Bioavailability studies with ciglitazone in beagles II. Effect of propantheline bromide and metoclopramide HCL on bioavailability of a tablet

Bioavailability studies in fasted dogs with ciglitazone (CGZ), an oral hypoglycemic agent, suggested that an absorption window could contribute to the poor oral availability of CGZ. If so, propantheline bromide (PPB) could increase the residence time of CGZ at absorption sites and increase its bioavailability. Using this rationale, a Latin square study was conducted with CGZ in fasted dogs (n = 10) using treatments of a single 125mg tablet with and without 1.2 mg kg−1 i.m. PPB. PPB was given in a single dose 1 h prior to administration of CGZ. Plasma concentrations of CGZ were assayed by HPLC. PPB significantly increased the AUC of CGZ by a ratio of 1.2 : 1 (p < 0.01). PPB also increased Tmax from 2–8 h (p<0.001), and appeared to produce first order absorption of CGZ. In a separate CGZ study using fasted dogs (n = 10), a single 125mg tablet was administered with and without i.v. metoclopramide HCI (MCP). A 10mg dose of MCP was given 15 min prior to dosing with CGZ and repeated 1 h after dosing. MCP increases GI motility and was expected to decrease residence time of CGZ. MCP had no effect on Tmax, but significantly decreased AUC by 8 per cent (p = 0.05). MCP also reduced Cmax by 16 per cent (p = 0.06). Taken as a whole, these data suggest that the effect of meals to increase bioavailability of CGZ could be mediated at least in part, through an increase in GI residence time.