Effect of altered gastric emptying on caffeine absorption.

The effect of altered gastric emptying on caffeine absorption (tablets; 366.1 mg) was studied in patients with gastric stasis or after Billroth II partial gastrectomy with adequate gastric emptying and in healthy subjects with slowed gastric emptying due to a fibre-free and a fibre-rich liquid test meal of an elemental diet, respectively. Compared with controls (n = 15), a significantly slowed caffeine absorption was found in gastric stasis (n = 8) by means of a lower absorption rate constant KA (0.018 +/- 0.007 vs. 0.122 +/- 0.110 min-1 in controls) and a prolonged peak time tmax (160 +/- 77 vs. 46 +/- 19 min). Similar results were obtained after a fibre-free and a fibre-rich liquid test meal, respectively (n = 8 and n = 8, respectively; KA 0.035 +/- 0.01 and 0.035 +/- 0.023 min-1, respectively; tmax 91 +/- 24 and 93 +/- 23 min, respectively vs. KA 0.10 +/- 0.06 min-1 and tmax 50 +/- 14 min in controls; n = 7). After B II with adequate gastric emptying (n = 11) the absorption rate was within the normal range. The significantly lower average of the peak concentration cmax and of the area under the serum concentration-time curve x elimination rate constant (AUC x KE) in gastric stasis (5.9 +/- 1.8 micrograms/ml and 8.9 +/- 3.2 mg/l, respectively) and after B II partial gastrectomy (8.8 +/- 2.6 micrograms/ml and 10.8 +/- 3.0 mg/l, respectively) compared with controls (17.7 +/- 9.4 micrograms/ml and 20.8 +/- 10.7 mg/l respectively) probably reflect reduced bioavailability, which is apparently unchanged after a liquid test meal.