A new index, the core erosion ratio, of compression-coated timed-release tablets predicts the bioavailability of acetaminophen.

Although compression-coated tablets are a commonly used timed-release drug delivery technology, their utility is often limited by poor bioavailability. To try to improve the bioavailability of these tablets, the effect of their core composition of compression-coated tablet on in vivo pharmacokinetics was investigated. First, the extent of mass reduction of cores in different compression-coated tablet core formulations was used to establish a new index, the core erosion ratio. The data show that adding excipients with high water solubility to the core results in a greater core erosion ratio. Next, to elucidate the effect of core erosion ratio on in vivo acetaminophen (AAP) release, three compression-coated tablet formulations with similar in vitro AAP release profiles but different core erosion ratios were administered to four fasted dogs. The time for first appearance (TFA) of AAP in plasma did not differ significantly among formulations, indicating that the in vivo lag time was the same for all formulations. In separate experiments, necroscopy revealed that 3h after oral administration, the tablets were located in the ileum and colon and that all three formulations had identical GI transit times. However, the area under the AAP plasma concentration-time curve was greater in dogs given formulations with larger core erosion ratios. These results suggest that a formulation with a large core erosion ratio can significantly increase in vivo drug release from compression-coated tablets, leading to increased drug absorption from the lower GI tract.

Release of recombinant human bone morphogenetic protein 2 from a newly developed carrier.

After implantation of a polymer-coated gelatin sponge (PGS) containing either 0.4 or 1.0 mg of 125I-rhBMP-2 for each 1 cm(3) of PGS into the right ulnar of rabbits, changes in the level of radioactivity at the implant site and in the blood were measured for 21 days after implantation, and the cumulative excretion ratio of radioactivity in the urine and feces was calculated. For both doses, radioactivity at the implant site was eliminated biphasically. The concentration of trichloroacetic acid (TCA)-precipitable radioactivity in the blood reached a maximum 6 h after implantation, at which time it was equivalent to 1.41% of the administered dose (0.4 mg/cm(3)). The remaining radioactivity was eliminated rapidly thereafter, falling below the detection limit within 48 h. The t(1/2alpha) was about 0.1 days, the t(1/2beta) was about 3 days, and the mean resident time (MRT) value was about 4 days. By 17 days after implantation, 88.1% of the administered radioactivity had been excreted in the urine, and 1.7% had been excreted in the feces. TCA precipitation test results indicated that most of the radioactivity excreted in urine was a low-molecular weight decomposition product. At 21 days after implantation, the radioactivity of the PGS implant site had declined to 0.5% of the administered amount. Autoradiographs of the implant site taken 28 days after implantation revealed that, at both doses, the residual radioactivity was confined to the area of the implanted PGS. These results indicate that PGS retains an appropriate amount of recombinant human bone morphogenetic protein 2 (rhBMP-2) at the orthotopically implanted site for at least 21 days enough to induce bone regeneration. Thus, PGS shows great clinical potential as a carrier for rhBMP-2.

Effect of central urocortin on carbon tetrachloride-induced acute liver injury in rats.

The effect of intracisternal injection of urocortin, an endogenous ligand for corticotropin-releasing factor (CRF) 2 receptor, on carbon tetrachloride (CCl4)-induced acute liver injury was investigated in rats. Intracisternal injection of urocortin dose-dependently enhanced elevation of serum alanine aminotransferase and aspartate aminotransferase levels induced by CCl4. Intracisternal urocortin also aggravated CCl4-induced histological changes of the liver. The aggravating effect of central urocortin on CCl4-induced acute liver injury was abolished by chemical sympathectomy, but not by vagotomy. These data demonstrate that urocortin acts in the brain to exacerbate acute liver injury through the sympathetic nervous system and suggest a possible involvement of the CRF2 receptor in the central CRF-induced exacerbation of acute liver injury in rats.

