Possible roles of intestinal P-glycoprotein and cytochrome P450 3A on the limited oral absorption of irinotecan.

OBJECTIVES: Irinotecan is a widely intravenously used drug for the treatment of certain types of solid tumours. The oral administration of irinotecan has recently been recognized as being a more effective method for the treatment than intravenous administration. However, the limited oral bioavailability of irinotecan poses a problem for its oral delivery. In this study, we report on an investigation of the mechanism responsible for the limited oral absorption of irinotecan using rats as models. METHODS: The intestinal absorption of irinotecan in the absence and presence of several compounds was examined using intestinal loop method. The pharmacokinetics of irinotecan was investigated when verapamil, an inhibitor of the P-glycoprotein (P-gp) and cytochrome P450 3A (CYP3A) was pre-administered. KEY FINDINGS: The intestinal absorption of irinotecan was enhanced in the presence of verapamil, indicating that efflux by intestinal P-gp contributes to its limited oral absorption. Indeed, the oral bioavailability of irinotecan was increased when verapamil was orally pre-administered. This increased oral bioavailability was accompanied by a slight but significant decrease in the formation of a metabolite produced by the action of CYP3A. CONCLUSION: The findings presented herein suggest that intestinal efflux by P-gp is mainly and intestinal metabolism by CYP3A is partially responsible for the limited oral absorption of irinotecan.

Tumor Growth Suppression With Novel Intra-arterial Chemotherapy Using Epirubicin-entrapped Water-in-oil-in-water Emulsion In Vivo.

BACKGROUND/AIM: A mixture of anticancer agents and iodized poppy seed oil (IPSO) has been widely used for intra-arterial chemotherapy of hepatocellular carcinoma. However, the anticancer agents can easily separate from IPSO, so the therapeutic potential is limited. We developed epirubicin-entrapped water-in-oil-in-water emulsion (WOW-Epi) using a double-membrane emulsification technique. MATERIALS AND METHODS: We delivered WOW-Epi through a hepatic arterial injection to VX2 hepatic tumor rabbit model (1.2 mg/kg). RESULTS: VX2 tumor growth was selectively suppressed in the WOW-Epi-treated group compared with the control treated groups. The accumulation of WOW in nearby cancer cells was confirmed via electron-microscopy. Endocytosis seemed to be the mechanism underlying the uptake of WOW. CONCLUSION: WOW-Epi led to tumour growth suppression in vivo. WOW does not cause toxicity to arterial vessels. WOW-Epi will be hopefully used for repeated intra-arterial chemotherapy to HCC patients in the near future.

Relationship between UGT1A1*27 and UGT1A1*7 polymorphisms and irinotecan-related toxicities in patients with lung cancer.

BACKGROUND: The objective of this study was to evaluate the effects of gene polymorphisms, including UGT1A1*7, *27, and *29, on the safety of irinotecan therapy. METHODS: The eligibility criteria were: lung cancer patients scheduled to undergo irinotecan therapy, aged ≥ 20 years, with a performance status of 0-2. Thirty-one patients were enrolled and their blood was collected and used to examine the frequency of UGT1A1*6, *7, *27, *28, and *29 polymorphisms and the concentrations of irinotecan, SN-38, and SN-38G after irinotecan therapy. RESULTS: The patients' characteristics were as follows: male/female 25/6, median age 71 years (range 55-84), stage IIB/IIIA/IIIB/IV 2/6/11/12, and adenocarcinoma/squamous cell carcinoma/small cell carcinoma/other 14/10/3/4, respectively. The -/-, *6/-, *7/-, *27/-, *28/-, and *29/- UGT1A1 gene polymorphisms were observed in 10 (32%), 10 (32%), 2 (6%), 2 (6%), 7 (23%), and 0 (0%) cases, respectively. The UGT1A1*27 polymorphism occurred separately from the UGT1A1*28 polymorphism. The lowest leukocyte counts of the patients with the UGT1A1*27 and UGT1A1*6 gene polymorphisms were lower than those observed in the wild-type patients. SN-38 tended to remain in the blood for a prolonged period after the infusion of irinotecan in patients with UGT1A1*27 or UGT1A1*28 polymorphisms. No severe myelotoxicity was seen in the patients with UGT1A1*7. CONCLUSION: UGT1A1*27 can occur separately from UGT1A1*28 and is related to leukopenia during irinotecan treatment. UGT1A1*7 is less relevant to irinotecan-induced toxicities, and UGT1A1*29 seems to have little clinical impact.

