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A tryptophan catabolite, kynurenic acid, is involved in schizophrenia and uremia; there is little information on the mechanism of its disposition. Recently, our laboratory showed that kynurenic acid is a good substrate of human organic anion transporters hOAT1 and hOAT3. In this study, we performed uptake experiment using Xenopus laevis oocytes to characterize the transport of kynurenic acid by rat homologs of the transporters, rOAT1, and rOAT3. These transporters stimulated the uptake of kynurenic acid into oocytes, and transport by rOAT3 was marked. The Km values of the transport were estimated to be 8.46 μM for rOAT1 and 4.81 μM for rOAT3, and these values are comparable to their human homologs. The transport activity of kynurenic acid by rOAT1 was about one quarter of that of p-aminohippurate, although they were at the similar levels in hOAT1. A comparative experiment with hOAT1 was added in this study, showing that uptake amounts of kynurenic acid by hOAT1-expressing oocytes were 4 times greater than rOAT1-expressing oocytes. rOAT3 transported kynurenic acid as efficiently as estrone sulfate; this phenomenon was also observed in hOAT3. In conclusion, transport of kynurenic acid by rOAT1 and rOAT3 was shown. The characteristics of rOAT3 were similar to hOAT3, but low transport activity of kynurenic acid by rOAT1 was exhibited compared with hOAT1.

Nonsteroidal anti-inflammatory drugs (NSAIDs) delay the renal excretion of antifolate methotrexate by inhibiting human organic anion transporters hOAT1 (SLC22A6) and hOAT3 (SLC22A8). In this study, uptake experiments were performed using Xenopus laevis oocytes to assess stereoselectivity in the inhibitory characteristics of flurbiprofen, ibuprofen and naproxen against hOAT1 and hOAT3. Uptake of p-aminohippurate by hOAT1 was inhibited by each enantiomer of the three NSAIDs, and the inhibitory effect was superior in each (S)-enantiomer around 10 µM. The apparent 50% inhibitory concentrations were estimated to be 0.615 µM for (S)-flurbiprofen, 2.84 µM for (S)-ibuprofen and 1.93 µM for (S)-naproxen, and these values were significantly lower than those of the respective (R)-enantiomers [(R)-flurbiprofen: 2.35 µM, (R)-ibuprofen: 6.14 µM, (R)-naproxen: 5.26 µM]. Furthermore, the (S)-NSAIDs at 3 µM reduced methotrexate accumulation in hOAT1-expressing oocytes more strongly than the corresponding (R)-enantiomers. All enantiomers inhibited hOAT3-mediated transport of estrone sulfate and methotrexate, but there was no difference between both enantiomers of each NSAID in the inhibitory potencies. Eadie-Hofstee plot analysis showed that (S)-flurbiprofen and (R)-flurbiprofen inhibited hOAT1 and hOAT3 in a competitive manner. These findings represent the stereoselective inhibitory potencies of flurbiprofen, ibuprofen and naproxen on hOAT1, and the (S)-enantiomers are greater. In contrast, stereoselectivity was not recognized in their inhibitory effect on hOAT3.

Several kinds of food have been shown to influence the absorption and metabolism of drugs, although there is little information about their effect on the renal excretion of drugs. In this study, we performed uptake experiments using Xenopus laevis oocytes to assess the inhibitory effects of chlorogenic acid, caffeic acid and quinic acid, which are contained in coffee, fruits and vegetables, on human organic anion transporters hOAT1 and hOAT3; these transporters mediate renal tubular uptake of anionic drugs from blood. Injection of hOAT1 and hOAT3 cRNA into oocytes stimulated uptake of typical substrates of hOAT1 and hOAT3 (p-aminohippurate and estrone sulfate, respectively); among the three compounds tested, caffeic acid most strongly inhibited these transporters. The apparent 50% inhibitory concentrations of caffeic acid were estimated to be 16.6 µM for hOAT1 and 5.4 µM for hOAT3. Eadie-Hofstee plot analysis showed that caffeic acid inhibited both transporters in a competitive manner. In addition to the transport of p-aminohippurate and estrone sulfate, that of antifolates and antivirals was inhibited by caffeic acid. These findings show that caffeic acid has inhibitory potential against hOAT1 and hOAT3, suggesting that renal excretion of their substrates could be affected in patients consuming a diet including caffeic acid.

The transport of antifolate aminopterin by human organic anion transporters hOAT1 (SLC22A6) and hOAT3 (SLC22A8) was characterized using Xenopus laevis oocytes and was compared with that of methotrexate. Although hOAT1 and hOAT3 transported both aminopterin and methotrexate, uptake of methotrexate was greater in hOAT3-expressing oocytes than in hOAT1-expressing oocytes, and aminopterin was transported by hOAT1 more efficiently. The apparent 50% inhibitory concentration (IC(50)) of aminopterin for p-aminohippurate uptake by hOAT1 was lower than that of methotrexate (methotrexate: 998 microM, aminopterin: 160 microM). On the other hand, IC(50) values of these antifolates for estrone sulfate transport by hOAT3 were comparable (methotrexate: 61.5 microM, aminopterin: 59.2 microM). The Michaelis-Menten constant and maximum velocity of aminopterin transport by hOAT1 were calculated to be 226 microM and 72.5 pmol/ oocyte/2 hr, respectively. Probenecid and non-steroidal anti-inflammatory drugs strongly inhibited the transport. These findings show that both aminopterin and methotrexate are substrates of hOAT1 and hOAT3, and that there are differences between the antifolates in terms of their transport characteristics.

Nonsteroidal anti-inflammatory drugs (NSAIDs) delay renal excretion of antifolate methotrexate by inhibiting human organic anion transporters hOAT1 (SLC22A6) and hOAT3 (SLC22A8). In this study, we performed uptake experiments using Xenopus laevis oocytes to assess the inhibitory effect of selective cyclooxygenase-2 inhibitors on hOAT1 and hOAT3. The uptake of methotrexate into oocytes was increased by the injection of hOAT1 and hOAT3 cRNA, and transport was strongly inhibited by lumiracoxib. The apparent 50% inhibitory concentrations of lumiracoxib were estimated to be 3.3 µM and 1.9 µM for uptake of p-aminohippurate by hOAT1 and of estrone sulfate by hOAT3, respectively. Eadie-Hofstee plot analysis showed that lumiracoxib inhibited hOAT1 and hOAT3 in a competitive manner. For other cyclooxygenase-2 inhibitors celecoxib, etoricoxib, rofecoxib and valdecoxib, slight to moderate inhibition of hOAT3 only was observed. These findings show that lumiracoxib has inhibitory potential toward hOAT1 and hOAT3, comparable to that of nonselective NSAIDs.

