New approaches to the management of peripheral vertigo: efficacy and safety of two calcium antagonists in a 12-week, multinational, double-blind study

Current and Emerging Medical Therapies for Dizziness

Medical therapies for dizziness are aimed at vertigo reduction, secondary symptom management, or the root cause of the pathologic process. Acute peripheral vertigo pharmacotherapies include antihistamines, calcium channel blockers, and benzodiazepines. Prophylactic pharmacotherapies vary between causes. For Meniere disease, betahistine and diuretics remain initial first-line oral options, whereas intratympanic steroids and intratympanic gentamicin are reserved for uncontrolled symptoms. For cerebellar dizziness and oculomotor disorders, 4-aminopyridine may provide benefit. For vestibular migraine, persistent postural perceptual dizziness and mal de débarquement, treatment options overlap and include selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants and calcium channel blockers.

Current Insights into Treating Vertigo in Older Adults

The number of older people has been increasing over recent decades in Western populations. Dizziness, imbalance, and vertigo constitute some of the most common complaints in older patients, and risk of falling is the most frequent and worrying consequence. It has been reported that 15–20% of the adult population experiences these debilitating symptoms. Among the diseases that may be associated with vertigo, the three classes of otological, central, and functional (psychological) dizziness may be distinguished. Overall, vestibular disorders account for 48% of vertiginous complaints in the older population. The main focus of this article is to review the forms of pharmacotherapy for vertigo, especially with regard to older patients, who may be treated simultaneously with other drugs for different comorbidities. Interactions with other drugs should be considered in the choice of a particular course of treatment. Moreover, overuse of pharmacotherapy for the management of vertigo in the elderly may prevent the development of the central compensatory mechanism that sustains both static and dynamic imbalance after a vertiginous crisis. In the majority of patients, vestibular and physical rehabilitation are strongly advised and rarely contraindicated.

Cinnarizine as an alternative recommendation for migraine prophylaxis: a narrative review

INTRODUCTION

Despite the available prophylactic and acute drugs for migraine management, this disabling disorder remains undertreated especially among pediatrics. In this review, the authors aim at assessing the preventive role cinnarizine plays in treating migraine based on previously published studies.

AREAS COVERED

Randomized clinical trials, randomized controlled trials, non-randomized open-label trials, and retrospective studies concerning cinnarizine in migraine prevention in children and adults were reviewed. Especial attention was given to the response rate, migraine characteristics, and tolerability.

EXPERT OPINION

The majority of reviewed trials demonstrated that cinnarizine is comparable to the conventional drugs used in migraine prophylaxis. However, most of the reviewed studies were limited by a non-controlled open-label design. Due to poor planning and possibility of high placebo responses, particularly in children and adolescents, the interpretation of open-label studies' results should be done cautiously. The evidence shows that cinnarizine's effectiveness was more promising in pediatric migraineurs and adults with migraine-associated vertigo such as vestibular migraine. Therefore, while the efficacy of cinnarizine cannot be dismissed, before reaching a definite conclusion on its effectiveness, it is necessary to do further high-quality RCTs among both children and adults.

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.

[Vascular mechanisms in Meniere's disease]

Meniere's disease (MD) is chronic multifactorial medical condition caused by endolymphatic hydrops, which etiology is unclear. This review highlights possible vascular mechanisms of MD. Impairment of vascular regulation, further ischemic damage of labyrinth and venous drainage pathology could lead to endolymphatic hydrops. Epidemiologic studies reveal high comorbidity of MD and migraine. Both diseases could be the result of trigeminovascular dysfunction. Betahistine, the medication with vascular effect, is widely used in treatment of MD, the effectiveness of calcium channel blockers is evaluated. Keywords: vertigo, Meniere's disease, endolymphatichydrops, migraine, vascular mechanisms, betahistine.

Nimodipine for the treatment of otolaryngic indications

PURPOSE

The uses of nimodipine for otolaryngic indications are reviewed, and recommendations for its use in clinical practice are provided.