A new recombinant human bone morphogenetic protein-2 carrier for bone regeneration.

A gelatin sponge was formed by foaming and heat treating a gelatin solution, followed by coating the solid with poly(D,L-lactic-co-glycolic acid) to reinforce the gelatin framework. This sponge was tested for its suitability as a biodegradable porous, recombinant human bone morphogenetic protein (rhBMP)-2 carrier. Incorporation of rhBMP-2 into the sponge was closely related to its bulk density of gelatin sponge. The calcium content in the sponges, as assessed by an ectopic bone formation assay in rats, increased with the increasing sponge bulk density. Histologic and peripheral quantitative computed tomography analysis of implants in this ectopic assay system revealed cell growth throughout the carrier in 4 weeks after implantation regardless gelatin bulk density. The carrier containing rhBMP-2 maintained its three-dimensional structure after implantation; the carrier resisted collapse caused by soft tissue pressure during rapid bone formation as assessed by soft X-ray photographs. These results indicate that this newly developed sponge has excellent carrier characteristics to introduce rhBMP-2 into areas needed for bone regeneration.

Stabilization of minodronic acid in aqueous solution for parenteral formulation.

The composition, concentration, and buffer pH of potential minodronic acid formulations were evaluated for their drug stability and for their tendency to generate particles after storage for up to 4 weeks at 60 degrees C. The results indicate that citrate and tartrate buffers maintain drug stability and inhibit the formation of particles. The stability of minodronic acid in these solutions increased slightly as the buffer concentration increased, exhibiting less particle formation than in other buffers. Since citrate buffer was considered the most promising stabilizer for minodronic acid, the pH-stability relationship in 100 mM citrate with pH ranging from 3 to 7 was evaluated during storage for 4 weeks at 60 degrees C. The results demonstrate that solution pH of 3-5 result in optimal stability of minodronic acid with no formation of precipitates. A white precipitate was observed in citrate-containing sample solutions with pH of 6 and 7. Analysis of the isolated precipitate provided support for the hypothesis that the precipitate is a complex between minodronic acid and aluminum ions apparently leached from the glass of the ampoules.

Rapid improvement of icterus and pruritus by the oral administration of colestimide in two cases of drug-induced hepatitis.

We report two cases of drug-induced hepatitis refractory to therapy of ursodeoxycholic acid and prednisolone, who were relieved of icterus and pruritus immediately by the oral administration of colestimide. Their liver dysfunction was not improved, by withdrawal of causative drugs or by treatment with prednisolone and ursodeoxycholic acid. Colestimide (3.0 g/day), a strong basic anion-exchange resin, was orally taken before breakfast and evening meal, leading to rapid and complete relief of icterus and pruritus. These cases suggested that colestimide would be useful for patients with cholestasis in drug-induced hepatitis, because this agent has few side effects and it is easy to take.

Role of calcitonin gene-related peptide and capsaicin-sensitive afferents in central thyrotropin-releasing hormone-induced hepatic hyperemia.

The involvement of capsaicin-sensitive afferent neurons and calcitonin gene-related peptide (CGRP) in the central thyrotropin-releasing hormone (TRH)-induced hepatic hyperemia was investigated in urethane anesthetized rats. Both systemic capsaicin pretreatment and intravenous administration of CGRP receptor antagonist, human CGRP-(8-37), completely abolished the stimulatory effect of hepatic blood flow induced by intracisternal injection of TRH analog (RX-77368; p-Glu-His-(3,3'-dimethyl)-Pro-NH2, 100 ng), assessed by the hydrogen gas clearance method. These data demonstrate the involvement of capsaicin-sensitive afferent neurons and CGRP in the central TRH-induced stimulation of hepatic blood flow.

Synthesis of phenoxyacetic acid derivatives as highly potent antagonists of gastrin/cholecystokinin-B receptors. III.