A traditional Chinese herbal medicine, Kampo medicine, maoto, has been widely used in the treatment of febrile symptoms caused by viral infection. This herbal extract granule for oral use, however, is not well accepted by infants or young children due to its unpleasant taste and odor. Therefore, we prepared Kampo medicine, maoto, suppository and investigated the pharmaceutical and clinical efficacy of the suppository. Kampo medicine, maoto, granules were micro-pulverized and homogeneously dispersed into Hosco-H15 to prepare suppositories containing 0.25 to 1.0 g herbal extract by the conventional fusion method. Content of l-ephedrine, an index compound of Kampo medicine, maoto, in the extract granules and suppositories was determined by using a high performance liquid chromatographic method. Physicochemical experiments revealed that the suppository containing 0.5 g herbal extract had the most suitable melting point of 34 degrees C. Contents of l-ephedrine in the suppository were constant, 93-96% of those in the same amount of the extract granules in different three lots. Upper and lower portions of the suppository had the same content of l-ephedrine. The suppository maintained more than 95% of l-ephedrine content through 6 months at 4 degrees C, room temperature and 40 degrees C, although maldistribution of the extract constituent was observed after storage at 40 degrees C. The suppository was administered to 21 pediatric febrile patients at a dose of 1/3 to 2 full pieces depending on their body weight and physical status. Significant reduction (p

As a basic approach to identifying the distribution mechanism of quinolone antibiotics into saliva, salivary excretion of five fluoroquinolones, ciprofloxacin (CPFX), norfloxacin (NFLX), lomefloxacin (LFLX), ofloxacin (OFLX) and sparfloxacin (SPFX), was compared in rats. Blood, parotid and mandibular saliva were periodically collected from the anesthetized rats after bolus i.v. administration (10 mg/kg) of the quinolones. Quantification of the fluoroquinolones was performed by HPLC methods. The saliva-to-plasma unbound concentration (S/Pu) ratios of the fluoroquinolones in parotid saliva were larger than those of mandibular saliva. These five quinolones had considerably different S/Pu ratios from 0.014 to 1.497, while the S/Pu ratios theoretically calculated by the pH-partition theory were around 1.0 to 1.3, which showed no relationship to the corresponding measured ratios. Satisfactory linear correlations were observed in the plots of measured S/Pu ratios against 1-octanol-water partition coefficients of the fluoroquinolones in both types of saliva. These results indicate that fluoroquinolones possess different diffusibility in salivary distribution among the drugs and between parotid and mandibular glands. It was also clarified that the lipophilicity of the fluoroquinolones primarily determines the extent of salivary excretion.

This study was carried out to investigate the effects of Sho-saiko-to (Xiao Chai Hu Tang), a Chinese traditional medicine, on the gastric function including the gastric emptying rate (GER) and intragastric pH in rats. Additionally, the effects of the GER and intragastric pH on tolbutamide absorption after oral administration were examined. The GER measured at 40 min after dosing was reduced to about 70% by the pretreatment of Sho-saiko-to (500 mg/kg). The plasma tolbutamide concentration in the rats treated with a 250 mg/kg dose of Sho-saiko-to was significantly lower than that in the control group. Plasma tolbutamide concentrations increased along with the GER in the group co-administered Sho-saiko-to, and there were significant correlations between the GERs and plasma levels in both time points at 20 and 40 min after administration. In the study using pylorus-ligated rats, Sho-saiko-to significantly elevated the intragastric pH, but induced no change in the concentrations of tolbutamide dissolved in the gastric content. Additionally, Sho-saiko-to did not change the area under the plasma concentration-time curve (AUC) of tolbutamide up to 60 min after administration into the stomach loop, and gastric absorption has been considered to minimally contribute to whole absorption of tolbutamide in the gastrointestinal tract. These results indicate that Sho-saiko-to has an inhibitory effect on the function of gastric emptying in rats. The reduced gastric emptying could affect gastrointestinal absorption, resulting in the lower plasma concentration of tolbutamide after oral administration. Furthermore, it is suggested that Sho-saiko-to can raise the intragastric pH but affect neither the intragastric dissolution nor the gastric absorption of tolbutamide.

To supply drug information using documents is very important to ensure patient safety and the proper use of prescribed drugs. Such documents should include easily understandable information for patients. In the development process of drug information leaflets at our hospital, we incorporated reviews of the documents made by normal individuals and not medical professionals. It was found that more than 100 of descriptions in the documents were given in language that was too technical to be understood by normal individuals. Approximately half of these descriptions were related to “drug effects”. We reviewed the information for 500 of 997 drugs using supplementary interpretations and more conventional expressions to make the drug information leaflets more intelligible.Acceptability of the leaflets by patients was evaluated based on a questionnaire survey to which 300 outpatients responded. As a result, most of the patients reported that the “drug effects” and “initial symptoms of adverse reactions” in the documents were easy to understand by 89% and 81 % of the patients, respectively.From these results, our drug information service using more intelligible leaflets was found to effectively promote a better understanding of prescribed drugs, thus leading to their safe and proper use.

Dissolution rate is considered an important factor affecting absorption and efficacy after the oral administration of tolbutamide. Since in many cases traditional Chinese medicines, including Sho-saiko-to (TJ-9, Xiao Chaihu Tang), are taken with other drugs, it is likely that the dissolution and absorption of concomitant drugs in the gastrointestinal tract are influenced by the presence of traditional Chinese medicines. In this study, the effects of TJ-9 on the in vitro dissolution of tolbutamide were examined. We carried out the dissolution test of tolbutamide in the absence or presence of traditional Chinese medicines (Kakkon-to, TJ-1; Hachimi-jio-gan, TJ-7; Chorei-to, TJ-40; Shakuyaku-kanzo-to, TJ-68; TJ-9; Glycyrrhizae Radix, GR; glycyrrhizin, GL) by using a pH 1.2 dissolution medium. Tolbutamide was determined by HPLC assay. The moment parameters, ie., mean dissolution time (MDT), and the dissolution rate constant up to 20 min (kd) were estimated from the dissolution profiles on the basis of the first-order kinetics. Preparations containing GR, namely TJ-1, TJ-9 and TJ-68, significantly reduced the kd and increased the MDT of tolbutamide, while TJ-7 and TJ-40 had no effect on the early dissolution profile of tolbutamide. The extent of decrease in the kd in the presence of TJ-1, TJ-9 and TJ-68 was dependent on their GR contents. Similar inhibitory effects on the dissolution rate of tolbutamide were observed when GR alone was added to the test medium. In addition, GL, a major constituent of GR, induced a 50% increase in MDT and a 30% decrease in kd. The above results indicate that Chinese traditional preparations containing GR have an inhibitory effect on the in vitro dissolution of tolbutamide, which is derived from GL in the preparations.