SUMMARY

Nimodipine is currently indicated for the improvement of neurologic outcomes in adult patients with aneurysmal subarachnoid hemorrhage (aSAH). However, other oral and i.v. calcium channel blockers have not exhibited the same beneficial effects in patients with aSAH, leading clinicians to believe that nimodipine possesses unique neuroprotective effects in addition to its calcium channel-blocking and vasodilatory properties. Consequently, clinical investigations of nimodipine have been conducted for cochlear and facial nerve preservation after vestibular schwannoma (VS) surgery, symptomatic management of Ménière's disease and peripheral vertigo, and recovery of vocal cord paralysis after laryngeal nerve injury. Three prospective randomized studies have investigated nimodipine for hearing and/or nerve preservation in patients undergoing VS resection, the results of which have suggested a potential benefit of initiating nimodipine during the perioperative period. Several studies of Ménière's disease and/or peripheral vertigo have reported improved symptom control with nimodipine. For vocal fold paralysis associated with recurrent laryngeal nerve (RLN) injury, nimodipine may increase the recovery rate based on the results of 1 nonrandomized prospective study that used nimodipine in a protocolized manner. One small pilot study found that nimodipine improved facial nerve function after maxillofacial surgery.

CONCLUSION

Due to its proposed vasoactive and neuroprotective effects, nimodipine may play a role in the treatment of a number of otolaryngic pathologies including VS, Ménière's disease, peripheral vertigo, RLN injury, and facial weakness after maxillofacial surgery. Small studies have shown improved symptom control and recovery after surgery. Since all of the aforementioned indications are still considered off label, clinicians and patients should collaboratively assess the risks and benefits before initiating treatment.

Integrating virtual screening and biochemical experimental approach to identify potential anti-cancer agents from drug databank

Chemical libraries constitute a reservoir of pharmacophoric molecules to identify potent anti-cancer agents. Virtual screening of heterocyclic compound library in conjugation with the agonist-competition assay, toxicity-carcinogenicity analysis, and string-based structural searches enabled us to identify several drugs as potential anti-cancer agents targeting protein kinase C (PKC) as a target. Molecular modeling study indicates that Cinnarizine fits well within the PKC C2 domain and exhibits extensive interaction with the protein residues. Molecular dynamics simulation of PKC-Cinnarizine complex at different temperatures (300, 325, 350, 375, and 400[Formula: see text]K) confirms that Cinnarizine fits nicely into the C2 domain and forms a stable complex. The drug Cinnarizine was found to bind PKC with a dissociation constant Kd of [Formula: see text]M. The breast cancer cells stimulated with Cinnarizine causes translocation of PKC-[Formula: see text] to the plasma membrane as revealed by immunoblotting and immunofluorescence studies. Cinnarizine also dose dependently reduced the viability of MDAMB-231 and MCF-7 breast cancer cells with an IC[Formula: see text] of [Formula: see text] and [Formula: see text]g/mL, respectively. It is due to the disturbance of cell cycle of breast cancer cells with reduction of S-phase and accumulation of cells in G1-phase. It disturbs mitochondrial membrane potentials to release cytochrome C into the cytosol and activates caspase-3 to induce apoptosis in cancer cells. The cell death was due to induction of apoptosis involving mitochondrial pathway. Hence, the current study has assigned an additional role to Cinnarizine as an activator of PKC and potentials of the approach to identify new molecules for anti-cancer therapy. Thus, in silico screening along with biochemical experimentation is a robust approach to assign additional roles to the drugs present in the databank for anti-cancer therapy.

