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PubMed1982

[P-hydroxyphenylacetic acid concentrations in cerebrospinal fluid].

Using reversed-phase high-performance liquid chromatography and electrochemical detection with a rapid one-step purification on Sephadex G-10 column, we have developed a sensitive technique to measure p-hydroxyphenylacetic acid (PHPA), the oxidatively deaminated metabolite of p-tyramine, in cerebrospinal fluid (CSF). The method has been shown to offer simplicity, high sensitivity and low cost for the analysis of PHPA. By using this method PHPA can be measured concurrently with the dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in small amounts of CSF (0.5 ml or less). The concentrations of PHPA ranged 4.2 to 17.0 ng/ml with a mean value of 7.8 ng/ml+/-1.1 SEM in lumbar CSF of non-neurological control patients. PHPA value is consistent with the results of earlier studies using different methods. PHPA concentrations in both schizophrenic (4.7+/-0.6 ng/ml, n=11) and epileptic patients (5.8+/-0.4 ng/ml, n=28) were significantly lower than those in control patients. A concentration gradient of PHPA was found along the ventricular-lumbar axis. Probenecid markedly increased PHPA in lumbar CSF. These observations suggest that PHPA in lumbar CSF is derived at least in part from the brain and eliminated from CSF by a probenecid-sensitive transport mechanism. There was a significant correlation between PHPA and HVA concentrations in CSF. This is an interesting finding since a reciprocal relationship between dopamine turnover and p-tyramine concentrations has been found in the striatum of experimental animals. A number of recent studies suggest that p-tyramine may act as neurotransmitter or neuromodulator in specific neuronal systems. The present method should be useful in clinical investigations to clarify a functional role of p-tyramine in the brain.

Adolescent↗
PubMed1981

Structural specificity in the renal tubular transport of tyrosine.

The structural requirements for aromatic amino acid reabsorption and secretion in the dog were investigated using a series of tyrosine analogs. In clearance experiments, l-tyrosine and l-phenylalanine underwent net reabsorption at rates 5 to 6 times greater than those of the corresponding d-enantiomers and about 1.5 time those of o- and m-dl-tyrosine. 3-(p-hydroxyphenyl)Propionic acid underwent net secretion under conditions of polyuria and high urinary pH and net reabsorption under conditions of oliguria and low pH. In stop-flow experiments, (U/Pl-amino acid)/(U/Pln) ratios, where U/P = concentration in urine and plasma and In = inulin, of proximal tubular samples were 1.5 to 5-fold greater than the control (free-flow) values of 0.1 to 0.3, indicating tubular secretion. Secretion was inhibited, and net reabsorption enhanced, by probenecid, p-aminohippuric acid and 2,4-dinitrophenol. (U/Pd-amino acid)/(U/PIN) ratios of proximal tubular samples were below the control values of 0.6 to 0.8, indicating tubular reabsorption. Probenecid had no effect on the overall pattern but caused a slight decrease in the relative clearance values. The stop-flow pattern of 3-(p-hydroxyphenyl)propionic acid excretion was similar to that of the I-amino acids. It was concluded that the I-amino acids undergo bidirectional transport and that the I-configuration and amino group are required for optimal active reabsorption, whereas ring hydroxylation has little effect on reabsorption transport. No absolute structural requirements for active secretion were elucidated.

Absorption↗
PubMed1995

Specificity of p-aminohippurate transport system in the OK kidney epithelial cell line.

