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Biomedical subjects

Eric Rubin

Publications and source records attributed to Eric Rubin.

At least 19 recordsLinked to original sources
PubMed2007

Gabapentin does not reduce smoked cocaine self-administration: employment of a novel self-administration procedure.

Previously, we reported that gabapentin, a nonselective gamma-aminobutyric acid agonist, reduced 'positive' subjective effects of cocaine without reducing cocaine self-administration. We speculated that the self-administration procedure used in that study was not sensitive to subtle shifts in the reinforcing effects of cocaine. Thus, this study examined the effects of gabapentin maintenance on cocaine self-administration using a purchase-cocaine choice procedure. During this 48-day inpatient/outpatient study, nontreatment-seeking cocaine abusers (n = 12) were maintained on gabapentin (0, 600, 1200 mg/day); four doses of cocaine (0, 12, 25, 50 mg) were each tested twice under each gabapentin condition. All cocaine testing was conducted while participants were inpatients. Before the start of each session, participants were provided with 25 dollars (five 5 dollar bills, one for each choice opportunity) and smoked the 'sample' cocaine dose once. Subsequently, participants were given five opportunities to purchase the sampled dose of cocaine (at 5 dollars per dose) or to keep 5 dollars for that choice trial. Choice to self-administer cocaine increased significantly with escalating cocaine doses; gabapentin maintenance did not alter choice to self-administer cocaine. These results concur with findings from our previous investigations of gabapentin and with those from a clinical trial examining the effects of larger gabapentin doses on cocaine use by treatment-seeking cocaine-dependent individuals. Together, the data indicate that gabapentin does not show promise as a treatment medication for cocaine dependence.

Adult↗
PubMed2006

Smoked cocaine self-administration by humans is not reduced by large gabapentin maintenance doses.

Previously, we reported that gabapentin, a lambda-aminobutyric acid (GABA) agonist, significantly reduced "positive" subjective effects of cocaine without reducing cocaine self-administration. We speculated that the gabapentin doses used in that study were too low to detect subtle shifts in the reinforcing effects of cocaine. Thus, the present study examined the effects of larger gabapentin maintenance doses on cocaine-related effects, including self-administration. During this 48-day double-blind, crossover design study, the effects of gabapentin maintenance (0, 2400, 3200 mg/day) on response to cocaine (0, 12, 25, 50 mg) were investigated in six cocaine-dependent individuals not seeking treatment for their cocaine use. Active cocaine significantly increased choice to self-administer cocaine, subjective-effect ratings (e.g., "Good Drug Effect"), blood pressure, and heart rate. Gabapentin did not decrease cocaine self-administration, cardiovascular measures, or most subjective effects of cocaine. These data agree with findings from a clinical trial examining the effects of similar gabapentin doses on cocaine use by treatment-seeking cocaine-dependent individuals and suggest that gabapentin does not show promise as a treatment medication for cocaine dependence.

Adult↗
PubMed2006

Concurrent cannabis use during treatment for comorbid ADHD and cocaine dependence: effects on outcome.

Cannabis is the most widely used illicit substance in the United States with especially high prevalence of use among those with psychiatric disorders. Few studies have examined the relationship between concurrent cannabis use and treatment outcome among patients receiving treatment for comorbid substance abuse and psychiatric disorders. This study investigated the effects of cannabis use on treatment retention and abstinence from cocaine among cocaine dependent patients with Attention Deficit Hyperactivity Disorder (ADHD). Cocaine dependent patients diagnosed with current ADHD (DSM-IV, N = 92) aged 25 to 51 participated in a randomized clinical trial of methylphenidate for treatment of ADHD and cocaine dependence in an outpatient setting. The majority of patients (69%) used cannabis during treatment. Results suggest that moderate/intermittent cannabis users had greater retention rates compared to abstainers and consistent users (p = .02). This study is the first to examine concurrent cannabis use in cocaine dependent patients diagnosed with ADHD.

Adolescent↗
PubMed2006

Severity of dependence and motivation for treatment: comparison of marijuana- and cocaine-dependent treatment seekers.