In order to improve the biological characteristics of DA-3934 (5), a novel gastrin/cholecystokinin (CCK)-B receptor antagonist, phenoxyacetic acid derivatives replacing the N-methyl-N-phenylcarbamoylmethyl moiety of 5 with various alkyl chains have been synthesized and their biological activity evaluated. The relationship between the structure of these compounds and their human gastrin receptor binding affinity showed that there should be the optimal size among the various N-alkyl chains. Also a significant increase in the receptor binding affinity was achieved by several compounds. Among those compounds, 2-[3-[3- [N-cyclohexylmethyl-N-[2-(N-methyl- N-phenylcarbamoylmethoxy)phenyl]carbamoylmethyl]ureido]pheny l]acetic acid (22c) and (+/-)-2-[3-[3-[N-[2-(N-methyl-N- phenylcarbamoylmethoxy)phenyl]-N-(3-methylpentyl)carbamoy lmethyl]ureido] phenyl]acetic acid (22h) exhibited high affinity for human gastrin receptors and were also more potent inhibitors in a pentagastrin-induced gastric acid secretion model than the parent compound, 5. The ED50 values of these compounds when administered intraduodenally to rats were 0.12 and 0.63 mg/kg, respectively.

Effect of ursodeoxycholic acid on autoimmune-associated chronic hepatitis C.

BACKGROUND: Hypergammaglobulinaemia and various auto-antibodies which are commonly seen in autoimmune hepatitis are also found in patients with chronic hepatitis C. We recently reported that ursodeoxycholic acid (UDCA) improved liver function tests and immunoserological markers in patients with type I autoimmune hepatitis. The aim of this study was to prospectively evaluate the efficacy of UDCA on autoimmune-associated chronic hepatitis C. METHODS: Immunoglobulin G (IgG), anti-nuclear antibodies (ANA) and anti-smooth muscle antibodies (ASMA) were determined in 95 patients with chronic hepatitis C. All patients were positive for hepatitis C virus RNA. Autoimmune-associated chronic hepatitis C (C-AIH) was defined by elevated serum IgG level (> or = 2.0 g/dL) and high titres of ANA and/or ASMA (> or = 1 : 160). Nine (9%) of 95 patients were diagnosed as C-AIH. All the C-AIH patients and 30 of the remaining 86 chronic hepatitis C patients without autoimmune features (CHC) were treated with UDCA (600 mg/day) for 1 year. RESULTS: Autoimmune-associated chronic hepatitis C patients included one man and eight women and their AIH scores, as defined by the International Autoimmune Hepatitis Group, were significantly higher than the CHC patients. Before UDCA therapy, there were no significant differences in aspartate aminotransferase (AST), alanine aminotransferase (ALT) and y-glutamyl transpeptidase (gamma-GTP) levels between C-AIH and CHC patients. However, after 1 year UDCA therapy, AST, ALT and gamma-GTP were significantly lower in C-AIH patients (P< 0.05) than in CHC patients. In C-AIH, ANA titres in seven of nine patients and ASMA titres in five of seven patients were reduced after 1 year UDCA treatment. CONCLUSIONS: These results suggest that UDCA is a useful therapeutic agent for autoimmune-associated chronic hepatitis C.

Effect of central corticotropin-releasing factor on carbon tetrachloride-induced acute liver injury in rats.