The effects of Sho-saiko-to on the pharmacokinetics of tolbutamide were investigated in rats. After intravenous administration of tolbutamide (5 mg/kg), no significant change in the pharma-cokinetics of tolbutamide was observed in both groups of single and multiple (7 days) pre-administration of Sho-saiko-to (50 mg/kg). In the study of single oral administration of tolbutamide (50 mg/kg), co-administration of Sho-saiko-to tended to accelerate the initial absorption rate of tolbutamide. The area under the plasma concentration-time curve of tolbutamide after oral administration was significantly reduced by Sho-saiko-to. Subsequently, a significant decrease was observed in the oral bioavailability of this drug when Sho-saiko-to was given concomitantly. These findings suggest that Sho-saiko-to reduces the bioavailability of tolbutamide after oral dministration in rats, and that this change is not related to hepatic metabolism.

A simple and sensitive high-performance liquid chromatographic method for the analysis of acetazolamide (AZ) in rat blood (plasma/serum, whole blood and serum ultrafiltrate), brain tissue and cerebrospinal fluid (CSF) was described. Quantitative extraction of AZ with ethyl acetate from both buffered plasma and brain tissue homogenate (pH 8.0) was achieved. Each extract was evaporated to dryness and the residue was chromatographed on a reversed-phase column. CSF was directly analysed without extraction step. The limits of detection were 0.05 microgram ml-1 for plasma, 0.02 microgram g-1 for brain tissue and 0.004 microgram ml-1 for CSF. Calibration curves were linear over the working ranges of 0.1-100 micrograms ml-1 for plasma, 0.05-50 micrograms g-1 for brain tissue and 0.025-50 micrograms ml-1 for CSF. The reproducibility of AZ assay in the rat biologic media indicated very low relative standard deviations (RSDs). The recoveries of AZ added to plasma and brain tissue were more than 96% with an RSD of less than 5%. The present method was applied to studies of plasma concentration profiles of the drug after administration and its distribution into central nervous system.

Carmofur-loaded microspheres composed of polylactic acid (PLA) with a molecular weight of 20, 000 were prepared as a parenteral dosage form applicable as a sustained release preparation for cancer chemotherapy by a solvent evaporation method on a clean bench in a biological clean room. The amount of residual organic solvent in the microspheres was determined, and the physicochemical characteristics including the release of the drug from the microspheres were also investigated. The periods required to evaporate the methylene chloride remained in the microspheres below 100 ppm at 30, 35 and 40°C were 35, 9 and 5 days, respectively. The shape of microspheres was completely spherical and the surface was found to be quite smooth by scanning electron microscopic observation. Particles with diameter of 20 to 100 μm occupied about 85% of all microspheres, and the mean diameter of the microspheres dried at 35 and 40°C was about 60-80 μm. The release of the drug from the microspheres was relatively sustained, and it took 14 days to release more than 90%. In the sterility test, no growth of microorganism was not observed and thus the microspheres prepared under the biologically clean condition were confirmed to be aseptic. These findings suggest that the present PLA microspheres containing carmofur may be applicable as sustained-release preparation for the cancer chemotherapy.

To clarify the effect of plasma albumin on the salivary excretion of mexiletine, we have investigated the kinetics of and correlation between plasma and saliva levels following bolus intravenous administration (5 mg/kg) in male Sprague-Dawley rats (analbuminemic and normal). Parotid and mandibular saliva was collected separately by stimulating salivation with constant rate infusion of pilocarpine (50 μg/kg/min). In both rats, the mexiletine levels in plasma, parotid and mandibular saliva declined biexponentially with time in almost parallel fashion. Although the mexiletine levels in both types of saliva were lower than that in plasma (p < 0.05 or 0.01), the drug level in parotid saliva was always higher than that in mandibular saliva in both groups (p < 0.05 or 0.01). Furthermore, in both rats, significant correlations were observed when all data relating mexiletine concentration in plasma and saliva were included (p < 0.001). The saliva to plasma drug concentration ratios (S/P ratios) for both saliva in analbuminemic rats (0.814±0.162 for parotid saliva, 0.367±0.074 for mandibular saliva) were higher than those in normal rats (0.727±0.110 for parotid saliva, 0.197±0.061 for mandibular saliva) (p < 0.01). These changes in the S/P ratios between both groups could not be explained by the pH for either parotid or mandibular saliva. In contrast, the slight increase in the unbound fraction of the drug in analbuminemic rats, though it was not significant from the unbound fraction in normal rats, tended to be consistent with the difference in the S/P ratios for both salivary glands. These aspects suggest the possibility that the extent of salivary excretion of mexiletine may be influenced by the albumin concentration and dependent on the unbound fraction in plasma.

To investigate the in vitro metabolism of [6]-gingerol, one of the major pharmacological constituents of ginger, in the intestine, [6]-gingerol was added to the jejunal mucosal and muscular tissue homogenates isolated from rats in high (50μg/ml) and low (10μg/ml) concentrations, and the residual [6]-gingerol concentration was periodically determined. In addition, the stability of [6]-gingerol at 20 μg/ml in rat whole blood was also examined in vitro to compare with the metabolic degradation in rat jejunal tissues. In the incubation mixture of rat mucosal layer with the high concentration, the residual [6]-gingerol was 96.5 ± 6.5% following 60 min of incubation. For the low that initial [6]-gingerol concentration, [6]-gingerol concentration was significantly decreased to 81.0 ± 6.1% after 60min (p < 0.001). On the other hand, cumulative amounts of [6]-gingerol decreased in jejunal mucosal homogenates with the high and low initial concentrations for 60min being 0.236 ± 0.449 and 0.231 ± 0.084μg/mg protein, respectively. The residual [6]-gingerol in the incubation mixture of muscular homogenate was about 95-98% at 60 min after the incubation in both the initial concentrations. Furthermore, no change was observed in the [6]-gingerol concentration in the incubation mixture of whole blood. These results suggest that [6]-gingerol may be subject to some metabolic degradation in the mucosal layer of rat jejunum. This first-pass metabolism in the jejunal region would be one of the reasons for the considerable amount which was not recovered as [6]-gingerol in the previous in situ absorption study.

Beta-methyldigoxin (MD), a new semi-synthesized cardiac glycoside, has been widely used for treatment of congestive heart failure. Since any dosage form other than tablet form is not commercially available for MD, it has been necessary to prepare powder by pulverizing the tablet when dose adjustment is required. It has recently been suggested that the loss of content in digoxin powder is caused by adhesion to the wrapping papers. In the present study, we examined the content-uniformity and adhesiveness of MD in powder by pulverizing. In addition, we investigated the effect of magnesium stearate, a lubricant, on the adhesion of MD to wrapping paper.The content and content-uniformity of MD in powders were influenced by the numbers of tablet, namely, the amount of preparation. The extent of lost content and the variation in content-uniformity of MD increased with a decrease in the number of tablets. There was large adhesion of MD to wrapping papers. The percentage of MD lost by adhesion became exceedingly greater when the amount of powder per package became smaller. Furthermore, the percentage of MD lost in powder increased after dividing and packing by automatic machine, ranging from 17.1 to 37.3% of the initial value. When one package contained a small amount of powder, there was no remarkable effect of the lubricant on loss of MD after dividing and packing. This study confirms that attention should be given to prevent the possibility of MD content being lost in practical use.

