Structure–affinity relationship in the interactions of human organic anion transporter 1 with caffeine, theophylline, theobromine and their metabolites

It is well known that human organic anion transporter 1 (hOAT1) transports many kinds of drugs, endogenous compounds, and toxins. However, little is known about the structure-affinity relationship. The aim of this study was to elucidate the structure-affinity relationship using a series of structurally related compounds that interact with hOAT1. Inhibitory effects of xanthine- and uric acid-related compounds on the transport of p-aminohippuric acid were examined using CHO-K1 cells stably expressing hOAT1. The order of potency for the inhibitory effects of xanthine-related compounds on PAH uptake was 1-methyl derivative>7-methyl derivative>3-methyl derivative falling dotsxanthine>1,3,7-trimethyl derivative (caffeine). The order of potency of the inhibition was 1,3,7-trimethyluric acid>1,3-dimethyluric acid>1,7-dimethyluric acid>1-methyluric acid>uric acid. A significant correlation between inhibitory potency and lipophilicity of the tested uric acid-related compounds was observed. The main determinant of the affinity of xanthine-related compounds is the position of the methyl group. On the other hand, lipophilicity is the main determinant of the affinity of uric acid-related compounds.

Genotyping of the N-acetyltransferase2 polymorphism in the prediction of adverse drug reactions to isoniazid in Japanese patients

To investigate the association between NAT2 genotypes and the incidence of isoniazid (INH)-induced adverse reactions, in the hope of identifying a pharmacogenetic approach that could be useful in the prediction and prevention of adverse reactions in Japanese patients, we retrospectively studied the genotypes of NAT2 in 102 Japanese patients treated with INH (without rifampicin co-administration). The subjects were classified into three groups according to their genotypes: rapid-type, intermediate-type, and slow-type. The clinical conditions of the patients were followed-up in order to evaluate the development of any adverse drug reactions (ADRs) and correlate them with patient genotypes. Six out of the 102 patients (5.9%) developed various ADRs following INH treatment. These reactions included nausea/vomiting, fever, visual impairment, and peripheral neuritis. We found a statistically significant difference between the incidence of ADRs and NAT2 genotype. The incidence of ADRs was significantly higher in the slow type than in the other two types, as 5 out of the 6 ADR patients were of the slow-type, and the other one was of the intermediate-type, while no patients of the rapid-type developed any ADRs. The results indicated that the genes coding for slow acetylation were associated with the incidence of serious ADRs following INH treatment. Our findings suggest that determination of NAT2 genotype might be clinically useful in the evaluation of patients at high risk of developing ADRs induced by INH.

Absorption of ester prodrugs in Caco-2 and rat intestine models

The aim of this study was to elucidate the absorption mechanism in Caco-2 and rat intestine models in order to improve the accuracy of prediction of oral absorption of ester prodrugs. Pivampicillin and cefcapene pivoxil hydrochloride (CFPN-PI), ester-type oral antibiotics, were chosen as model ester prodrugs. The level of esterase activity in Caco-2 cells was lower than that measured in the rat jejunum when p-nitrophenyl acetate was used as a substrate. Almost complete ester hydrolysis occurred before the ester prodrugs reached the basolateral side of the monolayer, and the disappearance of prodrugs was thought to be due to metabolism or transport after addition to the apical side of the monolayer. When pivampicillin and CFPN-PI were used, the amounts of ampicillin and cefcapene (CFPN) produced by hydrolysis of prodrugs were increased because intracellular degradation of prodrugs resulted in intracellular accumulation. On the other hand, when ampicillin or CFPN was used, only a small amount of the drug reached the basolateral side of the monolayers and no intracellular accumulation was observed. The permeability of CFPN-PI, the solubility of which is dependent on the acidity of gastric juice, across a Caco-2 monolayer or rat intestine, was also investigated by using an in vitro system that mimics the physiological state of the human gastrointestinal tract. The oral absorption of CFPN-PI in humans is predicted to be good either in the Caco-2 model or in the rat intestine model. It is concluded that our system may be a valuable tool for evaluation of oral absorption of ester prodrugs metabolized during permeation through the intestinal epithelium. Broader evaluation of such a system is warranted.