Development of the Virtual Physical Assessment Learning Material That Allows the Learners to Check Drug Efficacy and Early Detection of Adverse Effects through Virtual Experience.

We utilized the information and communication technology to develop the physical assessment (PA) learning materials in the virtual experience type. This learning material consists of two parts which include case learning and basic learning. We created example scenarios about various conditions that a pharmacist may experience in medical scenes such as in a hospital ward, community pharmacy, home, and drugstore. Illustrations of a virtual patient's avatar before and after taking the medicines were incorporated in the learning materials. The virtual training includes a stethoscope that was used in examining sounds (heart, pulmonary and bowel sounds) that served as evidences in the confirmation of drug efficacy and its possible adverse effects. In addition, we included the images of each body part, the 24 format question items, the palpation (rate and rhythm) of the radial artery, brachial artery and pedal artery, the clinical data obtained from several medical equipment, the pupillary reflex, and the urine dipstick test. This way, learners are able to experience PA with reference to the subjective and objective data from patient reception and questions. The virtual patient's avatar displayed on the monitor features auscultatory sounds on the stethoscope. It also features clinical data obtained from other medical equipment that can give the learners an interactive way of learning about various medical conditions. For evaluation, we gave out questionnaires on the virtual PA to pharmacy students. As a result, a high evaluation was reflected in terms of the degree of usefulness for both case learning and basic learning.

Pramipexole reduces parkinsonian tremor induced by pilocarpine infusion in the rat striatum.

OBJECTIVE: Pramipexole is widely prescribed for the treatment of Parkinson's disease. This dopamine (DA) receptor agonist has a higher affinity for D3 over D2 receptors. We compared the effect of pramipexole to apomorphine, a non-specific DA receptor agonist, on the suppression of tremulous jaw movements (TJMs) in a rat model, to elucidate the possible ameliorating effect of D3 receptor activation on parkinsonian tremor. RESULTS: In experiment 1, pilocarpine (4.0mg/kg) was injected into rats intraperitoneally, and the number of rapid vertical deflections of the lower jaw was counted for 20min immediately after the injection, to evaluate TJMs. TJMs were reduced by intraperitoneal administration of pramipexole (1.0mg/kg). In experiment 2, the number of TJMs was counted after the rats received intraperitoneal administration of either apomorphine (0.25, 1.0, 4.0mg/kg) or vehicle, followed by the micro-infusion of pilocarpine (50µg/1µL/side) or vehicle into the ventrolateral striatum (VLS) via implanted guide cannulae. In experiment 3, either pramipexole (0.25, 1.0, 4.0mg/kg) or vehicle was intraperitoneally administered, followed by the micro-infusion of pilocarpine or vehicle into the VLS 30min later. Pramipexole (1.0 and 4.0mg/kg) and apomorphine (1.0 and 4.0mg/kg) significantly reduced the number of TJMs induced by micro-infusion of pilocarpine into the VLS. CONCLUSIONS: These findings suggest that activation of D3, as well as D2 receptors could play important roles in the suppression of parkinsonian tremor.

Albumin-binding of diclofenac and the effect of a site II inhibitor in the aqueous humor of cataract patients with the instillation of diclofenac.

Diclofenac instillation has been used widely in cataract surgery to prevent postoperative inflammation. Since diclofenac binds strongly to albumin in the circulation, it does not have a sufficient effect on patients in whom diclofenac binds strongly to albumin in the aqueous humor. A decrease in diclofenac binding and an increase in free diclofenac levels are necessary in these patients. The binding of diclofenac to albumin was investigated in the aqueous humor. In a diclofenac binding assay with albumin in the aqueous humor of individual patients, diclofenac was extracted from aliquots of the aqueous humor, and its total levels were measured using ultra high performance liquid chromatography (UHPLC). Free diclofenac levels were measured using ultrafiltration and UHPLC. The albumin-binding fraction of diclofenac was 0.8 or higher in the aqueous humor of some patients. Ibuprofen significantly inhibited diclofenac binding to site II of albumin in mimic aqueous humor, but not in pooled aqueous humor. This difference may have been due to the weak binding of diclofenac to site II in the pooled aqueous humor. Flurbiprofen was used instead of diclofenac. Flurbiprofen has been shown to bind more strongly than diclofenac to the same site of albumin. Thus, the inhibitory effect of ibuprofen on the binding of flurbiprofen to albumin was investigated in pooled aqueous humor. The results indicated that ibuprofen significantly inhibited the flurbiprofen binding. An effective diclofenac administration method may be established for clinical application by the instillation of an appropriate inhibitor of binding to the albumin site II.

