Stimulation of pancreatic secretion by sulpiride

Atypical antipsychotics--effects of amisulpride on salivary secretion and on clozapine-induced sialorrhea

OBJECTIVE

Amisulpride is suggested for treatment of clozapine-induced sialorrhea. However, objective measurements of its effectiveness are lacking and, preclinically, amisulpride has no effect. We currently hypothesise that amisulpride acts by reducing the nervous- rather than the clozapine-driven salivary secretion.

MATERIAL AND METHODS

Effects of intravenous amisulpride (as well as of clozapine and raclopride, a dopamine D2/D3 antagonist) were investigated in rats, including those subjected to chronic preganglionic parasympathetic denervation (submandibular glands) or combined postganglionic parasympathetic and sympathetic denervation (parotid glands). In duct-cannulated glands, secretion was evoked reflexly, at low and maximum flow rates, and by electrical stimulation of the parasympathetic and sympathetic innervations, and administration of autonomimetics (including substance P).

RESULTS

Unlike clozapine, amisulpride had no effect on the reflexly evoked secretion at maximum rate. With respect to reflex secretion at low rate and to the secretion evoked by muscarinic, α-adrenergic, β-adrenergic and substance P receptors, amisulpride (in contrast to raclopride) dose dependently potentiated the responses. Amisulpride had no effect on gland blood flow.

CONCLUSIONS

No support for any inhibitory influence of amisulpride was found. Conversely, amisulpride universally enhanced secretion, suggesting that amisulpride is a potential drug for dry-mouth treatment. The mechanism behind the potentiation is currently unknown.

Inhibition of postprandial colonic motility by sulpiride in patients with irritable colon

Sulpiride, a benzamide derivative, selectively antagonizes dopaminergic receptors within and outside the central nervous system. Dopamine has previously been shown to increase colonic motility. In the present investigation the motor response of the pelvic colon to a standard 1000 calorie meal was studied in 12 patients with the irritable bowel syndrome. The meal induced a significant increase in motor activity, lasting for 1 h and greatest in the first 30 min. In 6 cases the administration of sulpiride 100 mg i.m. significantly reduced the postprandial increase in colonic motor activity. Thus dopaminergic receptors may be involved in the colonic motor response to food.