The variability of liver graft function and urinary 6beta-hydroxycortisol to cortisol ratio during liver regeneration in liver transplant recipients

The urinary ratio of 6beta-hydroxycortisol to cortisol (6beta-OHF/F) is considered to be the simplest and most practical method for estimation of hepatic cytochrome P450 3A4 (CYP3A4) activity as a non-invasive marker of human in vivo CYP3A4 activity. However, the inter- and intra-individual variability of the urinary 6beta-OHF/F ratio during liver regeneration and the effect of variability on optimal dose of tacrolimus have not yet been clarified. The objective of this study was to clarify the change in the urinary 6beta-OHF/F ratio during liver regeneration and to determine the effect of the liver graft function on the optimal tacrolimus dose in liver transplant recipients. Two liver transplant recipients (one male and one female) and eight healthy volunteers (five males and three females) were enrolled in this study. Urine samples were collected from the recipients from 08.00 hours for 24 h on post-transplant period, 1-10 and 21-30 days postoperatively. In the healthy volunteers, morning spot urine samples were collected at 08.00 hours. The mean urinary 6beta-OHF/F ratio in the immediate postoperative period was significantly low (p < 0.05). However, a marked difference in the regulation of CYP3A4 activity during liver regeneration was found in the two recipients. A significant correlation was found between the urinary 6beta-OHF/F ratio and the C/D ratio of tacrolimus (R = 0.658, p < 0.05). The urinary 6beta-OHF/F ratio is a useful probe for estimating the variability of CYP3A4 activity in liver transplant recipients in early postoperative phase. Future studies should evaluate the clinical usefulness of the urinary 6beta-OHF/F ratio as a predictor of tacrolimus pharmacokinetics in liver transplantation.

A new system for the prediction of drug absorption using a pH‐controlled Caco‐2 model: Evaluation of pH‐dependent soluble drug absorption and pH‐related changes in absorption

One purpose of this study was to develop a new system for the prediction of pH-dependent soluble drug absorption that takes into account the physiological condition of the gastrointestinal tract. Another purpose was to establish several models of different gastric acidities: a normal gastric acidity model, a low gastric acidity model (a model of achlorhydria), a temporarily elevated gastric acidity model (a model of a case in which an acidic drug was coadministered to temporarily elevate gastric acidity in the case of low gastric acidity), a weak antacid model (a model of a case in which a weak antacid drug, such as an H(2) receptor antagonist, was coadministered to temporarily elevate pH up to 6), and a strong antacid model (a model of a case in which a strong antacid drug, such as magnesium hydroxide, was coadministered to temporarily elevate pH up to 8.0). These models were used to evaluate variation in pH-related absorption in humans. Dipyridamole preparation (Persantin tablets) and glibenclamide preparation (Euglucon tablets), both poorly water-soluble and pH-dependent soluble drugs, were chosen as model drugs to determine whether absorption is altered by changes in levels of gastric acid. The extent of absorption of dipyridamole was remarkably lower when gastric pH was continuously elevated to 6.0, whereas it was increased when gastric pH temporarily decreased to 1.8. The extent of absorption of glibenclamide increased dramatically when gastric pH temporarily increased to 8.0, but did not change when gastric pH temporarily increased to 6.0. These results are consistent with reported results obtained in clinical studies. The results suggest that pH-related variations in absorption in humans can be accurately predicted using our new system.

