CNS-related (side-)effects of beta-blockers with special reference to mechanisms of action

Pathophysiological mechanisms of post-myocardial infarction depression: a narrative review

Myocardial infarction (MI) can have significant physical and mental consequences. Depression is a prevalent psychiatric condition after MI which can reduce the quality of life and increase the mortality rates of patients. However, the connection between MI and depression has remained under-appreciated. This review examines the potential connection between depression and MI by overviewing the possible pathophysiologic mechanisms including dysregulation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, coagulation system dysfunction, inflammation, environmental factors, as well as, genetic factors. Furthermore, depression can be an adverse event of medications used for MI treatment including beta-blockers, statins, or anti-platelet agents. The need for early detection and management of depression in patients with MI is, therefore, crucial for improving their overall prognosis. Adherence to treatments and regular follow-up visits can ensure the best response to treatment.

Metoprolol Inhibits Developmental Brain Sterol Biosynthesis in Mice

De novo sterol synthesis is a critical homeostatic mechanism in the brain that begins during early embryonic development and continues throughout life. Multiple medications have sterol-biosynthesis-inhibiting side effects, with potentially detrimental effects on brain health. Using LC-MS/MS, we investigated the effects of six commonly used beta-blockers on brain sterol biosynthesis in vitro using cell lines. Two beta-blockers, metoprolol (MTP) and nebivolol, showed extreme elevations of the highly oxidizable cholesterol precursor 7-dehydrocholesterol (7-DHC) in vitro across multiple cell lines. We followed up on the MTP findings using a maternal exposure model in mice. We found that 7-DHC was significantly elevated in all maternal brain regions analyzed as well as in the heart, liver and brain of the maternally exposed offspring. Since DHCR7-inhibiting/7-DHC elevating compounds can be considered teratogens, these findings suggest that MTP utilization during pregnancy might be detrimental for the development of offspring, and alternative beta-blockers should be considered.

New Insights on Metabolic and Genetic Basis of Migraine: Novel Impact on Management and Therapeutical Approach

Migraine is a hereditary disease, usually one-sided, sometimes bilateral. It is characterized by moderate to severe pain, which worsens with physical activity and may be associated with nausea and vomiting, may be accompanied by photophobia and phonophobia. The disorder can occur at any time of the day and can last from 4 to 72 h, with and without aura. The pathogenic mechanism is unclear, but extensive preclinical and clinical studies are ongoing. According to electrophysiology and imaging studies, many brain areas are involved, such as cerebral cortex, thalamus, hypothalamus, and brainstem. The activation of the trigeminovascular system has a key role in the headache phase. There also appears to be a genetic basis behind the development of migraine. Numerous alterations have been identified, and in addition to the genetic cause, there is also a close association with the surrounding environment, as if on the one hand, the genetic alterations may be responsible for the onset of migraine, on the other, the environmental factors seem to be more strongly associated with exacerbations. This review is an analysis of neurophysiological mechanisms, neuropeptide activity, and genetic alterations that play a fundamental role in choosing the best therapeutic strategy. To date, the goal is to create a therapy that is as personalized as possible, and for this reason, steps forward have been made in the pharmacological field in order to identify new therapeutic strategies for both acute treatment and prophylaxis.

β-adrenoceptor antagonists and nightmares: A pharmacoepidemiological-pharmacodynamic study

AIM

To compare different β-adrenoceptor antagonists for the risk of reporting nightmare.

METHODS

The study involved two approaches: first, we investigated in VigiBase^®, the World Health Organization Individual Case Safety Report (ICSR) database, the disproportionality between exposure to each β-adrenoceptor antagonists and reports of nightmares between 1967 and 2019. Second, in a pharmacoepidemiological-pharmacodynamic analysis, we assessed whether use of β-adrenoceptor antagonists with moderate and high lipid solubility or strong 5-HT_1A affinity were associated with an increased risk of reporting nightmares. We conducted multivariate logistic regression to estimate reporting odds ratios (RORs) of nightmares compared to all other adverse drug reactions.

RESULTS

Of the 126,964 reports recorded with β-adrenoceptor antagonists, 1138 (0.9%) were nightmares. The highest risk of reporting a nightmare was found with exposure of pindolol (adjusted ROR 2.82, 95%CI, 2.19-3.61), metoprolol (1.89, 1.66-2.16), and alprenolol (1.77, 1.06-2.97). Compared to use of low lipid solubility β-adrenoceptor antagonists, use of moderate or high lipid solubility β-adrenoceptor antagonists were significantly more associated with nightmare reports (aROR moderate vs. low 1.72, 95%CI 1.47-2.00 and aROR high vs. low 1.84, 95%CI 1.53-2.22). Use of moderate or high 5-HT_1A affinity of β-adrenoceptor antagonists was associated with an increased ROR of nightmares compared with low 5-HT_1A affinity of β-adrenoceptor antagonists (aROR moderate vs. low 1.22, 95%CI 1.04-1.43 and aROR high vs. low 2.46, 95%CI 1.93-3.13).

CONCLUSION

In our large pharmacovigilance study, nightmares are more frequently reported for pindolol and metoprolol, and among β-adrenoceptor antagonists with high lipid solubility and high 5-HT_1A receptor affinity.

Are Noradrenergic Transmission Reducing Drugs Antidepressants?

Major depressive disorder (MDD) remains a significant public health problem worldwide, and revised treatment strategies are therefore urgently needed, including the creation of novel antidepressant compounds or using existing molecular entities in new ways. Etiologic theories of MDD from decades ago have suggested that synaptic deficiencies of monoaminergic neurotransmitters play a causative role in this neuropsychiatric disorder, and that boosting monoamines with drugs such as SSRIs, SNRIs, TCAs, and MAOIs has antidepressant effects and in some individuals can even induce hypomania or mania. While other factors, such as various intracellular molecular pathways and hippocampal neurogenesis, undoubtedly also play a role in MDD, monoaminergic boosting drugs nonetheless have clearly demonstrated antidepressant properties. There is also, however, a body of studies in the preclinical literature suggesting that monoaminergic transmission reducing drugs, including noradrenergic ones, also have antidepressant-like behavioral properties in rodents. Given that there is increasing evidence that the monoamines have u-shaped or Janus-faced dose-response properties, in which a mid-range value is "optimal" in a variety of behavioral and physiological processes, it is plausible that either too much or too little synaptic norepinephrine in key circuits may exacerbate MDD in some individuals. Here we briefly review rodent depression-related behavioral data, focusing on the forced swim test, from three major classes of noradrenergic transmission reducing drugs (alpha2 agonists, beta blockers, alpha1 antagonists), and find much support for the hypothesis that they have antidepressant-like properties. Whether these drugs are antidepressants in human subjects remains to be determined.

