Tremor and β(2)-adrenergic agents: is it a real clinical problem?

A severe tremor caused by a beta2 agonist in a patient with asthma-chronic obstructive pulmonary disease overlap

A 46-year-old male developed respiratory distress due to asthma-chronic obstructive pulmonary disease overlap and experienced severe tremor caused by beta2 agonist inhalant. We present our successful experience with tizanidine administration.

Revisiting asthma pharmacotherapy: where do we stand and where do we want to go?

Several current guidelines/strategies outline a treatment approach to asthma, which primarily consider the goals of improving lung function and quality of life and reducing symptoms and exacerbations. They suggest a strategy of stepping up or down treatment, depending on the patient's overall current asthma symptom control and future risk of exacerbation. While this stepwise approach is undeniably practical for daily practice, it does not always address the underlying mechanisms of this heterogeneous disease. In the last decade, there have been attempts to improve the treatment of severe asthma, such as the addition of a long-acting antimuscarinic agent to the traditional inhaled corticosteroid/long-acting β2-agonist treatment and the introduction of therapies targeting key cytokines. However, despite such strategies several unmet needs in this population remain, motivating research to identify novel targets and develop improved therapeutic and/or preventative asthma treatments. Pending the availability of such therapies, it is essential to re-evaluate the current conventional "one-size-fits-all" approach to a more precise asthma management. Although challenging, identifying "treatable traits" that contribute to respiratory symptoms in individual patients with asthma may allow a more pragmatic approach to establish more personalised therapeutic goals.

Association between Inhaled β2-agonists Initiation and Risk of Major Adverse Cardiovascular Events: A Population-based Nested Case-Control Study

Purpose

Despite ample evidence underpinning the efficacy of β₂-agonists in asthma and chronic obstructive pulmonary disease (COPD), the occurrence of β₁- and β₂-adrenoceptors in the heart suggests that β₂-agonists may have deleterious cardiac effects. We investigated the association between new users of long-or short-acting β₂-agonists (LABA or SABA) or ICS (inhaled corticosteroids)/LABA and major adverse cardiovascular events (MACE).

Methods

A nested case–control analysis was conducted using the UK Clinical Practice Research Datalink of patients with asthma, COPD or asthma–COPD overlap with initial treatment of LABA, SABA, ICS/LABA, ICS, long-or short-acting muscarinic antagonist (LAMA or SAMA) between 01 January 1998 and 31 July 2018. The primary outcome was MACE, defined as the first occurrence of stroke, heart failure, myocardial infarction, arrhythmia, or cardiovascular death. Each case was matched with up to 10 controls on age, sex, date of cohort-entry, and duration of follow-up. The risk of MACE associated with β₂-agonists was estimated using conditional logistic regression after controlling for potential confounders.

Results

The cohort included 180,567 new users of β₂-agonists, ICS, SAMA, or LAMA. Among asthmatics, β₂-agonists were not associated with the risk of MACE (SABA vs ICS: HR 1.29 [0.96–1.73]; ICS/LABA vs ICS, HR 0.75 [0.33–1.73]). In contrast, among COPD patients, LABA (HR, 2.38 [1.04–5.47]), SABA (HR, 2.02 [1.13–3.59]) and ICS/LABA (HR, 2.08 [1.04–4.16]) users had an increased risk of MACE compared with SAMA users. Among patients with asthma–COPD overlap, SABA (HR, 2.57 [1.26–5.24]) was associated with an increased risk of MACE compared with ICS.

Conclusion

In conclusion, initiation of LABA, SABA, or ICS/LABA in COPD or SABA in asthma–COPD overlap is associated with increased risk of MACE. No associations were observed among patients with asthma.

Aerobic performance among healthy (non-asthmatic) adults using beta2-agonists: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To examine the effect of beta2-agonists on aerobic performance in healthy, non-asthmatic study participants.

DESIGN

Systematic review and meta-analysis.

