Gastric emptying of liquids is delayed by co-ingesting solids: a study using salivary paracetamol concentrations

Paracetamol concentrations in plasma, a frequently used index of gastric emptying (GE) of liquids, are closely correlated with those in saliva. GE of liquids is delayed by co-ingesting solids. No researchers have used salivary paracetamol concentrations to show this phenomenon. The aim of this study was to elucidate whether salivary paracetamol concentrations can detect the food-induced delay in liquid GE.

Paracetamol absorption was measured twice in five healthy male volunteers. Following an overnight fast, they received 10 mg/kg paracetamol in 200 ml water alone on one occasion, and received this solution after consuming a 400 kcal-containing cookie on another occasion. After thorough rinsing of the month, 1 ml saliva was obtained, simultaneously with 2 ml blood, at 0, 0.25, 0.5, 0.75, 1.0, 2.0, 3.0, 4.0, and 6.0 h after paracetamol intake. The peak concentration (C(max)), the time to C(max) (t(max)), the area under the curve (AUC), and C(max)/AUC in plasma were calculated. Salivary C(max) and t(max) were also determined.

Plasma C(max) and AUC were not significantly different between the two occasions. In contrast, significant differences in plasma t(max) and C(max)/AUC ( P < 0.05) established the food-induced delay in GE. Salivary t(max) could detect the delayed GE, whereas salivary C(max) could not.

Salivary t(max) can document the solid meal-induced delay in liquid GE.