Substrate specificity of the p-aminohippurate (PAH) transport system was investigated in the OK kidney epithelial cells. PAH uptake by OK cells from the basal side was inhibited by beta-lactam antibiotics such as benzylpenicillin (PCG) and cefazolin. The inhibition of PAH uptake by PCG was competitive and the Ki value was calculated as 108.8 microM. Transcellular transport of PCG across OK cell monolayers occurred unidirectionally from the basal to apical side, and transcellular transport and basolateral uptake were inhibited by PAH, probenecid and beta-lactam antibiotics. The basolateral uptake of cefazolin and cefotiam was also inhibited by PAH and probenecid. The basolateral uptake of PAH and PCG were not affected by aliphatic dicarboxylates with 3 or 4 carbon atoms, but were strongly inhibited by those with 5 or 6 carbon atoms. The inhibitory effect became weaker for a longer dicarboxylate with 7 carbon atoms, then increased again with increasing number of carbon atoms. Such a pattern of inhibition by dicarboxylates is essentially the same with that observed in rat renal proximal tubules in situ. These findings suggest that the PAH transport system in OK cells has a substrate specificity similar to that in rat renal proximal tubules, which is involved in the active secretion of various organic anions including drugs.

Animals↗
PubMed1994

Characterization of and the influence of calcium channel blockers on the renal excretion of pyrimidine anticancer agents.

The renal handling of two anticancer (a-Ca) pyrimidines 5-fluorodeoxyuridine (FUdR) and 5-fluorouracil (5-FU) was investigated in clearance experiments in CF-1 mice using specific inhibitors of classical renal transport systems. The 5-FU was derived from the metabolism of FUdR. Based on the FUdR:inulin clearance ratio and 5-FU:inulin clearance ratio, it was determined that FUdR was secreted into renal tubules while 5-FU underwent reabsorption. The secretion of FUdR was inhibited by cimetidine and dipyridamole but not by probenecid or phloridzin. While the clearance ratio of 5-FU:inulin was significantly reduced by phloridzin, it (i.e., the ratio) was not affected by cimetidine, dipyridamole, or probenecid. The impact of two calcium channel blockers, diltiazem (DZM) and verapamil (VER), on the renal handling of FUdR and 5-FU was also examined. VER increased the secretion of FUdR without affecting the reabsorption of 5-FU while DZM slightly decreased the secretion of FUdR and prevented the reabsorption of 5-FU. These data suggest that the organic cation carrier and a dipyridamole-sensitive nucleoside transporter are involved in the renal excretion of FUdR; that the renal transport of both FUdR and 5-FU is associated with the calcium channel; and that 5-FU utilizes, at least in part, the glucose transporter for its reabsorption.

Absorption↗
PubMed1976

Amoxycillin in single oral dose for uncomplicated gonorrhoea.

One hundred and sixty-two cases of uncomplicated gonorrhoea were treated with 3g of amoxycillin swallowed in front of an observer. The failure rate of 2.1 percent was low, but did not reach the effectiveness of the standard gonopen probenecid regime, with which failures are a rarity. There were no side effects. It is suggested that 3g of amoxycillin be combined with 1g of probenecid as the treatment of choice, if an oral treatment regime is chosen.

Administration, Oral↗
PubMed1993

Pharmacokinetics of gyrase inhibitors, Part 2: Renal and hepatic elimination pathways and drug interactions.

This article focuses on the relationship of the physicochemical properties of gyrase inhibitors to their hepatic and renal elimination pathways. Luminal fluid concentrations of gyrase inhibitors are affected by an active process and can be inhibited by agents such as probenecid that inhibit tubular secretion of anions. Probenecid may inhibit base transport in the proximal tubule and appears to inhibit base transport as well. Available data suggest that all gyrase inhibitors can be secreted as anions by the proximal tubules. Cimetidine, which is cationic at physiologic pH, inhibits base transport in the proximal tubule and appears to inhibit base transport of gyrase inhibitors. Reabsorption also affects tubular concentrations. Models that describe the effects of urinary flow and pH are discussed. The N4'-methylated derivatives are the most lipophilic, and addition or removal of the methyl group can, but does not always, affect reabsorption. The data indicate that all gyrase inhibitors undergo tubular secretion as either acids or bases and that some also are significantly reabsorbed. Hepatic handling and resultant excretion of metabolites are also influenced by the presence or absence of N4'-methylation. A step in the hepatic handling of N4'-methylated gyrase inhibitors that leads to N4'-oxidation has not yet been found in rufloxacin. Rebiotransformation of N4'-oxides was described in liver perfusion experiments. The potential for interaction with theophylline is not identical for all gyrase inhibitors. Enoxacin is the strongest inhibitor of theophylline and caffeine metabolism, followed by tosufloxacin, ciprofloxacin, and pefloxacin. Fleroxacin, ofloxacin, rufloxacin, and sparfloxacin have no or negligible effects. A likely mechanism for this interaction is the inhibition of subsets of the cytochrome P-450 enzyme. Structure activity relationships were established for this interaction. Piperazine ring-cleaved compounds and naphthyridine nuclei were shown to be most active inhibitors of cytochrome P-4501A2. The effect of various substituents was also tested, leading to an equation that predicts inhibition of 3-caffeine demethylation. Piperazine ring-cleaved compounds are more inhibitory than parent compounds, and a nitrogen at position 4 or 7, respectively, reduces or increases inhibitory activity. Data on interactions of rifampin and cyclosporine with gyrase inhibitors are conflicting. Rifampin increases the clearance of fleroxacin but does not change the elimination half-life significantly. Although norfloxacin may interfere with metabolism of the S enantiomer of warfarin, fleroxacin does not affect pharmacokinetics of either the R or S enantiomer or the anticoagulant response.(ABSTRACT TRUNCATED AT 400 WORDS)

