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At least 19 recordsLinked to original sources
PubMedDate not supplied

The influence of gastrointestinal agents on resorption and metabolism of cyclosporine after heart transplantation: experimental and clinical results.

The clinical effectiveness of cyclosporine is limited by changes in resorption and metabolism of cyclosporine and by possible drug interactions. This study examined the influence of five gastrointestinal agents on duration and resorption of cyclosporine and dosage/level relations: cimetidine, famotidine, pirenzepine, aluminum hydroxide, and omeprazole. These gastrointestinal agents were studied in 64 rat experiments, in which the impact of each single drug and of drug combinations on cyclosporine resorption and metabolism was tested. A standardized dosage of cyclosporine was given orally, and the duration was calculated for the maximum whole blood level of cyclosporine to be achieved; the dosage/level quotient was calculated. Cimetidine, famotidine, pirenzepine, and combination treatment prolonged duration of cyclosporine resorption. Furthermore, cimetidine, famotidine, and omeprazole lowered the dosage/level quotient, thus leading to higher cyclosporine levels with the same dosage; pirenzepine increased the dosage/level quotient. For clinical comparison, 163 heart transplant patients who had received standard triple-drug immunosuppressive therapy were analyzed. The time interval until a therapeutic cyclosporine level was achieved and the dosage/level quotient were once again calculated. Similar to the results in the animal experiments, cimetidine and famotidine significantly delayed the resorption of cyclosporine; cimetidine, famotidine, and omeprazole lowered the cyclosporine dosage/level quotient, thus leading to higher cyclosporine levels with the same dosage. Aluminum hydroxide did not lead to any changes in the resorption or metabolism of cyclosporine. Most examined gastrointestinal agents, and particularly H2-blocking drugs, led to significant prolongation of cyclosporine resorption and cyclosporine level alterations. The initial prolongation of cyclosporine resorption was successfully avoided by intravenous administration of cyclosporine for the first 4 postoperative days in 40 consecutive patients.

Absorption↗
PubMed1976

[Synthesis of gastrointestinal agents].

The importance of syntheses of biologically active polypeptides especially of gastrointestinal hormones for medical research, is analyzed; six points, as the main goals of a synthetic approach, are discussed with respect to their special significance and are confirmed by six examples.

Chemistry, Organic↗
PubMedDate not supplied

Study on interaction of gastrointestinal agents in the presence of cytoprotective drugs. Part III. In vitro study on the adsorption of selected prokinetic drugs on sucralfate.

Adsorbance of certain prokinetic drugs, regulating the motility of the digestive tract, on a cytoprotective drug--sucralfate was investigated. The evaluation of adsorbance capability was carried out by means of a statistical method in in vitro conditions, taking into account environmental pH, concentration of the investigated drugs as well as the form of sucralfate. Obtained results prove that the analyzed active agents are adsorbed on sucralfate at all the investigated pH ranges and the capability of sucralfate binding depends on its form and environmental pH. The highest binding capability was revealed by samples with pH = 3.6 in the presence of sucralfate in the form of suspension, while the lowest binding capability was observed at pH = 1.5 in the presence of sucralfate in the form of paste. The adsorbance capacity of sucralfate (k) at pH = 3.6 is the highest for cisaprid (k = 8.5) and it is significantly lower for metoclopramide (k = 1.5)

Adsorption↗
PubMedDate not supplied

Study of interaction of gastrointestinal agents in the presence of cytoprotective drugs. Part II. In vitro study on the adsorption of selected spasmolytic drugs on sucralfate.

The subject of the research was the adsorption of selected musculotropic and cholinolytic spasmolytics on a cytoprotective drug--sucralfate. Adsorption evaluation was made by a static method, in vitro, the environment reaction, the concentrations of the tested drugs and the sucralfate form being taken into account. The obtained results prove that the analysed therapeutic substances are adsorbed on the sucralfate in all pH. The highest bonding capacity was observed in tests at pH=3.6, in the presence of sucralfate, which at this pH occurs in the form of suspension. The lowest capacity was at pH=1.5 in the presence of sucralfate in the paste form. In the group of the tested drugs, scopolamine butylbromide is adsorbed best, drotaverine hydrochloride little less and papaverine hydrochloride least of all.

Adsorption↗
PubMed1997

Medication-prescribing errors in a teaching hospital. A 9-year experience.