Influence of continuous venovenous haemodiafiltration on the pharmacokinetics of tacrolimus in liver transplant recipients with small-for-size grafts

In adult-to-adult living donor liver transplantation (LDLT), the graft volume is inevitably much smaller than the ideal liver mass (standard liver volume) for the recipient's metabolic demand. Patients with small-for-size grafts are treated with continuous venovenous haemodiafiltration (CVVHD) for the artificial liver support. However, little is known about the influence of CVVHD on the elimination of tacrolimus. The objective of this study was to elucidate the effect of CVVHD on the pharmacokinetics of tacrolimus in recipients of LDLT with small-for-size grafts. Three liver transplant recipients (one male and two females) and donors (two males and one female) were enrolled in this study. Blood samples from inflow port and outflow port were obtained on the first day at the start of CVVHD. Whole-blood concentrations of tacrolimus were measured immediately using the microparticle enzyme immunoassay (MEIA; Abbott Laboratories). There was no significant difference between concentrations of tacrolimus in blood sampled at inflow port and outflow port sites and t(1/2)-values of tacrolimus in the three recipients were 29.9, 63.6 and 28.8 h. CVVHD did not cause a decrease in the blood tacrolimus concentration. Adjustment to the dose or dosing interval is not required for patients treated with tacrolimus during CVVHD.

An in vitro system for prediction of oral absorption of relatively water-soluble drugs and ester prodrugs

We developed an in vitro system simulating the physiological condition in the gastrointestinal (GI) tract for prediction of oral absorption of relatively water-soluble drugs and ester prodrug pivampicillin. This evaluation system includes a drug-dissolving vessel (DDV, assumed stomach), a pH adjustment vessel (PAV, assumed intestine) and a side-by-side diffusion chamber that is mounted by a Caco-2 monolayer, which is grown on a polycarbonate filter, or by a rat intestine between the donor and receiver compartments. Our proposed system can accommodate large amounts of solid drugs, simulating a drastic pH change process in GI tract, that is, an orally administered solid drug is dissolved in the stomach (pH 1-2) and transferred to the intestine (pH 6), and that dissolution process can also be monitored. The optimal flow rates for our system are 0.35-1.10 ml/min. Using this system, cumulative permeations of eight relatively water-soluble drugs were compared, and these cumulative permeations indicated the ability of drug absorption in humans. Drugs that permeated across a Caco-2 monolayer at cumulative permeation of more than 0.03% or over 0.04% in rat intestine can be almost completely absorbed in humans. If the cumulative permeation across a Caco-2 monolayer is lower than 0.03% or below 0.04% in the rat intestine, there was a good linear correlation between cumulative permeation across a Caco-2 monolayer and oral absorption in humans, or between cumulative permeation across a rat intestine and oral absorption in humans. In the case of relatively water-soluble drugs, a good linear correlation was obtained between cumulative permeation across a Caco-2 monolayer and cumulative permeation across a rat intestine. This result indicates that it is possible to predict the oral absorption of a relatively water-soluble drug in humans based on the cumulative permeation of the drug across a Caco-2 monolayer and/or a rat intestine. The time course of permeation of the ester prodrug pivampicillin, which is metabolized in a Caco-2 monolayer or in a rat intestine, was also evaluated. It stated clearly that it is also possible to predict the oral absorption of pivampicillin in humans based on the cumulative permeation across a Caco-2 monolayer or rat intestine. Our newly developed system enables more kinds of oral preparations and also pH-dependent soluble drugs to be evaluated.

Inhibitory Effects of Basic Drugs on the Sodium-Dependent Transport of L-Alanine via System B0 in the Small Intestine

To elucidate the mechanism of the interaction of basic drugs with Na(+)-dependent L-alanine absorption from the small intestine, we investigated the effect of imipramine on the transport of L-alanine via system B(0), which is thought to be one of the main Na(+)-dependent systems for intestinal absorption of short-chain neutral amino acids, including L-alanine. The uptake of L-alanine by cells that express hATB(0) (human amino acid transporter B(0)) was inhibited in the presence of imipramine. The Eadie-Hofstee plot showed that the inhibition was not competitive with the substrate (L-alanine) but competitive with Na(+). When rat intestinal brush border membrane vesicles were used, several basic drugs had inhibitory effects. Inhibition was also observed in intestinal absorption evaluated by an in situ single-pass perfusion technique. However, the potencies of inhibition were different. The potency of inhibition was dependent on the lipophilicity of the drugs.