4-Quinolones↗
PubMed1993

Gout: modern management of an ancient malady.

If Dr. Sydenham could have benefited from today's therapy, he likely would not have had to endure thirty years of "violent ... torture" that gave birth to his most elegant and classic description of acute gout. The five key points to remember in management of the gouty spectrum are: (1) Establish the diagnosis as clearly as possible or as clearly as seems necessary under the clinical circumstances (i.e. arthrocentesis with crystal analysis to establish diagnosis is not always necessary with reliable patients when septic joint seems highly unlikely). (2) Treat acute attacks with NSAIDs alone or perhaps steroids--or rarely IV colchicine under special circumstances. (3) DO NOT START ALLOPURINOL OR PROBENECID DURING AN ACUTE FLARE OF GOUT--IT MAY MAKE THE EPISODE WORSE. (4) The pattern of disease over time (frequency and severity of attacks) determines whether or not one decides to use an agent such as allopurinol, probenecid, or prophylactic colchicine chronically once a patient is over the acute attack--the mere presence of increased uric acid and a single or rare gouty attack would not usually require any other than the appropriate acute therapy. (5) The presence of visible tophi, uric acid renal calculi and destructive gouty arthritis nearly always warrant uric acid lowering therapy.

Allopurinol↗
PubMed1996

Quantification of phenylbutazone in equine sera by use of high-performance liquid chromatography with a nonevaporative extraction technique.

OBJECTIVE: To develop a sensitive, rugged high-performance liquid chromatography (HPLC) method for the measurement of phenylbutazone (PBZ) in equine sera, using a rapid, nonevaporative extraction technique. SAMPLE POPULATION: Sera from 5 nonexercising adult horses. PROCEDURE: After addition of sodium chloride and acetonitrile to serum samples, reverse-phase HPLC analysis for PBZ and oxyphenbutazone (OXY) was performed directly on extracts, using diode array UV spectrophotometric detection. Probenecid was used as an internal standard. Data were evaluated by standard means of statistical analysis. RESULTS: Recoveries of PBZ, OXY, and probenecid from spiked samples were acceptable (ie, > or = 80%) and within run retention times were reproducible. Chromatograms were free of interfering substances, and linearity of calibration curves was observed throughout operational ranges. Coefficients of variation at each fortified PBZ concentration were in the 5 to 10% range. The method was applicable to analysis of PBZ and OXY in serum extracts from horses dosed with PBZ (4.4 mg/kg of body weight, IV) in a controlled environment. Track samples analyzed by use of this method and a conventional liquid/liquid extraction method gave comparable results (mean deviation, 1.6%) for PBZ concentrations. CONCLUSION: The HPLC protocol described is suitable for measuring PBZ and OXY in equine sera to regulate PBZ administration in horses involved in pari-mutuel racing.