The change in rat serum, brain and cerebrospinal fluid (CSF) concentration-time profiles, and serum protein binding of nalidixic acid (NA) caused by fenbufen was studied.Periodically following the bolus i.v. administration of NA (10 mg/kg) alone or with fenbufen (20 mg/kg) to 10-week old male Wistar rats, aliquots of CSF and blood were collected and then the whole brain was readily excised from the rat sacrificed by microwave irradiation. Serum (total and unbound), brain and CSF levels for the drug were determined by HPLC method.Serum levels for NA declined mono-exponentially with time in both groups, and coadministered fenbufen caused a significant duration in the serum level for the quinolone. The fraction of NA bound to serum protein was hardly affected by fenbufen. In both groups, brain and CSF levels for NA rose quite rapidly after drug administration and then declined along with the serum levels. Even in the group given NA alone, both brain and CSF levels for the quinolone were considerably high, yielding approximately 1.4 and 1.1 as the ratio to the serum unbound levels, respectively. Fenbufen was found to increase these brain and CSF concentrations significantly to exactly the same extent as observed in serum levels, showing no change in the ratio of brain (about 1.4) or CSF (about 1.1) concentration to serum unbound concentration for NA from the ratio obtained for NA alone.These results indicate that the duration of the brain or CSF level for NA in the coadministered group was merely due to the increase in the serum level for NA and that fenbufen did not affect the permeability of NA into the CNS.

Kynurenic acid, a catabolite of tryptophan, is suggested to be involved in schizophrenia, and is known to be a uremic toxin, although there is little information about the mechanism of its disposition. In this study, we performed uptake experiment using Xenopus laevis oocyte expression system to examine the transport of kynurenic acid by human organic anion transporters hOAT1 (SLC22A6) and hOAT3 (SLC22A8), which mediate the transport of organic anions in the brain and kidney. The uptake of p-aminohippurate in hOAT1-expressing oocytes and of estrone sulfate in hOAT3-expressing oocytes was strongly inhibited by kynurenic acid, and other tryptophan catabolites, kynurenine and quinolinic acid, showed moderate and no inhibition, respectively. The apparent 50% inhibitory concentrations of kynurenic acid were estimated to be 12.9 μM for hOAT1, and 7.76 μM for hOAT3. Both hOAT1 and hOAT3 markedly stimulated the uptake of kynurenic acid into oocytes, and the K(m) values of the transport were calculated to be 5.06 μM and 4.86 μM, respectively. The transport efficiencies of kynurenic acid by hOAT1 and hOAT3 were comparable to those of p-aminohippurate and estrone sulfate, respectively. Probenecid inhibited kynurenic acid transport by hOAT1 and hOAT3. These findings show the interaction of kynurenic acid with hOAT1 and hOAT3, and that kynurenic acid is their substrate. It is suggested that these transporters are involved in the disposition of kynurenic acid.

Nonsteroidal anti-inflammatory drugs (NSAIDs) delay the renal excretion of antifolate methotrexate by inhibiting human organic anion transporters hOAT1 (SLC22A6) and hOAT3 (SLC22A8). In this study, uptake experiments were performed using Xenopus laevis oocytes to assess stereoselectivity in the inhibitory characteristics of flurbiprofen, ibuprofen and naproxen against hOAT1 and hOAT3. Uptake of p-aminohippurate by hOAT1 was inhibited by each enantiomer of the three NSAIDs, and the inhibitory effect was superior in each (S)-enantiomer around 10 µM. The apparent 50% inhibitory concentrations were estimated to be 0.615 µM for (S)-flurbiprofen, 2.84 µM for (S)-ibuprofen and 1.93 µM for (S)-naproxen, and these values were significantly lower than those of the respective (R)-enantiomers [(R)-flurbiprofen: 2.35 µM, (R)-ibuprofen: 6.14 µM, (R)-naproxen: 5.26 µM]. Furthermore, the (S)-NSAIDs at 3 µM reduced methotrexate accumulation in hOAT1-expressing oocytes more strongly than the corresponding (R)-enantiomers. All enantiomers inhibited hOAT3-mediated transport of estrone sulfate and methotrexate, but there was no difference between both enantiomers of each NSAID in the inhibitory potencies. Eadie-Hofstee plot analysis showed that (S)-flurbiprofen and (R)-flurbiprofen inhibited hOAT1 and hOAT3 in a competitive manner. These findings represent the stereoselective inhibitory potencies of flurbiprofen, ibuprofen and naproxen on hOAT1, and the (S)-enantiomers are greater. In contrast, stereoselectivity was not recognized in their inhibitory effect on hOAT3.

University Medical Information Network (UMIN) has been developed by connecting all of the national university hospital host computers. Through this network, hospital personnel share in the benefits of various medical information services. We attempted to send/receive MSDOS drug information system files by UMIN. UMIN does not accept binary data, but the “ish file converter” has enabled us to convert binary data files to text files for uploading and downloading. New ADMICS (Advanced Drug Mixture Information & Consultation System) has been developed on FMR (Fujitsu) personal computers by investigating ADMICS files on PC-9800 (NEC) personal computers. A batch file made it possible to update ADMICS automatically and immediately with files downloaded from UMIN. UMIN is expected to facilitate collaboration among university hospitals in utilizing application programs and databases originally developed on MS-DOS at each university hospital.

In order to investigate the utility of therapeutic monitoring of mexiletine aided by the saliva drug levels, serum (total and unbound fraction) and saliva drug concentrations were measured in six inpatients with ventricular arrhythmia who were given an oral daily dose of 150 or 300 mg (t. i. d.) of mexiletine hydrochloride.Mexiletine levels in saliva were consistently much higher than the levels in serum of the patients. Saliva level to total and unbound serum drug concentration ratio (S/S ratio) varied markedly among patients from 4.5 to 32.0 and from 9.6 to 68.6, respectively, on the first day of medication. The predicted levels of mexiletine in the serum on day 7 and day 14 using the mean S/S ratio obtained on the first day of medication were almost identical to the observed levels in three of these patients, who showed a small ratio of saliva to total serum concentration, less than about 9 (or 21 for the ratio to unbound concentration). There was no correlation between the mexiletine level in saliva and the salivary flow rate.Four patients who received the drug at a daily dose of 300mg showed almost favorable trough drug levels in the serum total fraction ranging from 0.164 to 0.583 μg/ml, and ventricular premature contraction (VPC) in these patients was almost completely reduced (94.7-100.0%), except for one non-responder. Two patients who received 150 mg of the drug showed steady-state trough levels in the serum total fraction of less than 0.1μg/ml and the VPC of one of these two patients was hardly controlled. We, therefore, increased the daily dose to 300 mg in this patient, who was well controlled thereafter.From these findings, it is suggested that it may be possible to estimate the serum mexiletine levels from the saliva drug levels by using the initial S/S ratios inpatients with ratios of less than about 9.

