The Use of Beta-Adrenergic Blocking Agents in Anxiety Disorders and Schizophrenia

Alternative Therapy of Psychosis: Potential Phytochemicals and Drug Targets in the Management of Schizophrenia

Schizophrenia is a chronic mental and behavioral disorder characterized by clusters of symptoms including hallucinations, delusions, disorganized thoughts and social withdrawal. It is mainly contributed by defects in dopamine, glutamate, cholinergic and serotonergic pathways, genetic and environmental factors, prenatal infections, oxidative stress, immune system activation and inflammation. Management of schizophrenia is usually carried out with typical and atypical antipsychotics, but it yields modest benefits with a diversity of side effects. Therefore, the current study was designed to determine the phytochemicals as new drug candidates for treatment and management of schizophrenia. These phytochemicals alter and affect neurotransmission, cell signaling pathways, endocannabinoid receptors, neuro-inflammation, activation of immune system and status of oxidative stress. Phytochemicals exhibiting anti-schizophrenic activity are mostly flavonoids, polyphenols, alkaloids, terpenoids, terpenes, polypropanoids, lactones and glycosides. However, well-designed clinical trials are consequently required to investigate potential protective effect and therapeutic benefits of these phytochemicals against schizophrenia.

Understanding the pharmacokinetics of anxiolytic drugs

INTRODUCTION

Anxiety disorders are considered the most common mental disorders and they can increase the risk for comorbid mood and substance use disorders, significantly contributing to the global burden of disease. For this reason, anxiolytics are the most prescribed psychoactive drugs, particularly in the Western world.

AREAS COVERED

This review aims to analyze pharmacokinetic profile, plasma level variations so as the metabolism, interactions and possible relation to clinical effect of several drugs which are used primarily as anxiolytics. The drugs analyzed include benzodiazepines, anticonvulsants (pregabalin, gabapentin), buspirone, β-blockers and antihistamines (hydroxyzine). Regarding the most frequently used anxiolytic benzodiazepines, data on alprazolam, bromazepam, chlordesmethyldiazepam, chlordiazepoxide, clotiazepam, diazepam, etizolam, lorazepam, oxazepam, prazepam and clonazepam have been detailed.

EXPERT OPINION

There is a need for a more balanced assessment of the benefits and risks associated with benzodiazepine use, particularly considering pharmacokinetic profile of the drugs to ensure that patients, who would truly benefit from these agents, are not denied appropriate treatment. An optimal pharmacological approach involving an integrative pharmacokinetic and pharmacodynamic optimization strategy would ensure better treatment and personalization of anxiety disorders. So it would be desirable for the development of new anxiolytic drug(s) that are more selective, fast acting and free from the unwanted effects associated with the traditional benzodiazepines as tolerance or dependence.

Concomitant medication of psychoses in a lifetime perspective

OBJECTIVE

Patients treated with antipsychotic drugs often receive concomitant psychotropic compounds. Few studies address this issue from a lifetime perspective. Here, an analysis is presented of the prescription pattern of such concomitant medication from the first contact with psychiatry until the last written note in the case history documents, in patients with a diagnosis of psychotic illness.

METHODS

A retrospective descriptive analysis of all case history data of 66 patients diagnosed with schizophrenia or schizophrenia-like psychotic disorders.

RESULTS

Benzodiazepines and benzodiazepine-related anxiolytic drugs had been prescribed to 95% of the patients, other anxiolytics, sedatives or hypnotic drugs to 61%, anti-parkinsonism drugs to 86%, and antidepressants to 56% of the patients. However, lifetime doses were small and most of the time patients had no concomitant medication. The prescribed lifetime dose of anti-parkinsonism drugs was associated with that of prescribed first-generation but not second-generation antipsychotics.

CONCLUSIONS

Most psychosis patients are sometimes treated with concomitant drugs but mainly over short periods. Lifetime concomitant add-on medication at the individual patient level is variable and complex but not extensive.