Age- and gender-related differences in carbohydrate concentrations of alpha1-acid glycoprotein variants and the effects of glycoforms on their drug-binding capacities

OBJECTIVE

Alpha(1)-acid glycoprotein (AAG) is a major binding protein for neutral and basic drugs because of its great drug affinity. AAG has three main genetic variants--F1, S, and A variants. Several attempts have been made to elucidate the differences in compositions of the carbohydrate moiety and structure-function relationships such as drug-binding differences. However, there have been few reports on age- and gender-related differences in compositions or concentrations of the carbohydrate moiety of AAG variants. The aim of this study was to clarify the age- and gender-related differences in carbohydrate concentrations and in drug-binding capacities of AAG glycoforms.

METHODS

The sera used in this study were obtained from 32 healthy subjects (17 men and 15 women, aged 16-84 years). The AAG glycoforms were isolated by hydroxyapatite chromatography. The binding capacity of AAG to disopyramide (DP), which is a basic drug, was determined using the ultrafiltration method. The concentrations of N-acetylneuraminic acid (NeuAc) and monosaccharides in AAG were determined using high-pH anion-exchange chromatography with pulsed-amperometric detection.

RESULTS

The mean plasma AAG concentration in the female subjects was significantly lower than that in the male subjects (0.67 +/- 0.12 mg/ml, mean +/- SD, in females, n = 15, versus 0.81 +/- 0.17 mg/ml in males, n = 17, P < 0.05), but no age-related differences were found (0.75 +/- 0.18 mg/ml in young subjects, n = 24, versus 0.77 +/- 0.12 mg/ml in older subjects, n = 8, n.s.). However, the degree of branching of the glycan chain in the female subjects was significantly lower than that in the male subjects (1.61 +/- 0.17 mol/mol, mean +/- SD, in females, n = 15, versus 1.75 +/- 0.23 mol/mol in males, n = 17, P < 0.05). There was a significant inverse relationship between the binding capacity of AAG to DP (Cb/AAG) and the degree of branching of the glycan chain. The binding capacity (Cb/AAG) decreased as the degree of branching in AAG glycans increased. The binding capacity (Cb/AAG) in the female subjects was significantly higher than that in the male subjects (2.79 +/- 0.59 mg/g AAG in females, mean +/- SD, n = 15, versus 2.37 +/- 0.29 mg/g AAG in males, n = 17, P < 0.05). CONCLUSION. The degree of branching of the glycan chain in AAG plays an important role in drug-binding capacity. Gender-related differences in drug-binding capacity (Cb/AAG) may be caused by differences in the ratios of the extent of branching of the glycan chain in AAG.

Liquid chromatographic method for the determination of ganciclovir and/or acyclovir in human plasma using pulsed amperometric detection