ELIGIBILITY CRITERIA

We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials published until December 2019. Studies examining the effect of beta2-agonists on maximal physical performance lasting longer than 1 min were included in the meta-analysis. Data are presented as standardised difference in mean (SDM) with 95% CI.

RESULTS

The present meta-analysis includes 47 studies. The studies comprise 607 participants in cross-over trials, including 99 participants in three-way cross-over trials and 27 participants in a four-way cross-over trial. Seventy-three participants were included in parallel trials. Beta2-agonists did not affect aerobic performance compared with placebo (SDM 0.051, 95% CI -0.020 to 0.122). The SDM for the included studies was not heterogeneous (I²=0%, p=0.893), and the effect was not related to type of beta2-agonist, dose, administration route, duration of treatment or performance level of participants. Beta2-agonists had no effect on time trial performance, time to exhaustion or maximal oxygen consumption (p<0.218).

CONCLUSION/IMPLICATION

The present study shows that beta2-agonists do not affect aerobic performance in non-asthmatic subjects regardless of type, dose, administration route, duration of treatment or performance level of participants. The results of the present study should be of interest to WADA and to anyone who is interested in equal opportunities in competitive sports.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018109223.

Can β2-agonists have an ergogenic effect on strength, sprint or power performance? Systematic review and meta-analysis of RCTs

OBJECTIVES

We aimed to examine the effect of β2-agonists on anaerobic performance in healthy non-asthmatic subjects.

DESIGN

Systematic review and meta-analysis.

ELIGIBILITY CRITERIA

We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials, published until December 2019, examining the effect of β2-agonists on maximal physical performance lasting 1 min or shorter. Data are presented as standardised difference in mean (SDM) with 95% confidence intervals (95% CI).

RESULTS

34 studies were included in the present meta-analysis. The studies include 44 different randomised and placebo-controlled comparisons with β2-agonists comprising 323 participants in crossover trials, and 149 participants in parallel trials. In the overall analyses, β2-agonists improved anaerobic performance by 5% (SDM 0.29, 95% CI 0.16 to 0.42), but the effect was related to dose and administration route. In a stratified analysis, the SDM was 0.14 (95% CI 0.00 to 0.28) for approved β2-agonists and 0.46 (95% CI 0.24 to 0.68) for prohibited β2-agonists, respectively. Furthermore, SDM was 0.16 (95% CI 0.02 to 0.30) for inhaled administration and 0.51 (95% CI 0.25 to 0.77) for oral administration, respectively, and 0.20 (95% CI 0.07 to 0.33) for acute treatment and 0.50 (95% CI 0.20 to 0.80) for treatment for multiple weeks. Analyses stratified for the type of performance showed that strength (0.35, 95% CI 0.15 to 0.55) and sprint (0.17, 95% CI 0.06 to 0.29) performance were improved by β2-agonists.

CONCLUSION/IMPLICATION

Our study shows that non-asthmatic subjects can improve sprint and strength performance by using β2-agonists. It is uncertain, however, whether World Anti-Doping Agency (WADA)-approved doses of β2-agonists improve performance. Our results support that the use of β2-agonists should be controlled and restricted to athletes with documented asthma.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018109223.

Long-term safety and efficacy studies of epinephrine HFA metered-dose inhaler (Primatene® Mist): a two-stage randomized controlled trial