Propylthiouracil (PTU), an antithyroid drug, has been widely used to treat hyperthyroidism. Since any dosage form other than tablet form is not commercially available for PTU, it is necessary to prepare the powder by pulverizing the tablet when dose adjustment is required. To clarify the efficacy of pulverizing the PTU tablet, we investigated the content uniformity, adhesiveness and long-term stability of PTU in three kinds of powders prepared with different excipients; EFC lactose, powdered lactose and potato starch.The content uniformity of PTU was excellent in all powders. In addition, there was no adhesion of PTU to two kinds of wrapping papers. On the other hand, dividing and packaging tests performed by automatic machine showed a slight effect of the excipients on PTU adhesion to the machine, specifically the lost amount of PTU after dividing and packaging was approximately 6-10% of the initial amount in all powders.PTU in these powders was almost completely stable by 90 days under the following storage conditions: R. H. 92% at 30°C, exposure to light at room temperature, and protection from light at 5°C. In addition, there was no apparent difference in the remaining percentage of PTU among these powders under each of the storage conditions. However, PTU remaining under R. H. 92% at 30°C tended to be lower than those under other storage conditions.The present findings suggest that these PTU preparations made by pulverizing tablets are applicable to practical long-term therapy use.

It is well known that nonsteroidal anti-inflammatory drugs (NSAIDs) delay the elimination of methotrexate. One of the mechanisms is thought to be inhibition of methotrexate uptake via human organic anion transporter 3 (hOAT3, SLC22A8) in the renal proximal tubule by NSAIDs. In this study, we evaluated the inhibitory effects of selective cyclooxygenase-2 inhibitor etoricoxib on hOAT3 by uptake experiments using Xenopus laevis oocytes. The injection of hOAT3 cRNA stimulated the uptake of methotrexate into the oocytes, and its transport was inhibited by etoricoxib. Etoricoxib inhibited estrone sulfate uptake by hOAT3 dose dependently, and the 50% inhibitory concentration was estimated to be 9.8 μM. Eadie-Hofstee plot analysis showed that etoricoxib inhibited hOAT3 in a competitive manner. These findings show that etoricoxib has inhibitory effect on hOAT3, and that the potential is comparable to that of traditional NSAIDs.

Objectives This study was designed to investigate the effects of Sho-saiko-to (Xiao Chai Hu Tang), a Chinese traditional medicine, on the membrane permeability of tolbutamide in the intestinal tract. We carried out an in-situ loop study with rat jejunum and a transport study with Caco-2 cell monolayers. Methods In the in-situ loop study, absorption clearance of tolbutamide was estimated from the drug concentrations in the loop and plasma. The apical-to-basolateral and basolateral-to-apical transport of tolbutamide and d-mannitol, a paracellular transport marker, was assessed using Caco-2 cell monolayers cultured on a polycarbonate membrane. Key findings The absorption clearance of tolbutamide was enhanced by a concomitant dose of Sho-saiko-to over 10 min in the rat in-situ loop. Sho-saiko-to increased the apical-to-basolateral transport of tolbutamide, whereas the basolateral-to-apical transport of this drug was reduced by Sho-saiko-to. On the other hand, in both directions the Papp of d-mannitol was reduced by the presence of Sho-saiko-to. Furthermore, the apical-to-basolateral transport of tolbutamide in ATP-depleted Caco-2 cells was diminished by Sho-saiko-to. These findings suggest that Sho-saiko-to can facilitate the epithelial membrane permeability of tolbutamide across the rat jejunum in-situ and Caco-2 cell monolayers. Since Sho-saiko-to suppressed the passive transport of tolbutamide from the apical-to-basolateral side, enhanced permeability may be related to effects of Sho-saiko-to on the energy-dependent transport of tolbutamide in the intestine. Conclusions Our findings suggest that Sho-saiko-to might facilitate the energy-dependent transport of tolbutamide across the rat jejunum in-situ and Caco-2 cell monolayers.

A plastic bag, which is composed of 3 layers i.e.polypropyrene, nylon and polyester films, has been devised for sterilization of liquid preparations for external use by an autoclave.Physico-chemical tests such as heavy metal, nonvolatile residue and water vapor permeation were carried out to evaluate the suitability as a container for liquid preparations.The adsorption of chlorhexidine gluconate and benzalkonium chloride from aqueous solutions to the plastic bag was investigated.This bag was adopted for the requirements under physico-chemical tests for plastics.There was no decrease of chlorhexidine gluconate or benzalkonium chloride by adsorption to the plastic bag under autoclaving at 115°C for 30min, and subsequent storage at room temperature for 4 weeks.It was suggested that the newly-devised plastic bag was very useful for sterilization of liquid preparations in hospital pharmacy.

An automated system for printing the drug envelopes has been developed by connecting with the prescription ordering system.The hardware of this system consists of a printer as terminal of the ordering system and a heat-sealing and cutting machine.Informations such as patient's name, directions and dosage, etc.were utilized from the patient database and the ordering database by physician prescribing which were kept in host computer.These data were automatically printed out on the continuous paper, and then the paper was heat-sealed and cut for the drug envelopes.The drug envelopes were produced rapidly and accurately with this system. It was suggested that the developed system was very useful for printing the drug envelopes in hospital pharmacy.

Azathioprine injection was prepared as an immunosuppressive dosage form for organ transplantation. The stability of azathioprine in the injection was investigated under various sterilization and storage conditions.The amount of azathioprine was determined by highperformance liquid chromatography.The amount of azathioprine in the injection decreased slightly after autoclaving but any significant difference was not observed among three sterilization conditions such as 115°C for 30 min, 121°C for 20 min and 126°C for 15 min.Azathioprine in the injection which was autoclaved at 115°C for 30 min was completely stable under subsequent storage at room temperature on exposure to light for 4 weeks.The present azathioprine injection was found to be useful as an immunosuppressive agent for organ transplantation.

