Betahistine: what's new on the agenda?

Betahistine mesylate reduces the damage of blue light exposure in Drosophila model

Previous studies have demonstrated the efficacy of betahistine mesylate in treating vertigo and angioneurotic headache, enhancing microcirculation, and facilitating histamine release. However, limited research has been conducted on the drug's potential in mitigating blue light-induced damage. Thus, this study utilized Drosophila as the model organism and employed the Siler model to investigate the impact of various concentrations of betahistine mesylate on the lifespan, under 3000 lx blue light irradiation. At the same time we measure food intake, spontaneous activity, and sleep duration of Drosophila. The findings of this study indicate that a high concentration of betahistine mesylate can decrease the initial mortality (b0) in male flies, mitigating the damage of blue light to Drosophila. Consequently, this delays the aging process in male Drosophila and extends their average lifespan. After betahistine mesylate ingestion, locomotor activity upon blue light exposure decreased significantly in male Drosophila. In conclusion, this study offers initial evidence supporting the investigation of the regulatory mechanisms of betahistine mesylate on lifespan and its potential anti-blue light effects.

Historical Therapies for Suspected Autonomic Dysregulation in Meniere's Disease

OBJECTIVE

This narrative review examines how speculative belief that the autonomic nervous system causes Meniere's Disease (MD) led otolaryngologists to adopt invasive surgical procedures and medical treatments still offered today.

DATA SOURCES

Google Scholar, PubMed.

REVIEW METHODS

A comprehensive literature review (1860-2022) was performed using the terms "Meniere AND (sympathetic OR sympathectomy OR vasomotor OR cervical ganglion)," returning 5360 items. All abstracts were briefly reviewed, relevant publications selected for further study, and key articles discussed by all authors. As it became clear that betahistine was related to the historical narrative, an additional search was performed using "Betahistine AND Meniere AND (vasomotor OR sympathetic OR sympathectomy OR cervical ganglion OR autonomic)," which yielded 336 results.

RESULTS

In the 19th and 20th centuries, growing knowledge of human anatomy led the scientific community to speculate that autonomic dysregulation caused many medical conditions. Excessive sympathetic mediated vasomotor changes were thought to cause hypertension, ischemia, and tissue damage. Clinicians applied the hypothesis to MD, assigning the sympathetic nervous system responsible for vertigo secondary to paroxysmal vasospasm and for hearing loss to poor cochlear nutrition. Despite limited animal experiments and isolated clinical observations, otolaryngologists performed sympathectomies, and, in the 1970s, replaced the procedure with betahistine as an alternative medical treatment.

CONCLUSION

Premature excitement about a plausible hypothesis led to unnecessary and unwarranted operations. Despite absent evidence of sympathetic overactivation in MD, surgeons eagerly adopted sympathectomies, and later betahistine. Rigorous evaluation of the validity of these treatment practices is needed.

LEVEL OF EVIDENCE

5 Laryngoscope, 134:535-542, 2024.

Betahistine Prescribing Practices in England: An Analysis of Prescribing and National Spending Pre- and Post-BEMED Trial

OBJECTIVE

Betahistine has not been proven to be superior to placebo in the BEMED study, a multicenter, double-blind, randomized, placebo controlled trial. Our study aimed to establish the prescribing practices of clinicians in England in relation to betahistine and to assess if there has been any change in prescribing practices since the publication of the BEMED trial.

STUDY DESIGN

Retrospective study and clinician survey.

PATIENTS

All patients who were prescribed betahistine from primary care.

MAIN OUTCOME MEASURE

Total quantity of betahistine prescribed and total actual cost.

RESULTS

The average total monthly quantity prescribed was 11,143,253 tablets (range, 10,056,516-12,276,423). Prescribing did not decrease from the period before (January 2014-February 2016) to after (February 2016-February 2021) the publication of the BEMED trial, with the average monthly prescribing before publication being 11,294,848 tablets (range, 10,280,942- 12,276,423) and the average monthly prescribing after publication being 11,081,123 tablets (range, 10,056,516-11,915,707). The average actual monthly cost increased from the period before publication to after publication from a sum of £279,264.82 to a sum of £428,846.22. Most (90.5%) of the survey respondents prescribed betahistine for Menière's disease. Less than half (38.09%) prescribed betahistine for indications other than Menière's disease. Only 45.24% of the clinicians were aware of the results of the BEMED trial.