Central neuropeptides play important roles in many instances of physiological and pathophysiological regulation mediated through the autonomic nervous system. In regard to the hepatobiliary system, several neuropeptides act in the brain to regulate bile secretion, hepatic blood flow, and hepatic proliferation. Stressors and sympathetic nerve activation are reported to exacerbate experimental liver injury. Some stressors are known to stimulate corticotropin-releasing factor (CRF) synthesis in the central nervous system and induce activation of sympathetic nerves in animal models. The effect of intracisternal CRF on carbon tetrachloride (CCl4)-induced acute liver injury was examined in rats. Intracisternal injection of CRF dose dependently enhanced elevation of the serum alanine aminotransferase (ALT) level induced by CCl4. Elevations of serum aspartate aminotransferase, alkaline phosphatase, and total bilirubin levels by CCl4 were also enhanced by intracisternal CRF injection. Intracisternal injection of CRF also aggravated CCl4-induced hepatic histological changes. Intracisternal CRF injection alone did not modify the serum ALT level. Intravenous administration of CRF did not influence CCl4-induced acute liver injury. The aggravating effect of central CRF on CCl4-induced acute liver injury was abolished by denervation of hepatic plexus with phenol and by denervation of noradrenergic fibers with 6-hydroxydopamine treatment but not by hepatic branch vagotomy or atropine treatment. These results suggest that CRF acts in the brain to exacerbate acute liver injury through the sympathetic-noradrenergic pathways.

Neuropeptide Y stimulates bile secretion via Y1 receptor in the left dorsal vagal complex in rats.

Neuropeptide Y (NPY) injected into the cerebrospinal fluid and the left dorsal vagal complex enhances bile acid-independent and bicarbonate-dependent bile secretion through vagal muscarinic pathways in animal models. NPY binds to and activates six different receptor subtypes, and NPY Y1 and Y2 receptors are distributed in the dorsal vagal complex. We sought to determine which NPY receptor subtypes are involved in central stimulation of bile secretion by examining the effect of microinjection of specific NPY receptor agonists into the dorsal vagal complex. The bile duct was cannulated in urethane-anesthetized and bile acid-compensated rats. After measuring basal secretion, NPY, peptide YY (PYY), [Leu31, Pro34]NPY, NPY(13-36), or NPY(3-36) was microinjected into the either right or left dorsal vagal complex and bile secretion was observed for 100 minutes. Hepatic branch vagotomy was performed 2 hours before the peptide injection. Microinjection of NPY and PYY (8 pmol) into the left dorsal vagal complex increased bile secretion. [Leu31, Pro34]NPY microinjected into the left dorsal vagal complex also dose-dependently (1-8 pmol) stimulated bile acid-independent and bicarbonate-dependent bile secretion. Microinjection of NPY(13-36) into the left dorsal vagal complex did not stimulate and NPY(3-36) dose-dependently inhibited bile secretion. Stimulation of bile secretion by [Leu31, Pro34]NPY was abolished by hepatic branch vagotomy. NPY acts in the left dorsal vagal complex to stimulate bile acid-independent and bicarbonate-dependent bile secretion via Y1 receptor subtype.

Synthesis of phenoxyacetic acid derivatives as highly potent antagonists of gastrin/cholecystokinin-B receptors. II.

A series of phenoxyacetanilide derivatives was synthesized and their antagonist activities for human gastrin/cholecystokinin (CCK)-B and CCK-A receptors were evaluated. Among the compounds synthesized, 2-[3-[3-[N-[2-(N-methyl-N-phenylcarbamoylmethoxy)phenyl]-N-(N-meth yl-N- phenylcarbamoylmethyl)carbamoylmethyl]-ureido]phenyl]acetic acid (20i, DA-3934) exhibited high affinity for gastrin/CCK-B receptors and high selectivity over CCK-A receptors. DA-3934 and its methyl ester derivative inhibited pentagastrin-induced gastric acid secretion in rats in a dose-dependent manner.

Efficacy of ursodeoxycholic acid in Japanese patients with type 1 autoimmune hepatitis.