We have developed a simple, rapid and highly sensitive method for determining plasma concentrations of ganciclovir and/or acyclovir by using reversed-phase chromatography followed by pulsed amperometric detection. A linear relationship between the amount of ganciclovir (0.05-10 microg/ml plasma) or acyclovir (0.1-20 microg/ml plasma) and peak height ratio was obtained. The relative standard deviations of all standard curves were greater than or equal to 0.999. The limits of detection for ganciclovir and acyclovir quantitation were 10 ng/ml and 50 ng/ml (signal/noise >3), respectively. Daily fluctuations of plasma standard curves (n=5) for the ganciclovir and acyclovir samples were small, with relative standard deviations (RSD) of 3.3 and 4.5% (n=5), respectively. The intra-assay precision for the ganciclovir and acyclovir samples were 6.9 (n=5) and 5.5% (n=5), respectively. Inter-assay precision of ganciclovir (n=3) and acyclovir (n=3) ranged from 2.6 to 6.8% and 3.5 to 5.0%, respectively. Using this method, the pharmacokinetics and removal of ganciclovir during continuous hemodiafiltration (CHDF) in a liver transplant recipient being treated for severe cytomegalovirus infection was investigated. The mean (+/-SD) ratio of ganciclovir concentrations at the inlet and outlet of the dialyzer (C(outlet)/C(inlet)) was 0.56+/-0.09. The areas under the curves of ganciclovir up to 12 h postdosing (AUC(0-->12)) at the inlet and outlet of the dialyzer were 12.54 microg h/ml and 7.16 microg h/ml, respectively. The ultrafiltrate of ganciclovir was 16.6 mg. The terminal elimination half-life (T(1/2)) of ganciclovir during CHDF was 3.6 h. These results demonstrate that CHDF effectively removes ganciclovir. Until formal guidelines have been established, ganciclovir or acyclovir dosage should be adjusted according to the results of monitoring of plasma drug concentration. The method described here is suitable for clinical monitoring of plasma ganciclovir or acyclovir levels in solid organ transplant recipients and for use in studies involving pharmacokinetics.

Allele and genotype frequencies of CYP2B6 and CYP3A5 in the Japanese population

OBJECTIVE

The goal of this study was to determine the frequencies of allelic variants of CYP2B6and CYP3A5 in the Japanese population.

METHODS

Genotyping of CYP2B6 (*2, *3, *4, *5, *6, and *7) and CYP3A5 ( *2, *3, *4, *5, and *6) was carried out in 265 unrelated Japanese subjects by polymerase chain reaction (PCR), restriction fragment length polymorphism and allele-specific, real-time PCR assays.

RESULTS

Allele frequencies for CYP2B6*2, *3, *4, *5, *6, and *7 in 256 Japanese subjects were 0.047, 0, 0.093, 0.011, 0.164, and 0, respectively. Ethnic variation in allele frequencies relative to that in Caucasian subjects was observed for CYP2B6*4 (0.093 vs 0.040), *5 (0.011 vs 0.109), *6 (0.164 vs 0.256), and *7 (0 vs 0.030). Allele frequencies for CYP3A5*2, *3, *4, *5, and *6 in 265 Japanese subjects were 0, 0.740, 0, 0.004, and 0, respectively. The frequency of the CYP3A5*1 allele is 2.8 times higher in Japanese than in Caucasians.

CONCLUSIONS

Our results contribute to a better understanding of the molecular basis of ethnic differences in drug response, which may help to improve individualization of drug therapy and offer a preliminary basis for more rational use of drugs that are substrates for CYP2B6 and CYP3A5 in the Japanese population.

Effective fluconazole therapy for liver transplant recipients during continuous hemodiafiltration

Fungal infections are still one of the main causes of death and complications after solid organ and bone marrow transplants. The authors evaluated the effect of continuous hemodiafiltration (CHDF) on the pharmacokinetics of fluconazole in liver transplant recipients. Six liver transplant patients (primary biliary cirrhosis, n = 2; fulminant hepatitis, n = 2; viral hepatitis, n = 2) were enrolled in this study. In one patient not receiving CHDF, the fluconazole levels increased with increasing dosages. In contrast, in patients undergoing CHDF, the dosage of fluconazole was increased from 100 mg/d to 200 mg/d, but fluconazole did not reach the targeted levels. It appears that the targeted trough level cannot be achieved by administration of fluconazole at a dosage of 100 to 200 mg/d during CHDF. A higher dosage (600-1000 mg/d) of fluconazole may be required to achieve the therapeutic drug level in patients undergoing CHDF. In patients undergoing CHDF, fluconazole was given at a dosage of 800 mg/d and reached the targeted levels. In addition, after CHDF, the dosage of fluconazole was decreased to 100 mg/d, and fluconazole reached the near-targeted trough level. These results demonstrate that CHDF removes fluconazole from the blood at an efficiently high rate, resulting in its ineffective blood level. To guarantee safe and effective fluconazole therapy, the trough levels should be monitored routinely during CHDF.