CONCLUSIONS

Knowledge of the BEMED trial among otology and neurotology subspecialists is lacking. The results of the BEMED have made no difference to prescribing practice, and in fact, the cost of the medication to the health bill has increased.

Effects of Adjunctive Betahistine Therapy on Lipid Metabolism in Patients with Chronic Schizophrenia: A Randomized Double-Blind Placebo-Controlled Study

OBJECTIVE

This study aims to explore the ability of betahistine to inhibit weight gain and abnormal lipid metabolism in patients with chronic schizophrenia.

METHODS

A comparison study of betahistine or placebo therapy was conducted for 4 weeks in 94 patients with chronic schizophrenia, who were randomly divided into two groups. Clinical information and lipid metabolic parameters were collected. Positive and Negative Syndrome Scale (PANSS) was used to assess psychiatric symptoms. Treatment Emergent Symptom Scale (TESS) was used to evaluate treatment-related adverse reactions. The differences in lipid metabolic parameters before and after treatment between the two groups were compared.

RESULTS

Repeated measures analysis of variance (ANOVA) revealed that after 4 weeks of betahistine/placebo treatment, the interaction effect of time and group was statistically significant on low-density lipoprotein cholesterol (F = 6.453, p = 0.013) and waist-to-hip ratio (F = 4.473, p = 0.037), but did not reveal any significant interaction effect of time and group on weight, body mass index or other lipid metabolic parameters, as well as the time main effect and group main effect (all p > 0.05). Betahistine had no significant impact on PANSS, and no side effects related to betahistine were detected.

CONCLUSION

Betahistine may delay metabolic abnormalities in patients with chronic schizophrenia. It does not affect the efficacy of the original antipsychotics. Thus, it provides new ideas for the treatment of metabolic syndrome in patients with chronic schizophrenia.

EHealth and Its Role in Supporting Audiological Rehabilitation: Patient Perspectives on Barriers and Facilitators of Using a Personal Hearing Support System With Mobile Application as Part of the EVOTION Study

Background

Hearing loss is a major public health challenge. Audiology services need to utilise a range of rehabilitative services and maximise innovative practice afforded by technology to actively promote personalized, participatory, preventative and predictive care if they are to cope with the social and economic burden placed on the population by the rapidly rising prevalence of hearing loss. Digital interventions and teleaudiology could be a key part of providing high quality, cost-effective, patient-centred management. There is currently very limited evidence that assesses the hearing impaired patient perspective on the acceptance and usability of this type of technology.

Aim

This study aims to identify patient perceptions of the use of a hearing support system including a mobile smartphone app when used with Bluetooth-connected hearing aids across the everyday life of users, as part of the EVOTION project.

Methods

We applied a questionnaire to 564 participants in three countries across Europe and analysed the following topics: connectivity, hearing aid controls, instructional videos, audiological tests and auditory training.

Key Findings

Older users were just as satisfied as younger users when operating this type of technology. Technical problems such as Bluetooth connectivity need to be minimised as this issue is highly critical for user satisfaction, engagement and uptake. A system that promotes user-controllability of hearing aids that is more accessible and easier to use is highly valued. Participants are happy to utilise monitoring tests and auditory training on a mobile phone out of the clinic but in order to have value the test battery needs to be relevant and tailored to each user, easy to understand and use. Such functions can elicit a negative as well as positive experience for each user.

Conclusion

Older and younger adults can utilise an eHealth mobile app to complement their rehabilitation and health care. If the technology works well, is tailored to the individual and in-depth personalised guidance and support is provided, it could assist maximisation of hearing aid uptake, promotion of self-management and improving outcomes.