Systemic side effects of glaucoma medications

Glaucoma is a progressive loss of retinal ganglion cells leading to visual field loss. Lowering intraocular pressure is currently the only modifiable risk factor to slow glaucoma progression. Intraocular pressure-lowering options include topical and systemic medications, lasers, and surgical procedures. Glaucoma eye drops play a major role in treating this blinding disease. Similar to all medications, the glaucoma medications have their own adverse effects. The majority of glaucoma medications work by stimulating or inhibiting adrenergic, cholinergic, and prostaglandin receptors, which are distributed all over the body. Therefore, the glaucoma medications can affect organs other than the eye. This review will discuss the systemic adverse effects of carbonic anhydrase inhibitors, sympathomimetics, para-sympathomimetics, beta blockers, prostaglandin analogs, hyperosmotic agents, and novel glaucoma medications with a stress on pregnant patients, breastfeeding mothers, and paediatric patients.

Preventive Oral Treatment of Episodic Migraine: An Overview

Background

Migraine is a common primary headache disorder and Episodic migraine is characterized by the occurrence of up to 14 headache days in a month. The preventive treatment of migraine is useful in patients with frequent migraine attacks, impaired activities of daily living, failure of acute pain management, disabling aura and limitations in the use of acute treatment. It is aimed at reducing headache frequency and intensity, improve response to acute treatment of migraine and improve the quality of life.

Aim

To analyze the evidence for the efficacy and tolerability of preventive oral drugs used in the management of episodic migraine.

Methods

A narrative review of the references were reviewed by searching the literature for the articles published in PubMed in English language using all the following MeSH keywords "preventive treatment", "preventive oral treatment", AND "episodic migraine", "migraine".

Results

Out of articles identified in the search, 38 articles were reviewed for evidence and summarized. The various oral drugs used in the prevention of episodic migraine are antihypertensives (beta-blockers, calcium channel blockers and Angiotensin-converting enzyme inhibitors/Angiotensin receptor blockers), antidepressants (tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors), antiepileptic drugs (valproic acid, topiramate, lamotrigine) and other miscellaneous agents. HURT questionnaire and HALT 30 index are useful in assessing response to treatment in the follow up of migraine patients.

Conclusion

An appropriately chosen oral drug is useful in the preventive treatment of episodic migraine. In patients, who fail to respond to the preventive treatment, it is essential to review the diagnosis of migraine, titrate the dosage and duration of preventive treatment and ensure patient compliance. In those patients who fail to respond to monotherapy, polytherapy is a useful option to be considered.

The association between beta-blocker therapy and daytime sleepiness in obstructive sleep apnoea

Daytime sleepiness is a cardinal symptom of obstructive sleep apnoea (OSA) and a well-recognised side effect of beta-blockers, therefore patients with OSA under this treatment may have worse sleepiness. However, the interaction between daytime sleepiness and beta-blockers use has not been thoroughly investigated in patients with OSA before. We analysed the data of 2183 individuals (1852 patients with OSA and 331 snorer controls) from 3 countries (Greece, Hungary and Moldova). Medical history, including medication usage and the Epworth Sleepiness Scale (ESS) were recorded. Patients and controls were divided into somnolent (ESS ≥ 11) and non-somnolent (ESS < 11) groups, and the association between-blocker use with the somnolent group was investigated with multivariate logistic regression analysis adjusted for confounders. Sensitivity analyses were performed in each cohort, in the severity subgroups, in patients who did not take statins and in those who had polysomnography as a diagnostic test. There was no relationship between beta-blocker usage and the somnolent OSA (p = 0.24) or control (p = 0.64) groups. These results were similar in sensitivity analyses (all p > 0.05). ESS was related to BMI (ρ = 0.25), total sleep time (ρ = 0.07), AHI (ρ = 0.32), oxygen desaturation index (ρ = 0.33) and minimum oxygen saturation (ρ =  – 0.32, all p < 0.05) in OSA, and was higher in patients with hypertension, diabetes and cerebro/cardiovascular disease and those who took statins (all p < 0.05). In general, beta-blockers are not associated with increased daytime sleepiness in OSA. Thus, the diagnosis of OSA should not discourage initiation of beta-blocker treatment, if it is clinically indicated.

The association between beta-blocker therapy and daytime sleepiness in obstructive sleep apnoea

Daytime sleepiness is a cardinal symptom of obstructive sleep apnoea (OSA) and a well-recognised side effect of beta-blockers, therefore patients with OSA under this treatment may have worse sleepiness. However, the interaction between daytime sleepiness and beta-blockers use has not been thoroughly investigated in patients with OSA before. We analysed the data of 2183 individuals (1852 patients with OSA and 331 snorer controls) from 3 countries (Greece, Hungary and Moldova). Medical history, including medication usage and the Epworth Sleepiness Scale (ESS) were recorded. Patients and controls were divided into somnolent (ESS ≥ 11) and non-somnolent (ESS < 11) groups, and the association between-blocker use with the somnolent group was investigated with multivariate logistic regression analysis adjusted for confounders. Sensitivity analyses were performed in each cohort, in the severity subgroups, in patients who did not take statins and in those who had polysomnography as a diagnostic test. There was no relationship between beta-blocker usage and the somnolent OSA (p = 0.24) or control (p = 0.64) groups. These results were similar in sensitivity analyses (all p > 0.05). ESS was related to BMI (ρ = 0.25), total sleep time (ρ = 0.07), AHI (ρ = 0.32), oxygen desaturation index (ρ = 0.33) and minimum oxygen saturation (ρ =  – 0.32, all p < 0.05) in OSA, and was higher in patients with hypertension, diabetes and cerebro/cardiovascular disease and those who took statins (all p < 0.05). In general, beta-blockers are not associated with increased daytime sleepiness in OSA. Thus, the diagnosis of OSA should not discourage initiation of beta-blocker treatment, if it is clinically indicated.

β-blocker prescription is associated with lower cumulative risk of knee osteoarthritis and knee pain consultations in primary care: a propensity score matched cohort study

Objectives

To examine the association between β-blocker prescription and first primary-care consultation for knee OA, hip OA, knee pain and hip pain.

Methods

Data source: Clinical Practice Research Datalink. Participants aged ≥40 years in receipt of new oral β-blocker prescriptions were propensity score (PS) matched to an unexposed control. Cox proportional hazard ratios (HRs) and 95% CIs were calculated, and adjusted for non-osteoporotic fractures, number of primary-care consultations for knee or hip injury, and, the number of primary-care consultations, out-patient referrals and hospitalizations in the 12 months preceding cohort entry. Analysis was stratified according to β-blocker class and for commonly prescribed drugs. P < 0.05 was considered statistically significant.