Hepatitis C virus infection in patients with B-cell non-Hodgkin's lymphoma

OBJECTIVE

As a causative role of hepatitis C virus (HCV) in B-cell lymphoproliferative disorders (LPD) has been suggested by several reports, we investigated the prevalence of HCV infection among patients with LPD at our hospital with the aim of clarifying the clinical features and the outcome for HCV antibody-positive patients with non-Hodgkin's lymphoma (NHL).

METHODS

Retrospective chart review.

PATIENTS

A total of 123 patients with B-cell LPD (4 with chronic lymphocytic leukemia, 17 with multiple myeloma, and 100 with B-cell NHL), 38 patients with non-B-cell LPD (5 with adult T-cell lymphoma, 8 with Hodgkin's disease, and 25 with non-B-cell NHL) and 516 patients with miscellaneous diseases other than liver diseases or LPD (control) were studied.

RESULTS

HCV infection was detected in 17 of 100 patients with B-cell NHL versus none of 25 patients with non-B-cell NHL (p=0.023) and in 34 patients (6.6%) in the control group with miscellaneous diseases (p=0.0011). In HCV-positive B-cell NHL, primary liver involvement was detected in 3 of 17 patients compared to none of 83 HCV-negative patients (p=0.0019). Intermediate-grade lymphoma (Working Formulation) was the most frequent histology. Eleven of 15 HCV-positive patients achieved complete remission after chemotherapy, and 6 of 7 deaths were caused by liver-related diseases.

CONCLUSION

The prevalence of HCV infection was higher in patients with B-cell NHL than in those with non-B-cell NHL and the control group. Primary liver involvement and liver-related causes of death were frequent in HCV-positive patients with B-cell NHL.

Experimental studies of thermal therapy for severe nonvariceal bleeding in dogs

BACKGROUND

There are several methods of achieving endoscopic hemostasis for nonvariceal hemorrhage, including use of a heater probe, bipolar electrocoagulation, use of a Gold probe, and injection therapy with epinephrine or ethyl alcohol. However, due to clinical variations, clinical studies comparing thermal with injection therapy have yielded conflicting results. Therefore, we used a canine model of acute bleeding from gastric serosal vessels to examine the efficacy of the heater probe and the Gold probe in achieving hemostasis and to compare the injurious effects of these methods with injection therapy.

METHODS

Seven mongrel dogs were used in the study. Four were assigned to acute experiments in which transected blood vessels were allowed to bleed profusely. Two dogs of this group were treated with either a large or small Gold probe, while the other two were treated with either a large or small heater probe. In the other three dogs, we tested the chronic effects of the heater probe, the Gold probe, and injection therapy with dilute epinephrine.

RESULTS

Complete hemostasis was achieved for all four dogs in the acute experiments. Dogs treated with either a large or small heater probe had coagulation necrosis that extended to the serosa and muscularis but not to the mucosa. The large Gold probe had similar results, but the small Gold probe caused tissue damage to the serosa, muscularis, submucosa, and mucosa at several of the application sites. Both probes caused scarring of the gastric wall. In the chronic experiments, we found that the Gold probe caused larger mucosal ulcers than the heater probe. All ulcers healed in 3 weeks. The epinephrine injection caused localized swelling and discoloration, but after 1 week the tissue returned to normal.

CONCLUSIONS

Both the heater probe and the Gold probe are effective in achieving hemostasis in a canine model of nonvariceal hemorrhage, and both methods are superior to injection therapy. For active bleeding ulcers, we currently recommend a combination therapy, using first injection therapy and then a heater or Gold probe. However, clinicians should be aware of the potential for tissue damage.