Influence of betahistine repeated administration on a weight gain and selected metabolic parameters in the model of excessive eating in rats

It is important to search for a promising therapeutic target or small molecules that can control excessive eating since limiting the intake of foods, especially tasty ones, could be effective in the treatment or prevention of obesity. Some studies indicate betahistine as an unique drug having the ability to ameliorate, for example, antipsychotic-induced weight gain. This study aimed to determine whether repeated administration of betahistine (histamine H1R agonist and H3R antagonist) could be beneficial in reducing the intake of tasty foods or the body's response to overeating via mechanisms such as by influencing the levels of hormones involved in the regulation of food intake or the levels of selected metabolic parameters. Studies were performed in the excessive eating model in rats, which perfectly illustrates the harmful high-caloric intake from freely available tasty products rich in sugar and fat. Our results indicated that repeated administration of betahistine to rats caused lower gain of body mass compared to the control rats fed palatable feed. Interestingly, betahistine treatment increased the consumption of cheese, which is a source of histamine. Although betahistine did not prevent the development of metabolic disorders, such as reduced glucose tolerance, in test animals, it significantly increased the level of high-density lipoprotein cholesterol, which could certainly be considered beneficial. Further studies should be conducted to investigate the effect of repeated administration of betahistine on satiety, gastrointestinal disorders, and the preference for histamine-containing foods.

[Betahistine in vestibular disorders: current concepts and perspectives]

The goal of this paper is to review the pharmacological profile of betahistine and evidence for using it in the treatment of common vestibular disorders. Betahistine is a weak agonist for histamine H1 receptors and strong antagonist for histamine H3 receptors. It demonstrates the maximum benefit in different types of peripheral vertigo, especially in Meniere's disease. The best results in decreasing intensity of vertigo, frequency of attacks and stimulation of vestibular compensation were obtained in daily dose 48 mg during 3 months. In benign paroxysmal positional vertigo betahistine is used to treat residual dizziness after successful treatment of otolithiasis and to reduce the severity of vertigo during repositioning maneuvers. In vestibular neuritis betahistine stimulates central compensation during vestibular rehabilitation. A new once-daily drug formulation of modified-release betahistine is non-inferior to traditional and has a comparable safety profile, and could improve patient adherence. The implication of betahistine in the treatment of central vestibular disorders is under-researched. The efficacy of betahistine in increasing of vestibular compensation in post-stroke central vestibular disorders, persistent postural-perceptual dizziness and its role in vestibular migraine need further investigation.

Betahistine for tinnitus

BACKGROUND

Tinnitus is a symptom defined as the perception of sound in the absence of an external source. In England alone there are an estimated ¾ million general practice consultations every year where the primary complaint is tinnitus, equating to a major burden on healthcare services. Clinical management strategies include education and advice, relaxation therapy, tinnitus retraining therapy, cognitive behavioural therapy, sound enrichment using ear-level sound generators or hearing aids, and drug therapies to manage co-morbid symptoms such as sleep difficulties, anxiety or depression. As yet, no drug has been approved for tinnitus by a regulatory body. Nonetheless, over 100,000 prescriptions for betahistine are being filled every month in England, and nearly 10% of general practitioners prescribe betahistine for tinnitus.

OBJECTIVES

To assess the effects of betahistine in patients with subjective idiopathic tinnitus.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL, via the Cochrane Register of Studies); Ovid MEDLINE; Ovid Embase; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 23 July 2018.

SELECTION CRITERIA

Randomised controlled trials (RCTs) recruiting patients of any age with acute or chronic subjective idiopathic tinnitus were included. We included studies where the intervention involved betahistine and this was compared to placebo, no intervention or education and information. We included all courses of betahistine, regardless of dose regimens or formulations and for any duration of treatment.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcomes included tinnitus loudness and significant adverse effects (upper gastrointestinal discomfort). Our secondary outcomes included tinnitus symptom severity as measured by the global score on a multi-item tinnitus questionnaire, depressive symptoms, symptoms of generalised anxiety, health-related quality of life, other adverse effects (e.g. headache, drowsiness, allergic skin reactions (pruritis, rashes) and exacerbation of tinnitus) and tinnitus intrusiveness. We used GRADE to assess the quality of evidence for each outcome; this is indicated in italics.