Results

A total of 111 718 β-blocker–exposed participants were 1:1 PS matched to unexposed controls. β-blocker prescription was associated with reduced cumulative risk of knee OA, knee pain, and hip pain consultations [with a HR (95% CI) of 0.90 (0.83, 0.98), 0.88 (0.83, 0.92) and 0.85 (0.79, 0.90), respectively]. Propranolol and atenolol were associated with a lower incidence of knee OA and knee pain consultations with a HR of between 0.78 and 0.91. β-blockers were associated with reduced incidence of consultation for large-joint lower-limb OA/pain as a composite outcome, defined as the earliest of knee OA, knee pain, hip OA or a hip pain consultation [with a HR (95% CI) of 0.87 (0.84, 0.90)].

Conclusion

Commonly used β-blockers have analgesic properties for musculoskeletal pain. Atenolol might be a therapeutic option for OA and cardiovascular co-morbidities in which β-blockers are indicated, while propranolol may be suitable for people with co-morbid anxiety. A confirmatory randomized controlled trial is needed before clinical practice is changed.

Treating psychiatric symptoms and disorders with non-psychotropic medications

A few drugs prescribed in internal medicine, ie, non-psychotropic drugs, can be used to treat certain neuropsychiatric disorders. For most of these situations, the level of evidence remains low. But when sufficient data becomes available, these molecules are then included in official guidelines for the treatment of neuropsychiatric disorders. In this article we review interesting drugs which may be relevant from an evidence-based medicine point of view, and could become part of psychiatric practice in the future.


Age-dependent changes in cardiac performance, motor function, QoL, and mental status in metoprolol-treated chronic heart failure patients

No previous study reports the effect of age on cardiac performance, motor function and quality of life (QoL) in Chinese chronic heart failure (CHF) patients. This single-center, prospective study enrolled CHF patients with resting heart rate (RHR) > 80 bpm, who were treated with metoprolol and were followed up at 1, 3, 6, and 12 months. Changes in cardiac, motor, and QoL parameters between patients aged ≥60 years and those aged <60 years were compared at all time points. P < 0.05 was considered significant. A total of 154 patients were enrolled (median age: 66.39 years; 116 aged ≥60 years, 38 aged <60 years; 95% New York Heart Association class III-IV). RHR decreased significantly in both patient groups (P < 0.0001 for both groups). Patients aged ≥60 years had a significant improvement in both ejection fraction (EF) at 6 and 12 months and in cardiac index (CI) at 3, 6, and 12 months. However, no major difference was observed in motor function in both groups. Significantly higher SF-8 scores showed greater improvement in QoL in the <60 age group at 12 months (P = 0.0008). Metoprolol demonstrated improvement in cardiac performance, motor function, QoL, and anxiety with increase in depression and burnout in both genders; however, the findings were independent of age.

Propranolol treatment prevents chronic central sensitization induced by repeated dural stimulation

Migraine is currently conceptualized as a chronic disease with episodic manifestations. In some patients, migraine attack frequency increases, leading to chronic migraine. Daily preventive therapy is initiated to decrease attack frequency. Propranolol, a first-line medication for migraine prophylaxis, reduces attack frequency in nearly 50% of patients receiving it. However, the mechanisms of its antimigraine action are unclear. We examined the effect of daily propranolol treatment (10 mg·kg per os, 8 days) in a rat model of recurrent activation of dural nociceptors (repeated infusion of an inflammatory soup (IS) on the dura through a cannula every 2-3 days). Propranolol does not abort IS-induced acute cephalic mechanical allodynia but blocks the development of a chronic cutaneous hypersensitivity upon repeated IS injections. Furthermore, propranolol prevents (1) the elevated touch-evoked Fos expression within the trigeminocervical complex, (2) enhanced both spontaneous activity, and evoked responses of second-order trigeminovascular neurons, (3) elevated touch-evoked rostral ventromedial medulla and locus coeruleus Fos expression and (4) diffuse noxious inhibitory controls impairment, induced by repeated IS injections. Our results suggest that propranolol exerts its prophylactic action, at least in part, by blocking the chronic sensitization of descending controls of pain, arising from the rostral ventromedial medulla and locus coeruleus, and in turn preventing the maintenance of a state of facilitated trigeminovascular transmission within the trigeminocervical complex. Assessing changes in these brain areas has the potential to elucidate the mechanisms for migraine transformation and to reveal novel biological and molecular targets for specific migraine-preventive therapies.

Current Prophylactic Medications for Migraine and Their Potential Mechanisms of Action

A relatively high number of different medications is currently used for migraine prevention in clinical practice. Although these compounds were initially developed for other indications and differ in their mechanisms of action, some general themes can be identified from the mechanisms at play. Efficacious preventive drugs seem to either suppress excitatory nervous signaling via sodium and/or calcium receptors, facilitate GABAergic inhibition, reduce neuronal sensitization, block cortical spreading depression and/or reduce circulating levels of CGRP. We here review such mechanisms for the different compounds.

Impact of metoprolol treatment on cardiac function and exercise tolerance in heart failure patients with neuropsychiatric disorders

OBJECTIVE

To investigate the impact of neuropsychiatric disorders on the effect of metoprolol on cardiac and motor function in chronic heart failure (CHF) patients.

METHODS

From February 2013 to April 2016, CHF patients with clinical mental disorders received metoprolol (23.75 or 47.5 mg, once daily, orally) at the Second Affiliated Hospital of Kunming Medical University. Mental status was confirmed by means of the Hospital Anxiety and Depression Scale (HADS) and the Copenhagen Burnout Inventory (CBI) scale. Cardiac function parameters such as systolic blood pressure (SBP), ejection fraction (EF) and cardiac index (CI) as well as motor function including the 6 meter walk test (6MWT) and the Veteran's Specific Activity Questionnaire (VSAQ) were assessed as primary outcomes of the study.

RESULTS

A total of 154 patients (median age, 66.39 years; men, n = 101) were allocated into eight groups based on their mental status. There were no significant differences in heart rate (HR) or SBP control achieved by metoprolol in any groups compared with the control (patients with normal mental status). Furthermore, biphasic ejection fraction (EF) changes were observed in all the groups with a decrease in the first month and increase from the sixth month. However, this increase was significantly lower (p < .001) than the EF achieved with metoprolol treatment in the control group except for the anxiety group. A similar pattern was seen for CI, 6MWT and VSAQ changes in all the groups. Patients in the anxiety group responded similarly to the patients with normal mental status.

CONCLUSION

Depressive and high burnout symptoms, but not anxiety, lower the improvement of cardiac and motor function by metoprolol treatment in CHF.