The change in plasma concentration-time profile, serum protein binding and renal and biliary clearances of ciprofloxacin caused by coadministration of fenbufen has been studied in rats administered an intravenous dose of ciprofloxacin (5 mg kg−1) alone or with fenbufen (10 mg kg−1). Coadministered fenbufen significantly prolonged the plasma elimination half-life of ciprofloxacin from 40.5 to 57.6 min and tended to reduce the total body clearance of this quinolone by about 20%. The extent of ciprofloxacin binding to rat serum protein was not affected by fenbufen, nor did it affect the biliary clearance of the quinolone. However, fenbufen tended to reduce renal clearance and significantly decreased the cumulative renal excretion of the quinolone during at least the first 3 h after drug administration. These results suggest a possible reduction of ciprofloxacin clearance owing to inhibition of renal excretion by fenbufen.

The morphine hydrochloride suppository (MoS) containing sodium caprate (CA-MoS) or.sodium 5-methoxysalicylate (MS-MoS) was studied physicochemically and biopharmaceutically.The hardness and melting point of such suppository freshly prepared or stored for 4 weeks were not affected by the absorption enhancers on comparison with those of MoS.The release of morphine from CA-MoS was much slower than that from MoS or MS-MoS.In the absorption experiments in vitro using the isolated rectal preparation of rabbit, percent of drug amount that was absorbed (i.e.accumulated in the tissue and permeated) after the application of MoS, CA-MoS and MS-MoS was 61.7, 63.1, and 86.5%, respectively. The rectal transport of morphine in vitro was significantly enhanced in the presence of sodium 5-methoxysalicylate. No histological change was observed in mucosal tissue of the rectum exposed to these absorption enhancers.

In order to clarify the possibility of pharmacokinetic interaction between quinolone and fenbufen, the plasma concentration-time profiles and serum protein binding of enoxacin, fenbufen and its active metabolite, felbinac, were investigated in rats. The rats were administered an intravenous dose of enoxacin (5 mg/kg) and fenbufen (10 mg/kg) alone or concomitantly. Coadministration with fenbufen tended to prolong the plasma elimination half-life of enoxacin by about 20%, whereas it showed no effect on the area under plasma concentration-time curve, total body clearance or distribution volume of enoxacin. The extent of enoxacin binding to rat serum tended to be slightly reduced by fenbufen in vivo and in vitro. Plasma concentration-time curves, pharmacokinetic parameters and serum protein binding of fenbufen and felbinac were not affected at all by the coadministration with enoxacin. These aspects suggest that there may be only a minor possibility of the pharmacokinetic interaction between enoxacin and fenbufen.

Summary: Sulfonylurea hypoglycemic agents have interindividual variability in the gastrointestinal absorption rate. However, the absorption mechanism at the intestinal epithelium has not yet been clarified. To elucidate contribution of the specific mechanism for transepithelial transport of sulfonylureas, the apical-to-basolateral and basolateral-to-apical transport studies of tolbutamide were carried out using Caco-2 cell monolayers cultured on the polycarbonate membrane. The transported amounts of the substrate were measured by HPLC to estimate the apparent permeability coefficients (P app ). In the apical-to-basolateral flux, the transport activity of tolbutamide was facilitated when the pH of the apical medium was more acidic than the basolateral one. ATP-depletion decreased the P app of tolbutamide. The kinetic analysis of the permeation rate indicated that the saturable process largely contributed to the tolbutamide flux. The P app of tolbutamide was lowered by an ionophore and monocarboxylic acids, while dicarboxylic acids and the inhibitor for the anion exchanger had no effect. In addition, mutual inhibition with benzoic acid was observed in transepithelial transport of tolbutamide. On the other hand, the permeation rate of tolbutamide from the basolateral to apical side was concentration-independent and neither affected by metabolic inhibitors, probenecid nor inhibitors for P-glycoprotein. In conclusion, these results suggest that apical-to-basolateral transport of tolbutamide across the Caco-2 cell monolayers is mediated by the pH-dependent specific system, presumably shared with other organic anions such as benzoic acid.

To investigate the kinetics and correlation between serum and saliva levels of mexiletine, serum (total and unbound) and saliva drug concentration-time courses have been analysed in five normal healthy volunteers after administration of a single oral dose (200 mg) of the drug. Mexiletine levels in saliva were always higher than those in serum. The drug concentration-time curve in each sample was analysed according to the non-linear least squares regression program MULTI, for a two-compartment model with first-order absorption. The saliva drug concentration in the post-absorption phase was found to be well correlated with either corresponding serum total or serum unbound drug level in four of the subjects. Although there was a large inter-individual variation in the ratio of saliva to serum drug concentrations as well as in the pharmacokinetic parameters, an almost consistent ratio was obtained in each individual.

Pharmacokinetic changes of various drugs have been reported in renal or hepatic failure. The present study employed ciprofloxacin, a quinolone antibiotic having neurotoxic side effects, to assess the influence of these diseases on distribution of ciprofloxacin into the central nervous system (CNS). After intravenous dosing of ciprofloxacin (10–30 mg kg−1), ciprofloxacin levels in plasma and brain were measured in normal rats (Wistar, male, 10-week-old) and those with acute renal and hepatic injuries which were induced by uranyl nitrate and carbon tetrachloride (CCl4), respectively. In the uranyl nitrate-treated rats, the plasma elimination half-life of ciprofloxacin was prolonged and the total body clearance was reduced when compared with those in the normal rats. Similar but smaller changes were observed in the CCl4-treated group. Brain levels of ciprofloxacin were significantly increased by both uranyl nitrate and CCl4 treatments. A proportional correlation between serum unbound levels and brain levels of ciprofloxacin was observed in the normal group. However, brainto-serum unbound concentration ratios of ciprofloxacin were reduced in the rats with renal or hepatic failure. These results suggest that renal failure as well as hepatic failure retards elimination of ciprofloxacin from the blood, leading to elevation of the CNS level, and also that ciprofloxacin distribution in the brain is reduced in these disease states.

A novel high-performance liquid chromatographic method for the fluorometric determination of a newer quinolone, ciprofloxacin (CPFX), in rat brain and cerebrospinal fluid (CSF) was developed. CPFX in brain homogenate was extracted and injected onto a reversed-phase column without fluorescence derivatization. CSF was directly analyzed without the extraction procedure. Calibration curves were linear over the concentration ranges of 10 to 500 ng/g for brain and 5 to 500 ng/ml for CSF. The recoveries of CPFX added to brain were more than 97% with a coefficient of variation of less than 4%. The present method was sensitive and reliable enough to be utilized for detailed pharmacokinetic studies of CPFX in rat brain and CSF.