Discovery and Development of Calcium Channel Blockers

In the mid 1960s, experimental work on molecules under screening as coronary dilators allowed the discovery of the mechanism of calcium entry blockade by drugs later named calcium channel blockers. This paper summarizes scientific research on these small molecules interacting directly with L-type voltage-operated calcium channels. It also reports on experimental approaches translated into understanding of their therapeutic actions. The importance of calcium in muscle contraction was discovered by Sidney Ringer who reported this fact in 1883. Interest in the intracellular role of calcium arose 60 years later out of Kamada (Japan) and Heibrunn (USA) experiments in the early 1940s. Studies on pharmacology of calcium function were initiated in the mid 1960s and their therapeutic applications globally occurred in the the 1980s. The first part of this report deals with basic pharmacology in the cardiovascular system particularly in isolated arteries. In the section entitled from calcium antagonists to calcium channel blockers, it is recalled that drugs of a series of diphenylpiperazines screened in vivo on coronary bed precontracted by angiotensin were initially named calcium antagonists on the basis of their effect in depolarized arteries contracted by calcium. Studies on arteries contracted by catecholamines showed that the vasorelaxation resulted from blockade of calcium entry. Radiochemical and electrophysiological studies performed with dihydropyridines allowed their cellular targets to be identified with L-type voltage-operated calcium channels. The modulated receptor theory helped the understanding of their variation in affinity dependent on arterial cell membrane potential and promoted the terminology calcium channel blocker (CCB) of which the various chemical families are introduced in the paper. In the section entitled tissue selectivity of CCBs, it is shown that characteristics of the drug, properties of the tissue, and of the stimuli are important factors of their action. The high sensitivity of hypertensive animals is explained by the partial depolarization of their arteries. It is noted that they are arteriolar dilators and that they cannot be simply considered as vasodilators. The second part of this report provides key information about clinical usefulness of CCBs. A section is devoted to the controversy on their safety closed by the Allhat trial (2002). Sections are dedicated to their effect in cardiac ischemia, in cardiac arrhythmias, in atherosclerosis, in hypertension, and its complications. CCBs appear as the most commonly used for the treatment of cardiovascular diseases. As far as hypertension is concerned, globally the prevalence in adults aged 25 years and over was around 40% in 2008. Usefulness of CCBs is discussed on the basis of large clinical trials. At therapeutic dosage, they reduce the elevated blood pressure of hypertensive patients but don't change blood pressure of normotensive subjects, as was observed in animals. Those active on both L- and T-type channels are efficient in nephropathy. Alteration of cognitive function is a complication of hypertension recognized nowadays as eventually leading to dementia. This question is discussed together with the efficacy of CCBs in cognitive pathology. In the section entitled beyond the cardiovascular system, CCBs actions in migraine, neuropathic pain, and subarachnoid hemorrhage are reported. The final conclusions refer to long-term effects discovered in experimental animals that have not yet been clearly reported as being important in human pharmacotherapy.

Cinnarizine: A Contemporary Review

Cinnarizine, is approved for nausea, vomiting, motion sickness, inner ear disorders and is considered as first-line pharmacotherapy for management of vertigo. It acts by anti-vasoconstrictor activity, reducing blood viscosity and reducing nystagmus in labyrinth. Lack of adequate literature on clinical evidence of cinnarizine and its combination (dimenhydrinate) in vertigo management prompted this review. A specific MEDLINE literature search strategy was designed combining Medical Subject Headings, free-text keywords (like cinnarizine and vertigo) using Boolean operators (1970-2016) for clinical studies, clinical reviews and meta-analyses of cinnarizine. Analyses of studies validated cinnarizine's efficacy in peripheral and central vertigo versus placebo or other therapies, and was well-tolerated by the patients recruited across different studies. Cinnarizine and/ or its combinations are favorable in management of vestibular disorders wherein cinnarizine acts predominantly peripherally on labyrinth and dimenhydrinate acts centrally on vestibular nuclei and associated centers in brainstem. Combination therapy of cinnarizine and/ or its combinations demonstrated a better safety profile than either of the mono-components, offering a viable therapeutic option in vertigo management.

Principles of vestibular pharmacotherapy

Ideally, vestibular pharmacotherapy is intended, through specific and targeted molecular actions, to significantly alleviate vertigo symptoms, to protect or repair the vestibular sensory network under pathologic conditions, and to promote vestibular compensation, with the eventual aim of improving the patient's quality of life. In fact, in order to achieve this aim, considerable progress still needs to be made. The lack of information on the etiology of vestibular disorders and the pharmacologic targets to modulate, as well as the technical challenge of targeting a drug to its effective site are some of the main issues yet to be overcome. In this review, my intention is to provide an account of the therapeutic principles that have shaped current vestibular pharmacotherapy and to further explore crucial questions that must be taken into consideration in order to develop targeted and specific pharmacologic therapies for each type and stage of vestibular disorders.