Although marijuana dependence is prevalent, most individuals with marijuana dependence do not seek treatment. There are few data characterizing treatment seeking marijuana-dependent patients compared to patients presenting for treatment of other drugs regarding the severity of illness and motivation for treatment. Forty-two marijuana-dependent individuals were compared to 58 cocaine-dependent individuals seeking treatment. Compared to cocaine-dependent patients, those with marijuana dependence were younger and less likely to be dependent on alcohol or other drugs. Both groups had similar rates of comorbid anxiety and affective disorders. Marijuana-dependent individuals had lower total number of dependence symptoms but had a higher percentage of individuals endorsing withdrawal symptoms. Although marijuana-dependent individuals had less outpatient treatment exposure, the difference between the two groups was not significant and motivation for change, based on the University of Rhode Island Change Assessment, was similar for both groups of treatment seekers. However, the Circumstances, Motivation, Readiness for Treatment Scale suggested that cocaine-dependent individuals were more motivated for treatment. Taken together, these data suggest that treatment seeking marijuana-dependent individuals have substantial withdrawal dependence symptomatology although it is less clear if they are as motivated to seek out treatment as cocaine-dependent treatment seekers.

Adult↗
PubMed2005

A phase I study of the dolastatin-15 analogue tasidotin (ILX651) administered intravenously daily for 5 consecutive days every 3 weeks in patients with advanced solid tumors.

PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicity, and pharmacokinetics of the dolastatin-15 analogue, tasidotin (ILX651), when administered i.v. daily for 5 days every 3 weeks. EXPERIMENTAL DESIGN: Thirty-six patients with advanced solid tumors received a total of 114 courses through eight dose levels ranging from 2.3 to 36.3 mg/m(2). Pharmacokinetic samples were collected in cycle 1. RESULTS: Neutropenia was the principal dose-limiting toxicity at 36.3 mg/m(2)/d along with grade 3 ileus and elevated aspartate amino transaminase/alanine amino transaminase (n = 1). At the maximum tolerated dose, 27.3 mg/m(2), 4 of 14 patients experienced dose-limiting grade 4 neutropenia. The other principal toxicities consisted of mild-to-moderate elevated transaminases, alopecia, fatigue, and nausea. One patient with melanoma metastatic to liver and bone treated at 15.4 mg/m(2)/d experienced a complete response and received 20 courses of tasidotin. Two other patients with melanoma had mixed responses of cutaneous metastases at 27.3 mg/m(2)/d associated with either stable or progressive visceral disease. In addition, nine patients had stable disease. There was no accumulation of tasidotin following repeated daily dosing. Tasidotin decayed from plasma in a biphasic fashion with a half-life of <45 minutes in most cases. CONCLUSION: The maximum tolerated dose and recommended phase II dose for tasidotin when administered on this schedule was 27.3 mg/m(2)/d. The favorable toxicity profile of tasidotin compared with other antitubulin agents (particularly the lack of severe cumulative neuropathy, peripheral edema, and fatigue), the observed antitumor activity of tasidotin, and its novel mechanism of action support further disease-directed evaluations of this agent on this 5-day schedule every 3 weeks.

Adult↗
PubMed2005

A randomized placebo-controlled trial of gabapentin for cocaine dependence.

BACKGROUND: In laboratory animals, augmentation of GABA neurotransmission results in inhibition of cocaine self-administration and inhibition of reinstatement to cocaine-seeking behaviors. If parallel effects were observed in humans, GABA-ergic medication should be effective both in the abstinence-induction as well as in the relapse-prevention phase of cocaine dependence treatment. Gabapentin is an anticonvulsant medication that increases human brain GABA levels. We evaluated the safety and efficacy of gabapentin combined with relapse-prevention therapy in the treatment of cocaine-dependent individuals. DESIGN: The study involved 129 individuals with cocaine dependence. Of the 99 participants, who were randomized into a double-blind trial 88% were males, 66% were minorities and with an average age of 39 years (range 22-58 years). After 2 weeks of placebo lead-in, participants were randomized to receive either gabapentin 3200 mg (1600 mg bid) or placebo for 12 weeks, followed by 2 weeks of placebo lead-out. Prior to randomization, participants were stratified into four groups based on the principal route of cocaine use (smokers versus intranasal users) and the level of cocaine use during the 2 weeks of lead-in (high level versus low level). Throughout the 16 weeks study, participants received weekly individual relapse-prevention therapy. The outcome measures included: days of cocaine use and a binary indicator of abstinence based on urine toxicology test, self-reported cocaine craving and retention in treatment. RESULTS: Forty-nine percent of randomized patients completed 12 weeks of the trial. Retention did not differ by treatment group but cocaine-smokers dropped out of treatment at a significantly faster rate than intranasal users. For the entire sample, odds of cocaine use over the course of the study did not differ between gabapentin- and placebo-treated individuals. There was a significant difference in the odds of cocaine use between high and low-use groups, with the odds in high-use groups decreasing over time and odds in the low-use groups gradually increasing over the course of the study, such that by the end of the study low and high users were similarly likely to use cocaine. In the low-use group, there was a non-significant trend suggesting that gabapentin-treated subjects had more favorable outcome compared to placebo-treated individuals. There was no treatment effect on abstinence rates, craving or other substance use. Gabapentin at 3200 mg/day was very well tolerated in this group of cocaine-dependent participants. CONCLUSIONS: When combined with weekly individual relapse-prevention therapy, gabapentin 1600 mg bid was no more effective than placebo in the treatment of cocaine dependence. When reviewed in conjunction with other published studies, gabapentin and other GABA enhancing anticonvulsant medications may deserve further study as relapse-preventive agents in cocaine-dependent individuals who achieve abstinence early in treatment.