Animals↗
PubMed1977

Hemodynamic and natriuretic effects of bumetanide and furosemide in the cat.

Renal hemodynamic and natriuretic effects of bumetanide and furosemide were studied by clearance and micropuncture methods in cats. Furosemide (0.04-5.0 mg/kg i.v.) effects increased with increasing doses up to a maximal fractional sodium (FEna) and water (V/GFR) excretion of 23%. GFR and superficial single nephron GFR remained constant. Renal blood flow (RBF) increased up to 45% over control. A preferential increase in outer cortical RBF occurred at 5.0 mg/kg. Bumetanide (0.001-0.14 mg/kg i.v.) raised FEna and V/GFR maximally by 26%. Only at a supramaximal dose (0.69 mg/kg) did bumetanide raise RBF and depress filtration fraction. Probenecid (50 mg/kg i.v.) failed to block the natriuretic effect of bumetanide (0.025 microgram/kg-min) when infused into one renal artery but abolished the natriuretic action of furosemide (1.0 microgram/kg-min). Probenecid failed to displace the dose-response curve for bumetanide.

Animals↗
PubMed1997

Cidofovir use in acyclovir-resistant herpes infection.

Herpes infections continue to be prevalent, especially in immunocompromised patients. Some of these patients will develop resistant HSV infections. Therefore, it is important to explore new treatment options. Animal studies have shown cidofovir to be effective in the treatment and prevention of HSV infections. Human data are limited, with only one randomized, double-blind, placebo-controlled trial performed to date. The results from this study look promising; however, due to the small sample size, a larger clinical trial is warranted. The human data available as case reports are suboptimal in the quality of reporting time frames for resolution of lesions/symptoms and outcomes of therapy. Another problem with the case report data is that the TK status of the herpes simplex isolates was not reported. This would have helped substantiate the acyclovir resistance seen in these patients. It was evident in these case reports that acyclovir resistance can be overcome, as acyclovir-resistant strains became sensitive following cidofovir therapy. This may be because TK(+) viruses have been shown to establish latency more readily than do TK(-) viruses. This pattern suggests that alternating between acyclovir and cidofovir therapies may provide a strategy to manage the emergence of alternatively acyclovir-sensitive and -resistant infections. At present, only the intravenous formulation of cidofovir is commercially available. Advantages of the intravenous formulation include weekly dosing and efficacy. Disadvantages are the complexity of administration and the adverse effect profile. The most common adverse effects with this formulation include nephrotoxicity manifested as proteinuria (12%), and increased creatinine (5%) and neutropenia (15%). Administration of probenecid and NaCl 0.9% hydration are used to reduce the incidence and severity of nephrotoxicity in patients who are receiving cidofovir. Probenecid also has toxicities, including nausea, vomiting, headache, fever, and flushing. The topical formulation of cidofovir looks promising for mucocutaneous HSV infection because it is usually undetectable in the blood following topical administration. Therefore, systemic adverse effects should be minimized. A cidofovir gel product (Forvade, Gilead Sciences) is currently being reviewed by the Food and Drug Administration for the treatment of refractory HSV. Ultimately, more controlled clinical studies are necessary to determine whether routine cidofovir use can be justified in patients with acyclovir-resistant HSV infection.

Acyclovir↗
PubMed1998

Pgp and MRP activities using calcein-AM are prognostic factors in adult acute myeloid leukemia patients.