Fixed combination of cinnarizine and dimenhydrinate in the prophylactic therapy of vestibular migraine: an observational study

Vestibular migraine (VM) is one of the most frequent causes of episodic vertigo, with a lifetime prevalence of 0.98%. Prophylactic therapy includes calcium channel blockers, beta-blockers, antiepileptic drugs and antidepressants. We studied the association of cinnarizine 20 mg and dimenhydrinate 40 mg (Arlevertan) in a group of 22 patients affected by definite VM. Proposed therapy included one tablet twice a day for 1 month, which was repeated three times with 1 month of interval between drug intake; results were compared with those of a control group of 11 VM patients who asked to observe only lifestyle measures for migraine. The main outcome was the number of vertigo and headache crises in the 6 months before therapy and in the 6 months of follow-up. Subjects performing Arlevertan presented during the 6 months of therapy a decrease of vertigo attacks from 5.3 to 2.1 and of headaches from 4.3 to 1.7 (p < 0.0001); 68% of these subjects reported a decrease of at least 50% of vertigo attacks, while 63% of headaches. Conversely, vertigo attacks decreased from 3.5 to 2.2 and headaches from 2.6 to 2 in patients observing only lifestyle; 18% of these subjects reported a decrease of at least 50% of vertigo crises and 27% of headaches. Our data do not differ from those of previous works assessing efficacy of different prophylactic therapies for VM and reporting consistent reduction of vertigo spells in a rate of patients ranging from 60 and 80%.

Recent advances in delivery systems and therapeutics of cinnarizine: a poorly water soluble drug with absorption window in stomach

Low solubility causing low dissolution in gastrointestinal tract is the major problem for drugs meant for systemic action after oral administration, like cinnarizine. Pharmaceutical products of cinnarizine are commercialized globally as immediate release preparations presenting low absorption with low and erratic bioavailability. Approaches to enhance bioavailability are widely cited in the literature. An attempt has been made to review the bioavailability complications and clinical therapeutics of poorly water soluble drug: cinnarizine. The interest of writing this paper is to summarize the pharmacokinetic limitations of drug with special focus on strategies to improvise bioavailability along with effectiveness of novel dosage forms to circumvent the obstacle. The paper provides insight to the approaches to overcome low and erratic bioavailability of cinnarizine by cyclodextrin complexes and novel dosage forms: self-nanoemulsifying systems and buoyant microparticulates. Nanoformulations need to systematically explored in future, for their new clinical role in prophylaxis of migraine attacks in children. Clinical reports have affirmed the role of cinnarizine in migraine prophylaxis. Research needs to be dedicated to develop dosage forms for efficacious bioavailability and drug directly to brain.

Cinnarizine for the prophylaxis of migraine associated vertigo: a retrospective study

Objective

To assess the efficacy and safety of cinnarizine for the prophylaxis of migraine associated vertigo in the vestibular migraine and migraine with brainstem aura.

Background

Vestibular migraine and migraine with brainstem aura are two principal clinical syndromes that frequently are associated with vertigo. Since cinnarizine is a well-tolerated calcium channel blocker which has acceptable effect on both vertigo and migraine headache, we carried out this study to evaluate the efficacy and safety of this medication in vestibular migraine and also migraine with brainstem aura associated with vertigo.

Methods

This was a retrospective, single-center, open-label, investigation of the effects of cinnarizine on vestibular migraine and migraine with associated with vertigo. We assessed the change in monthly frequency of vertigo and also frequency, duration and intensity of migraine attacks after one, two and three months of cinnarizine administration.

Results

The mean frequency of vertigo and also the mean frequency, duration and intensity of migraine headaches per month were reduced significantly after three months of cinnarizine therapy (all p < 0.001).