MAIN RESULTS

This review included five studies (with a total of 303 to 305 participants) comparing the effects of betahistine with placebo in adults with subjective idiopathic tinnitus. Four studies were parallel-group RCTs and one had a cross-over design. The risk of bias was unclear in all of the included studies.Due to heterogeneity in the outcomes measured and measurement methods used, very limited data pooling was possible. When we pooled the data from two studies for the primary outcome tinnitus loudness, the mean difference on a 0- to 10-point visual analogue scale at one-month follow-up was not significant between betahistine and placebo (-0.16, 95% confidence interval (CI) -1.01 to 0.70; 81 participants) (very low-quality evidence). There were no reports of upper gastrointestinal discomfort (significant adverse effect) in any study.As a secondary outcome, one study found no difference in the change in the Tinnitus Severity Index between betahistine and placebo (mean difference at 12 weeks 0.02, 95% CI -1.05 to 1.09; 50 participants) (moderate-quality evidence). None of the studies reported the other secondary outcomes of changes in depressive symptoms or depression, anxiety symptoms or generalised anxiety, or health-related quality of life as measured by a validated instrument, nor tinnitus intrusiveness.Other adverse effects that were reported were not treatment-related.

AUTHORS' CONCLUSIONS

There is an absence of evidence to suggest that betahistine has an effect on subjective idiopathic tinnitus when compared to placebo. The evidence suggests that betahistine is generally well tolerated with a similar risk of adverse effects to placebo treatments. The quality of evidence for the reported outcomes, using GRADE, ranged from moderate to very low.If future research into the effectiveness of betahistine in patients with tinnitus is felt to be warranted, it should use rigorous methodology. Randomisation and blinding should be of the highest quality, given the subjective nature of tinnitus and the strong likelihood of a placebo response. The CONSORT statement should be used in the design and reporting of future studies. We also recommend the development of validated, patient-centred outcome measures for research in the field of tinnitus.

Effect of Betahistine and Metformin on Antipsychotic-Induced Weight Gain: An Analysis of Two Clinical Trials

Antipsychotic-induced weight gain is one of the most common adverse effects of antipsychotic treatment. However, there are no well-established interventions for the weight gain yet. In this study, we pooled the data from two clinical trials, which were originally examining the efficacy of betahistine and the efficacy of metformin in treating antipsychotic-induced weight gain and insulin resistance. A total of 67 people with schizophrenia or bipolar disorder treated with antipsychotics were assigned to 36 mg day^-1 betahistine (n = 13) or 1,000 mg day^-1 metformin (n = 25) or placebo (n = 29) treatment for 12 weeks, with evaluation at baseline and week 12. The primary outcome was the body mass index (BMI). After treatment, metformin group had a mean decrease in BMI of 1.46 ± 0.14 (p < 0.001) and insulin resistance index (IRI) of 4.30 ± 2.02 (p < 0.001). The betahistine group had no significant alteration in BMI or IRI. However, placebo group had a mean increase in BMI of 1.27 ± 0.77 (p < 0.001) and IRI of 0.45 ± 0.86 (p < 0.001). Between the two treatment groups, metformin significantly decreased weight, BMI, fasting glucose, insulin level, and IRI but not waist circumference when compared with betahistine. Moreover, metformin significantly decreased weight, BMI, waist circumference, fasting glucose, insulin level, and IRI when compared with placebo, whereas betahistine significantly decreased body weight, waist circumference, BMI, insulin level, and IRI but not fasting glucose when compared with placebo. In this study, we found that both metformin treatment and betahistine treatment were efficacious in improving antipsychotic-induced weight gain and insulin resistance, and metformin was more efficacious in preventing and revising the weight gain induced by antipsychotics. Clinical Trial Registration: www.ClinicalTrials.gov, NCT00451399(Study 1), NCT00709202(Study 2).