Although Sho-saiko-to (Xiao Chai Hu Tang), a major Chinese traditional medicine, is frequently prescribed with other synthetic or biotechnological drugs for the treatment of various chronic diseases, there is a dearth of information about interactions between sho-saiko-to and co-administered drugs. This paper reports the effects of Sho-saiko-to on the pharmacokinetics and glucose responses of a sulphonylurea hypoglycaemic agent, tolbutamide, after their oral administration in rats. After oral administration of tolbutamide (50 mg kg−1) with or without Sho-saiko-to extract powder (300 mg kg−1) to male Sprague-Dawley rats cannulated in the jugular vein, plasma tolbutamide and glucose levels were periodically measured. Co-administration of Sho-saiko-to tended to elevate the plasma tolbutamide concentration in the absorption phase. A two-compartment lag-time model was found to describe the plasma tolbutamide concentration-time data. The maximum concentration of tolbutamide was significantly increased and time to reach the maximum concentration was reduced to about 70% by co-administration with Sho-saiko-to. There was no significant change in area under the curve or in the elimination half-life of tolbutamide. The extent of the lowering effect of tolbutamide on plasma glucose levels was increased up to 0.75 h and decreased after 5 h after co-administration of Sho-saiko-to. In conclusion, these studies suggest that sho-saiko-to slightly hastens the gastrointestinal absorption of tolbutamide. Furthermore, it is considered that elevation of the gastrointestinal absorption rate by Sho-saiko-to might potentiate the hypoglycaemic effect of this sulphonylurea in the early period after oral administration.

To establish the cerebral microvascular endothelial cell (CMEC) culture system for animals commonly utilized in in vivo studies, we developed a method for isolation and culture of rat CMECs, and the model system was used in preliminary in vitro transport experiments. The isolated rat brains were minced. After an incubation with dispase, a fraction of microvessels was obtained by the dextran gradient. The tissue was filtered and dissociated using collagenase/dispase. After the enzyme treatment, the microvessels were layered onto the top of Percoll gradient and centrifuged for purification. Specific enzyme activities of alkaline phosphatase and gamma-glutamyltransferase in the preparations gradually increased as the isolation process progressed. The isolated cells reached confluence after 5-7 days in culture. The cultured cells had Factor VIII-related antigen and an uptake of acetylated-low density lipoprotein labeled with 1,1'-dioctadecyl-3,3, 3',3'-tetramethyl-indocarbocyamine perchlorate (Dil-Ac-LDL). In the transport studies, thawed cells after several months under -80 degrees C were used. The cultured cells after the freezing preservation also had CMEC characteristics, the same as the cells seeded immediately after isolation. The permeability of [14C]-mannitol, an impermeable marker for blood-brain barrier, was considerably reduced when the cell monolayer was present. The transport of [3H]3-O-methyl-D-glucose was significantly inhibited by the unlabeled compound. Furthermore, 2,4-dinitrophenol, an uncoupler of oxidative phosphorylation, significantly diminished the transport of [3H]L-proline. These results indicated that the cell monolayer obtained in the present study could be applicable to drug transport studies through the blood-brain barrier in vitro.

In order to obtain in vitro evidence for a specific transport system of valproic acid (VPA) at the blood-cerebrospinal fluid (CSF) interface, the uptake of VPA by isolated rat choroid plexus was investigated. The uptake clearance of [3H]VPA decreased with the increase of the unlabeled VPA concentration in the incubation medium. Kinetic analysis yielded an apparent Km of 10.0 mM, Vmax of 0.0871 mumol s-1 g-1 and Kns, a permeability coefficient of the nonsaturable component, of 6.85 microL s-1 g-1, indicating that both saturable and nonsaturable systems may contribute to VPA uptake by choroid plexus. Organic anions, penicillin G, p-aminohippurate, salicylate, and probenecid significantly inhibited VPA uptake by choroid plexus. We suggest that VPA translocation through choroidal membrane is partly operated by the organic anion transport system. A significant decrease of VPA uptake induced by 2,4-dinitrophenol, stilbenedisulfonate, and hypothermia (10 degrees C) indicates the involvement of an energy-dependent, carrier-mediated transport system. These results demonstrate that VPA is actively transported through the rat choroidal epithelium via a saturable system probably shared by organic anions.

Pharmacokinetic behavior involved in the entry of four quinolone antibacterial agents, norfloxacin (NFLX), ciprofloxacin (CPFX), ofloxacin (OFLX) and nalidixic acid (NA), into cerebrospinal fluid (CSF) was comparatively investigated in rats. Periodically, after the bolus i.v. dose of each quinolone (10 mg/kg), aliquots of CSF were collected by cisternal puncture and blood samples were then withdrawn from the jugular vein. CSF and serum (total and unbound) levels of the drugs were determined by HPLC method. Transport parameters for three new quinolones (NFLX, CPFX, OFLX) into CSF were obtained by physiological model analysis. Serum levels of OFLX and NFLX declined bi-exponentially with time, whereas the serum levels of NA and CPFX declined in mono-exponential and tri-exponential fashion, respectively. Fractions of each quinolone unbound to serum protein (approximately 0.7 for NFLX, CPFX, and OFLX, 0.12 for NA) were almost the same at any point in time. The CSF levels of these quinolones rose quite rapidly after drug administration, and then declined, along with their serum levels. Both the CSF level and the ratio of CSF concentration to serum unbound concentration were the highest for NA, followed by OFLX, CPFX and NFLX. These values of the four quinolones were almost proportional to the apparent partition coefficient (Papp) between n-octanol and phosphate buffer (pH 7.0) values of each reported in a previous paper [Tsuji et al., Antimicrob. Agents Chemother., 32, 190 (1988)]. In the three new quinolones, OFLX had a larger value of apparent diffusional clearance between blood and CSF (PAc) than CPFX and NFLX.(ABSTRACT TRUNCATED AT 250 WORDS)

A high-performance liquid chromatographic method for the determination of nalidixic acid (NA) in rat serum, brain and cerebrospinal fluid (CSF) was developed. NA in rat serum and brain homogenate was extracted and injected onto a reversed-phase column. CSF was directly analysed without extraction procedure. The limits of detection were 0.05 microgram ml-1 for serum, 0.07 microgram g-1 for brain and 0.02 microgram ml-1 for CSF, respectively. Calibration curves were linear over the concentration ranges 0.1-50 micrograms ml-1 for serum, 0.12-9 micrograms g-1 for brain and 0.05-10 micrograms ml-1 for CSF, respectively. The reproducibility of NA assay in rat biological media ranged from 1 to 4% relative standard deviations (RSD). The recoveries of NA added to serum and brain were higher than 96% with an RSD of less than 4%. The present method was found to be applicable to pharmacokinetic study of NA in rat serum, brain and CSF.