An advanced objective structured clinical examination using patient simulators to evaluate pharmacy students' skills in physical assessment.

OBJECTIVE: To implement an advanced objective structured clinical examination (OSCE) in the curriculum and to evaluate Japanese pharmacy students' skills in physical assessment such as measuring pulse and blood pressure, and assessing heart, lung, and intestinal sounds. DESIGN: An advanced OSCE was implemented in a hospital pharmacy seminar as a compulsory subject. We programmed patient simulators with 21 different patient cases in which normal and abnormal physiological conditions were produced. The virtual patients were then used to evaluate the physical assessment skills of fifth-year pharmacy students. ASSESSMENT: Significant differences were observed between the average of all the detailed evaluations and the mean results for the following skills: pulse measurement, blood pressure measurement, deflating the cuff at a rate of 2-3 mmHg/sec, listening to heart sounds, and listening to lung sounds. CONCLUSION: Administering an advanced OSCE using virtual patients was an effective way of assessing pharmacy students' skills in a realistic setting. Several areas in which pharmacy students require further training were identified.

A diclofenac suppository-nabumetone combination therapy for arthritic pain relief and a monitoring method for the diclofenac binding capacity of HSA site II in rheumatoid arthritis.

Diclofenac suppository, a non-steroidal anti-inflammatory drug (NSAID), is used widely in rheumatoid arthritis (RA) patients with severe arthritic pain. As the binding percentage of diclofenac to serum proteins is high, its free (unbound) concentration after rectal administration is low. To increase temporarily the free concentration of diclofenac and to enhance its analgesic effect by inhibiting the protein binding of diclofenac, the analgesic effect of diclofenac was examined before and after the start of an inhibitor administration to RA patients with insufficient control of arthritic pain, and the protein binding capacity of diclofenac was evaluated. Binding experiments were performed by ultrafiltration, and arthritic pain was recorded by the face scale. Free fractions of diazepam and diclofenac were augmented by increasing 6-methoxy-2-naphthylacetic acid (6-MNA; the active metabolite of the NSAID nabumetone) concentrations. The free fraction of diazepam increased after the start of nabumetone administration to RA patients, and arthritic pain relief was observed. These results suggest that 6-MNA has an inhibitory effect on the protein binding of diclofenac and the free fraction of diazepam can be used to evaluate the binding capacity of diclofenac. It is considered that diclofenac suppository-nabumetone combination therapy and the method for protein binding monitoring by diazepam can positively benefit RA patients with insufficient control of arthritic pain.

Caffeine increases the antitumor effect of Cisplatin in human hepatocellular carcinoma cells.

Caffeine is thought to increase the antitumor effect of cisplatin or DNA-damaging agents because it is known that caffeine inhibits DNA repair. Caffeine-assisted chemotherapy has been used in the treatment of osteosarcomas. In addition, there are several reports about combination chemotherapy with caffeine for certain malignancies other than osteosarcomas. However, there are no reports that show the utility of combination chemotherapy with caffeine for hepatocellular carcinoma (HCC). We examined the combined effects of caffeine and cisplatin in human HCC cell lines, and screened for a more effective administration method of caffeine in vitro. Human HCC cell lines (HepG2, HLF, HuH-7, and Li-7) were exposed to caffeine (0-0.5 mM) and cisplatin (0-1.2 µg/mL) for 72 h, either alone or in combination. Cell numbers were measured by WST-8 assay, and cell apoptosis was determined by annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) binding assay. As a result, caffeine increased the antitumor effect of cisplatin on cell proliferation and cell apoptosis in the HCC cell lines. Moreover, this effect was dependent on the amount of exposure to caffeine. These results suggest that caffeine-assisted chemotherapy is useful for HCC treatment.

Hyuganatsu orange (Citrus tamurana Hort. Ex Tanaka) contains a water soluble substance that suppresses bone loss in ovariectomized rats.

We investigated whether Hyuganatsu orange (Citrus tamurana Hort. ex Tanaka) contains water and acetic-acid soluble substances that increase bone mineral density (BMD) in ovariectomized rats. In in vivo study, femoral BMD can significantly increased. In in vitro study, tartrate-resistant acid phosphatase (TRAP) positive cells significantly decreased. We speculate that Hyuganatsu orange contains biologically active substances other than hesperidin that increase BMD.