Perioperative hepatic functional risk assessed with technetium-99m diethylenetriamine pentaacetic acid-galactosyl human serum albumin liver scintigraphy in patients undergoing pancreaticoduodenectomy complicated by obstructive jaundice

CONCLUSION

Liver scintigraphy with technetium-99m diethylenetriamine pentaacetic acid-galactosyl human serum albumin (Tc-GSA) can be used to predict outcome of biliary drainage and hepatic function after pancreaticoduodenectomy in patients with pancreatic, biliary, and ampullary carcinomas complicated by obstructive jaundice.

BACKGROUND

Preoperative obstructive jaundice has been reported as a crucial risk factor for serious postoperative complications in patients undergoing pancreaticoduodenectomy. The aim of the present study was to investigate whether Tc-GSA liver scintigraphy can assess hepatic functional risk in patients with pancreatic, biliary, and ampullary carcinomas complicated by obstructive jaundice.

METHODS

Liver scintigraphy was performed before biliary drainage in 18 patients with obstructive jaundice. The maximum removal rate of Tc-GSA (GSA-Rmax; standard normal value > or = 0.60) was calculated. These patients underwent pancreaticoduodenectomy with wide lymphadenectomy. The efficacy of preoperative biliary drainage was assessed with the decrease in serum bilirubin concentration in the first week after biliary drainage. Postoperative liver function was assessed with the increase in serum bilirubin concentration, which was the difference between the immediate preoperative and maximal postoperative bilirubin concentrations.

RESULTS

Serum bilirubin decreased more in the first week after biliary drainage in patients with GSA-Rmax > or = 0.60 (7.64 +/- 1.09 mg/Dl/wk) than in patients with GSA-Rmax < 0.60 (3.56 +/- 1.25 mg/DL/wk, p = 0.042). Postoperative bilirubin increased less in patients with GSA-Rmax > or = 0.60 (0.81 +/- 0.30 mg/dL) than in patients with GSA-Rmax < 0.60 (4.00 +/- 0.69 mg/DL, p = 0.0012). Multivariate analysis showed that GSA-Rmax significantly predicted the postoperative bilirubin increase (p = 0.020).

A general approach for the prediction of the intestinal absorption of drugs: regression analysis using the physicochemical properties and drug-membrane electrostatic interaction

A general method for predicting the intestinal absorption of a wide range of drugs using multiple regression analysis of their physicochemical properties and the drug-membrane electrostatic interaction was developed. The absorption rates of tested drugs from rat jejunum were measured by the in situ single-pass perfusion technique. The drugs used in this study were divided into three groups for regression analysis, and a smaller "test" set of compounds was used to assess the predictive capacity of the regression equation. When the analysis was applied to each respective group of drugs (i.e., anionic, cationic, and nonionized compounds), obtained regression coefficients were 0.569, 0.821, 0.728 by using the organic solvent (n-octanol)/buffer partition coefficient, 0.730, 0.734, 0.914 using the permeation rate across a silicon membrane, and 0.790, 0.915, 0.941 using an EVA membrane, respectively. However, smaller regression coefficients of 0.377, 0. 468, and 0.718 were obtained when these three groups of drugs were put together for prediction. Meanwhile, correlation was improved remarkably when drug-membrane electrostatic interactions, namely, hydrogen-bonding donor (Halpha) and acceptor (Hbeta) activity or index of electricity (Ec), were added to the other parameters of lipophilicity and permeation rate across the EVA membrane (r = 0.880 and 0.883, respectively). Moreover, the equation obtained from these regression analyses was applicable even to the prediction of the absorption of the zwitterionic drugs. These results suggest that including the electrostatic interaction parameters in addition to lipophilicity and permeability across artificial membranes would afford a better prediction for the intestinal absorption of the vast majority of drugs.