Noradrenergic modulation of extinction learning and exposure therapy

Memory consolidation is enhanced by emotional arousal, an effect mediated by noradrenergic beta-receptor signaling. Norepinephrine strengthens consolidation of both appetitive and aversive learning, and is implicated in extinction of conditioned responses. In this review, we summarize work on the noradrenergic mechanisms of extinction learning and implications for extinction-based exposure therapy. The evidence suggests that norepinephrine release evoked by conditioned stimuli during extinction strengthens extinction memory via beta-receptor signaling. The modulatory effect of norepinephrine during extinction depends on predictable presentation of conditioned stimuli and optimal levels of norepinephrine release. Mechanistically, norepinephrine acts to increase cellular excitability and enhance synaptic plasticity within extinction-related neural circuitry. Currently, drugs that modulate norepinephrine are being used to treat symptoms of anxiety disorders, and are now being tested as pharmacotherapeutic prophalactics in the prevention of chronic posttraumatic stress reactions and as adjuncts to extinction-based exposure therapy. Studies of these new applications of noradrenergic drugs show a converging pattern of results with basic science suggesting ways in which basic laboratory findings can be translated into procedures to enhance clinical outcomes.

Chronic propranolol induces deficits in retention but not acquisition performance in the water maze in mice

Agents that alter adrenergic receptors, such as "beta-blockers," also alter memory storage. However, reports suggest that beta-adrenergic receptor antagonists, such as propranolol, have conflicting behavioral effects with acute vs chronic dosing. This study was designed to evaluate the effects of chronic propranolol on retention for a spatial learning task. Adult male ICR mice were given daily injections of propranolol (2, 4, 8, or 12 mg/kg ip) or 0. 9% NaCl for 15 days prior to, and during, trials in a Morris water maze. Mice received five massed acquisition (escape) trials in each of three daily sessions, followed by a single 60-s probe trial on the fourth day. The location of the submerged platform was constant for each animal over acquisition trials, but varied across animals; starting position varied across trials. A 5 (dose) x 3 (trial blocks) mixed factorial ANOVA for escape time yielded a significant trial blocks effect only (p <.001), showing performance improving over sessions. Time spent in the target quadrant on the probe trial was shorter under all doses of propranolol when compared to vehicle group (all p <.001), indicating poorer retention of prior platform location. This effect, however, was not dose-related. Swim speed was not significantly affected by propranolol. These data demonstrate that chronic dosing with propranolol can impair retention of spatial learning, which cannot be attributed to reduced arousal or motor function.

Chronic administration of propranolol impairs inhibitory avoidance retention in mice

Adrenergic systems are importantly involved in memory storage processes. As such, agents that alter adrenergic receptors, such as "beta-blockers," also alter memory storage. However, the anxiety literature cautions that beta-adrenergic receptor antagonists, such as propranolol, may have different behavioral effects with acute vs chronic dosing. The effects of chronic propranolol specifically on memory modulation are unknown. This study was designed to evaluate the effects of chronic propranolol on retention for an aversive task, in which there is endogenous adrenergic activation. Adult male ICR mice were given daily injections of one of four doses of propranolol (2, 4, 8, and 12 mg/kg) or 0.9% NaCl vehicle for 15 days prior to, and continuing during, behavioral tests of exploration and retention. Exploratory behavior, as an index of anxiety level, was measured in a conventional elevated plus-maze, whereas retention of an aversive experience was measured in a step-through inhibitory avoidance apparatus. Sensitivity to aversive footshock was also evaluated. Compared to controls, propranolol-treated mice showed a dose-dependent decrease in retention for the inhibitory avoidance task, but no effect on anxiety on the plus-maze or on footshock sensitivity. Taken together with results from previous studies, it is apparent that propranolol can have different behavioral effects when administered acutely vs chronically, and its chronic effects significantly impair memory storage processes. Since these drugs are typically used chronically, and often in older adults, they could contribute to functional memory impairments.