BACKGROUND: Improved understanding of medication prescribing errors should be useful in the design of error prevention strategies. OBJECTIVE: To report analysis of a 9-year experience with a systematic program of detecting, recording, and evaluating medication-prescribing errors in a teaching hospital. METHODS: All medication-prescribing errors with potential for adverse patient outcome detected and averted by staff pharmacists from January 1, 1987, through December 31, 1995, were systematically recorded and analyzed. Errors were evaluated by type of error, medication class involved, prescribing service, potential severity, time of day, and month. Data were analyzed to determine changes in medication-prescribing error frequency and characteristics occurring during the 9-year study period. RESULTS: A total of 11,186 confirmed medication-prescribing errors with potential for adverse patient consequences were detected and averted during the study period. The annual number of errors detected increased from 522 in the index year 1987 to 2115 in 1995. The rate of errors occurring per order written, per admission, and per patient-day, all increased significantly during the study duration (P < .001). Increased error rates were correlated with the number of admissions (P < .001). Antimicrobials, cardiovascular agents, gastrointestinal agents, and narcotics were the most common medication classes involved in errors. The most common type of errors were dosing errors, prescribing medications to which the patient was allergic, and prescribing inappropriate dosage forms. CONCLUSIONS: The results of this study suggest there may exist a progressively increasing risk of adverse drug events for hospitalized patients. The increased rate of errors is possibly associated with increases in the intensity of medical care and use of drug therapy. Limited changes in the characteristics of prescribing errors occurred, as similar type errors were found to be repeated with increasing frequency. New errors were encountered as new drug therapies were introduced. Health care practitioners and health care systems must incorporate adequate error reduction, prevention, and detection mechanisms into the routine provision of care.

Drug Prescriptions↗
PubMed1999

Effect of prucalopride, a new enterokinetic agent, on gastrointestinal transit and anorectal function in healthy volunteers.

BACKGROUND: Prucalopride (PR) is a novel 5-HT4 agonist enterokinetic compound. AIM: To evaluate its effect on bowel function, gut transit and anorectal function in healthy volunteers using a double-blind, placebo-controlled crossover study. METHODS: Twenty-four healthy volunteers (12 men, 12 women, mean age 25 years, range 20-53 years) were randomly assigned to 1 mg/placebo or 2 mg/placebo (PL). The trial consisted of five consecutive 1 week periods: no drug treatment, PR treatment or PL, washout, PL or PR, no treatment. Subjects maintained a diary of bowel function during the entire study period. Total intestinal transit time (TITT), mean colonic transit time (MCTT) and anorectal function (anal manometry, rectal sensitivity and rectal compliance) were assessed at the end of both treatment periods. Electrocardiography and blood sampling were performed for safety analysis; blood sampling was also used to check compliance. RESULTS: No subjects withdrew from the study. Treatment with PR 2 mg showed a statistically significant increase in mean number of weekly stools (11.5 vs. 7.1 compared to PL, P = 0.04) and in the percentage of loose/watery stools (48 vs. 12% compared to PL, P = 0.005). Within 1 week, stool frequency and consistency returned to baseline values when treatment was stopped. MCTT was shortened significantly with both doses, i.e. from 35 h on PL to 25 h on PR 1 mg (P = 0.01) and from 43 h on PL to 22 h on PR 2 mg (P = 0.02). Anorectal function was unaffected by PR. Transient and moderate headache occurred in nine subjects during PR treatment and in six subjects during PL treatment. CONCLUSION: Prucalopride is well tolerated by healthy subjects and has a marked and consistent effect on stool frequency and consistency, and on colonic transit. In the present study prucalopride did not affect visceral sensitivity or sphincter function. It holds promise for patients with slow transit constipation.

Adult↗
PubMed1997

In vivo animal tests of an artifact-free contrast agent for gastrointestinal MRI.

A variety of shortcomings are associated with most currently used gastrointestinal contrast agents for magnetic resonance imaging (MRI). Artifacts resulting from peristalsis and other motions in the abdominal region are produced by many positive contrast agents (which increase signal intensity). Although this is not a problem for negative contrast agents (which decrease signal intensity), some negative contrast agents produce magnetic susceptibility artifacts that are especially pronounced at high field strength and with gradient echo pulse sequences. These susceptibility artifacts are produced by both paramagnetic and diamagnetic agents. It has been demonstrated in phantoms, however, that susceptibility matching can be used to produce contrast agents with desirable relaxation and contrast properties but without deleterious susceptibility artifacts. We now report results of animal tests of such an oral contrast agent, consisting of a suspension of superparamagnetic iron oxide particles and diamagnetic barium sulfate particles, compared to individual suspensions of the iron oxide and of the barium sulfate. Iron oxide was the least effective and the matched susceptibility mixture was the most effective for the intestine, which has traditionally been the most difficult region of the GI tract to visualize clearly. Matched susceptibility mixtures, which are inherently able to yield images free of susceptibility artifacts without compromising contrast, show promise of being improved oral negative contrast agents for use in gastrointestinal MRI.