Side effects associated with current and prospective antimigraine pharmacotherapies

INTRODUCTION

Migraine is a neurovascular disorder. Current acute specific antimigraine pharmacotherapies target trigeminovascular 5-HT1B/1D, 5-HT1F and CGRP receptors but, unfortunately, they induce some cardiovascular and central side effects that lead to poor treatment adherence/compliance. Therefore, new antimigraine drugs are being explored. Areas covered: This review considers the adverse (or potential) side effects produced by current and prospective antimigraine drugs, including medication overuse headache (MOH) produced by ergots and triptans, the side effects observed in clinical trials for the new gepants and CGRP antibodies, and a section discussing the potential effects resulting from disruption of the cardiovascular CGRPergic neurotransmission. Expert opinion: The last decades have witnessed remarkable developments in antimigraine therapy, which includes acute (e.g. triptans) and prophylactic (e.g. β-adrenoceptor blockers) antimigraine drugs. Indeed, the triptans represent a considerable advance, but their side effects (including nausea, dizziness and coronary vasoconstriction) preclude some patients from using triptans. This has led to the development of the ditans (5-HT1F receptor agonists), the gepants (CGRP receptor antagonists) and the monoclonal antibodies against CGRP or its receptor. The latter drugs represent a new hope in the antimigraine armamentarium, but as CGRP plays a role in cardiovascular homeostasis, the potential for adverse cardiovascular side effects remains latent.

The enigma of site of action of migraine preventives: no effect of metoprolol on trigeminal pain processing in patients and healthy controls

Background

Beta-blockers are a first choice migraine preventive medication. So far it is unknown how they exert their therapeutic effect in migraine. To this end we examined the neural effect of metoprolol on trigeminal pain processing in 19 migraine patients and 26 healthy controls. All participants underwent functional magnetic resonance imaging (fMRI) during trigeminal pain twice: Healthy subjects took part in a placebo-controlled, randomized and double-blind study, receiving a single dose of metoprolol and placebo. Patients were examined with a baseline scan before starting the preventive medication and 3 months later whilst treated with metoprolol.

Results

Mean pain intensity ratings were not significantly altered under metoprolol. Functional imaging revealed no significant differences in nociceptive processing in both groups. Contrary to earlier findings from animal studies, we did not find an effect of metoprolol on the thalamus in either group. However, using a more liberal and exploratory threshold, hypothalamic activity was slightly increased under metoprolol in patients and migraineurs.

Conclusions

No significant effect of metoprolol on trigeminal pain processing was observed, suggesting a peripheral effect of metoprolol. Exploratory analyses revealed slightly enhanced hypothalamic activity under metoprolol in both groups. Given the emerging role of the hypothalamus in migraine attack generation, these data need further examination.

Medicinal-Induced Behavior Disorders

Commonly used medications can have neuropsychiatric and behavioral effects that may be idiosyncratic or metabolic in nature, or a function of interactions with other drugs, toxicity, or withdrawal. This article explores an approach to the patient with central nervous system toxicity, depending on presentation of sedation versus agitation and accompanying physical signs and symptoms. The effects of antihypertensives, opioids, antibiotics, antiepileptic agents, steroids, Parkinson's disease medications, antipsychotics, medications for human immunodeficiency virus infection, cancer chemotherapeutics, and immunotherapies are discussed. A look at the prevalence of adverse reactions to medications and the errors underlying such occurrences is included.

Safety and efficacy of a fixed versus unfixed brinzolamide/timolol combination in Japanese patients with open-angle glaucoma or ocular hypertension

Background

The purpose of this study was to assess the safety and efficacy of fixed-combination brinzolamide 1%/timolol 0.5% (BRINZ/TIM-FC) compared with concomitant brinzolamide 1% and timolol 0.5% (BRINZ + TIM) in Japanese patients with open-angle glaucoma (primary open-angle, exfoliation, pigmentary) or ocular hypertension.

Methods

This randomized, double-masked, multicenter, parallel-group, positive-control, Phase III study was conducted in Japan and included patients aged ≥20 years. Baseline intraocular pressure was assessed after 4 weeks of treatment with timolol 0.5%. Patients were randomized to twice-daily BRINZ/TIM-FC or BRINZ + TIM for 8 weeks (treatment phase). The primary endpoint was mean intraocular pressure reduction from baseline to week 8 at 11 am, at which time noninferiority of BRINZ/TIM-FC versus BRINZ + TIM was evaluated. Data were analyzed using repeated-measures analysis of covariance and t-tests. Adverse events and ophthalmic/physiologic variables were assessed.

Results

In total, 319 patients of mean age 64±12 years were enrolled in the treatment phase. BRINZ/TIM-FC and BRINZ + TIM were associated with reductions in mean intraocular pressure from baseline throughout the study (ranges −2.5 to −3.4 mmHg and −2.7 to −3.3 mmHg, respectively). Mean between-group differences in intraocular pressure reduction ranged from 0 to −0.3 mmHg; the upper limit of the 97.5% confidence interval for week 8 at 11 am was <1.1 mmHg, indicating noninferiority of BRINZ/TIM-FC. Treatment-related adverse events were observed in 3% and 12% of patients receiving BRINZ/TIM-FC and BRINZ + TIM, respectively. No substantial changes in other safety parameters were reported.

Conclusion

Twice-daily BRINZ/TIM-FC reduced intraocular pressure by levels similar to concomitant BRINZ + TIM in Japanese patients with open-angle glaucoma or ocular hypertension and was noninferior to BRINZ + TIM. Both treatments were well tolerated.

(R,R')-4'-methoxy-1-naphthylfenoterol targets GPR55-mediated ligand internalization and impairs cancer cell motility

(R,R')-4'-Methoxy-1-naphthylfenoterol (MNF) promotes growth inhibition and apoptosis of human HepG2 hepatocarcinoma cells via cannabinoid receptor (CBR) activation. The synthetic CB1R inverse agonist, AM251, has been shown to block the anti-mitogenic effect of MNF in these cells; however, AM251 is also an agonist of the recently deorphanized, lipid-sensing receptor, GPR55, whose upregulation contributes to carcinogenesis. Here, we investigated the role of MNF in GPR55 signaling in human HepG2 and PANC-1 cancer cell lines in culture by focusing first on internalization of the fluorescent ligand Tocrifluor 1117 (T1117). Initial results indicated that cell pretreatment with GPR55 agonists, including the atypical cannabinoid O-1602 and l-α-lysophosphatidylinositol, dose-dependently reduced the rate of cellular T1117 uptake, a process that was sensitive to MNF inhibition. GPR55 internalization and signaling mediated by O-1602 was blocked by MNF in GPR55-expressing HEK293 cells. Pretreatment of HepG2 and PANC-1 cells with MNF significantly abrogated the induction of ERK1/2 phosphorylation in response to AM251 and O-1602. Moreover, MNF exerted a coordinated negative regulation of AM251 and O-1602 inducible processes, including changes in cellular morphology and cell migration using scratch wound healing assay. This study shows for the first time that MNF impairs GPR55-mediated signaling and, therefore, may have therapeutic potential in the management of cancer.