Conclusion

This study suggests that cinnarizine is safe and effective in reducing both headache and vertigo aspects of “migraine plus vertigo” among the patients who suffer from either vestibular migraine or migraine with brainstem aura associated with vertigo.

Efficacy and safety of cinnarizine in the prophylaxis of migraine headaches in children: an open, randomized comparative trial with propranolol

Migraine headaches are common in children. Early diagnosis and appropriate interventions are mandatory to prevent decades of suffering and diminished quality of life. There is need for data regarding the efficacy and safety of prophylactic agents in children with migraine; therefore, we designed a randomized clinical trial to compare the efficacy and safety of cinnarizine with that of a well-known prophylactic agent (propranolol) in the prophylaxis of pediatric migraine headache. A total of 120 patients aged between 6 and 17 years were recruited and 113 patients succeeded in completing all phases of the trial. Of them, 57 patients were given cinnarizine, and propranolol was administered in 56 patients. Reduction in headache frequency was the main response to treatment. Cinnarizine reduced the baseline headache frequency by more than 50% in 74.6% of patients and the mean headache frequency per month was reduced from 11.851 ± 0.739 (mean ± SEM) to 3.358 ± 0.739 (mean ± SEM) attacks per month (P < 0.001). In the propranolol group, more than 50% reduction of the baseline headache frequency was seen in 72.5% of patients and the mean headache frequency per month was reduced from 10.264 ± 0.830 (mean ± SEM) to 2.774 ± 0.830 (mean ± SEM) attacks per month (P < 0.001). No significant difference was seen in 50% reduction of the baseline headache frequency between treatment groups (P = 0.358). No significant adverse effects were reported. In this open study, cinnarizine appeared thus as effective as propranolol and safe for the prophylaxis of migraine in children, but this remains to be confirmed in a double-blind placebo-controlled trial.

Neuropharmacology of vestibular system disorders

This work reviews the neuropharmacology of the vestibular system, with an emphasis on the mechanism of action of drugs used in the treatment of vestibular disorders. Otolaryngologists are confronted with a rapidly changing field in which advances in the knowledge of ionic channel function and synaptic transmission mechanisms have led to the development of new scientific models for the understanding of vestibular dysfunction and its management. In particular, there have been recent advances in our knowledge of the fundamental mechanisms of vestibular system function and drug mechanisms of action. In this work, drugs acting on vestibular system have been grouped into two main categories according to their primary mechanisms of action: those with effects on neurotransmitters and neuromodulator receptors and those that act on voltage-gated ion channels. Particular attention is given in this review to drugs that may provide additional insight into the pathophysiology of vestibular diseases. A critical review of the pharmacology and highlights of the major advances are discussed in each case.

Pharmacological modulation of transmitter release by inhibition of pressure-dependent potassium currents in vestibular hair cells

Vestibular vertigo may be induced by increases in the endolymphatic pressure that activate pressure-dependent K(+) currents (I(K,p)) in vestibular hair cells. I(K,p) have been demonstrated to modulate transmitter release and are inhibited by low concentrations of cinnarizine. Beneficial effects against vestibular vertigo of cinnarizine have been attributed to its inhibition of calcium currents. Our aim was to determine the extent by which the inhibition of I(K,p) by cinnarizine may alter the voltage response to stimulating currents and to analyze whether such alterations may be sufficient to modulate the activation of Ca(2+) currents and transmitter release. Vestibular type II hair cells from guinea pigs were studied using the whole-cell patch-clamp technique. In current clamp, voltage responses to trains of stimulating currents were recorded. In voltage clamp, transmitter release was assessed from changes in the cell capacitance, as calculated from the phase shift during application of sine waves. Cinnarizine (0.05-3 microM) concentration dependently reversed the depressing effects of increases in the hydrostatic pressure (from 0.2 to 0.5 cm H(2)O) on the voltage responses to stimulating currents. Voltage protocols that simulated these responses were applied in voltage clamp and revealed a significantly enhanced transmitter release in conditions mimicking an inhibition of I(K,p). Cinnarizine (< or =0.5 microM) did not inhibit calcium currents. We conclude that cinnarizine, in pharmacologically relevant concentrations, enhances transmitter release in the presence of elevated hydrostatic pressure by an indirect mechanism, involving inhibition of I(K,p), enhancing depolarization, and increasing the voltage-dependent activation of Ca(2+) currents, without directly affecting Ca(2+) current.