Using Caenorhabditis elegans as a Model for Obesity Pharmacology Development

The Caenorhabditis elegans model is a rapid and inexpensive method to address pharmacologic questions. We describe the use of C. elegans to explore 2 pharmacologic questions concerning candidate antiobesity drugs and illustrate its potential usefulness in pharmacologic research: (1) to determine a ratio of betahistine-olanzapine that blocks the olanzapine-induced intestinal fat deposition (IFD) as detected by Nile red staining and (2) to identify the mechanism of action of a pharmaceutical candidate AB-101 that reduces IFD. Olanzapine (53 μg/mL) increased the IFD (12.1 ± 0.1%, P < 0.02), which was blocked by betahistine (763 μg/mL, 39.3 ± 0.01%, P < 0.05) in wild-type C. elegans (N2). AB-101 (1.0%) reduced the IFD in N2 (P < 0.05), increased the pharyngeal pumping rate (P < 0.05), and reversed the elevated IFD induced by protease inhibitors atazanavir and ritonavir (P < 0.05). AB-101 did not affect IFD in a ACS null mutant strain acs-4(ok2872) III/hT2[bli-4(e937) let-?(q782) qIs48](I;III) suggesting an involvement of the lipid oxidation pathway and an upregulation of CPT-1. Our studies suggest that C. elegans may be used as a resource in pharmacologic research. This article is intended to stimulate a greater appreciation of its value in the development of new pharmaceutical interventions.

Betahistine for symptoms of vertigo

BACKGROUND

Vertigo is a symptom in which individuals experience a false sensation of movement. This type of dizziness is thought to originate in the inner ear labyrinth or its neural connections. It is a commonly experienced symptom and can cause significant problems with carrying out normal activities. Betahistine is a drug that may work by improving blood flow to the inner ear. This review examines whether betahistine is more effective than a placebo at treating symptoms of vertigo from different causes.

OBJECTIVES

To assess the effects of betahistine in patients with symptoms of vertigo from different causes.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2015, Issue 8); PubMed; EMBASE; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. We also contacted manufacturers and researchers in the field. The date of the search was 21 September 2015.

SELECTION CRITERIA

We included randomised controlled trials of betahistine versus placebo in patients of any age with vertigo from any neurotological diagnosis in any settings.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcome was the proportion of patients with reduction in vertigo symptoms (considering together the intensity, frequency and duration those symptoms).

MAIN RESULTS

We included 17 studies, with a total of 1025 participants; 12 studies were published (567 patients) and five were unpublished (458 patients). Sixteen studies including 953 people compared betahistine with placebo. All studies with analysable data lasted three months or less. The majority were at high risk of bias, but in some the risk of bias was unclear. One study, at high risk of bias, included 72 people with benign paroxysmal positional vertigo (BPPV) and compared betahistine with placebo; all patients also had particle repositioning manoeuvres. The studies varied considerably in terms of types of participants, their diagnoses, the dose of betahistine and the length of time it was taken for, the study methods and the way any improvement in vertigo symptoms was measured. Using the GRADE system, we judged the quality of evidence overall to be low for two outcomes (proportion of patients with improvement and proportion with adverse events).Pooled data showed that the proportion of patients reporting an overall reduction in their vertigo symptoms was higher in the group treated with betahistine than the placebo group: risk ratio (RR) 1.30, 95% confidence interval (CI) 1.05 to 1.60; 606 participants; 11 studies). This result should be interpreted with caution as the test for statistical heterogeneity as measured by the I(2) value was high.Adverse effects (mostly gastrointestinal symptoms and headache) were common but medically serious events in the study were rare and isolated: there was no difference in the frequency of adverse effects between the betahistine and placebo groups, where the rates were 16% and 15% respectively (weighted values, RR 1.03, 95% CI 0.76 to 1.40; 819 participants; 12 studies).Sixteen per cent of patients from both the betahistine and the placebo groups withdrew (dropped out) from the studies (RR 0.96, 95% CI 0.65 to 1.42; 481 participants; eight studies).Three studies looked at objective vestibular function tests as an outcome; the numbers of participants were small, techniques of measurement very diverse and reporting details sparse, so analysis of this outcome was inconclusive.We looked for information on generic quality of life and falls, but none of the studies reported on these outcomes.

AUTHORS' CONCLUSIONS

Low quality evidence suggests that in patients suffering from vertigo from different causes there may be a positive effect of betahistine in terms of reduction in vertigo symptoms. Betahistine is generally well tolerated with a low risk of adverse events. Future research into the management of vertigo symptoms needs to use more rigorous methodology and include outcomes that matter to patients and their families.