Prophylactic Treatment of Migraine

Migraine is a common chronic neurological disease characterized by episodic attacks of headache and associated symptoms. The pharmacological treatment of migraine may be acute or prophylactic, and patients with frequent, severe headaches often require both approaches. Prophylactic treatment is used to reduce the frequency, duration, or severity of attacks, to enhance the benefits of acute treatments, and to improve patient's ability to function normally. Prophylactic treatment may also prevent progression from episodic migraine to chronic migraine and may result in reductions in health-care cost. The currently available pharmacological options for migraine prophylaxis include a wide array of medications. The major medication groups for prophylactic treatment include β-blockers, anticonvulsant, drugs such as topiramate and valproate, antidepressant drugs, such as amitriptyline and selective serotonin and selective serotonin-norepinephrine reuptake inhibitors (SNRIs), calcium channel antagonists and neurotoxins. The agent for prophylactic treatment should be chosen based on the efficacy and side-effect profile of the drug, and the patient's coexistent and comorbid conditions.

A review on the putative association between beta-blockers and depression

Several kinds of systematic studies have been conducted verifying the putative association between β-blockers and depressive symptoms. However, many of these studies had important limitations in their design. In most of the studies, no effect of β-blockers on depressive symptoms was seen. Because individual susceptibility cannot be ruled out, clinicians must stay vigilant, especially with patients who have a positive personal or family history and who have been prescribed lipophilic β-blockers. However, fear for depression should not be the reason for reluctance in prescribing β-blockers to cardiovascular patients.

Patient outcome in migraine prophylaxis: the role of psychopharmacological agents

INTRODUCTION

Migraine is a serious illness that needs correct treatment for acute attacks and, in addition, a treatment prophylaxis, since patients with migraine suffer during acute attacks and also between attacks.

METHODS

A systematic review of the most relevant clinical trials of migraine headache and its epidemiology, pathophysiology, comorbidity, and prophylactic treatment (medical and nonmedical) was carried out using "Medline" and "PsychINFO" from 1973 to 2009. Approximately 110 trials met our inclusion criteria and were included in the current review.

RESULTS

The most effective pharmacological treatment for migraine prophylaxis is propranolol and anticonvulsants such as topiramate, valproic acid, and amitriptyline. Nonmedical treatments such as acupuncture, biofeedback, and melatonin have also been proposed. Peripheral neurostimulation has been suggested for the treatment of chronic daily headache that does not respond to prophylaxis and for the treatment of drug-resistant primary headache. The majority of the pharmacological agents available today have limited efficacy and may cause adverse effects incompatible with long-term use.

LIMITATIONS

The review was limited by the highly variable and often insufficient reporting of the complex outcome data and by the fact that migraine prophylaxis trials typically use headache diaries to monitor the course of the disease. The results of the different studies were also presented in different ways, making comparison of the results difficult.

DISCUSSION

An adequate prophylaxis is crucial in reducing disability and preventing the evolution of the problem into a chronic progressive illness. The implications of the present findings were discussed.

A randomized trial of propranolol versus sodium valproate for the prophylaxis of migraine in pediatric patients

BACKGROUND

Migraine is the most common of the paroxysmal disorders to affect the brain in the pediatric population. Both propranolol and sodium valproate (valproic acid) have been advocated as prophylactic agents for childhood migraine.

OBJECTIVE

To compare the efficacy and tolerability of propranolol and sodium valproate in the prevention of migraine in the pediatric population.

METHODS

Sixty-three children (aged 5-15 years) with migraine without aura, as defined by the 2004 International Headache Society (IHS) criteria, were included in this prospective, double-blind clinical trial and were randomly assigned to two groups. Group A (n = 32 patients) received propranolol 3 mg/kg/day and group B (n = 31 patients) received sodium valproate 30 mg/kg/day, with at least 6 months of follow up. The propranolol dosage was adjusted to 2 mg/kg/day and the sodium valproate dosage to 15 mg/kg/day, after the first follow-up visit. Participants were evaluated by using a detailed questionnaire that asked about the features of headaches and general health characteristics. The study endpoints were successful treatment for a 4- to 6-month period; 3 months of a persistent unsuccessful or incomplete response to treatment; intolerable side effects; and/or patient non-adherence. All data were analyzed longitudinally by comparing baseline data with data from each follow-up.

RESULTS

A total of 60 patients completed the full headache prophylaxis period. The baseline headache frequency was reduced by more than 50% in 83% of propranolol recipients and in 63% of sodium valproate recipients (statistically not significant); the overall reduction of baseline headache frequency per month was better in group A (p = 0.044). The mean headache frequency per month was reduced from 13.86 +/- 2.11 to 4.23 +/- 3.24 in group A, and from 13.23 +/- 2.43 to 5.83 +/- 4.04 in group B; the difference between the two groups was statistically significant (p < 0.01). The mean headache duration per week was decreased from 9.9 +/- 7.4 hours to 3.2 +/- 5.9 hours in group A, and from 9.1 +/- 6.9 hours to 3.7 +/- 5.0 hours in group B; although there was no statistically significant difference between propranolol and sodium valproate, headache duration was markedly improved with each drug (p < 0.002). Reduction of headache severity by at least one grade was seen in 64% of patients in group A and in 56% in group B, and complete cessation of headache attacks occurred in 14% of patients in group A and 10% in group B (not significant). Minor side effects appeared to be fairly well tolerated by patients in both groups, with no significant difference in side effects between the two groups.

CONCLUSION

This prospective study supports the efficacy of propranolol and sodium valproate as prophylaxis for pediatric migraine without aura, based on IHS criteria. There were no significant differences between these two drugs in all evaluated parameters except for the mean headache frequency per month, which was lower with propranolol than with sodium valproate.

Migraine preventive treatment

Migraine is a chronic neurological disease. Preventive therapy is given in an attempt to reduce the frequency, duration, or severity of attacks. Circumstances that might warrant preventive treatment include recurring migraine attacks that significantly interfere with the patient's daily routines, despite appropriate acute treatment; frequent headaches; contraindication to, failure of, overuse of, or intolerance to acute therapies; patient preference; frequent, very long, or uncomfortable auras; and presence of uncommon migraine conditions. The major medication groups for preventive migraine treatment include beta-adrenergic blockers, antidepressants, calcium channel antagonists, serotonin antagonists, and anticonvulsants. The choice of preventive treatment depends on the individual drug's efficacy and adverse events, the patient's clinical features, frequency, and response to prior treatment, and the presence of any comorbid or coexistent disease.