Adult↗
PubMed2005

Temperament characteristics, as assessed by the tridimensional personality questionnaire, moderate the response to sertraline in depressed opiate-dependent methadone patients.

During a randomized, double-blind, placebo controlled study of the effects of sertraline in depressed methadone-maintained patients, 82 completed the tridimensional personality questionnaire (TPQ) to assess whether temperament dimensions can affect treatment-related changes in mood and drug use. Mood outcome significantly differed according to scores on the reward dependence scale (RD). Low RD participants displayed a significantly better mood response to sertraline than high RD participants. Participants with high harm avoidance (HA) scores were more likely to be abstinent at the end of the 12 week trial of sertraline than low HA participants. High persistence (P) participants were less likely to be abstinent at the end of the 12-week trial. These results suggest that temperament dimensions may be important for identifying substance dependent patients more likely to benefit from pharmacological interventions for comorbid depressive disorders.

Adult↗
PubMed2005

Mycobacterium tuberculosis and the host response.

Mycobacterium tuberculosis remains a leading cause of morbidity and mortality worldwide. Advances reported at a recent international meeting highlight insights and controversies in the genetics of M. tuberculosis and the infected host, the nature of protective immune responses, adaptation of the bacillus to host-imposed stresses, animal models, and new techniques.

Animals↗
PubMed2005

Utility of lead-in period in cocaine dependence pharmacotherapy trials.

We examined whether drug use behaviors during a 2-week lead-in for a pharmacotherapy trial were predictive of retention in treatment and of the level of cocaine use during the subsequent 12 weeks of treatment. Fifty cocaine dependent patients were grouped based on: (1) principal route of cocaine administration: intranasal versus smoking, and (2) level of cocaine use during the 2-week lead-in: high versus low. Results indicate that level of cocaine use during the 2-week lead-in was a significant predictor of cocaine use during the subsequent 12 weeks of treatment. Patients with reported higher level of use during the lead-in period were more likely to continue using cocaine during the treatment. Patients who used smoking as their primary route of cocaine use were more likely to drop out early in the treatment. Findings of this study suggest that route and level of cocaine use during lead-in be used as a covariate in models testing treatment effect.

Adult↗
PubMed2004

Membrane transport of camptothecin: facilitation by human P-glycoprotein (ABCB1) and multidrug resistance protein 2 (ABCC2).

BACKGROUND: The purpose of the present study was to continue the investigation of the membrane transport mechanisms of 20-(S)-camptothecin (CPT) in order to understand the possible role of membrane transporters on its oral bioavailability and disposition. METHODS: The intestinal transport kinetics of CPT were characterized using Caco-2 cells, MDCKII wild-type cells and MDCKII cells transfected with human P-glycoprotein (PGP) (ABCB1) or human multidrug resistance protein 2 (MRP2) (ABCC2). The effects of drug concentration, inhibitors and temperature on CPT directional permeability were determined. RESULTS: The absorptive (apical to basolateral) and secretory (basolateral to apical) permeabilities of CPT were found to be saturable. Reduced secretory CPT permeabilities with decreasing temperatures suggests the involvement of an active, transporter-mediated secretory pathway. In the presence of etoposide, the CPT secretory permeability decreased 25.6%. However, inhibition was greater in the presence of PGP and of the breast cancer resistant protein inhibitor, GF120918 (52.5%). The involvement of additional secretory transporters was suggested since the basolateral to apical permeability of CPT was not further reduced in the presence of increasing concentrations of GF120918. To investigate the involvement of specific apically-located secretory membrane transporters, CPT transport studies were conducted using MDCKII/PGP cells and MDCKII/MRP2 cells. CPT carrier-mediated permeability was approximately twofold greater in MDCKII/PGP cells and MDCKII/MRP2 cells than in MDCKII/wild-type cells, while the apparent Km values were comparable in all three cell lines. The efflux ratio of CPT in MDCKII/PGP in the presence of 0.2 microM GF120918 was not completely reversed (3.36 to 1.49). However, the decrease in the efflux ratio of CPT in MDCKII/MRP2 cells (2.31 to 1.03) suggests that CPT efflux was completely inhibited by MK571, a potent inhibitor of the Multidrug Resistance Protein transporter family. CONCLUSIONS: The current results provide evidence that PGP and MRP2 mediate the secretory transport of CPT in vitro. However, the involvement of other transporters cannot be ruled out based on these studies. Since these transporters are expressed in the intestine, liver and kidney variations in their expression levels and/or regulation may be responsible for the erratic oral absorption and biliary excretion of CPT observed in human subjects.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