Betahistine decreases olanzapine-induced weight gain and somnolence in humans

Olanzapine's efficacy in schizophrenia is attributed to antagonism of dopamine and serotonin receptors. Olanzapine is also a potent histamine-H1 antagonist that results in weight gain and somnolence. Betahistine is a centrally acting histamine-H1 agonist, and therefore may reduce olanzapine's effect on histamine receptors in the brain. Olanzapine's high affinity for the histamine-H1 receptor warrants the use of high doses of betahistine. Forty-eight healthy women were recruited and randomized to receive either betahistine 144 mg/day or matching placebo for 4 weeks. Due to the high dose of betahistine, olanzapine was started only on the second week and titrated up to 10 mg/day, and co-administration continued for an additional 2 weeks. Only nominal differences in adverse events were noted between the treatment groups. Betahistine caused a 37% reduction in mean weight gain (1.24 kg in the betahistine arm vs. 1.93 kg in the placebo arm; p=.049) and 60% reduction in the mean increase in daytime Epworth sleepiness scores (1.82 units in the betahistine group vs. 3.57 units in the placebo group; p=.042). The present study suggests that betahistine-olanzapine co-administration, in healthy female subjects, yields an acceptable safety profile with mitigation of weight gain and somnolence. This should be further tested in a patient cohort.

The histaminergic system as a target for the prevention of obesity and metabolic syndrome

The control of food intake and body weight is very complex. Key factors driving eating behavior are hunger and satiety that are controlled by an interplay of several central and peripheral neuroendocrine systems, environmental factors, the behavioral state and circadian rhythm, which all concur to alter homeostatic aspects of appetite and energy expenditure. Brain histamine plays a fundamental role in eating behavior as it induces loss of appetite and has long been considered a satiety signal that is released during food intake (Sakata et al., 1997). Animal studies have shown that brain histamine is released during the appetitive phase to provide a high level of arousal preparatory to feeding, but also mediates satiety. Furthermore, histamine regulates peripheral mechanisms such as glucose uptake and insulin function. Preclinical research indicates that activation of H1 and H3 receptors is crucial for the regulation of the diurnal rhythm of food consumption; furthermore, these receptors have been specifically recognized as mediators of energy intake and expenditure. Despite encouraging preclinical data, though, no brain penetrating H1 receptor agonists have been identified that would have anti-obesity effects. The potential role of the H3 receptor as a target of anti-obesity therapeutics was explored in clinical trials that did not meet up to the expectations or were interrupted (clinicaltrials.gov). Nonetheless, interesting results are emerging from clinical trials that evaluated the attenuating effect of betahistine (an H1 agonist/H3 antagonist) on metabolic side effects associated with chronic antipsychotics treatment. Aim of this review is to summarize recent results that suggest the clinical relevance of the histaminergic system for the treatment of feeding disorders and provide an up-to-date summary of preclinical research. This article is part of the Special Issue entitled 'Histamine Receptors'.

Betahistine ameliorates olanzapine-induced weight gain through modulation of histaminergic, NPY and AMPK pathways

Olanzapine is widely used to treat schizophrenia and other disorders, but causes adverse obesity and other metabolic side-effects. Both animal and clinical studies have shown that co-treatment with betahistine (a histaminergic H1 receptor agonist and H3 receptor antagonist) is effective for ameliorating olanzapine-induced weight gain/obesity. To reveal the mechanisms underlying these effects, this study investigated the effects of co-treatment of olanzapine and betahistine (O+B) on expressions of histaminergic H1 receptor (H1R), AMP-activated protein kinase (AMPK), neuropeptide Y (NPY), and proopiomelanocortin (POMC) in the hypothalamus associated with reducing olanzapine-induced weight gain. Olanzapine significantly upregulated the mRNA and protein expressions of H1R, while O+B co-treatment significantly downregulated the H1R levels, compared to the olanzapine-only treatment group. The NPY mRNA expression was significantly enhanced by olanzapine, but it was significantly reversed by O+B co-treatment. The hypothalamic H1R expression was positively correlated with total food intake, and NPY expression. Olanzapine also increased AMPKα activation measured by the AMPKα phosphorylation (pAMPKα)/AMPKα ratio compared with controls, whereas O+B co-treatment decreased the pAMPKα/AMPKα ratio, compared with olanzapine only treatment. The pAMPKα/AMPKα ratio was positively correlated with total food intake and H1R expression. Although olanzapine administration decreased the POMC mRNA level, this level was not affected by O+B co-treatment. Therefore, these results suggested that co-treatment with betahistine may reverse olanzapine-induced body weight gain via the H1R-NPY and H1R-pAMPKα pathways.

