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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. [ABSTRACT FROM AUTHOR]

Aim: A Phase 1 study was performed to evaluate safety, pharmacokinetics (PK) and pharmacodynamics (PD) of the selective histamine H4 receptor antagonist SENS‐111, an oral small molecule. Methods: One hundred healthy subjects were randomized in a placebo‐controlled, double‐blind study evaluating single‐ascending doses (SAD; 100–500 mg) and multiple‐ascending doses (MAD; 50–150 mg day−1, 4 days; 200–250 mg day−1, 7 days). Effects of SENS‐111 on nystagmus and vertigo induced by modified caloric tests were measured in the MAD studies. Population PK and PK/PD models were developed using a nonlinear mixed‐effects approach. Results: SENS‐111 was well tolerated with mild to moderate events. No sedation was reported. A maximal tolerated dose was not reached. Dose‐proportional increases in concentrations were seen up to 200 mg and more than dose‐proportional thereafter, with mean half‐life between 24 and 56 h. The caloric test induced mild but measurable vertigo and nystagmus with large intra/inter‐individual variation for all parameters. SENS‐111 did not significantly impact nystagmus but significantly improved latency of vertigo appearance/disappearance, duration and European Evaluation of Vertigo questionnaire parameters vs. baseline. A two‐compartment model with first‐order absorption, distribution and elimination best fit the data. PK/PD indirect modelling applied to vertigo duration and latency of appearance indicated maximum activity between 100 and 500 ng ml−1 plasma concentrations, corresponding to 100 and 200 mg day−1, which are appropriate for clinical efficacy evaluations in vestibular diseases. Conclusions: SENS‐111 is a well‐tolerated first‐in‐class H4 receptor antagonist with acceptable PK for oral daily dosing. PK/PD modelling determined plasma concentrations and doses for efficacy studies in patients with vertigo symptoms. [ABSTRACT FROM AUTHOR]