Administration, Oral↗
PubMed1997

Blockage of the HERG human cardiac K+ channel by the gastrointestinal prokinetic agent cisapride.

Cisapride, a gastrointestinal prokinetic agent, is known to cause long Q-T syndrome and ventricular arrhythmias. The cellular mechanism is not known. The human ether-á-go-go-related gene (HERG), which encodes the rapidly activating delayed rectifier K+ current and is important in cardiac repolarization, may serve as a target for the action of cisapride. We tested the hypothesis that cisapride blocks HERG. The whole cell patch-clamp recording technique was used to study HERG channels stably expressed heterologously in HEK293 cells. Under voltage-clamp conditions, cisapride block of HERG is dose dependent with a half-maximal inhibitory concentration of 6.5 nM at 22 degrees C (n = 25 cells). Currents rapidly recovered with drug washout. The onset of block by cisapride required channel activation indicative of open or inactivated state blockage. Block of HERG with cisapride after channel activation was voltage dependent. At -20 mV, 10 nM cisapride reduced HERG tail-current amplitude by 5%, whereas, at + 20 mV, the tail-current amplitude was reduced by 45% (n = 4 cells). At -20 and + 20 mV, 100 nM cisapride reduced tail-current amplitude by 66 and 90%, respectively. We conclude that cisapride is a potent blocker of HERG channels expressed in HEK293 cells. This effect may account for the clinical occurrence of Q-T prolongation and ventricular arrhythmias observed with cisapride.

Cation Transport Proteins↗
PubMedDate not supplied

Gadopentetate dimeglumine as an oral negative gastrointestinal contrast agent for MRCP.

BACKGROUND: We investigated the feasibility of using intravenous magnetic resonance (MR) contrast agent as a gastrointestinal oral negative contrast agent to null the bowel signal during MR cholangiopancreatography (MRCP). METHODS: In the first part of the study, a phantom study was performed to select the optimal concentration of MR contrast agent to be used as an oral negative contrast agent in MRCP. In the second part of the study, 23 consecutive patients suffering from different pancreaticobiliary diseases were imaged with a single-shot fast spin-echo pulse sequence. The data acquisition was started without oral contrast agent and then repeated with oral contrast agent. From the MR images taken with and without oral contrast agent, the gallbladder, cystic duct, common bile duct, and pancreatic duct were assessed and graded by two radiologists. RESULTS: The oral contrast agent was tolerated well by all patients. In all patients the high signal intensity from the intestinal fluid was completely suppressed. The depictions of the gallbladder and cystic duct were slightly and moderately improved, respectively, whereas the depictions of the common bile duct and pancreatic duct were markedly improved by the oral contrast agent administration. CONCLUSION: Diluted intravenous MR contrast agent can be an effective and safe oral negative contrast agent in eliminating signal intensity of the gastrointestinal tract, thus improving the depiction of the biliary system in MRCP.

Biliary Tract Diseases↗
PubMed1987

Bioavailability of three oral dosage forms of cisapride, a gastrointestinal stimulant agent.

Relative bioavailability of the investigational gastrointestinal stimulant agent cisapride after oral administration was determined in healthy men. Treatments administered were (A) two 5-mg tablets; (B) one 10-mg tablet; (C) 10 mL of a 1-mg/mL suspension; and (D) 10 mL of a 1-mg/mL aqueous reference solution. The study had a randomized four-way, crossover design; drug administration was followed by a standard breakfast. Plasma cisapride concentrations in blood samples drawn over 48 hours were measured by high-performance liquid chromatography. Individual and mean values for bioavailability parameters were subjected to analysis of variance followed by multiple comparison testing. Time to maximum concentration was shortest after administration of the solution. There was a significant difference in mean peak plasma concentrations between treatment A (48.8 +/- 12.8 ng/mL) and treatment D (41.6 +/- 10.6 ng/mL), with treatment A producing a 17.3% higher peak concentration. No significant differences between treatments were found for area under the plasma concentration-time curve. The overall mean elimination half-life was 7.01 hours. The results of the study indicate that the tablet and suspension dosage forms of cisapride are bioequivalent to the reference solution.

Administration, Oral↗
PubMed2001

Erythromycin as a gastrointestinal prokinetic agent.

Erythromycin is a potent stimulator of gastrointestinal (GI) motility and can be a useful agent to treat GI stasis in patients who are critically ill. However, it is not licensed for this indication and has serious drug interactions which may limit its utility. Erythromycin derivatives which lack antibiotic activity have been developed but are still undergoing pre-marketing investigations.