Comparison of bisoprolol and diazepam in the treatment of cardiac neurosis

In order to compare the beta blockers bisoprolol and diazepam in the treatment of cardiac neurosis, 40 patients (16 males and 24 females, mean age: 39 +/- 11 years) were examined in a double-blind, crossover study. Following a 4-week placebo period, patients were randomized to receive either bisoprolol 10 mg daily or diazepam 5 mg twice daily for 4 weeks. After a second 4-week washout period on placebo, patients were switched to the alternative regimen for a further 4 weeks. At the end of the placebo periods and during each phase of treatment, the following parameters were evaluated: somatic symptoms by self-assessment questionnaire, anxiety state by Hamilton rating scale, reaction time to both acoustic and visual stimuli, blood pressure, and heart rate. Both treatments were effective in reducing somatic symptoms of cardiac neurosis, but bisoprolol was significantly more effective than diazepam (p less than 0.01). On the contrary, diazepam was superior to bisoprolol in improving the Hamilton scale related to psychic symptoms. Only diazepam prolonged reaction times. Both treatments were well tolerated; however, 12 patients complained of drowsiness and nine of sedation under diazepam. In conclusion, bisoprolol appeared to be as effective as diazepam in the treatment of cardiac neurosis, but with better effects on somatic symptoms and without affecting patients' psychomotor performance.

Acute and chronic effects of propranolol on extinction of rewarded running in the rat

Three experiments examined the effect of propranolol injected IP on a series of 16 extinction trials at 24-hour intertrial intervals after continuously rewarded running. In Experiment I, propranolol (1, 5 or 10 mg/kg) was injected, in different groups, shortly before or shortly after each extinction trial, but without effect. In Experiment II, the same doses were injected daily for 18 days preceding extinction, to allow longer for any long-term drug effect to accumulate. Propranolol (1 mg/kg) facilitated extinction. In Experiment III, a single dose (7.5 mg/kg) was injected before or after extinction trials as in Experiment I; the acute effect was to impair extinction. These results are consistent with previous findings in the Skinner box that propranolol has an acute disinhibitory effect on nonrewarded responses and a long-term inhibitory one. These effects have different dose-response relationships.

Biphasic effects of propranolol on extinction of rewarded responding

The effect of propranolol (5 mg/kg intraperitoneally) was investigated on the extinction of: (i) lever-pressing reinforced on a random interval (RI 64 s) schedule; and (ii) continuously reinforced running (1 min intertrial interval). Although there was evidence of an initial effect in each case to facilitate responding (increased rate of lever-pressing or speed of running), the opposite effect emerged as extinction continued; that is, propranolol promoted extinction. These results are inconsistent with the author's hypothesis, suggested by earlier studies, that acute administration of propranolol antagonizes the inhibitory effects of non- reward on behaviour.

Beta-blockers in anxiety disorders

Studies evaluating the antianxiety and antipanic properties of beta-blockers do not support their routine use in treating either generalized anxiety disorder or panic disorder. The use of propranolol for anxiety disorders accompanied by physical symptoms, especially cardiovascular complaints, may be effective in some patients when combined with benzodiazepines or perhaps in some non-responders to conventional treatment. Better designed studies are needed to evaluate the exact role of beta-blocking agents in treating anxiety. The efficacy of propranolol in patients with panic disorder has not been widely researched, but preliminary results have not been encouraging. Propranolol may provide symptomatic relief in some patients with residual somatic complaints (i.e., palpitations and tachycardia), when combined with the patient's ongoing drug regimen. Because beta-blockers may induce depression, they should be used cautiously--if at all--in panic patients with concurrent depressive illness.

Potentiation of haloperidol-induced catalepsy by beta-adrenoceptor antagonists in mice

Several clinical papers have reported that beta-adrenoceptor antagonists were useful in the management of schizophrenia and tardive dyskinesia. The present study examined effects of beta-antagonists on haloperidol (HAL)-induced catalepsy using mice in order to study the relationship between beta-antagonists and central dopaminergic functions. Catalepsy was tested by the standard bar test 30 min after intraperitoneal treatment of HAL. Beta-antagonists were administered subcutaneously just after HAL-treatment. Propranolol, alprenolol, oxprenolol and pindolol increased the incidence of catalepsy compared to HAL alone. Atenolol, not penetrating into the brain, and the sedative and hypnotic drug chlordiazepoxide did not potentiate it. These results suggest that the potentiation of HAL-catalepsy by beta-antagonists is based on their central action. Therefore, a central beta-receptor appears to be implicated in the regulation of the central dopaminergic functions.