Hepatocyte growth factor suppresses the anticancer effect of irinotecan by decreasing the level of active metabolite in HepG2 cells.

In the liver, carboxylesterase (CES) converts irinotecan (CPT-11) to its active metabolite SN-38, which exerts anticancer effects. SN-38 is metabolized to an inactive metabolite SN-38 glucuronide by uridine 5'-diphospho-glucuronosyltransferase 1A1 (UGT1A1). Therefore, single nucleotide polymorphisms (SNPs) of the UGT1A1 gene are responsible for the severe adverse effects associated with the disruption of SN-38 metabolism. However, despite having SNPs of the UGT1A1 gene, many patients metabolize SN-38 sufficiently to avoid severe adverse effects. Among these patients, we found individuals with elevated serum concentrations of hepatocyte growth factor (HGF). The aim of this study was to evaluate whether HGF alters the metabolism of CPT-11, resulting in a reduction in the anticancer effect of CPT11. The cytotoxicity of CPT-11 and SN-38 was evaluated in HepG2 cells pretreated with HGF. Furthermore, we explored the level of expression and mechanisms of activity of CES and UGT1A1. HGF suppressed the cytotoxicity of CPT-11 by decreasing intracellular SN-38 levels that resulted from a decrease in CES2 and an increase in UGT1A1. Furthermore, this HGF-induced suppression was improved by pretreatment with an inhibitor of HGF receptor c-Met, and the improvement was synergistically potentiated by epidermal growth factor receptor (EGFR) inhibitors. Moreover, HGF induced phosphorylation of signal transducer and activator of transcription 3 and transactivated EGFR. These results suggest that HGF is a possible causative agent of acquired clinical resistance in chemotherapy with CPT-11 and could be useful as a predictor of clinical resistance. Additional treatment using c-Met and/or EGFR inhibitors could be a novel strategy to overcome resistance.

Hepatic fibrosis does not affect the pharmacokinetics of 5-fluorouracil in rats.

In the case of cancer chemotherapy for hepatocellular carcinoma, 5-fluorouracil (5-FU) is used widely, and has typically been given by intrahepatic arterial (i.a.) infusion to increase treatment efficacy and to reduce systemic toxicity. 5-Fluorouracil is eliminated primarily by the liver, and so its use in patients with hepatic disease can be difficult. This study investigated the effect of hepatic fibrosis on the pharmacokinetics of 5-FU in rats. Experimental hepatic fibrosis was induced by carbon tetrachloride treatment. 5-fluorouracil was infused for 15 min into the hepatic artery or the saphenous vein of the rats at a dose of 1.25 mg/kg. There were no significant differences in the plasma concentration and AUC of 5-FU between hepatic disease rats and their controls after both intravenous and intraarterial injection. This result is probably attributed to the fact that there were no significant differences in hepatic blood flow and dihydropyrimidine dehydrogenase (DPD; an initial and rate-limiting enzyme in 5-FU catabolism) activity between hepatic disease rats and their controls, because the total clearance of 5-FU after intravenous and intraarterial administration is mainly limited by hepatic blood flow and DPD activity, respectively. In conclusion, the pharmacokinetics of 5-FU is not affected by hepatic fibrosis, unlike that of many hepatically metabolized drugs.

Effect of acute hepatic failure on the hepatic first-pass effect of 5-fluorouracil in rats.

OBJECTIVES: In cancer chemotherapy for hepatocellular carcinoma, 5-fluorouracil is widely used and has typically been given by intrahepatic arterial (i.a.) infusion to increase treatment efficacy and reduce systemic toxicity. 5-Fluorouracil is eliminated primarily by the liver and so the hepatic first-pass effect after intrahepatic arterial administration of 5-fluorouracil may be lower in patients with hepatic failure, and systemic toxicity may not be reduced. In this study, we have investigated the effect of acute hepatic failure on the first-pass effect of 5-fluorouracil in rats. METHODS: Experimental acute hepatic failure was induced by treatment with carbon tetrachloride (CCl4). 5-Fluorouracil was infused for 15 min into the hepatic artery or the saphenous vein of rats at a dose of 1.25 mg/kg. KEY FINDINGS: Hepatic availability in 50% CCl4-treated (severe hepatic failure) rats was higher than in controls. CONCLUSIONS: The hepatic first-pass effect after intrahepatic arterial administration of 5-fluorouracil was lower in severe hepatic failure. Therefore, the reducing effect of the systemic toxicity after intrahepatic arterial administration may be lower in severe hepatic failure.