Endoscopic management of Dieulafoy lesions of the stomach: a case study of 26 patients

BACKGROUND AND STUDY AIMS

We studied the clinical features and therapeutic outcome in patients with a diagnosis of Dieulafoy lesion.

PATIENTS AND METHODS

Twenty-six patients who had upper gastrointestinal bleeding from Dieulafoy lesions received endoscopic therapy. The clinical and endoscopic features, and the outcome of therapy, were analysed retrospectively.

RESULTS

Hemostasis was attempted by hemoclipping in 18 patients, heater probe in six patients and ethanol injection in two patients. The initial therapy was successful in 22 (84.6%) cases. Hemostasis was achieved with additional endoscopic therapy in three cases (11,5%). Surgical treatment was needed only in one case, owing to uncontrolled bleeding. One patient died during the hospital stay from a cause unrelated to the Dieulafoy lesion. There were no side effects related to endoscopic therapy. None of these patients presented with rebleeding from Dieulafoy lesions over a mean long-term follow-up of 36 months.

CONCLUSIONS

Bleeding from Dieulafoy lesions can be managed successfully by endoscopic methods, and these should be regarded as the first choice in their management. We emphasize the role of hemoclipping, a mechanical method, for the endoscopic treatment of these lesions.

Bleeding esophageal ulcers caused by NSAIDs

This report describes four patients with NSAID-induced esophageal ulcers documented by endoscopy. The cause of injury was ibuprofen alone in two patients, aspirin in one patient, and a combination of aspirin and ibuprofen in one patient. The most common findings were anemia, retrosternal pain, and dysphagia. Three patients had bleeding esophageal ulcers requiring blood transfusions. One patient had massive bleeding which was controlled by endoscopic hemostasis. Three patients were followed up by endoscopy, which showed healing in 3-4 weeks. These NSAID-induced ulcers had characteristic endoscopic features, namely, a large, shallow, discrete ulcer in the midesophagus near the aortic arch with normal surrounding mucosa. These findings suggest that the injury resulted from mucosal contact with NSAIDs. A precise history and immediate endoscopic examination were most important in establishing the diagnosis of esophageal ulcer. Healing occurs if drug-induced injury is recognized early and treatment is appropriately started with antacids and H2 blockade. Offending medication should be discontinued and patients should be counseled to take pills in an upright posture with liberal amounts of fluids well before retiring for the night.

[Fluoroscopic contrast medium percutaneous ethanol injection therapy (FCM-PEIT): newly developed clinical useful method for injecting ethanol into nodules of hepatocellular carcinoma]

We have performed fluoroscopic contrast medium percutaneous ethanol injection therapy (FCM-PEIT) total 266 times to 82 hepatocellular carcinoma (HCC) nodules in 44 HCC cases: FCM-PEIT is the newly developed method that HCC nodules are punctured by a needle and injected with ethanol mixed with water-soluble contrast medium (Iopamidol containing 370 mg/ml iodine) (vol/vol: 7/3) under the fluoroscopic observation as well as ultrasonic diagnostic equipment (US). Autopsy analyses have demonstrated nearly complete tumor necrosis by FCM-PEIT. We analyzed the detectable rate (%) of the contrast medium-mixed ethanol (CME) leakage out of HCC nodules by US-alone, fluoroscope-alone, and US-fluoroscope observation. The detectable rate of the leakage was 63% by US-fluoroscope, while was only 32% by US-alone. Particularly, all leakages into intra hepatic bile duct were missed by US-alone. The maximal CME-amount for injection without any leakage was not uniform and not related to the size of HCC nodules. The present results suggest that FCM-PEIT is clinically more useful method for the treatment of HCC compared to general PEIT that HCC nodules are injected with ethanol under the US-alone observation, since it is easy to confirm whether ethanol can be sufficiently injected into HCC nodules without any leakage.