Pancreatic excretion of 5,5-dimethyl-2,4-oxazolidinedione in patients with chronic pancreatitis

Effect of dimethadione derived from repeated oral administration of trimethadione on pancreatic secretion in dogs

The effect of the weak organic acid of dimethadione (DMO) on secretin-stimulated pancreatic secretion was studied with repeated oral administration of trimethadione (TMO), the precursor of DMO, to dogs at a dose of 10 to 160mg/kg/day for a period of 14 days. The bicarbonate concentration in pancreatic juice at a steady state decreased significantly, reflecting a close correlation with the dose of TMO and DMO concentrations in plasma and pancreatic juice. The maximal decrement from the control of cases of no TMO administration was 18.8 mEq/l (12.1% of the control level). The chloride concentration in pancreatic juice showed a reciprocal relation to the bicarbonate concentration. The sum of both anion concentration was constant, irrespective of the dose of TMO. The average carbon dioxide tension of pancreatic juice in all doses of TMO was lower than that of the control, but differences were not statistically significant. The pH, flow rate, sodium and potassium concentrations in pancreatic juice at a steady state did not differ significantly in relation to the dose of TMO. These findings suggest that repeated oral administration of TMO cause a significant decrease in bicarbonate concentration in pancreatic juice, resulting probably from the buffer action of bicarbonate on protons provided from the undissociated form of DMO.

Macroautoradiographic and densitometric studies of [14C]dimethadione in rats: accumulation of the compound in the pancreas

Whole-body autoradiographic and densitometric distribution studies were performed on rats to investigate the accumulation of [14C]dimethadione (DMO) in the pancreas. [14C]DMO was intravenously administered at a dose of 167 microCi/0.5 mg/kg. Animals were sacrificed 1, 15, 30, 60 and 180 min after administration of the radioactive compound. The compound was found to rapidly distribute in all body tissues. The distribution pattern of the compound in the pancreas was spotty or linear due to the presence of the radioactive compound in blood of intrapancreatic vessels and in pancreatic ducts at higher levels than parenchyma. The radioactivity of pancreatic ducts became more evident with time, indicating the gradual accumulation of the compound in the ducts. These findings provide morphological evidence that DMO is accumulated in the pancreas and possibly eliminated from pancreatic juice. Densitometry revealed that the levels of radioactive compound in the pancreas were virtually as high as those in the liver and kidney.

Comparative pharmacokinetic study of trimethadione and dimethadione for lysis of pancreatic stones

In order to investigate the biological equivalence of dimethadione (DMO) and its precursor trimethadione (TMO), comparative pharmacokinetic studies were performed in 6 beagle dogs. DMO and TMO power was given orally at the same molar dose of 1.0 g and 1.11 g (7.7 mM), respectively. Plasma concentration of DMO and TMO was determined at an appropriate interval. Four pharmacokinetic parameters were calculated from the plasma concentration-time curves of DMO and TMO; the peak plasma concentration (Cmax), the time to the peak concentration of Cmax (Tmax), the area under the plasma concentration-time curve (AUC), and the biological half-life (t 1/2). In the plasma concentration-time curve of DMO, Tmax after oral administration of TMO was longer than that after administration of DMO. This resulted from the presence of the conversion process of TMO to DMO in the body, because of the very short Tmax observed in the plasma concentration-time curve of TMO. Cmax, AUC and t 1/2 did not differ significantly between the drugs. The results obtained indicate that TMO is biologically equivalent to DMO in regard to plasma concentration of DMO.

The excretion of dimethadione in pure pancreatic juice and bile in postoperative patients

The excretion of dimethadione (DMO) in pure pancreatic juice and bile was studied in postoperative patients undergoing external drainage of pancreatic juice and in those who had undergone percutaneous transhepatic cholangiodrainage. During and after oral administration of trimethadione, which is the precursor of DMO, pancreatic DMO concentration closely paralleled plasma DMO concentration. Pancreatic juice/plasma concentration ratio for DMO exceeded 1.0. In a patient with a large pancreatic cyst communicating with the main pancreatic duct, pancreatic DMO concentration after single rapid injection of secretin inversely correlated with the flow rate, while its output depended directly on the rate. Biliary DMO output after secretin injection was closely dependent on the flow rate, but was extremely low. The present results are essentially compatible with the findings previously observed in dogs.

Clinical evaluation of pancreatic excretion test with dimethadione and oral BT-PABA test in chronic pancreatitis

Further evaluation of the pancreatic excretion test with 5,5-dimethyl-2,4-oxazolidinedione (dimethadione, DMO) was made in comparison with the pancreozymin-secretin (PS) test on 100 normal subjects, 79 patients with chronic pancreatitis, and 83 patients with nonpancreatic disease. The diagnostic sensitivity of the oral N-benzoyl-L-tyrosyl-PABA (BT-PABA) test was estimated in 42 patients with chronic pancreatitis, on whom both PS and DMO excretion tests were performed as test of reference for exocrine pancreatic function. Pancreatic DMO excretion after secretin injection was significantly diminished in chronic pancreatitis. The DMO excretion test was more sensitive than the PS test to detect chronic pancreatitis and to distinguish between mild to moderate and advanced noncalcific chronic pancreatitis. The specificity of the DMO excretion test was more than adequate to find out pancreatic disease. The 6-hr urinary PABA excretion was significantly reduced in chronic pancreatitis. The BT-PABA test, however, showed the low sensitivity in mild to moderate chronic pancreatitis.