Objective: A new epinephrine hydrofluoroalkane (HFA) asthma metered-dose inhaler (MDI) was reformulated to replace the previously marketed epinephrine chlorofluorocarbon (CFC) MDI. In addition to the HFA propellant change, several enhanced modifications (i.e. changed from solution to suspension, 43% dose reduction, etc.) were made to the formulation of epinephrine HFA MDI. This study evaluates the 6-month long-term safety and efficacy profile of the new epinephrine HFA MDI.Method: The long-term safety study consists of two 3-month, multi-center, double- or evaluator-blinded, parallel-group, placebo, and active controlled stages. In each stage, subjects aged ≥12 years with intermittent or mild-to-moderate persistent asthma were randomized to receive epinephrine HFA (2 × 125 mcg/inhalation), placebo HFA, or epinephrine CFC (2 × 220 mcg/inhalation). Bronchodilator efficacy was assessed in Stage 1 and was determined primarily by the change in the forced expiratory volume in 1 s (ΔFEV1) at Week 12, relative to the same day baseline.Results: The primary efficacy endpoint (AUC_0-6hrs of %ΔFEV1 at Week 12) for epinephrine HFA (47.3 ± 54.2) closely paralleled those for the active control, epinephrine CFC (41.0 ± 43.4). Both groups were found to be overall comparable in bronchodilator efficacy. Both also showed low incidence rates of AEs with tremor being most commonly reported for epinephrine HFA. All AEs found were non-serious and non-significant. The observed changes in vital signs, ECG, serum glucose, and potassium were minimal and not clinically relevant.Conclusion: This study demonstrated that the new epinephrine HFA is overall comparable, in both safety and efficacy, to the previous epinephrine CFC.

β2-Adrenoceptor signalling bias in asthma and COPD and the potential impact on the comorbidities associated with these diseases

Inhaled selective β2-agonists are the most widely used treatment for obstructive airway diseases. The classical mechanism of action of these drugs is considered as their ability to activate β2-adrenergic receptors (β2-AR) on airway smooth muscle leading to G-protein activation and subsequent generation of c-AMP causing bronchodilation. However, there is now growing evidence to suggest that binding of β2-agonists to β2-AR is pleotropically coupled to many intracellular pathways whereby depending on the state of the β2-AR when activated, a subset of different intracellular responses can be triggered. This is called biased agonism (or functional selectivity) and this type of activity has now been observed with different types of G protein-coupled receptor (GPCR), not just β2-AR. Accordingly, drug efficacy for many agonists binding to GPCRs can no longer be solely described in terms of a single relationship between binding of a ligand to a receptor and the subsequent magnitude of the cellular response, but is often far more complex reflecting a specific complement of signals following binding of a ligand to its receptor. These differences in responses depending on what state the receptor is in when the ligand binds to it can subsequently influence the intracellular signalling that in turn can influence the efficacy of β2-AR ligands. Such findings suggest that in the future it may be possible to develop new synthetic β2-agonists that could preferentially confine their activity in stabilizing/activating the receptor to a certain conformation which could lead to improved drugs either to reduce adverse responses or to avoid drugs that activate certain conformations of the receptors that may lead to tolerance or desensitization following repeated activation.

Involvement of cAMP/EPAC/Akt signaling in the antiproteolytic effects of pentoxifylline on skeletal muscles of diabetic rats

Advances in the knowledge of the mechanisms controlling protein breakdown in skeletal muscles have allowed the exploration of new options for treating muscle-wasting conditions. Pentoxifylline (PTX), a nonselective phosphodiesterase (PDE) inhibitor, attenuates the loss of muscle mass during catabolic conditions, mainly via inhibiting protein breakdown. The aim of this study was to explore the mechanisms by which PTX inhibits proteolysis in the soleus and extensor digitorum longus (EDL) muscles of streptozotocin-induced diabetic rats. The levels of atrogin-1 and muscle RING finger-1 were decreased, as were the activities of caspase-3 (EDL) and calpains (soleus and EDL), in diabetic rats treated with PTX, which at least partly explains the drop in the ubiquitin conjugate (EDL) levels and in proteasome activity (soleus and EDL). Treatment with PTX decreased PDE activity and increased cAMP content in muscles of diabetic rats; moreover, it also increased both the protein levels of exchange protein directly activated by cAMP (EPAC, a cAMP effector) and the phosphorylation of Akt. The loss of muscle mass was practically prevented in diabetic rats treated with PTX. These findings advance our understanding of the mechanisms underlying the antiproteolytic effects of PTX and suggest the use of PDE inhibitors as a strategy to activate cAMP signaling, which is emerging as a promising target for treating muscle mass loss during atrophic conditions. NEW & NOTEWORTHY cAMP signaling has been explored as a strategy to attenuate skeletal muscle atrophies. Therefore, in addition to β₂AR agonists, phosphodiesterase inhibitors such as pentoxifylline (PTX) can be an interesting option. This study advances the understanding of the mechanisms related to the antiproteolytic effects of PTX on skeletal muscles of diabetic rats, which involve the activation of both exchange protein directly activated by cAMP and Akt effectors, inhibiting the expression of atrogenes and calpain/caspase-3-proteolytic machinery.