A phase I trial of weekly paclitaxel, 13- cis-retinoic acid, and interferon alpha in patients with prostate cancer and other advanced malignancies.

PURPOSE: Based on prior studies demonstrating the effect of 13- cis-retinoic acid and interferon alpha (CRA/IFN) in decreasing the expression of the antiapoptotic protein bcl-2, our prior clinical study of CRA/IFN with paclitaxel (TAX) administered every 3 weeks, and data demonstrating increased activity of weekly TAX against prostate cancer, we designed a phase I study of weekly TAX in combination with CRA/IFN in patients with prostate cancer and other advanced malignancies. To develop a marker of drug effect, we assessed bcl-2 downregulation in patient peripheral blood mononuclear cells (PBMC). METHODS: Enrolled in the study were 14 patients with prostate cancer or other advanced malignancies, and 13 were treated with 1 mg/kg CRA on days 1 and 2, 6 MU/m(2) IFN subcutaneously on days 1 and 2, and TAX at increasing doses on day 2 each week for 6 weeks out of an 8-week cycle. The effect of CRA/IFN on bcl-2 expression was assessed in PBMCs by immunoblotting. RESULTS: The combination of CRA/IFN and TAX was well tolerated. Dose-limiting toxicities (DLT) in the first cycle of therapy included one patient with fever and neutropenia, and one patient with grade 4 hypertriglyceridemia. The recommended phase II dose of TAX in this combination was 80 mg/m(2). Of 13 patients assessable by tumor markers or scans, 5 had stable disease and 2 had a biochemical partial response including a patient with a decrease in PSA of >50% while on study. The assessment of patient PBMC bcl-2 was feasible in ten patients. CONCLUSIONS: This is the first study in which the safety and clinical activity of weekly TAX combined with CRA/IFN has been demonstrated. The assessment of PBMC bcl-2 is feasible in this weekly chemotherapy schedule

Aged↗
PubMed2003

Gemcitabine combined with sequential paclitaxel and carboplatin in patients with urothelial cancers and other advanced malignancies.

BACKGROUND: To investigate a novel schedule of gemcitabine (G), paclitaxel (P), and carboplatin (C), based on preclinical studies demonstrating greater activity and decreased toxicity of administering P prior to C. MATERIAL/METHODS: The effect of the P and C drug sequence on tumor cell viability was assessed with a tetrazolium assay on T24 bladder and DU145 prostate cancer cells. Patients with transitional cell cancer (TCC) and other advanced malignancies were treated with G and P on days 1, 8, and 15 of each 28 day cycle. C was administered on day 2 at an AUC of 5. Doses of G and P were varied among cohorts of three patients. RESULTS: Preclinical studies demonstrated that the sequence of P followed by C induced greater cytotoxicity than the reverse sequence. The recommended phase II dose (RPTD) was defined as 70 mg/m2 P, 300 mg/m2 G, and C with AUC of 5. Therapy was well tolerated; fever and neutropenia occurred in only one patient at the RPTD. Grade 3 thrombocytopenia occurred in 5 of 21 patients treated at the RPTD. Out of all 37 patients treated on study, 9 achieved a partial tumor response (PR) and two patients achieved a complete response (CR). Out of the 15 patients with TCC, six had a PR and two had a CR. CONCLUSIONS: Preclinical studies demonstrated that the sequence of paclitaxel followed by carboplatin was more effective than the opposite sequence. Administration of gemcitabine and paclitaxel followed by carboplatin was well tolerated and clinically active. GCP should be compared to other combination regimens under investigation for the treatment of TCC.