Anti-Bacterial Agents↗
PubMed1995

Effect of cellulose concentration on the efficacy of a cellulose-based oral contrast agent for gastrointestinal ultrasonography.

We investigated the value of an ingested gastrointestinal ultrasonographic transmission (GUT) agent in improving the visualization of visceral and retroperitoneal anatomy during the standard abdominal sonographic examination. In particular, we examined the effect of varying the cellulose dispersion concentration on the ability of this agent to facilitate visualization of bowel mucosa and adjacent organs and compared degassed cellulose dispersions to degassed water in the same subjects. Fasting abdominal ultrasonography was performed on 24 healthy human volunteers before and after ingestion of a degassed cellulose-based liquid transmission agent. Each agent was assessed using 22 microns fiber length cellulose dispersions at 1, 2 and 3% wt/vol. Ingestion of all concentrations of the gastrointestinal sonographic transmission agent resulted in clear differentiation of the bowel from adjacent structures. Statistically significant improvement in visualization of the pancreas, retroperitoneal vessels, left kidney, and spleen was noted at 20 minutes postingestion. No statistically significant difference was identified between the three cellulose concentrations. No toxicity or limiting side effects were encountered. Such agents may obviate additional imaging in patients who previously would have had a suboptimal ultrasonographic examination.

Administration, Oral↗
PubMed1993

Erythromycin: a motilin agonist and gastrointestinal prokinetic agent.

Erythromycin, a commonly used antibiotic, has recently emerged as a potential gastrointestinal prokinetic agent. This follows a decade of research into the mechanism of well-recognized gastrointestinal side effects of erythromycin. Early investigations demonstrated that erythromycin increased gastrointestinal motility, and more recent studies suggest that it fortuitously binds to and stimulates the receptor for the gastrointestinal peptide motilin. From this work it appears that a new and powerful class of gastrointestinal prokinetic agents will evolve from erythromycin and its derivatives. The role of motilin in the genesis of the fasting and fed patterns of gastrointestinal motility is emerging through the study of these motilin agonists.

Animals↗
PubMed1996

Microbial conversion of EM574 and EM523, gastrointestinal motor stimulating agents.

EM574 exerts gastrointestinal motor stimulating (GMS) activity even after being converted to its metabolites P1 and P2 in dogs. These metabolites were isolated from dog liver using a series of chromatographic procedures. Their structures were determined to be the 15- and 14-hydroxyl derivatives of EM574, respectively, by spectral analysis. Large scale preparation by microbial transformation was investigated for further evaluation of the metabolites, because the amounts obtained by oxidation with dog liver homogenate were limited. Three strains of actinomycetes, Amycolatopsis tolypophorus IFO 13151, Dactylosporangium variesporum IFO 14104 and Nocardia capreola IFO 12847, were found to have the aiming oxidative potency. HPLC analysis of the crude extracts from these three cultures showed that the bioactive metabolites, EM574 P1 and P2 were produced. They were isolated from the culture broth with the other bioactive products EM574 P3 and P4. These bioactive products were prepared by large scale cultivation. EM574 P3 and P4 showed GMS activity comparable to that of EM574 P1 and P2. The structures of EM574 P3 and P4 were elucidated by spectral analysis and found to be the 3"-O-demethyl derivatives of EM574 P2 and EM574, respectively. Moreover, the absolute configuration at the C14 position of P2 was determined to be R by spectral analysis of the 6-membered cyclic carbonate of EM574 P2.

Actinomycetales↗
PubMed2003

Selective effects of serotonergic psychoactive agents on gastrointestinal functions in health.

This study evaluated the effects of serotonergic psychoactive agents on gastrointestinal functions in healthy human subjects. Participants received one of four regimens in a randomized, double-blind manner: buspirone, a 5-HT(1A) receptor agonist (10 mg twice daily); paroxetine, a selective serotonin reuptake inhibitor (20 mg daily); venlafaxine-XR, a selective serotonin and norepinephrine reuptake inhibitor (75 mg daily); or placebo for 11 days. Physiological testing performed on days 8-11 included scintigraphic assessment of gastrointestinal and colonic transit, the nutrient drink test, and assessment of the postprandial change in gastric volume. Fifty-one healthy adults (40 females, 11 males) participated in this study. No effects on gastric emptying or colonic transit were identified with any agent. Small bowel transit of a solid meal was accelerated by paroxetine. Buspirone decreased postprandial aggregate symptom and nausea scores. Venlafaxine-XR increased the postprandial change in gastric volume. Buspirone, paroxetine, and venlafaxine-XR affect upper gastrointestinal functions in healthy humans. These data support the need for clinical and physiological studies of these agents in functional gastrointestinal disorders.

Adult↗