Pharmacotherapy of vertigo: any news to be expected?

Betahistine in Ménière's Disease or Syndrome: A Systematic Review

BACKGROUND

Ménière's disease is characterized by recurrent episodes of vertigo, hearing loss, and tinnitus, often with a feeling of fullness in the ear. Although betahistine is thought to be specifically effective for Ménière's disease, no evidence for a benefit from the use of betahistine exists, despite its widespread use. Reassessment of the effect of betahistine for Ménière's disease is now warranted.

SEARCH METHODS

We searched for randomized controlled trials (RCTs) in the Central Register of Controlled Trials (CENTRAL), Ovid Medline, Ovid Embase, CINAHL, Web of Science, Clinicaltrials.gov, ICTRP, and additional sources for published and unpublished trials, in which betahistine was compared to placebo.

DATA COLLECTION AND ANALYSIS

Our outcomes involved vertigo, significant adverse effect (upper gastrointestinal discomfort), hearing loss, tinnitus, aural fullness, other adverse effects, and disease-specific health-related quality of life. We used GRADE to assess the quality of the evidence.

MAIN RESULTS

We included 10 studies: 5 studies used a crossover design and the remaining 5 were parallel-group RCTs. One study with a low risk of bias found no significant difference between the betahistine groups and placebo with respect to vertigo after a long-term follow-up period. No significant difference in the incidence of upper gastrointestinal discomfort was found in 2 studies (low-certainty evidence). No differences in hearing loss, tinnitus, or well-being and disease-specific health-related quality of life were found (low- to very low-certainty of evidence). Data on aural fullness could not be extracted. No significant difference between the betahistine and the placebo groups (low-certainty evidence) could be demonstrated in the other adverse effect outcome with respect to dull headache. The pooled risk ratio for other adverse effect in the long term demonstrated a lower risk in favor of placebo over betahistine.

CONCLUSIONS

High-quality studies evaluating the effect of betahistine on patients with Ménière's disease are lacking. However, one study with low risk of bias found no evidence of a difference in the effect of betahistine on the primary outcome, vertigo, in patients with Ménière's disease when compared to placebo. The main focus of future research should be on the use of comparable outcome measures by means of patient-reported outcome measures.

Management of peripheral vertigo with antihistamines: New options on the horizon

Vertigo is associated with a wide range of vestibular pathologies. It increasingly affects the elderly, with a high cost to society. Solutions include vestibular suppressants and vestibular rehabilitation, which form the mainstay of therapy. Antihistamines represent the largest class of agents used to combat vestibular vertigo symptoms. Agents targeting the H₁ and H₃ receptors have been in clinical use for several decades as single agents. Nonetheless, effective management of vertigo proves elusive as many treatments largely address only associated symptoms, and with questionable efficacy. Additionally, the primary and limiting side effect of sedation is counterproductive to normal functioning and the natural recovery process occurring via central compensation. To address these issues, the timing of administration of betahistine, the mainstay H₃ antihistamine, can be fine-tuned, while bioavailability is also being improved. Other approaches include antihistamine combination studies, devices, physical therapy and behavioural interventions. Recently demonstrated expression of H₄ receptors in the peripheral vestibular system represents a new potential drug target for treating vestibular disorders. A number of novel selective H₄ antagonists are active in vestibular models in vivo. The preclinical potential of SENS-111 (Seliforant), an oral first-in-class selective H₄ antagonist is the only such molecule to date to be translated into the clinical setting. With an excellent safety profile and notable absence of sedation, encouraging outcomes in an induced vertigo model in healthy volunteers have led to ongoing clinical studies in acute unilateral vestibulopathy, with the hope that H₄ antagonists will offer new effective therapeutic options to patients suffering from vertigo.

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.

[In vitro equivalence evaluation of betahistine generic medicinal products as a tool potentially determining the efficacy of pharmacotherapy]

AIM

To compare release parameters of various betahistine drugs in vitro using a comparative dissolution kinetics test.

MATERIAL AND METHODS

Objects of research are solid dosage forms (tablets) containing betahistine in a dose of 24 mg permitted for medical use in the Russian Federation. A method of comparative dissolution kinetics test was carried out as follows. The study was performed on a paddle stirrer at a speed of 50 rpm in three different pH dissolution media (pH 1.2, 4.5, 6.8), simulating the main sections of the digestive tract in which the active ingredient was decomposed, released and absorbed. This was performed in a quality controlled environment using a citrate buffer solution with pH 6.8. The time points for sampling the medium were 10 min, 15 min, 20 min and 30 min.

RESULTS

The results of betahistine release were significant (RSD<10%) for all time points, except the first time point (RSD<20%). Regardless of pH, there was a complete release (≥85% over 15 minutes, <10%) of betahistine from betaserc, 24 mg, tablets (manufactured by Mylan Laboratories SAS). The dissolution profiles of betahistine in other investigational drugs did not show complete drug release (parameter <85% in 15 minutes, <10%) in different pH media. Therefore, dissolution profiles of the studied drugs were not comparable to the reference profile.