Cinnarizine in refractory migraine prophylaxis: efficacy and tolerability. A comparison with sodium valproate

This was a double-blind clinical trial designed to assess the efficacy and safety of the cinnarizine (CIN) in patients with migraine who were refractory to propranolol and tricyclic antidepressants in comparison with sodium valproate (SV) to investigate whether CIN could be at least as effective as SV. A total of 125 patients were treated in a treatment period of 12 weeks. All patients had at least one intake of trial medication and 2-week post baseline efficacy observation which all were included in the ITT analysis. Of the 125 subjects treated, 46 discontinued prematurely: 25 from the CIN and 21 from the SV group. The main reasons for premature discontinuation were: lost to follow up (25/46, 63.2%), insufficient response (16/46, 20%), and adverse events (5/46, 12.8%). No statistically significant inter-group differences in the number of discontinuation was observed (p > 0.05). In both groups, number of attacks, intensity, and duration of attacks significantly decreased (p < 0.05). No statistically significant inter-group differences were observed regarding the mean number of attacks, duration, and intensity of migraine attacks for any of the time intervals analysed, except for the mean reduction of third and fourth visits intensity from baseline which were significantly different in two groups (p < 0.05), with the CIN group showing more reduction. Analysis of the number of responders showed that in the CIN group 61.2% subjects were responders, and 63.8% in the SV group. No statistically significant differences between the treatment groups were found for any of the secondary parameters. Overall 26 subjects reported one or more adverse events during the study period: 13 subjects in each group. Five subjects discontinued prematurely due to adverse events; two in the CIN group with significant weight gain, and 3 in the SV group with significant weight gain and severe tremor. These results suggest that CIN is an effective and safe prophylactic agent even in severe migraine headache.

Open-Label Trial of Cinnarizine in Migraine Prophylaxis

OBJECTIVE

To assess the effectiveness and safety of cinnarizine as a migraine-preventive therapy.

METHODS

Sixty patients with more than 2 migraine headache attacks during a 4-week baseline entered the study and received a 25-mg tablet cinnarizine twice daily for the first 3 days and then 3 times daily. They were assessed on weeks 2, 6, 10, and 14. Reduction from baseline in 4-week migraine headache rate was the primary efficacy variable. Reduction in migraine attacks duration and severity was also evaluated.

RESULTS

The mean reduction in 4-week migraine headache rate was 4.6 +/- 2.2 from the baseline of 6.2 +/- 2.2 after 14 weeks of treatment, which was statistically significant (P < 0.001). Percent reduction in 4-week migraine frequency was 35% after 2 weeks, 74% after 6 weeks, 74% after 10 weeks, and 75% after 14 weeks of treatment. Significant reduction in attack duration (P < 0.001) and severity (P < 0.001) was also noted. No serious adverse events were observed in this series of patient.

CONCLUSION

Cinnarizine is an efficacious and well-tolerated prophylactic antimigraine medication, which has early onset effectiveness.

Cinnarizine has an atypical antipsychotic profile in animal models of psychosis

Cinnarizine, a drug known as a calcium channel blocker, is currently used for the treatment of migraine and vertigo. Induction of extrapyramidal signs by cinnarizine has been reported in the elderly, which is related to its moderate antagonistic properties at dopamine D2 receptors, resembling the mechanism of action of most antipsychotic drugs. Despite this effect, cinnarizine has never been tested as a putative antipsychotic drug. Here we evaluate the potential effect of cinnarizine in two pharmacological models of psychosis, namely amphetamine- and MK-801-induced hyperlocomotion, as well as its ability to induce catalepsy. Cinnarizine significantly counteracted MK-801 (0.25 mg/kg) and amphetamine (5mg/kg) locomotor effects at doses as low as 20mg/kg, having no incremental effect at 60 or 180 mg/kg. Regarding side-effects, cinnarizine induced no catalepsy in mice at the effective dose of 20 mg/kg, inducing only mild catalepsy at the doses of 60 and 180 mg/kg. Based on these results and on the antagonist effect of cinnarizine on dopamine D2 receptors, we suggest that it has a potential antipsychotic effect with an atypical profile that should be evaluated clinically.

