Development and validation of an LC-MS/MS-ESI method for the determination of lorglumide, a CCK-1 antagonist in mouse plasma: application to a pharmacokinetic study.

A highly sensitive, rapid assay method was developed and validated for the estimation of lorglumide in mouse plasma using liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in positive-ion mode. The assay procedure involves extraction of lorglumide and phenacetin (internal standard, IS) from mouse plasma with simple protein precipitation. Chromatographic separation was achieved using an isocratic mobile (0.2% formic acid solution-acetonitrile, 20:80, v/v) at a flow-rate of 0.5 mL/min on an Atlantis dC18 column maintained at 40 °C with a total run time of 4.0 min. The MS/MS ion transitions monitored were 459.2 → 158.4 for lorglumide and 180.1 → 110.1 for IS. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.42 ng/mL and the linearity range extended from 0.42 to 500 ng/mL. The intra- and inter-day precisions were in the ranges of 1.47-10.9 and 3.56-7.53, respectively.

Biochemical and pharmacological profiles of loxiglumide, a novel cholecystokinin-A receptor antagonist.

Loxiglumide ((+/-)-4-(3,4-dichlorobenzamido)-N-(3-methoxypropyl)-N- pentylglutaramic acid, CAS 107097-80-3, CR1505) is a new derivative of glutaramic acid. Radioligand displacement assay was performed to characterize the selectivity of loxiglumide to CCK-A (cholecystokinin-A) receptor (rat pancreas and bovine gallbladder) and CCK-B/gastrin receptors (guinea pig cerebral cortex and guinea pig gastric parietal cell). And tissue bioassay was performed to investigate the effect of the compound on contractions of the guinea pig gallbladder and ileum. Loxiglumide inhibited 125I-CCK-8 binding to rat pancreatic and bovine gallbladder membranes with IC50 values of 195 and 77.1 nmol/l, respectively. Loxiglumide also inhibited 125I-CCK-8 binding to guinea pig cerebral cortex membranes and parietal cells with IC50 values of 12363 and 15455 nmol/l, respectively. In addition, loxiglumide inhibited 125I-gastrin binding to guinea pig parietal cells with IC50 values of 6134 nmol/l. These results indicate that the affinity of loxiglumide to CCK-A receptor is at least 63 times greater than that to CCK-B/gastrin receptors. In vitro functional studies utilizing CCK-induced contractions of the isolated guinea pig gallbladder and ileum further demonstrate that loxiglumide acts as a competitive CCK antagonist with a high affinity to these tissues (gallbladder, pA2:6.71).

Inhibitory effect of intraduodenal infusion of loxiglumide on pancreatic exocrine secretion.

Inhibitory effect of loxiglumide (D,L-4-(3, 4-dichlorobenzoylamino)-5-(N-3-methoxypropyl-pentylamino)-5- oxo-pentanoic acid, CAS 107097-80-3) on exocrine pancreatic secretion was compared between intraduodenal and intravenous administration. Doubling doses of intravenous cholecystokinin octapeptide (CCK-8) resulted in a dose-dependent increase of pancreatic secretion from 50 to 400 ng/kg/h. Both intraduodenal and intravenous loxiglumide of 5 and 10 mg/kg/h produced a dose-dependent inhibition of the pancreatic protein secretion to all doses of CCK-8. Cumulative increment of pancreatic protein output was inhibited by 79% and 77% at 10 mg/kg/h of intraduodenal and intravenous loxiglumide, respectively. Extents of the inhibition were similar to each other between the two routes of loxiglumide infusion. However, plasma levels of loxiglumide after intraduodenal administration were about half of those observed after intravenous administration of the corresponding dose, although plasma CCK levels were not different. Intraduodenal loxiglumide is as effective as intravenous loxiglumide in inhibitory potency on pancreatic secretion. Therefore, possible therapeutic indications of oral loxiglumide could be expected.

Effects of a cholecystokinin receptor antagonist on intestinal phase of pancreatic and biliary responses in man.

The present study was designed (a) to characterize the activity of loxiglumide as a peripheral cholecystokinin (CCK) antagonist in healthy human subjects, and (b) to determine whether CCK is a physiologic regulator of the intestinal phase of meal-stimulated exocrine pancreatic and biliary secretions in man. Intravenous loxiglumide (22 mumol/kg per h) was highly potent in antagonizing CCK8-induced pancreatic enzyme and bile acid secretion as well as pancreatic polypeptide release. The potency and selectivity of loxiglumide as an antagonist of CCK provides the tool for evaluating the role of CCK as a physiological mediator of meal-induced pancreatic and biliary responses in humans. Infusion of a liquid test meal into the duodenum evoked an immediate response of pancreatic enzyme and bilirubin outputs, respectively. Intravenous loxiglumide significantly inhibited the meal-induced pancreatic amylase output by 63% (P less than 0.05), lipase output by 43% (P less than 0.05), and bilirubin output by 59% (P less than 0.05). These data suggest that CCK is a physiological mediator of the intestinal phase of meal-stimulated pancreatic and biliary responses.

Pharmacokinetics and tolerance of repeated oral doses of loxiglumide.