Anticholinergic activity of commonly prescribed medications and neuropsychiatric adverse events in older people

This study sought to determine whether the presence of in vitro anticholinergic activity (AA) among different drugs is associated with reporting of neuropsychiatric adverse events (NPAEs) and whether age affects this relationship. Retrospective case/noncase analyses using Australia's spontaneous Adverse Drug Reaction System (ADRS) database containing 150 475 reports determined crude and adjusted reporting odds ratios (RORs) for NPAEs for 23 drugs with various reported in vitro AA. Covariates were age (treated as a dichotomous variable [> or =65 years]), gender, and concomitant use of antipsychotics, benzodiazepines, tricyclic antidepressants, and drugs with recognized inherent anticholinergic properties (anticholinergic drugs). The interaction effect between these covariates and each drug exposure category was examined. Age (> or =65 years) has a significant association with greater odds relative to younger age for reporting NPAEs. Drugs with reported significant AA in vitro were not always associated with RORs greater than 1 for reporting NPAEs, highlighting a dissonance between the in vitro AA index and ADRS observations. Significant interactions were observed between age (> or =65 years) and exposure to cimetidine, anticholinergic drugs, antipsychotics, and tricyclic antidepressants in modifying odds for reporting NPAEs, reinforcing the need for cautious use and monitoring of drugs with AA in older people.

Preventive migraine treatment

The pharmacologic treatment of migraine may be acute (abortive) or preventive (prophylactic), and patients with frequent severe headaches often require both approaches. Preventive therapy is used to try to reduce the frequency, duration, or severity of attacks. The preventive medications with the best-documented efficacy are amitriptyline, divalproex, topiramate, and the beta-blockers. Choice is made based on a drug's proven efficacy, the physician's informed belief about medications not yet evaluated in controlled trials, the drug's adverse events, the patient's preferences and headache profile, and the presence or absence of coexisting disorders. Because comorbid medical and psychologic illnesses are prevalent in patients who have migraine, one must consider comorbidity when choosing preventive drugs. Drug therapy may be beneficial for both disorders; however, it is also a potential confounder of optimal treatment of either.

Neurocognitive costs and benefits of psychotropic medications in older adults

Psychotropic medications are widely used in older adults and may cause neurocognitive deficits. Older adults are at increased risk of developing adverse effects because of age-related pharmacodynamic and pharmacokinetic changes. This article provides a comprehensive review of the undesirable, and at times beneficial, effects of psychotropic medications. The review covers a wide range of medications that impair executive function, memory, and attention, as well as a much smaller group of medications that lead to improved neurocognitive function. Some of the most commonly used psychotropic medications in older adults, namely, antidepressants, sedatives, and hypnotics, are among the drugs that most consistently lead to cognitive impairments. Medications with anticholinergic properties almost invariably lead to neurocognitive dysfunction, despite symptom improvement. The neurocognitive costs and benefits of psychiatric medications should be considered in the context of disease treatment in older adults.

Migraine: Current concepts and emerging therapies

Migraine is a recurrent incapacitating neurovascular disorder characterized by attacks of debilitating pain associated with photophobia, phonophobia, nausea and vomiting. Migraine affects a substantial fraction of world population and is a major cause of disability in the work place. Though the pathophysiology of migraine is still unclear three major theories proposed with regard to the mechanisms of migraine are vascular (due to cerebral vasodilatation), neurological (abnormal neurological firing which causes the spreading depression and migraine) and neurogenic dural inflammation (release of inflammatory neuropeptides). The modern understanding of the pathogenesis of migraine is based on the concept that it is a neurovascular disorder. The drugs used in the treatment of migraine either abolish the acute migraine headache or aim its prevention. The last decade has witnessed the advent of Sumatriptan and the 'triptan' class of 5-HT1B/1D receptor agonists which have well established efficacy in treating migraine. Currently prophylactic treatments for migraine include calcium channel blockers, 5-HT2 receptor antagonists, beta adrenoceptor blockers and gamma-amino butyric acid (GABA) agonists. Unfortunately, many of these treatments are non specific and not always effective. Despite such progress, in view of the complexity of the etiology of migraine, it still remains undiagnosed and available therapies are underused. In this article, the diverse pieces of evidence that have linked the different theories of migraine with its pathophysiology are reviewed. Furthermore, the present therapeutic targets and futuristic approaches for the acute and prophylactic treatment of migraine, with a special emphasis to calcitonin gene-related peptide, are critically evaluated.

An analysis of administrative data found that proximate clinical event ratios provided a systematic approach to identifying possible iatrogenic risk factors or complications

OBJECTIVE

A method to generate hypotheses about iatrogenic risk factors and complications from administrative data was developed and tested using hospitalization of the elderly for depression as a model.

STUDY DESIGN AND SETTING

Hospital claims were selected for 30,998 elderly inpatients admitted for the first time for depression. Common principal diagnoses and procedures in hospitalizations within 90 days of the index depression admission were tallied. For each of these proximate clinical events, the ratio of how many happened before the index admission to how many occurred afterward was calculated. Ratios diverging markedly from unity were identified to generate hypotheses about possible risk factors associated with depression and complications associated with its management.

RESULTS

Hospitalization for degenerative joint disease or back problems; abdominal pain or gastritis and duodenitis; coronary artery disease; or cerebrovascular disease was more common before an index depression admission than after it, as were coronary artery surgery, total knee replacement, and cholecystectomy. Admissions for fracture of the femoral neck--an established iatrogenic complication--were disproportionately likely after the index admission. So were admissions for aspiration pneumonia or acute respiratory failure.

CONCLUSION

Proximate clinical event ratios provide a systematic approach to screening administrative data to identify candidates for further evaluation as possible iatrogenic risk factors or complications.

Role of alpha and beta adrenoceptors in locus coeruleus stimulation-induced reduction in rapid eye movement sleep in freely moving rats

Based on the results of independent studies the involvement of norepinephrine in REM sleep regulation was known. Isolated studies showed that the effect could be mediated through either one or more subtypes of adrenoceptors. Earlier we have reported that REM-OFF neurons continue firing during REM sleep deprivation and mild but continuous stimulation of locus coeruleus (LC) or picrotoxin injection into the LC, that did not allow the REM-OFF neurons in the LC to stop firing, reduced REM sleep. However, the mechanism of action and type of adrenoreceptors involved in REM sleep regulation were unknown. The possible mechanism of action has been investigated in this study. It was proposed that if LC stimulation-induced decrease in REM sleep was due to norepinephrine, adrenergic antagonist must prevent the effect. Therefore, in this study, the effects of alpha1, alpha2 and beta-antagonists, viz. prazosin, yohimbine and propranolol, respectively, and alpha2 agonist, clonidine, on LC stimulation-induced reduction in REM sleep were investigated. The results showed that stimulation of LC inhibited REM sleep by reducing the frequency of generation of REM sleep, although the duration per episode remained unaffected. This decrease in the frequency of REM sleep was blocked by beta-antagonist propranolol while the duration of REM sleep per episode was blocked by alpha1-antagonist, prazosin. Also, a critical level of norepinephrine in the system was required for the generation of REM sleep, however, a higher level may be inhibitory. Based on the results of this study and our earlier studies, an interaction between neurons, containing different neurotransmitters and their subtypes of receptors for LC-mediated regulation of REM sleep has been proposed.

