Rheoencephalographic and Other Studies of Betahistine in Humans: I. The Cerebral and Peripheral Circulatory Effects of Single Doses in Normal Subjects

Abstract

Two groups of six young normal male subjects were studied by an improved form of rheoencephalography (intracranial rheoncephalography), by photoplethysmography, and by impedance plethysmography to investigate the possible effects of single doses of betahistine hydrochloride (SERC) and placebo on the normal human cranial, cerebral, scalp, and calf circulations. Two subjects participated in both groups. The results of the two studies were similar and were combined for this presentation. One subject reported slight transient faintness and visual blurring after 20 mg of the drug. No other adverse or side effects were encountered. The results show that the drug causes definite, strong, reproducible, and dose-related responses in the studied circulations, typically those of decreases in their waveform amplitudes and pulse propagation times. Betahistine hydrochloride thus acts as a potent cerebral and peripheral microcirculatory vasodilator in normal humans when given orally. Split-dose studies indicate that responses followed each dose and that the second response was superimposed on the first. The value of using betahistine hydrochloride in overlapping doses is suggested. Atypical cranial, cerebral, scalp, and calf amplitude increases were found in some high-dosage (16-mg) trials. These increases may indicate that betahistine hydrochloride can also act as an arterial vasodilator in sufficiently high dosage, but they equally may indicate that sufficiently profound microcirculatory vasodilatation can elicit secondary arterial circulatory increases.

Betahistine Increases Vestibular Blood Flow

“…The opening of the periphery therefore overrides central constriction and results in a decrease in systemic BP. 3,8,29 BH is also known to effect the central nervous system by reducing the effects of excess histamine release in the medial vestibular nucleus. 30 The effect of BH on VBF was attenuated with H3-receptor antagonist pretreatment and suggests the involvement of this presynaptic receptor type in the effect.…”

The low-dose combination preparation Vertigoheel activates cyclic nucleotide pathways and stimulates vasorelaxation

“…The standard antivertiginous drug betahistine causes vasodilation through its histaminergic action [3,29]. Betahistine acts as a potent cerebral microcirculatory vasodilator in humans when given orally [42] and was shown to specifically increase cochlear blood flow in guinea pigs [23], consolidating the notion of a causal link between vertigo and impaired microvascular blood flow. On the other hand, histamine analogs have been associated with side effects, such as drowsiness and dry mouth, especially in elderly patients.…”

The effect of betahistine methanesulphonate upon cerebral blood flow [letter]

“…For example, Meyer, Matthew, Hartmann & Rivera (1974) report that in ten patients with a diagnosis of cerebrovascular ischaemic disease based on the history ofabrupt onset of focal neurological deficits and/or episodic but progressive and severe neurological deficit due to diffuse cerebral arteriosclerosis, mean regional cerebral blood flow increased by 20% + 4.75% (mean + s.d.). In healthy male volunteers cerebral blood flow, as measured by a rheoencephalographic method, was LETTERS TO THE EDITORS 309 o% 00oort-r -t n r-00 r-00 increased in a dose dependent fashion by betahistine hydrochloride (Seipel & Floam, 1975). It is unusual to find a drug that is taken orally that increases cerebral blood flow and we therefore designed a small trial to examine the effects of betahistine on cerebral blood flow in healthy volunteers.…”