Transdermal delivery of betahistine hydrochloride using microemulsions: physical characterization, biophysical assessment, confocal imaging and permeation studies

Transdermal delivery of betahistine hydrochloride encapsulated in various ethyl oleate, Capryol 90(®), Transcutol(®) and water microemulsion formulations was studied. Two different kinds of phase diagrams were constructed for the investigated microemulsion system. Pseudoplastic flow that is preferable for skin delivery was recorded for the investigated microemulsions. A balanced and bicontinuous microemulsion formulation was suggested and showed the highest permeation flux (0.50±0.030mgcm(-2)h(-1)). The effect of the investigated microemulsions on the skin electrical resistance was used to explain the high permeation fluxes obtained. Confocal laser scanning microscopy was used to confirm the permeation enhancement and to reveal the penetration pathways. The results obtained suggest that the proposed microemulsion system highlighted in the current work can serve as a promising alternative delivery means for betahistine hydrochloride.

Reducing olanzapine-induced weight gain side effect by using betahistine: a study in the rat model

Olanzapine is effective at treating multiple domains of schizophrenia symptoms. However, it induces serious metabolic side effects. Antipsychotic drug's antagonistic affinity to histamine H₁ receptors has been identified as a main contributor for weight gain/obesity side effects. This study therefore investigated whether a combined treatment of betahistine (a H₁ receptor agonist and H₃ receptor antagonist) could reduce the body weight/obesity induced by olanzapine. Female Sprague Dawley rats were treated orally with olanzapine (1 mg/kg, t.i.d.) and/or betahistine (2.67 mg/kg, t.i.d.), or vehicle for two weeks. Rats treated with olanzapine exhibited significant body weight gain and increased food intake. Co-treatment of olanzapine with betahistine significantly prevented (-45%) weight gain and reduced feeding efficiency compared to sole olanzapine treatment. Betahistine treatment alone had no effect on weight gain and food intake. Olanzapine reduced locomotor activity, but not betahistine. These findings demonstrate that olanzapine-induced body weight gain can partially be reduced by co-treatment with betahistine. Betahistine has H₃ receptor antagonistic effects to increase histamine release, which may augment its direct agonistic effects on H₁ receptors. These findings have important implications for clinical trials using betahistine to control antipsychotic-induced obesity side effects.

Mifepristone treatment of olanzapine-induced weight gain in healthy men

INTRODUCTION

Antipsychotic medications are associated with significant weight gain, type 2 diabetes mellitus, dyslipidemia, and increased cardiovascular risk. Suggested mechanisms of weight gain from antipsychotic medication include antagonism of histamine and serotonin receptors, and effects on the hypothalamic-pituitary-adrenal axis. The objective of this study was to determine if mifepristone, a glucocorticoid receptor antagonist, could prevent olanzapine-induced weight gain.

METHODS

This was a randomized, double-blind trial. Fifty-seven lean, healthy men (body mass index 18-25 kg/m(2)) aged 19-38 years were randomized to olanzapine (7.5 mg) (n=22), olanzapine (7.5 mg) plus mifepristone (600 mg) (n=24), or mifepristone (600 mg) (n=11) daily for 2 weeks in an institutional setting. Subjects were provided food ad libitum to accentuate weight gain. Body weight was measured daily.

RESULTS

The mean change in baseline weight was +3.2+/-0.9 kg in subjects receiving olanzapine versus +2.0+/-1.2 kg in those receiving olanzapine plus mifepristone (P<0.0001). Subjects receiving mifepristone alone had a similar degree of weight gain compared to those receiving olanzapine plus mifepristone. The olanzapine group had significant increases in waist circumference when compared with the olanzapine plus mifepristone group (3.7+/-1.3 cm vs. 2.2+/-1.9 cm, respectively; P=0.006). Fasting insulin and triglycerides increased more in the olanzapine group, although differences were not statistically significant.

CONCLUSION

Mifepristone was effective in attenuating the increase in weight associated with olanzapine treatment over a 2-week period. Longer-term studies are required to examine the durability and full magnitude of this response.