The increased risk of gallstone formation in acromegalics treated with the somatostatin analog octreotide has been related to an impaired gallbladder emptying. To determine the duration of these inhibitory effects, meal-stimulated gallbladder motility, plasma cholecystokinin (CCK), and pancreatic polypeptide (PP) were measured in five acromegalics treated for 6-32 months with 200-300 micrograms octreotide daily. Meal tests were performed 45 min, 8 hr and two weeks after the last 100-micrograms subcutaneous dose. Results were compared with those in normal subjects. Integrated postprandial gallbladder contraction (-125 +/- 194 cm3/120 min) and integrated PP secretion (-0.1 +/- 0.2 nmol/liter/120 min) were completely suppressed in the 45-min study, but significantly improved (P < 0.05) when measured 8 hr (1376 +/- 322 cm3/120 min and 3.0 +/- 1.0 nmol/liter/120 min) and two weeks (1437 +/- 263 cm3/120 min and 10.6 +/- 1.6 nmol/liter/120 min) after the last dose of octreotide. The integrated gallbladder contraction in acromegalics at 8 hr was comparable to that at two weeks and to that in normal subjects, but the integrated PP response at 8 hr was significantly smaller (P < 0.05 vs two weeks and vs normals). Integrated plasma CCK secretion at 45 min (0.13 +/- 0.06 nmol/liter/120 min) was not statistically significantly different from the response at 8 hr (0.15 +/- 0.02 nmol/liter/120 min) and from that in normal subjects, but it was significantly increased at two weeks after cessation of octreotide (P < 0.05 vs 45 min and 8 hr).(ABSTRACT TRUNCATED AT 250 WORDS)