Tremors in white rhinoceroses (<i>Ceratotherium simum</i>) during etorphine-azaperone immobilisation

Little is known about the mechanisms causing tremors during immobilisation of rhinoceros and whether cardiorespiratory supportive interventions alter their intensity. Therefore, we set out to determine the possible mechanisms that lead to muscle tremors and ascertain whether cardiorespiratory supportive interventions affect tremor intensity. We studied tremors and physiological responses during etorphine–azaperone immobilisation in eight boma-held and 14 free-living white rhinoceroses. Repeated measures analysis of variance and a Friedman test were used to determine differences in variables over time and between interventions. Spearman and Pearson correlations were used to test for associations between variables. Tremor intensity measured objectively by activity loggers correlated well (p < 0.0001; r² = 0.9) with visual observations. Tremor intensity was greatest when animals were severely hypoxaemic and acidaemic. Tremor intensity correlated strongly and negatively with partial pressure of oxygen (PaO₂) (p = 0.0003; r² = 0.9995) and potential of hydrogen (pH) (p = 0.02, r² = 0.97). It correlated strongly and positively with adrenaline concentrations (p = 0.003; r² = 0.96), and adrenaline correlated strongly and negatively with PaO₂ (p = 0.03; r² = 0.95) and pH (p = 0.03; r² = 0.94). Therefore, hypoxaemia and acidaemia were likely associated with the intensity of tremors through their activation of the release of tremorgenic levels of adrenaline. Tremors can be reduced if circulating adrenaline is reduced, and this can be achieved by the administration of butorphanol plus oxygen insufflation. Furthermore, to assist with reducing the risks associated with rhinoceros immobilisation, tremor intensity could be used as a clinical indicator of respiratory and metabolic compromise.

Bronchodilatory and B-adrenergic effects of methanolic and aqueous extracts of Althaea root on isolated tracheobronchial smooth rat muscle

BACKGROUND

The smooth muscle contractions of the tracheobronchial airways are mediated through the balance of adrenergic, cholinergic and peptidergic nervous mechanisms. This research was designed to determine the bronchodilatory and B-adrenergic effects of methanolic and aqueous extracts of root Althaea on the isolated tracheobronchial smooth muscle of the rat.

MATERIALS AND METHODS

In this experimental study, 116 tracheobronchial sections (5 mm) from 58 healthy male Sprague-Dawley rats were dissected and divided into 23 groups. The effect of methanolic and aqueous extracts of the root Althaea was assayed at different concentrations (0.2, 0.6, 2.6, 6.6, 14.6 μg/ml) and epinephrine (5 μm) in the presence and absence of propranolol (1 μM) under one g tension based on the isometric method. This assay was recorded in an organ bath containing Krebs-Henseleit solution for tracheobronchial smooth muscle contractions using potassium chloride (KCl) (60 mM) induction.

RESULTS

Epinephrine (5 μm) alone and root methanolic and aqueous extract concentrations (0.6-14.6 μg/ml) reduced tracheobronchial smooth muscle contractions induced using KCl (60 mM) in a dose dependent manner. Propranolol inhibited the antispasmodic effect of epinephrine on tracheobronchial smooth muscle contractions, but could not reduce the antispasmodic effect of the root extract concentrations.