Sodium Valproate versus Propranolol in paediatric migraine prophylaxis

In a randomized clinical trial the effect of Sodium Valproate in pediatric migraine prophylaxis was compared with that of Propranolol. One hundred and twenty patients with common migraine (migraine without aura) aged from 3 to 15 years who met the defined criteria enrolled into the study. Randomly the patients were divided in two groups of A and B, treating with sodium Valproate and Propranolol, respectively. Three phases of baseline period (phase I), titration and adjustment period (phases II) and fixed -dose treatment period (phase III) have been designed. A total of 57 patients in group A, and 58 patients in group B completed all phases of the trial. Seventy two percent of patients in group A and 69% of patients in group B have responded to Sodium Valproate and Propranolol, respectively, as a reduction of more than 50% in headache frequency per month. Further more both drugs have shown efficacy in reducing the severity and duration of headache and also better response to rescue medications (p value <0.01). There was no significant difference in all previously mentioned therapeutic effects between two groups (p value <0.05).

Persistency and clinical outcomes associated with latanoprost and beta-blocker monotherapy: evidence from a European retrospective cohort study

PURPOSE

To evaluate persistency (time on initial therapy) and the clinical impact of latanoprost versus beta-blocker monotherapy in treating glaucoma.

METHODS

This observational, multicenter, retrospective medical chart review study conducted in four European countries included patients with primary open-angle glaucoma or ocular hypertension who began their first glaucoma treatment with latanoprost or a beta-blocker between November 1996 and November 1998. Persistency and glaucoma-related clinical outcomes data were abstracted for the 2 years following treatment initiation.

RESULTS

In all, 260 patient charts were analyzed (94 latanoprost, 166 beta-blocker). Patients in the latanoprost group stayed on therapy twice as long as those who received a beta-blocker (p < 0.0001). After adjusting for baseline characteristics, patients receiving a beta-blocker as initial therapy were 3.8 times more likely to change therapy than those initially treated with latanoprost (p < 0.0001). Patients in the latanoprost group also experienced greater mean decreases in intraocular pressure (IOP) than those receiving a beta-blocker (7.4 mmHg versus 4.6 mmHg, respectively; p < 0.0001), and fewer had worsened optic nerve head excavation (1.7% versus 14.2%, respectively; p < 0.05) by the time of their first therapy change or last study visit, whichever came first.

CONCLUSIONS

Over a 2-year period, latanoprost was associated with significantly greater persistency and better clinical IOP outcomes compared with beta-blocker therapy.

Nightmares and panic disorder associated with carvedilol overdose

OBJECTIVE

To report a case of nightmares and sleep disorder associated with improper use of carvedilol, an alpha/beta-blocker, and to model the time course of receptor occupancy in this patient.

CASE SUMMARY

A 41-year-old man with panic disorder had been treated with alprazolam 1.2 mg/d (3 times daily), carvedilol 10 mg/d (once in the morning), and etizolam 0.5 mg (for anxiety attack). Although the physical and psychological symptoms gradually improved, he reported nightmares and panic attacks. An interview revealed that he had been taking carvedilol 5 mg twice a day after lunch and dinner on his own initiative, in addition to the prescribed dosage. The patient was asked to take carvedilol 10 mg only after breakfast, as had been advised. Consequently, the sleep disorder and nightmares disappeared.

METHODS

We calculated the time courses of beta(2)-adrenoceptor binding occupancy in the central nervous system after oral administration of carvedilol with the ordinary and improper regimens by using pharmacokinetic/pharmacodynamic parameters obtained from the literature.

RESULTS

Compared with the ordinary dose of carvedilol 10 mg once a day, the improper regimen (10 mg after breakfast followed by 5 mg after lunch and dinner) increases the beta(2)-adrenoceptor binding occupancy at night (2300) to as high as the mean beta(2)-adrenoceptor binding occupancy after an ordinary dose of propranolol.

CONCLUSIONS

The sleep disorder and nightmares experienced by this patient had been induced by elevation of central beta(2)-adrenoceptor binding occupancy at night as the result of improper use of carvedilol.

Migraine: preventive treatment

Migraine is a common episodic headache disorder. A comprehensive headache treatment plan includes acute attack treatment to relieve pain and impairment and long-term preventive therapy to reduce attack frequency, severity, and duration. Circumstances that might warrant preventive treatment include: (i) migraine that significantly interferes with the patient's daily routine despite acute treatment; (ii) failure, contraindication to, or troublesome side-effects from acute medications; (iii) overuse of acute medications; (iv) special circumstances, such as hemiplegic migraine; (v) very frequent headaches (more than two a week); or (vi) patient preference. Start the drug at a low dose. Give each treatment an adequate trial. Avoid interfering, overused, and contraindicated drugs. Re-evaluate therapy. Be sure that a woman of childbearing potential is aware of any potential risks. Involve patients in their care to maximize compliance. Consider co-morbidity. Choose a drug based on its proven efficacy, the patient's preferences and headache profile, the drug's side-effects, and the presence or absence of coexisting or co-morbid disease. Drugs that have documented high efficacy and mild to moderate adverse events (AEs) include beta-blockers, amitriptyline, and divalproex. Drugs that have lower documented efficacy and mild to moderate AEs include selective serotonin reuptake inhibitors (SSRIs), calcium channel antagonists, gabapentin, topiramate, riboflavin, and non-steroidal anti-inflammatory drugs.

Modulation of beta-adrenergic receptor subtype activities in perioperative medicine: mechanisms and sites of action

This review focuses on the mechanisms and sites of action underlying beta-adrenergic antagonism in perioperative medicine. A large body of knowledge has recently emerged from basic and clinical research concerning the mechanisms of the life-saving effects of beta-adrenergic antagonists (beta-AAs) in high-risk cardiac patients. This article re-emphasizes the mechanisms underlying beta-adrenergic antagonism and also illuminates novel rationales behind the use of perioperative beta-AAs from a biological point of view. Particularly, it delineates new concepts of beta-adrenergic signal transduction emerging from transgenic animal models. The role of the different characteristics of various beta-AAs is discussed, and evidence will be presented for the selection of one specific agent over another on the basis of individual drug profiles in defined clinical situations. The salutary effects of beta-AAs on the cardiovascular system will be described at the cellular and molecular levels. Beta-AAs exhibit many effects beyond a reduction in heart rate, which are less known by perioperative physicians but equally desirable in the perioperative care of high-risk cardiac patients. These include effects on core components of an anaesthetic regimen, such as analgesia, hypnosis, and memory function. Despite overwhelming evidence of benefit, beta-AAs are currently under-utilized in the perioperative period because of concerns of potential adverse effects and toxicity. The effects of acute administration of beta-AAs on cardiac function in the compromised patient and strategies to counteract potential adverse effects will be discussed in detail. This may help to overcome barriers to the initiation of perioperative treatment with beta-AAs in a larger number of high-risk cardiac patients undergoing surgery.