Ursodeoxycholic acid (UDCA) has been shown to have beneficial effects on patients with primary biliary cirrhosis, suggesting that UDCA has immunomodulating effects. We investigated the effect of UDCA in patients with autoimmune hepatitis (AIH) which is characterized by immunological abnormalities. Eight patients with type 1 AIH were treated with 600 mg of UDCA per day for 2 years. Based on the criteria of the International Autoimmune Hepatitis Group, five patients were diagnosed as definite and three as probable type 1 AIH. Liver function tests were performed every 4 weeks, before and during UDCA therapy and the serum levels of anti-nuclear antibodies (ANA), smooth muscle antibodies (SMA), immunoglobulin G and gamma globulin were determined every 3 months. The levels of serum aspartate aminotransferase and alanine aminotransferase significantly decreased from 154 +/- 24 IU/L and 170 +/- 17 IU/L before UDCA therapy to 31 +/- 3 IU/L and 25 +/- 5 IU/L (P < 0.001) after 1 year of treatment and 28 +/- 2 IU/L and 23 +/- 4 IU/L (P < 0.001) after 2 years of treatment. After 2 years of treatment, the levels of serum immunoglobulin G and gamma globulin significantly decreased (P < 0.05) and ANA titres (5/8 patients) were reduced and SMA (3/5 patients) became negative. Furthermore, hepatic histopathological changes of four patients were assessed after 1 year of treatment, and an improvement of intrahepatic inflammation, but not fibrosis, was observed. In conclusion, these results suggest that UDCA has a beneficial therapeutic effect in patients with type 1 autoimmune hepatitis.

Synthesis of phenoxyacetic acid derivatives as highly potent antagonists of gastrin/cholecystokinin-B receptors.

A novel series of phenoxyacetic acid derivatives was synthesized based on considerations of the three-dimensional structural similarity of YM022 and RP72540. The gastrin/cholecystokinin (CCK)-B and CCK-A receptor antagonist activities of these compounds were evaluated by investigation of their affinities for human gastrin/CCK-B receptors and human CCK-A receptors, respectively. It was found that N-methyl-N-phenyl-2-[2-[N-(N-methyl-N-phenyl-carbamoylmethyl)-N-[2 -[3-(3- methylphenyl)ureido]acetyl]amino]phenoxy]acetamide (20k, DZ-3514) exhibited high affinity for gastrin/CCK-B receptors and high selectivity over CCK-A receptors.

Central thyrotropin-releasing hormone stimulates hepatic DNA synthesis in rats.

Central neuropeptides play a role as physiological regulators in the autonomic nervous system. One of these neuropeptides, thyrotropin-releasing hormone (TRH), is distributed throughout the central nervous system (CNS) and acts as a neurotransmitter to regulate gastric functions through the vagus nerve. However, the autonomic nervous system is also involved in hepatic regeneration, but the effect of TRH is unknown. Therefore, the CNS's effect of TRH on hepatic DNA synthesis was studied in rats. Hepatic DNA synthesis was assessed by [Methyl-3H]thymidine incorporation 6, 12, 24, 48, and 72 hours after intracisternal injection of the TRH analog, RX 77368 (1, 5, 10, and 100 ng), and by 5-bromo-2'-deoxyuridine (BrdU) labeling of the liver section. Hepatic DNA synthesis was stimulated by intracisternal TRH analog (10 ng), with a peak response at 24 hours after peptide injection, and returned to baseline by 72 hours. This stimulatory effect by central TRH analog on hepatic DNA synthesis was dose-related, ranging from 1 ng to 10 ng (dpm/microg DNA at 24 hours [mean +/- SE]: saline, 95 +/- 6; 1 ng, 114 +/- 14; 5 ng, 318 +/- 57; 10 ng, 693 +/- 78; 100 ng, 710 +/- 135). Hepatocytes were randomly labeled by BrdU 24 hours after intracisternal TRH analog (10 ng). Intravenous TRH analog (10 ng) did not influence hepatic DNA synthesis. The stimulatory effect of TRH analog was blocked by hepatic branch vagotomy and atropine, but not by hepatic sympathectomy, 6-hydroxydopamine, insulin antibody, or hypophysectomy. These results indicate that TRH acts in the CNS to stimulate hepatic DNA synthesis through vagal and cholinergic mechanisms, and that TRH may be the chemical messenger involved in brain regulation of hepatic proliferation.