Safety, efficacy and pharmacokinetics of S-1 in a hemodialysis patient with advanced gastric cancer.

PURPOSE: The safety and efficacy of S-1 in hemodialysis patients have not been established. We evaluated the safety and efficacy and pharmacokinetics of S-1 in a hemodialysis patient with advanced gastric cancer. PATIENT: A 66-year-old Japanese man with chronic renal failure, who had undergone hemodialysis three times a week for 3 years. Based on the diagnosis of stage IV gastric cancer, S-1 therapy was started. S-1 was administered 11 times at a daily dose of 23.5 mg/m(2) (40 mg/body)after hemodialysis, followed by a rest. One course was a period of 28 days. Blood samples were obtained after the first administration of S-1 and before beginning the fourth course. The concentration of 5-FU was determined by high-performance liquid chromatography. RESULTS: Area under the concentration-time curve (AUC)of 5-FU was 2647.2 ng h/mL after administration of S-1 of 23.5 mg/m(2) (40 mg/body). During the S-1 treatment,serious adverse events such as neutropenia were not observed; however, decreases in hemoglobin level were observed (grade 3). The treatment was well tolerated. After the second course of chemotherapy, the primary lesion showed a partial response and lymph node metastases and liver metastases showed stable disease. CONCLUSIONS: Our results suggest that S-1 is an important treatment option for patients with hemodialysis with advanced gastric cancer.

[Medical emergency education using emergency care simulators in the School of Pharmaceutical Sciences].

Clinical pharmacy training III (bedside training) in the School of Pharmaceutical Sciences, Kyushu University of Health and Welfare is intended to train pharmacists who can also cope with medical emergencies. Therefore we produced original scenarios that provide experience of various medical emergencies using emergency care simulators. As a result, these simulators enabled students to experience dealing with various medical emergencies such as cardiopulmonary resuscitation, automated external defibrillation (AED), adrenalin administration, and oxygen inhalation. In addition, a survey on the necessity for and the degree of the understanding of training contents associated with emergency care simulators was performed before and at the end of clinical training. After clinical training, the necessity for and the degree of the understanding of these training contents significantly increased (p<0.01). The introduction of emergency care simulators into clinical pharmacy training provides experience of not only cardiopulmonary resuscitation but also the treatment procedures as well as observation of improvement in the pathological condition after drug administration, which increases pharmacists' awareness of patient needs in drug therapy. Therefore these simulators are helpful for pharmacy education aiming at improving pharmacists' pharmaceutical care ability.

Analysis of CYP3A inhibitory components of star fruit (Averrhoa carambola L.) using liquid chromatography-mass spectrometry.

In this study, we analyzed the CYP3A inhibitory components of star fruit Averrhoa carambola L., using liquid chromatography-mass spectrometry (LC-MS). The stereoisomer of procyanidin B1 and B2 and/or the trimer consisting of catechin and/or epicatechin were suggested to be potent inhibitory components.

Effect of acute hepatic failure on epirubicin pharmacokinetics after intrahepatic arterial injection in rats.

In the case of cancer chemotherapy for hepatocellular carcinoma, anthracycline anticancer agents such as epirubicin are widely used, and have typically been given by intrahepatic arterial (i.a.) infusion to increase treatment efficacy and to reduce systemic toxicity. The anthracyclines are eliminated primarily by the liver, and the use of these drugs in patients with hepatic failure can be difficult. In this study, we investigated the effect of acute hepatic failure on the pharmacokinetics of epirubicin after i.a. injection in rats. Experimental acute hepatic failure was induced by carbon tetrachloride-treatment. Epirubicin was injected into the hepatic artery or the saphenous vein of the rats at a dose of 2 mg/kg. After both intravenous (i.v.) and i.a. injection, the serum concentration and the AUC 0-24 of epirubicin in hepatic failure rats were significantly higher than the values in control rats. The AUC 0-24 ratio of hepatic failure (i.a.) to control (i.a.) was higher than the ratio of hepatic failure (i.v.) to control (i.v.). These results suggest that the influence of hepatic failure on serum epirubicin concentration is larger with the i.a. route than with the i.v. route. The liver concentration of epirubicin after i.a. administration in hepatic failure rats was significantly lower than that in control rats. This result suggests that the effect of the liver-selective drug targeting after i.a. injection in hepatic failure rats is lower than in normal rats. Therefore, we should be careful when administering epirubicin by the i.a. route in patients with acute hepatic failure.

