generally the poorest, before the application of the chronotherapy, when asthma was unstable and nocturnal symptoms frequent, was 276 +/- 45 L/min. Application of the tulobuterol patch at nighttime significantly increased (p < 0.001) the 03:00 h group average PEF to 363 +/- 67 L/min. Significant circadian rhythms in PEF were observed during the span of study when nocturnal symptoms were frequent as well as with the use of the tulobuterol patch. Before the initiation of tulobuterol chronotherapy, the bathyphase (trough time of the circadian rhythm) in PEF narrowed to around 04:00h, and the group circadian amplitude was 28.8 L/min. In contrast, the group circadian amplitude significantly (p < 0.01) decreased to 10.4 L/min, and the 24 h mean PEF increased significantly with tulobuterol patch chronotherapy. These changes indicate that tulobuterol chronotherapy significantly increased both the level and stability of airway function over the 24 h. The circadian rhythm in PEF varied with the severity and frequency of asthmatic symptoms with and without the nighttime application of the tulobuterol patch medication. We conclude that the parameters of the circadian rhythm of PEF proved useful both in determining the need for and effectiveness of tulobuterol chronotherapy for nocturnal asthma.

Daily expression of mRNAs for the mammalian Clock genes Per2 and clock in mouse suprachiasmatic nuclei and liver and human peripheral blood mononuclear cells

The mammalian circadian clock is located in the suprachiasmatic nucleus (SCN) of the hypothalamus and in most peripheral tissues. Clock genes drive the biological clock. However, circadian expression variations of the human clock genes are still unclear. In this study, we analyzed the daily variations of mPer2 and mClock mRNA expression in both the mouse SCN and liver to evaluate the central and peripheral alterations in the rodent clock genes. We also examined whether there are the daily variations of the clock genes hPer2 and hClock in human peripheral blood mononuclear cells (PBMCs). The daily variation of mClock and mPer2 mRNA expression in mouse SCN and liver were determined at ZT2, ZT6, ZT10, ZT14, ZT18 or ZT22. We isolated PBMCs from 9 healthy volunteers at 9:00 and 21:00 and examined the expression of hPer2 and hClock mRNA by RT-PCR analysis. The animals exhibited a robust daily rhythm in the RNA levels of mPer2 in the SCN and liver (P<0.01, respectively). In humans, hPer2 mRNA expression also had daily variation, and the hPer2 mRNA levels at 9:00 were significantly larger than those at 21:00 (P<0.01). While, the Clock mRNA in both mice and humans exhibited no daily variation. These findings suggest that the variation in hPer2 mRNA expression may be useful for assessing human peripheral circadian systems.

Theophylline chronotherapy of nocturnal asthma using bathyphase of circadian rhythm in peak expiratory flow rate

We studied the efficacy of theophylline chronotherapy for nocturnal asthma using the changes of the circadian rhythms in peak expiratory flow rate (PEF). Eight patients with nocturnal asthma were evaluated for the periods with nocturnal symptoms and with an evening dose of theophylline administered daily. Patients recorded their PEF every 4 hours on one of the days (from 7:00 to 23:00 h) in each period. Circadian rhythms in PEF were examined using the single and group-mean cosinor method. Significant circadian rhythms in PEF were observed in the period with nocturnal symptoms. When nocturnal symptoms were present, the bathyphase of PEF was present between midnight and morning. A significant circadian rhythm disappeared or PEF amplitude decreased during theophylline chronotherapy. The circadian rhythm in PEF was altered according to the severity of the asthma. In patients with symptoms present between midnight and early morning, an evening dose of theophylline chronotherapy can be prophylactically used for nocturnal asthma attacks. Consideration of the circadian rhythm and bathyphase of PEF is useful in selecting appropriate chronotherapy for nocturnal asthma.

Nocturnal worsening of asthma and sleep-disordered breathing

Asthma has a tendency, to destabilize and get worse at night, probably due to a nocturnal increase in airiway inflammation and bronchial responsiveness. Nocturnal airway narrowing in asthma is often associated with sleep disorders, such as episodes of nocturnal and early morning awakening, difficulty in maintaining sleep, and day time sleepiness. On the other hand, an association has been documented between nocturnal sleep-disordered breathing and asthma. This review highlights the causes of nocturnal worsening of asthma and examines the evidence pointing toward a causal relationship between nocturnal asthma and sleep-disordered breathing.