Neuropeptide Y in the dorsal vagal complex stimulates bicarbonate-dependent bile secretion in rats.

BACKGROUND & AIMS: Central administration of neuropeptide Y (NPY) enhances bile secretion through vagal pathways in animal models. NPY nerve fibers and receptors are localized in the dorsal vagal complex (DVC), and retrograde tracing techniques have shown that hepatic vagal nerves are projected mainly from the left DVC. However, nothing is known about the central sites of action for NPY to elicit bile secretion. The medullary sites of the action for NPY were investigated in this study. METHODS: The bile duct was cannulated in urethane-anesthetized and bile acid-compensated rats. After measuring basal secretion, NPY was microinjected into the DVC and bile response was observed for 100 minutes. Either left or right cervical vagotomy or hepatic branch vagotomy was performed 2 hours before the peptide. RESULTS: Microinjection of NPY (7-30 pmol) into the left DVC, but not the right DVC, dose-dependently increased bile acid-independent and bicarbonate-dependent bile secretion. Stimulation of bile secretion by NPY was eliminated by left cervical and hepatic branch vagotomy but not by right cervical vagotomy. CONCLUSIONS: NPY acts in the left DVC to stimulate bile acid-independent and bicarbonate-dependent bile secretion through the left cervical and hepatic vagus; these findings suggest that neuropeptides may act in the specific brain nuclei to regulate hepatic function.

Increase of sulfated ursodeoxycholic acid in the serum and urine of patients with chronic liver disease after ursodeoxycholic acid therapy.

The present study was undertaken in order to investigate the influence of ursodeoxycholic acid (UDCA) on the composition of sulfate-conjugated bile acids in the serum and urine of patients with chronic active hepatitis and compensated liver cirrhosis. After a 12 week UDCA treatment (600 mg/day), total serum bile acid concentration increased two-fold in patients with compensated liver cirrhosis and increased slightly in patients with chronic active hepatitis. The percentage of sulfated bile acids significantly increased in patients with both compensated liver cirrhosis and chronic active hepatitis. UDCA made up 63% of the total serum bile acids in compensated liver cirrhosis and 61% in chronic active hepatitis after UDCA treatment. Of the serum bile acids after UDCA treatment, 35.2 and 53.9% of UDCA was sulfate conjugated in compensated liver cirrhosis and chronic active hepatitis, respectively. Urinary excretion of total bile acid and UDCA after UDCA treatment in compensated liver cirrhosis were higher than in chronic active hepatitis. UDCA made up 68% of the total urinary bile acids in compensated liver cirrhosis and 64% in chronic active hepatitis after UDCA treatment. Of the urinary bile acids after UDCA treatment, 51.8 and 54.8% of UDCA was sulfate conjugated in compensated liver cirrhosis and chronic active hepatitis, respectively. UDCA treatment for compensated liver cirrhosis was less effective than for chronic active hepatitis. We found that sulfate conjugation is one of the major metabolic pathways for UDCA after UDCA treatment in chronic liver diseases.

Bioavailability of bropirimine 250 mg tablet in dogs: effect of food.

The postprandial effect on the bioavailability of bropirimine in dogs after oral administration of bropirimine tablets (Bropirimine 250 mg Tablet) was investigated. At a dose of 500 mg bropirimine (two tablets of bropirimine 250 mg), the maximum plasma concentration under the postprandial condition was about twice that observed under the fasting condition, and the area under the plasma concentration vs time curve under the postprandial condition was also twice that under the fasting condition. The absolute oral bioavailabilities of bropirimine were 41.1% under the fasting condition and 83.5% under the postprandial condition. It is considered that the longer gastric residence time and larger volume of the gastric fluid induced by food-intake caused the increase in dissolution of bropirimine which increased the bioavailability after oral dosing of bropirimine 250-mg tablets.