The effect of steady-state plasma concentrations on the salivary excretion of mexiletine was investigated following simultaneous bolus intravenous injection of the loading dose (2·7 or 16·1 mg kg−1) and constant-rate intravenous infusion of the maintenance dose (15 or 102 μg min−1 kg−1) in male Wistar rats. Parotid and mandibular saliva was collected separately by stimulating salivation with a constant-rate infusion of pilocarpine (50 μg kg−1 min−1) in each rat. The low and high steady-state levels of mexiletine in blood plasma were attained at 0·259 + 0·123 and 1·616 ± 0·475 μg mL−1, respectively, within the first 1–2 h after drug administration. Similarly, the two different steady-states in both parotid and mandibular saliva were attained. Although the mexiletine levels in both types of saliva were lower than that in plasma, the drug level in parotid saliva was always higher than that in mandibular saliva at any steady-state (P < 0·001 or 0·01). In parotid saliva, the high steady-state produced greater saliva to plasma drug concentration ratios (S/P ratio, 0·475 + 0·160) than that (0·386±0·131) at the low steady-state (P < 0·05). The S/P ratio for mandibular saliva at the high (0·204 ± 0·060) steady-state was also greater than that at the low (0·158 ± 0·050) steady-state (P < 0·01). These changes in the S/P ratio could not be explained by the pH for either parotid or mandibular saliva, but partially by the change in the unbound fraction of the drug which tended to be consistent with that in the ratio for both salivary glands. These findings suggest that the salivary excretion of mexiletine may be dependent on the plasma unbound concentration in rats.

The entry of two new quinolone antibacterial agents, norfloxacin and ofloxacin, into the central nervous system (CNS) of rats, and the effect of fenbufen on this was investigated. At various times after the administration of a bolus intravenous dose of norfloxacin or ofloxacin (10 mg kg−1) with or without fenbufen (20 mg kg−1), serum and cerebrospinal fluid (CSF) samples and whole brain were collected from the rats and the concentration of norfloxacin or ofloxacin in each sample was determined. Serum concentrations of both quinolones declined biexponentially with time and were significantly elevated by coadministration with fenbufen at the terminal phase. The fractions of these quinolones bound to serum protein were not altered by coadministration with fenbufen. Coadministered fenbufen raised the brain concentrations of both quinolones but did not affect their brain to serum unbound concentration ratios. In contrast, CSF to serum unbound concentration ratios as well as CSF concentrations of norfloxacin and ofloxacin were elevated by coadministration with fenbufen. Apparent diffusional clearances between blood and CSF of norfloxacin and ofloxacin estimated by the physiological model analysis increased by 1·9 and 2·6 times, respectively, after coadministration with fenbufen. These findings suggest that coadministered fenbufen may facilitate the entry of norfloxacin and ofloxacin into the CNS.

The pharmacokinetics of [6]-gingerol were investigated in rats with acute renal failure induced by bilateral nephrectomy, or those with acute hepatic failure induced by a single oral administration of carbon tetrachloride (CCl4), to clarify the contribution of the kidney and liver to the elimination process of [6]-gingerol. After bolus intravenous administration, a plasma concentration-time curve of [6]-gingerol was illustrated by a two-compartment open model. There was no significant difference in either the plasma concentration-time curve or any pharmacokinetic parameters between the control and nephrectomized rats. It is suggested, therefore, that renal excretion does not contribute at all to the disappearance of [6]-gingerol from plasma in rats. In contrast, hepatic intoxication with CCl4 elevated the plasma concentration of [6]-gingerol at the terminal phase. Its elimination half-life increased significantly, from 8.5 to 11.0 min, in CCl4-intoxicated rats. The extent of [6]-gingerol bound to serum protein was more than 90% and was affected very slightly by the CCl4-intoxication. These aspects indicate that [6]-gingerol is eliminated partly by the liver.

Salivary excretion of mexiletine was investigated following bolus intravenous administration (10 mg kg−1) in rats. Parotid and mandibular saliva was collected separately by stimulating salivation with constant rate infusion of pilocarpine (3 mg kg−1 h−1). The mexiletine levels in blood plasma and parotid and mandibular saliva declined biexponentially with time in almost parallel fashion. Although the mexiletine levels in both types of saliva were lower than that in plasma, the drug level in parotid saliva was always higher than that in mandibular saliva. Significant correlations were observed when all data relating mexiletine concentration in plasma and saliva were included (P < 0·001). The saliva/plasma drug concentration ratios (S/P ratios) did not vary to a large extent (0·56 ± 0·10 for parotid saliva, 0·21 ± 0·06 for mandibular saliva), but there was a consistent tendency for the higher plasma drug levels in the distribution phase to produce relatively high S/P ratios for both parotid and mandibular saliva. Moreover, the plasma mexiletine levels calculated by the equation of Matin et al (1974) employing the observed values for the saliva drug level, saliva pH and free fraction of mexiletine in plasma were significantly higher than the observed drug levels. Therefore, it is suggested that the salivary excretion of mexiletine could not be explained quantitatively by simple, passive secretion based on pH-partition theory.

A high-performance liquid chromatographic method to determine [6]-gingerol, a pungent constituent of ginger, in rat plasma was developed and a pharmacokinetic study was performed in rats. Quantitative analysis with high reproducibility was achieved for [6]-gingerol over the concentration range of 0.2-40 micrograms/ml. After bolus intravenous administration at a dose of 3 mg/kg, the plasma concentration-time curve was described by a two-compartment open model. [6]-Gingerol was rapidly cleared from plasma with a terminal half-life of 7.23 min and a total body clearance of 16.8 ml/min/kg. Serum protein binding of [6]-gingerol was 92.4%.

Ciprofloxacin (CPFX) is a new quinolone agent with potent, broad antibacterial activity. It is well absorbed and widely distributed into various body tissues and fluids when given orally [1,2]. Recently, it was reported that severe convulsion was induced in some patients who were given new quinolone antibacterial agents and non-steroidal anti-inflammatory drugs, including fenbufen (FNB) [3,4], which was later reported to potentiate the convulsant activity of various quinolones in mice [5]. FNB is readily biotransformed into 4-biphenylacetic acid (felbinac, FLB), which possesses anti-inflammatory activity [6-81. Therefore, in order to investigate possible pharmacokinetic interaction between these drugs, it is necessary to develop a simple, sensitive, selective and simultaneous assay method for the quinolone, FNB and FLB in biological fluids. We have already developed high-performance liquid chromatographic (HPLC) methods for simultaneous determination of quinolone involving ofloxatin, enoxacin or norfloxacin with FNB and FLB [9-l 11, and examined the effects of FNB and FLB on the pharmacokinetics of these three quinolones [12-141. However, no investigation has been carried out on the pharmacokinetic interaction of the newer quinolone, CPFX, with FNB and FLB. This paper describes a novel analytical method for the simultaneous determination of CPFX, FNB and FLB in rat plasma.