CONCLUSION

Starting from 10 minutes, the reference drug of betahistine (betaserc, 24 mg) has a consistently higher release at different pH levels (representing the various stages of gastric digestion), vs. other studied generic analogues showing significantly lower levels of betahistine release. None of the studied drugs were found to be equivalent in vitro.

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.

Vestibular effects of lidocaine intratympanic injection in rats

When lidocaine is locally delivered into the inner ear, it rapidly paralyzes the peripheral vestibular afferent neurons and induces unilateral vestibular loss. The goals of this study were to explore the possibility of developing intratympanic injection (IT) of lidocaine as a modality for treating acute vertigo. To evaluate the minimum concentration required, latent time, action duration, and possibility of lidocaine IT readministration to the vestibular system, we compared the development of horizontal nystagmus after IT of 2, 4, 6, 8, and 10% lidocaine solutions in rats. To identify the induction of vestibular compensation, c-Fos-like protein expression was observed in the vestibular nucleus. Results of our investigation showed that lidocaine IT concentrations greater than 4% induced vestibular hyporeflexia in the injected ear. In order to induce hyporeflexia 4 and 6% lidocaine solutions could also be repeatedly injected. Regardless of concentration, effects of the lidocaine IT dissipated gradually over time. Our findings could be used to develop novel methods for symptom control in vestibular disorder patients.

Intratympanic gentamicin injections for the treatment of Ménière's disease

Objective

To assess the success rate and complications of treatment with injections of intratympanic gentamicin to the middle ear of patients with Ménière's disease.

Study Design

Case series with chart review.

Setting

A tertiary otologic private ENT clinic.

Subjects and Methods

Patients with Ménière's disease, who had not responded to medical treatment. Included in the sample were patients with Ménière's disease who had been treated with injections of gentamicin into the middle ear. After each gentamicin application, patients were monitored for their symptoms and hearing. If symptoms persisted, they received another intratympanic injection of gentamicin. This method is referred to as the variable titration method. A retrospective chart review was performed, and questionnaires were used to assess hearing, functional status, tinnitus, ear fullness sensation, and the control of vertigo attacks in response to treatment.

Results

Nineteen patients were sampled. Eighteen patients (94%) had complete or substantial control of vertigo. Five patients (26%) had worse hearing results on their post-treatment audiogram, averaging 13 dB hearing loss (range, 5-25 dB). In response to the questionnaires, all patients reported a significant improvement in the quality of life after treatment.

Conclusion

The treatment was found to be highly effective. The variable titration method of injection prevents unnecessary injections for patients whose symptoms have already subsided.

Vertigo and Motion Sickness. Part II: Pharmacologic Treatment

Vertigo is a sensation of movement when no movement is actually occurring. It is often accompanied by visceral autonomic symptoms including pallor, diaphoresis, nausea, and vomiting. Vertigo is similar to motion sickness in that both may be caused by vestibular stimulation that does not match an internal model of expected environmental stimuli. Indeed, a functioning vestibular system is necessary for the perception of motion sickness. For this reason, many of the same drugs are used to treat both conditions. The investigation of drugs that treat motion sickness helps to discover medications that may treat vertigo caused by disease of the vestibular system. In this article, we discuss the pharmacologic agents that are now available for the treatment of vertigo and those agents that are still under study.

Betahistine for Menière's disease or syndrome

BACKGROUND

Menière's disease is characterised by attacks of hearing loss, tinnitus and disabling vertigo. Betahistine is used by many people to reduce the frequency and severity of these attacks but there is conflicting evidence relating to its effects.

OBJECTIVES

The objective of this review was to assess the effects of betahistine in people with Menière's disease.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register (The Cochrane Library issue 4,1999), MEDLINE (January 1966 to December 1999), EMBASE (January 1985 to December 1999) and Index Medicus (1962 to 1966). We checked reference lists of articles and contacted pharmaceutical companies for further studies.

SELECTION CRITERIA

Randomised controlled studies of betahistine versus placebo in Menière's disease.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for further information.

MAIN RESULTS

Six trials involving 162 patients were included. No trial met the highest quality standard set by the review because of inadequate diagnostic criteria or methods, and none assessed the effect of betahistine on vertigo adequately. Most trials suggested a reduction of vertigo with betahistine and some suggested a reduction in tinnitus but all these effects may have been caused by bias in the methods. One trial with good methods showed no effect of betahistine on tinnitus compared with placebo in 35 patients. None of the trials showed any effect of betahistine on hearing loss. No adverse effects were found with betahistine.

REVIEWER'S CONCLUSIONS

There is insufficient evidence to say whether betahistine has any effect on Menière's disease.