The study was conducted on 6 adult healthy subjects (5 males and 1 female) in order to investigate the pharmacokinetics and tolerance of repeated b.i.d. oral administration for 7 days of tablets containing 400 mg of loxiglumide (CR 1505). The pharmacokinetics of loxiglumide in plasma after the first single dose of 400 mg is characterized by a lag time of 16 +/- 4 min, a rapid invasion (kinv = 10 h-1), a Cmax of 11.9 +/- 5.1 mg/l at tmax of 2.3 +/- 0.8 h, a mean residence time (MRT) of 6.9 +/- 1.1 h and an AUC of 60.6 +/- 16.3 (mg/l) x h. After the last dose of 400 mg the lag time was 17 +/- 6 min, the Cmax 12.7 +/- 3.8 mg/l at tmax of 2.1 +/- 0.8 h, a MRT of 11.0 +/- 1.9 h and an AUC of 109.8 +/- 39.9 (mg/l) x h. The increases of the AUC and of MRT were statistically significant and are probably due to an accumulation of loxiglumide which occurs during the repeated dose course and reaches the steady state within 48 h of repeated administration. Due to this accumulation the Cmax increased by 7%. The increase was not statistically significant or clinically relevant. No dose adjustment seems required during a repeated dose dosing schedule with 400 mg b.i.d. In the urine loxiglumide and 3 metabolites were found, which were called Metabolite (Met.) 11.2, Met. 12.0 and Met. 12.8. Met. 12.0 was the most abundant, accounting for 45% of the loxiglumide related substances excreted in the urine.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of cholecystokinin antagonists on satiety induced by cholecystokinin octapeptide in dogs].

We administered two cholecystokinin antagonists to dogs intravenously (i.v.) and into the third cerebral ventricle (i.t.v.). Proglumide (3-300mg/kg/hr i.v. or 0.1-10mg/dog i.t.v.) reversed the satiety previously shown by mongrel dogs after i.t.v. CCK-8. A new glutaramic derivative, CR1409, blocked this satiety even more strongly when administered by either route. Proglumide increased proglumide levels in ventricular fluid, indicating its ability to cross the blood-brain barrier. However, i.t.v. proglumide did not appear in the blood during the observation period. These results suggest that systemic proglumide and CR1409 act as antagonists of the central CCK receptor concerning satiety in dogs; intravenously administered proglumide was found to cross the blood-brain barrier and partially but significantly reverse the satiety caused by CCK-8.

Proglumide potentiates morphine analgesia for acute postsurgical pain.

Proglumide, an antagonist of cholecystokinin, has been shown to potentiate morphine analgesia in animal and human experimental pain models. This study was undertaken to determine whether proglumide enhances morphine analgesia for patients experiencing postoperative pain. At onset of pain after the removal of impacted third molars, patients (n = 60) received intravenously either 4 mg morphine, 8 mg morphine, or 4 mg morphine plus proglumide (0.05, 0.5, or 5 mg). The administration of 8 mg morphine significantly reduced pain, in comparison with baseline and 4 mg morphine, for the first 30 minutes. The addition of 0.05 mg proglumide resulted in a significant increase in the magnitude and duration of the analgesic activity of 4 mg morphine; 0.5 and 5.0 mg proglumide did not produce this effect. No difference was seen in respiratory rate or in the frequency of side effects among the various forms of treatment. These data indicate that a low dose of proglumide potentiates both the magnitude and the duration of morphine analgesia in a clinical model of acute pain, without any detectable increase in side effects.

Pharmacokinetics of loxiglumide after single intravenous or oral doses in man.

Loxiglumide (D,L-4-(3,4-dichlorobenzoylamino)-5-(N-3-methoxypropyl-pentylam ino)-5-oxo-pentanoic acid, CR 1505) was given intravenously to 8 male healthy volunteers in a single dose of 2 mg/kg body weight (b.w.) or orally in a single dose of 5 mg/kg b.w. Loxiglumide was measured in plasma and in urine by HPLC during 48 h following the administration. After i.v. infusion the plasma levels were consistent with an open two-compartment pharmacokinetic model represented by the equation C (mg/l) = 43.791 x e-2.652 x h + 2.657 x e-0.139 x h. In the urine, besides loxiglumide, two metabolites were found and in the 48 h following the i.v. administration the urinary excretion of loxiglumide and of its metabolites accounted for 11.13% of the administered dose. After oral administration loxiglumide appeared in plasma with a lag time of 14 min, reached the peak 34 min after administration, being eliminated with an initial fast and a terminal slow elimination rate. The plasma levels were consistent with an open two-compartment pharmacokinetic model represented by the equation C (mg/l) = -46.72 x e-8.765 x (h-0.23) + 40.660 x e-1.383 x (h-0.23) + 6.057 x e-0.120 x (h-0.23). In the urine, besides loxiglumide, two metabolites were found and in the 48 h following the oral administration the excretion of loxiglumide and of its metabolites accounted for 7.67% of the administered dose. The absolute bioavailability of loxiglumide was calculated comparing the AUC(0-inf) found after oral and after i.v. administration and was estimated as 0.967, with p = 0.05 fiducial limit of 0.656-1.278.