Co-prescribing of medications used to treat obstructive lung disease, congestive heart failure and depression among users of topical beta blockers: estimates from three US Veterans Affairs Medical Centers

PURPOSE

To estimate the frequency of co-prescribing of medications used to treat obstructive lung disease, congestive heart failure, and depression among US armed service veterans for whom topical beta blockers (TBB) have been prescribed.

METHODS

Prescription data from the computerized medical record systems of three US Veterans Affairs Medical Centers were obtained during Fall 1999 to identify patients for whom active prescriptions existed for TBB and/or drugs commonly used to treat obstructive lung disease, congestive heart failure, and depression.

RESULTS

Among TBB users, the estimated co-prescribing rate of medications used to treat obstructive lung disease is in the range of 7.8-9.7%, of medications used to treat congestive heart failure is in the range of 4.3-25.1%, and of medications used to treat depression is in the range of 8.8-11.7%. The total number of TBB users with a concurrent prescription for one or more of the conditions studied was in the range of 30.2-45.7%.

CONCLUSIONS

Since TBB may cause systemic side-effects and thus potentially cause exacerbations of selected chronic conditions, it is important for researchers and prescribers to be aware of the frequency with which their patients with glaucoma may have other concomitant conditions.

Propafenone-induced ataxia: report of three cases

Propafenone is an effective antiarrhythmic drug used widely for the treatment of supraventricular and ventricular arrhythmias. Although it is generally well tolerated, 30 to 45% of patients may experience adverse cardiac effects. In 15 to 20% of patients, adverse effects may involve other organ systems. A wide variety of adverse central nervous system effects have been reported in association with propafenone; dizziness is the most common. Ataxia caused by propafenone has been reported to the pharmaceutical companies and drug monitoring agencies, but has not been well described or emphasized in the medical literature. We describe 3 elderly patients with moderate to severe ataxia that occurred while they were taking propafenone.

Relationship between cortical electrical and cardiac autonomic activities in the awake lizard, Gallotia galloti

ECG and EEG signals were simultaneously recorded in lizards, Gallotia galloti, both in control conditions and under autonomic nervous system (ANS) blockade, in order to evaluate possible relationships between the ANS control of heart rate and the integrated central nervous system activity in reptiles. The ANS blockers used were prazosin, propranolol, and atropine. Time-domain summary statistics were derived from the series of consecutive R-R intervals (RRI) of the ECG to measure beat-to-beat heart rate variability (HRV), and spectral analysis techniques were applied to the EEG activity to assess its frequency content. Both prazosin and atropine did not alter the power spectral density (PSD) of the EEG low frequency (LF: 0.5-7.5 Hz) and high frequency (HF: 7.6-30 Hz) bands, whereas propranolol decreased the PSD in these bands. These findings suggest that central beta-adrenergic receptor mechanisms could mediate the reptilian waking EEG activity without taking part any alpha(1)-adrenergic and/or cholinergic receptor systems. In 55% of the lizards in control conditions, and in approximately 43% of the lizards under prazosin and atropine, a negative correlation between the coefficient of variation of the series of RRI value (CV(RRI)) and the mean power frequency (MPF) of the EEG spectra was found, but not under propranolol. Consequently, the lizards' HRV-EEG-activity relationship appears to be independent of alpha(1)-adrenergic and cholinergic receptor systems and mediated by beta-adrenergic receptor mechanisms.

Contribution of P-glycoprotein to bunitrolol efflux across blood-brain barrier

In this study, we investigated the mechanism of the blood-brain barrier (BBB) transport of bunitrolol (BTL), as a model of beta-blocker, in vivo and in vitro. In order to define the contribution of P-glycoprotein (P-gp) to the active efflux of BTL from brain to blood, we examined the in vivo brain distribution of BTL in mdr1a(-/-) mice with a disrupted mdr1a gene. After intravenous administration of BTL to mdr1a(-/-) mice, the brain concentration and Kp value of BTL were significantly increased as compared with those in mdr1a(+/+) mice. Next, the contribution of the mdr1a P-gp to in vitro uptake of BTL was compared in LV500 cells and L cells (mouse mdr1a-expressing cells and host cells, respectively). The intracellular accumulations of [3H]vinblastine and BTL by LV500 cells were lower than those by L cells, but were significantly increased by verapamil, a P-gp inhibitor. Furthermore, the BTL uptake by KB-VJ300 cells, which express human P-gp, was also significantly lower than that by KB host cells, and was increased by verapamil. The steady-state uptake of BTL by LLC-GA5-COL300 cells, expressing human P-gp, was significantly increased in the presence of 20 microM cyclosporin A (another P-gp inhibitor), which had no effect in the LLC-PK1 host cells. On the other hand, the steady-state intracellular accumulation of BTL by MBEC4 cells, which express mdr1b P-gp instead of mdr1a P-gp, was not significantly changed in the presence of verapamil. This finding suggested that BTL is not a good substrate for mdr1b P-gp. In conclusion, our results suggest that BTL is transported from brain to blood by mdr1a P-gp in mice and by MDR1 in humans, and this presumably accounts for the low brain distribution of BTL.

Drug-induced nightmares

OBJECTIVE

To compile and assess the English-language literature on drug-induced nightmares, excluding nightmares secondary to drug withdrawal or drug-associated night terrors.

DATA SOURCES

Published articles, letters, case reports, and abstracts in English were identified by MEDLINE (1966-May 1998) searches using the search term nightmares, chemically induced. Additional articles were obtained from bibliographies of retrieved articles.

DATA EXTRACTION

All case reports of drug-induced nightmares were evaluated using the Naranjo algorithm for causality. Clinical studies of drugs that reported nightmares as an adverse effect were assessed for frequency of occurrence.

DATA SYNTHESIS

Nightmares, defined as nocturnal episodes of intense anxiety and fear associated with a vivid, emotionally charged dream experience, are generally classified as a parasomnia. Possible pharmacologic mechanisms for drug-induced nightmares, such as REM suppression and dopamine receptor stimulation, are reviewed. However, the vast majority of therapeutic agents implicated in causing nightmares have no obvious pharmacologic mechanism.

CONCLUSIONS

Assessing causality with an event such as a nightmare is difficult because of the high incidence of nightmares in the healthy population. Using qualitative, quantitative, and possible pharmacologic mechanism criteria, it appears that sedative/hypnotics, beta-blockers, and amphetamines are the therapeutic modalities most frequently associated with nightmares. These drug classes have a plausible pharmacologic mechanism to explain this effect. Dopamine agonists also have evidence of causality, with dopamine receptor stimulation as a possible pharmacologic mechanism.