Inhibitory effects of fruit juices on cytochrome P450 2C9 activity in vitro.

There is limited information on the effect of fruits on human cytochrome P450 (CYP) 2C9 activity. The objective of this study was to determine the effect of fruit juice on CYP2C9-mediated drug metabolism. Nine citrus fruits and eight tropical fruits were chosen. We investigated effects of the fruits on diclofenac 4'-hydroxylation and tolbutamide hydroxylation by human liver microsomes. Among the fruits, pineapple juice showed potent inhibition of CYP2C9 activity. The addition of 25 microl (5.0% v/v) of pineapple juice resulted in almost complete inhibition. Next we examined the inhibitory effect of bromelain, a cysteine protease in pineapple. Bromelain also strongly inhibited CYP2C9 activity. In addition, E-64, a cysteine protease inhibitor, almost entirely blocked inhibition by pineapple juice and bromelain. Thus we found that pineapple juice was a potent inhibitor of CYP2C9, and that the inhibitory effect might be due to the bromelain contained in pineapple.

Dosage plan of a flurbiprofen injection product using inhibition of protein binding by lipid emulsion in rats.

Flurbiprofen-axetil (FP-ax), a bolus injection product of a non-steroidal anti-inflammatory drug (NSAID), is a prodrug of flurbiprofen, an NSAID. As flurbiprofen strongly binds to site II of human serum albumin (HSA), the free (unbound) concentration of flurbiprofen after injection of FP-ax is low. We have examined the inhibitory effect of free fatty acid (FFA), a binding inhibitor for site II of HSA, on the binding of flurbiprofen in-vitro and in-vivo by ultrafiltration, to establish an effective dosage of FP-ax. In-vitro, fatty acid mixtures (FAs) inhibited the binding of flurbiprofen to rat serum albumin. The free fraction of flurbiprofen was remarkably increased by FAs in rat serum. In-vivo, FP-ax was injected into a control group (low FFA concentration in serum) and a lipid emulsion group (high FFA concentration in serum). The area under the curve of the free concentration of flurbiprofen during the alpha phase and the distribution volume of the central compartment of flurbiprofen were significantly higher in the lipid emulsion group than the control group (5.0- and 1.2-times, respectively). When FP-ax was administered at high FFA concentration, the free concentration of flurbiprofen and distribution of flurbiprofen to tissues increased transiently. This administration method may be useful for patients with cancer pain, having a potent analgesic effect.

Inhibition of carrier-mediated uptake of epirubicin reduces cytotoxicity in primary culture of rat hepatocytes.

Epirubicin, an antineoplastic drug, is considered to be taken up by tumor cells via a common carrier by facilitated diffusion and is then pumped out in an energy-dependent manner because epirubicin is a substrate for P-glycoprotein (P-gp). However, this study investigated the details of the influx mechanism of epirubicin and demonstrated that epirubicin uptake was mediated by active carrier systems in addition to facilitated diffusion in the primary culture of rat hepatocytes. The uptake of epirubicin gradually increased in a saturated manner when the concentrations were between 1 x 10(-7) M and 1 x 10(-6) M. In contrast, the uptake increased progressively in a linear manner when the concentration was high (greater than 1 x 10(-6) M). The uptake of epirubicin at a clinical concentration (7.5 x 10(-7) M) was significantly reduced at 4 degrees C and significantly inhibited when pretreated with metabolic inhibitors (carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), rotenone and sodium azide) by nearly 25%. Furthermore, an organic anion transporter inhibitor, namely, 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS); organic anion transport substrates, namely, para-aminohippurate (PAH), taurocholic acid and estradiol 17-beta-D-glucuronide; and organic cation transporter inhibitors, namely, verapamil and tetraethylammonium significantly reduced the uptake of epirubicin. Furthermore, pretreatment with verapamil and PAH significantly prevented epirubicin-induced reduction of proliferative activity in rat hepatocytes. These results indicated that the uptake of epirubicin was induced, at least in part, by the active transport protein in rat hepatocytes; the inhibition of the probable transport protein protected the intact normal cells from the injury induced by the cytotoxicity of epirubicin.