CONCLUSION

The methanolic and aqueous extracts of Althaea root inhibited the tracheobronchial smooth muscle contractions of rats in a dose dependent manner, but B-adrenergic receptors do not appear to engage in this process. Understanding the mechanism of this process can be useful in the treatment of pulmonary obstructive diseases like asthma.

Pharmacotherapy of essential tremor

Essential tremor (ET) is a common movement disorder but its pathogenesis remains poorly understood. This has limited the development of effective pharmacotherapy. The current therapeutic armamentaria for ET represent the product of careful clinical observation rather than targeted molecular modeling. Here we review their pharmacokinetics, metabolism, dosing, and adverse effect profiles and propose a treatment algorithm. We also discuss the concept of medically refractory tremor, as therapeutic trials should be limited unless invasive therapy is contraindicated or not desired by patients.

β2-agonist therapy in lung disease

β2-Agonists are effective bronchodilators due primarily to their ability to relax airway smooth muscle (ASM). They exert their effects via their binding to the active site of β2-adrenoceptors on ASM, which triggers a signaling cascade that results in a number of events, all of which contribute to relaxation of ASM. There are some differences between β2-agonists. Traditional inhaled short-acting β2-agonists albuterol, fenoterol, and terbutaline provide rapid as-needed symptom relief and short-term prophylactic protection against bronchoconstriction induced by exercise or other stimuli. The twice-daily β2-agonists formoterol and salmeterol represent important advances. Their effective bronchodilating properties and long-term improvement in lung function offer considerable clinical benefits to patients. More recently, a newer β2-agonist (indacaterol) with a longer pharmacodynamic half-life has been discovered, with the hopes of achieving once-daily dosing. In general, β2-agonists have an acceptable safety profile, although there is still controversy as to whether long-acting β2-agonists may increase the risk of asthma mortality. In any case, they can induce adverse effects, such as increased heart rate, palpitations, transient decrease in PaO2, and tremor. Desensitization of β2-adrenoceptors that occurs during the first few days of regular use of β2-agonist treatment may account for the commonly observed resolution of the majority of these adverse events after the first few doses. Nevertheless, it can also induce tolerance to bronchoprotective effects of β2-agonists and has the potential to reduce bronchodilator sensitivity to them. Some novel once-daily β2-agonists (olodaterol, vilanterol, abediterol) are under development, mainly in combination with an inhaled corticosteroid or a long-acting antimuscarinic agent.

Acute supra-therapeutic oral terbutaline administration has no ergogenic effect in non-asthmatic athletes

This study aimed to investigate the effects on a possible improvement in aerobic and anaerobic performance of oral terbutaline (TER) at a supra-therapeutic dose in 7 healthy competitive male athletes. On day 1, ventilatory threshold, maximum oxygen uptake [Formula: see text] and corresponding power output were measured and used to determine the exercise load on days 2 and 3. On days 2 and 3, 8 mg of TER or placebo were orally administered in a double-blind process to athletes who rested for 3 h, and then performed a battery of tests including a force-velocity exercise test, running sprint and a maximal endurance cycling test at Δ50 % (50 % between VT and [Formula: see text]). Lactatemia, anaerobic parameters and endurance performance ([Formula: see text] and time until exhaustion) were raised during the corresponding tests. We found that TER administration did not improve any of the parameters of aerobic performance (p > 0.05). In addition, no change in [Formula: see text] kinetic parameters was found with TER compared to placebo (p > 0.05). Moreover, no enhancement of the force-velocity relationship was observed during sprint exercises after TER intake (p > 0.05) and, on the contrary, maximal strength decreased significantly after TER intake (p < 0.05) but maximal power remained unchanged (p > 0.05). In conclusion, oral acute administration of TER at a supra-therapeutic dose seems to be without any relevant ergogenic effect on anaerobic and aerobic performances in healthy athletes. However, all participants experienced adverse side effects such as tremors.