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Gastric volume curves after intake of 240 mL of water with 35 mg caffeine (black) and without caffeine (grey) from literature [2,36,37].
Source publication
Gastric water emptying as a critical parameter for oral drug absorption can be investigated by several imaging techniques or by the interpretation of pharmacokinetics of appropriate substances. Recently introduced salivary caffeine kinetics is a valuable tool, but the required caffeine abstinence limits its applicability. To avoid the caffeine abst...
Context in source publication
Context 1
... further prove no relevant influence of salivary caffeine method on gastric emptying, we performed a comparison of literature data. Comparing data for emptying 240 mL of water with and without caffeine administered with an ice capsule, no relevant effect of caffeine addition can be observed, as shown in Figure 5. Thus, it can be concluded that the method does not affect gastric emptying. ...
Citations
... To distinguish the salivary caffeine concentrations natural 12 C-caffeine was added to the tablet, and stable isotope labelled 13 C 3 -caffeine was added to the ice capsule. The use of a stable isotope to monitor the release and absorption of caffeine measured by caffeine concentrations in saliva has already been applied to a recent study of in vivo oral dosage form disintegration [19], since 12 C-and 13 C 3 -caffeine have similar pharmacokinetic profiles [20]. ...
... The amount of 25 mg of caffeine used for the determination of gastric emptying is already below the usual dose of caffeine in caffeinated beverages, and thus should not raise concerns about its safety [30] or its pharmacological effect [31,32]. Similarly, in previous studies with the application of the salivary tracer technique, about 25-35 mg of caffeine were used [13,19,20]. Moreover, a recent study showed no influence of this caffeine labelling on gastric emptying by comparison of MRI data sets [20]. ...
... Similarly, in previous studies with the application of the salivary tracer technique, about 25-35 mg of caffeine were used [13,19,20]. Moreover, a recent study showed no influence of this caffeine labelling on gastric emptying by comparison of MRI data sets [20]. Black iron oxide was used to distinguish the core (black powder) from the coating (white powder) during manufacturing. ...
Because of the importance of gastric emptying for pharmacokinetics, numerous methods have been developed for its determination. One of the methods is the salivary tracer technique, which utilizes an ice capsule containing caffeine as a salivary tracer. Despite the ice capsule’s advantage in labeling ingested fluids with caffeine for subsequent salivary detection, its risk of premature melting before swallowing, and its complicated storage and preparation, limit its application, particularly in special populations (e.g., older people). For this reason, here, a compression-coated tablet was developed and validated against the ice capsule in a cross-over clinical trial. The two dosage forms were administered simultaneously to 12 volunteers in an upright position under fasted and fed state conditions. To distinguish the caffeine concentrations in saliva from each dosage form, regular type of caffeine (12C) was added to the tablet, while for the ice capsule 13C3 labelled caffeine was used. The salivary caffeine concentrations showed no statistically significant differences for the pharmacokinetic parameters tmax and AUC0→60 (p > 0.05). Thus, the new formulation is a useful tool for determining gastric emptying that can also be used in special populations.
... In recent years, some studies dealing with GI fluid dynamics have not adequately distinguished real fluid movement from apparent fluid movement. The effect of gastric emptying of ingested water and gastric fluid on drug absorption was reported by Grimm et al., while many aspects of intestinal fluid dynamics remain unclear 31,32 . In the present study, we analyzed GI fluid dynamics quantitatively from both perspectives (apparent and real) using FD-4 and [ 3 H]water. ...
The drug absorption profile is dependent on the luminal drug concentration, which in turn is influenced by the gastrointestinal (GI) fluid dynamics. In the present study, therefore, we aimed to examine the luminal fluid dynamics by kinetically analyzing fluid absorption and secretion along the GI tract in rats using the in situ closed-loop technique with non-absorbable fluorescein isothiocyanate-dextran 4000 (FD-4) and tritium water labeling ([ ³ H]water) under different osmotic conditions. We found that the luminal fluid volume in the jejunum and ileum, but not the colon, gradually decreased and reached a steady state. In contrast, [ ³ H]water almost completely disappeared in all intestinal regions. Kinetic analysis revealed the following rank order for the rate constant of fluid secretion: jejunum > ileum > colon, whereas a negligible regional difference was observed in the rate constant of fluid absorption. Fluid secretion under an isosmotic condition (300 mOsm/kg) was higher than that at 0 mOsm/kg in all intestinal regions, though no significant changes in fluid absorption were observed. Thus, the fluid secretion process appears to be the major determinant of the regional differences in GI fluid dynamics. Our findings indicate that the luminal fluid volume is altered as a result of water ingestion, absorption, and secretion, and finally reaches an apparent steady state, which is regulated mainly by the process of fluid secretion.