Inhibition of voltage-gated calcium currents in type II vestibular hair cells by cinnarizine

Cinnarizine is pharmaceutically used in conditions with vestibular vertigo such as Meniere's disease. It is thought to act on extra-vestibular targets. We hypothesized that cinnarizine, as a blocker of L-type Ca2+ channels, may directly target vestibular hair cells where Ca2+ currents are important for the mechano-electrical transduction and transmitter release. Our aim was to clarify whether cinnarizine affected voltage-dependent Ca2+ currents in vestibular type II hair cells. Such cells were isolated from inner ears of guinea pigs by enzymatic and mechanical dissection from the gelatinous otolithic membrane and studied with the patch-clamp technique in conventional whole-cell mode. Ca2+ currents were elicited by depolarizing pulses in a solution containing 1.8 mM Ca2+ and 40 mM Ba2+. These currents resembled L-type currents (I(Ca,L)) with respect to their voltage-dependence and their inhibition by nifedipine and Cd2+ but did not show time-dependent inactivation. The currents were inhibited by cinnarizine in a concentration-dependent and reversible manner. The IC50 was 1.5 microM. A block exceeding 80% was achieved with 10 microM. The onset of current block was faster with higher concentrations but the reversibility after wash-out was less, suggesting accumulation in the membrane. We conclude that these direct actions of cinnarizine on hair cells should be considered as molecular mechanisms contributing to therapeutic effects of cinnarizine in vertigo.

Pharmacological treatment of vertigo

This review discusses the physiology and pharmacological treatment of vertigo and related disorders. Classes of medications useful in the treatment of vertigo include anticholinergics, antihistamines, benzodiazepines, calcium channel antagonists and dopamine receptor antagonists. These medications often have multiple actions. They may modify the intensity of symptoms (e.g. vestibular suppressants) or they may affect the underlying disease process (e.g. calcium channel antagonists in the case of vestibular migraine). Most of these agents, particularly those that are sedating, also have a potential to modulate the rate of compensation for vestibular damage. This consideration has become more relevant in recent years, as vestibular rehabilitation physical therapy is now often recommended in an attempt to promote compensation. Accordingly, therapy of vertigo is optimised when the prescriber has detailed knowledge of the pharmacology of medications being administered as well as the precise actions being sought. There are four broad causes of vertigo, for which specific regimens of drug therapy can be tailored. Otological vertigo includes disorders of the inner ear such as Ménière's disease, vestibular neuritis, benign paroxysmal positional vertigo (BPPV) and bilateral vestibular paresis. In both Ménière's disease and vestibular neuritis, vestibular suppressants such as anticholinergics and benzodiazepines are used. In Ménière's disease, salt restriction and diuretics are used in an attempt to prevent flare-ups. In vestibular neuritis, only brief use of vestibular suppressants is now recommended. Drug treatments are not presently recommended for BPPV and bilateral vestibular paresis, but physical therapy treatment can be very useful in both. Central vertigo includes entities such as vertigo associated with migraine and certain strokes. Prophylactic agents (L-channel calcium channel antagonists, tricyclic antidepressants, beta-blockers) are the mainstay of treatment for migraine-associated vertigo. In individuals with stroke or other structural lesions of the brainstem or cerebellum, an eclectic approach incorporating trials of vestibular suppressants and physical therapy is recommended. Psychogenic vertigo occurs in association with disorders such as panic disorder, anxiety disorder and agoraphobia. Benzodiazepines are the most useful agents here. Undetermined and ill-defined causes of vertigo make up a large remainder of diagnoses. An empirical approach to these patients incorporating trials of medications of general utility, such as benzodiazepines, as well as trials of medication withdrawal when appropriate, physical therapy and psychiatric consultation is suggested.