The effect of blood flow promoting drugs on cochlear blood flow, perilymphatic pO(2) and auditory function in the normal and noise-damaged hypoxic and ischemic guinea pig inner ear

The effect of blood flow promoting drugs, such as hydroxyethyl starch (HES) either of low or high molecular weight (HES 70, HES 200), pentoxifylline, ginkgo biloba, naftidrofuryl and betahistine, and various combinations of the drugs was studied in unexposed and noise-exposed (broad-band noise, bandwidth 1-12 kHz, 106 dB SPL, 30 min) guinea pigs. The results were compared without therapy and placebo (isotonic saline, NaCl). The cochlear blood flow (CoBF) and the partial pressure of oxygen in the perilymph (PL-pO(2)) were continuously and simultaneously recorded over a period of 210 min. In addition, cochlear microphonics (CMs), compound action potentials of the auditory nerve (CAPs) and auditory brain stem responses (ABRs) were registered. Noise-induced hearing loss (NIHL) paralleled a decrease of PL-pO(2). Both were found to occur before evidence of reduced CoBF. PL-pO(2) and CoBF declined progressively post-exposure, while CMs, CAPs and ABRs showed no further deterioration or signs of recovery up to 180 min after cessation of noise. Treatment started 60 min post-exposure, respectively after 90 min, without manipulation in unexposed animals, and was then studied for a further 120 min. In unexposed animals, CoBF increased significantly during infusion of HES 70, HES 200, pentoxifylline and betahistine. NaCl, ginkgo biloba and naftidrofuryl did not alter CoBF. PL-pO(2) decreased significantly during infusion of all administered drugs and combinations, except for NaCl. CMs, CAPs and ABRs remained constant, with the exception of increased ABRs after infusion of HES 70 and HES 200. In noise-exposed animals, a sustained therapeutic effect on cochlear ischemia was achieved only by HES 200 and pentoxifylline. HES 70, betahistine and ginkgo biloba compensated cochlear ischemia only during infusion; however, 30-60 min after termination of therapy, no significant difference of values for CoBF was observed compared to the untreated noise-exposed groups. NaCl and naftidrofuryl showed no effect on CoBF. None of the applied drugs had a sustained compensatory effect on cochlear hypoxia. CMs, CAPs and ABRs improved significantly after HES 70, HES 200 and betahistine, resulting in partial recovery of CMs, and partial (betahistine) or even full (HES 70 and HES 200) recovery of CAPs and ABRs. In contrast, NaCl, pentoxifylline, ginkgo biloba and naftidrofuryl had no therapeutic effect on NIHL.

Dose-dependent effect of betahistine on the vestibulo-ocular reflex: a double-blind, placebo controlled study in patients with paroxysmal vertigo

The effect of betahistine on the vestibulo-ocular reflex (VOR) was assessed in 12 patients suffering from paroxysmal vertigo. Only patients who responded to betahistine treatment were admitted to the study in order to increase the probability of quantifying the effect of the drug on vestibular function. Patients received placebo or 16, 32 or 64 mg betahistine orally under double-blind conditions. Vestibular function was tested a few minutes before intake, and 1, 2, 3, 4, 6 and 8 h after intake, by torsion swing stimulus in the dark, visuo-vestibular interaction upon simultaneous visual and vestibular stimulation and high frequency passive head shaking. Betahistine significantly affected the velocity gain of low and high frequency VOR. The reduction in gain was maximal about 4 h after administration of the 16 mg dose in the torsion swing experiment and the 32 mg dose in the head shaking experiment. Above these doses, the effect on velocity gain was less marked. Betahistine had no effect on visuo-vestibular interaction or nystagmus duration during low frequency torsion. These results suggest that betahistine has a complex action on H3 receptors and that the site of action may be in the vestibular nuclei.

The pharmacological treatment of Menière's disease

The management of Menière's disease often provides a formidable clinical challenge largely because its precise aetiology is unknown. There is no known 'cure' once the condition is established, but drugs may be helpful in treating both the acute attacks of vertigo, and in more long-term management, particularly in the earlier fluctuant stage. These remedies are largely symptomatic and there are few if any properly controlled studies of their efficacy. Suppressant drugs may act centrally at neurotransmitter sites, or peripherally on the labyrinth. Conventional diuretics and osmotically acting agents have been given to reduce the endolymph fluid volume. Histamine analogues directly reduce inner ear fluid pressure mainly by increasing the cochlear blood flow, and are probably the treatment of choice. Otovestibulotoxic drugs given systemically to cause chemical labyrinthine ablation are frequently effective in abolishing attacks of vertigo but often resulted in disabling oscillopsia and ataxia. There is now evidence that local administration by intratympanic injection may well be more efficacious resulting in selective partial end organ ablation. To date innovative immune modifying regimes have not proved helpful.