Adult↗
PubMed2003

A phase I and pharmacologic study of the combination of marimastat and paclitaxel in patients with advanced malignancy.

BACKGROUND: Marimastat is a potent inhibitor of matrix metalloproteinases and in preclinical studies enhances the anti-tumor activity of certain chemotherapeutics. We performed a phase I clinical evaluation of the combination of oral marimastat and intravenous paclitaxel, to determine if these drugs could be co-administered safely, and to determine whether marimastat alters paclitaxel pharmacokinetics. MATERIAL/METHODS: Marimastat was administered twice daily and paclitaxel as a three hour infusion every three weeks. Doses of both marimastat and paclitaxel were escalated in cohorts of patients up to maximal doses of 10 mg for marimastat and 175 mg/m2 for paclitaxel. Paclitaxel plasma pharmacokinetic parameters were assessed in the absence (cycle 1) and presence (cycle 2) of marimastat. Trough marimastat plasma levels were evaluated during cycle 2. RESULTS: A total of 19 patients were treated at three different dose levels. There were no dose-limiting toxicities during the first cycle of therapy, resulting in dose escalation up to the planned maximal dose for each drug. Neutropenia was the most common significant toxicity at the highest dose level, with grade 3 or higher neutropenia occurring in 38% of patients. There were no complete or partial responses. Pharmacokinetic analyses indicate that marimastat does not alter paclitaxel clearance. At the 10 mg dose, the mean trough marimastat level was 14.8 Kg/L. CONCLUSIONS: Marimastat and paclitaxel can be co-administered safely at doses equivalent to those recommended for single-agent administration. Additional studies are necessary to determine whether this combination is more effective in controlling tumor progression than paclitaxel alone.

Adult↗
PubMed2002

Pilot study of gemcitabine (10 mg/m(2) per min) and cisplatin.

PURPOSE: Gemcitabine and cisplatin are routinely used in combination. In this combination, gemcitabine at conventional doses of 1000-1500 mg/m(2) is delivered weekly as a 30-minute bolus. Laboratory data suggest that the synthesis of gemcitabine triphosphate is saturable, and that gemcitabine infused at a rate of 10 mg/m(2) per min optimizes accumulation of the triphosphate. Early clinical experience suggests that gemcitabine delivered by a more prolonged infusion is more myelosuppressive. In this pilot study, we wished to assess if full-dose gemcitabine when given with cisplatin could be delivered by this more prolonged infusion. METHODS: In this study, all patients received cisplatin 75 mg/m(2). All gemcitabine doses were delivered at 10 mg/m(2) per min. For the initial cohort (level 1) the gemcitabine dose was 800 mg/m(2) per min. Subsequent escalations were 1000 mg/m(2) per min (level 2), and 1250 mg/m(2) per min (levels 3 and 4). For the first three cohorts, patients received gemcitabine on days 1, 8, and 15 and cisplatin on day 15 on a 28-day cycle. Patients on level 4 received gemcitabine on days 1 and 8 and cisplatin on day 8 on a 21-day cycle. Dose omissions or delays (holds) were mandated for NCI CTC grade 3 or 4 granulocytopenia or grade 2-4 thrombocytopenia. RESULTS: Entered onto this dose-finding study were 23 patients (12 male, 11 female) with advanced solid tumors. Seven patients were treatment-naive. Six patients were treated on level 1, five each on levels 2 and 3 and seven on level 4. Patients received one to seven cycles of treatment. Myelosuppression-related dose holds occurred at all levels. First-cycle dose holds occurred in three of six, four of five, three of five and two of seven patients on successive levels. First-cycle grade 3 or 4 granulocytopenia/thrombocytopenia occurred in three patients on level 1, one patient on level 2, two patients on level 3 and three patients on level 4. There were no partial or complete responses. Four patients were removed for toxicity (three myelosuppression, one nephrotoxicity), one at physician discretion, and 15 with disease progression. Three patients stopped therapy with stable disease after 5-6 months. On level 3, three of five patients remained on therapy for 4 months or more, compared to only one patient on each of the other three levels. CONCLUSIONS Weekly gemcitabine 1250 mg/m(2), utilizing a 10 mg/m(2) per min infusion rate, can be delivered with cisplatin 75 mg/m(2) with tolerable toxicity. When used in combination with cisplatin, however, the benefit of this fixed dose rate infusion gemcitabine compared to standard bolus gemcitabine remains to be determined.

Adult↗
PubMed2002

Characterization of a novel prostate-specific antigen-activated peptide-doxorubicin conjugate in patients with prostate cancer.

PURPOSE: To evaluate safety and pharmacokinetics (PK), and determine the recommended dose for efficacy studies, of L-377202, a novel peptide conjugate of doxorubicin (Dox) that releases the active metabolites leucine-doxorubicin (Leu-Dox) and Dox on cleavage by membrane-bound prostate-specific antigen (PSA). PATIENTS AND METHODS: Nineteen patients with advanced hormone-refractory prostate cancer were treated intravenously with 71 cycles of L-377202 at escalating dose levels of 20 (n = 1), 40 (n = 3), 80 (n = 4), 160 (n = 3), 225 (n = 6), and 315 mg/m(2) (n = 2) once every 3 weeks. Toxicity, response, and PK of L-377202 were assessed. RESULTS: L-377202 was well tolerated. Dose-limiting grade 4 neutropenia was noted in two of two patients administered 315 mg/m(2) (both patients were able to resume therapy at 225 mg/m(2)). The recommended dose for efficacy studies was 225 mg/m(2), which induced grade 4 neutropenia in one of six patients. PK studies demonstrated that L-377202 was metabolized to Leu-Dox and Dox. PK were linear; after administration of single doses of 225 mg/m(2), the mean area under the concentration-time profiles of L-377202, Leu-Dox, and Dox were 6 micromol x L/h, 4 micromol x L/h, and 1 micromol x L/h, and peak concentrations were 14 micromol/L, 5 micromol/L, and 120 nmol/L, respectively. At 225 and 315 mg/m(2), five patients completed at least three cycles of therapy; two patients had a greater than 75% decrease in PSA, and one patient had a stabilized PSA. No response was noted at dose levels less than 225 mg/m(2). CONCLUSION: This is the first study of selective drug delivery in humans using a novel PSA-activated agent. L-377202 was cleaved to produce detectable levels of the active metabolites Leu-Dox and Dox. L-377202 was well tolerated and established a safe dose level for further study.

Aged↗
PubMed2002

Intestinal transport of irinotecan in Caco-2 cells and MDCK II cells overexpressing efflux transporters Pgp, cMOAT, and MRP1.

Irinotecan (CPT-11) is a water-soluble camptothecin (CPT) derivative that has been recently approved in the United States for patients as a first-line therapy in advanced colorectal cancer. Phase I clinical trials using oral CPT-11 have shown poor and variable oral bioavailability. The present study was designed to investigate the intestinal absorption and efflux mechanisms of CPT-11 using in vitro cell culture models, Caco-2 cells, and engineered Madine-Darby canine kidney (MDCK) II cells overexpressing P-glycoprotein (Pgp), canalicular multispecific organic anion transporter (cMOAT), and multidrug resistance-associated protein (MRP1). The intestinal absorptive and secretory transport of CPT-11 was investigated using Caco-2 cell monolayers. Secretory transport was concentration-dependent and saturable. The secretory efflux permeability (P(eff)) of CPT-11 decreased with decreasing temperature, with an estimated activation energy of 19.6 +/- 2.9 kcal/mol suggesting the involvement of active transporters. The involvement of potential secretory transporters was further characterized in MDCK II cells. The secretory efflux carrier permeability (P(c)) was approximately 4- and approximately 2-fold greater in MDCK II/Pgp and MDCK II/cMOAT cells than that in MDCK II/wild-type cells. Furthermore, the secretory efflux P(eff) of CPT-11 was significantly decreased by Pgp inhibitors, elacridar (GF120918) (IC50 = 0.38 +/- 0.06 microM) and verapamil (IC(50) = 234 +/- 48 microM) in MDCK II/Pgp cells and by cMOAT inhibitor 3-([(3-(2-[7-chloro-2-quinolinyl]ethyl)phenyl]-[(3-dimethylamino-3-oxoprphyl)-thio)-methyl]-thio) propanoic acid (MK571) (IC50) = 469 +/- 60 micro;M) in MDCK II/cMOAT cells. Overall, the current study suggests that Pgp and cMOAT are capable of mediating the efflux of CPT-11 in vitro. Since both Pgp and cMOAT are expressed in the intestine, liver, and kidney, it is likely that these efflux transporters play a significant role limiting the oral absorption and disposition of this important anticancer drug.

ATP Binding Cassette Transporter, Subfamily B, Mem↗