Thirteen cell lines with different levels of Pgp and MRP expression were used to assess the ability of calcein acetoxymethyl ester (calcein-AM) uptake and calcein efflux to measure Pgp and MRP functions, respectively. There was a good correlation between MRP expression and the modulatory effect of probenecid (a specific modulator of MRP) on the calcein efflux (r = .91, P = .0003) and between Pgp expression and the modulatory effect of CsA on calcein-AM uptake (r = .96, P < .0001). In light of the high correlations for both proteins, we tested calcein-AM uptake and efflux in fresh myeloid leukemic cells. In 53 acute myeloid leukemia (AML) patients, there was also a good correlation between MRP expression (measured by reverse transcription-polymerase chain reaction and by MRPm6 expression by flow cytometry) and the modulatory effect of probenecid on the calcein fluorescence (r = .92, P < .0001) and between Pgp expression as measured by UIC2 antibody binding on flow cytometry and the modulatory effect of cyclosporin A on calcein-AM uptake (r = .83, P < .0001). Pgp activity was higher in CD34+ leukemia than in CD34- leukemia (2.26 +/- 1.50 v 1.46 +/- 1.21, respectively; P = .003), and MRP activity was higher in CD34- leukemia than in CD34+ leukemia (1.77 +/- 0.40 v 1.4 +/- 0. 29, respectively; P = .004). Pgp expression and activity (P = .004 and P = .01, respectively) and MRP activity (P = .03) but not MRP expression were prognostic factors for achievement of complete remission. These results suggest that functional testing (with calcein-AM +/- modulators) for the presence of both MRP and Pgp activities is of prognostic value and that MRP contributes to drug resistance in AML.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1984

Experimental retinal detachment. VI. The permeability of the blood-retinal barrier.

Fluorophotometry was used to study the permeability of the blood-retinal barrier in six monkeys with stable rhegmatogenous retinal detachments. Fluorescein transport was inhibited by probenecid. The rate of fluorescein disappearance (KvVv) was determined following intravitreal injection. In a separate experiment the equilibrium vitreous-plasma concentration ratio (Cv/Cp) was determined following intraperitoneal administration. Expressed in equivalent volumes of vitreous, the rate of fluorescein diffusion across the blood-retinal barrier (K'vVvCv/Cp) was 0.29 microL/min in control eyes and 0.73 microL/min in detached eyes. The rate of fluid movement across the blood-retinal barrier (K'vVv) [1 - (Cv/Cp)] was 2.89 microL/min in control eyes and 6.38 microL/min in detached eyes. Posterior movement of fluid contributes to retinal apposition under normal conditions and accounts for the rapid resolution of retinal detachment following closure of the retinal hole.

Animals↗
PubMed1975

Cerebrospinal fluid amine metabolites in acute schizophrenia.

The metabolites of serotonin, dopamine, and norepinephrine, 5-hydroxyindoleacetic acid (5HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxy-phenylethylene glycol (MHPG), respectively, were studied in cerebrospinal fluid of patients with acute schizophrenia. Base line levels of these metabolites were not significantly different from those in normal, neurological, and affectively ill controls. Accumulations of 5HIAA and HVA following probenecid administration, which provide a measure of serotonin and dopamine turnover, were also not significantly different in patients with acute schizophrenia and affective illness. After patients had recovered from their acute schizophrenic illness, HVA accumulations were significantly reduced. We discuss results in relation to amine hypotheses of schizophrenia and the suggestion that altered dopamine metabolism may reflect a biological change predisposing to acute schizophrenia.

Acute Disease↗
PubMed1986

Neurochemistry of dopamine in Huntington's dementia and normal aging.

We measured the dopamine metabolite homovanillic acid (HVA) in cerebrospinal fluid (CSF) before and after probenecid administration in normal controls and in patients with Huntington's disease. Baseline CSF HVA concentrations correlated positively with age in normal control subjects. Baseline CSF HVA concentrations were reduced in patients with Huntington's disease, and the degree of this reduction correlated with the severity of dementia and with the duration of disease. These results suggest that changes in the metabolism of dopamine by dopaminergic neurons may be associated with the dementia of Huntington's disease as well as with normal aging. These changes in dopaminergic functioning are apparently different in Huntington's disease than in normal aging and can be detected by measuring CSF HVA concentration.

Adult↗
PubMed1986

Dopaminergic effects of carbamazepine. Relationship to clinical response in affective illness.

Carbamazepine, a drug used widely to treat epilepsy and trigeminal neuralgia, has been shown to be effective in the acute and prophylactic treatment of manic-depressive illness. While the time course of its antimanic effects parallels that of classic neuroleptics, indirect clinical evidence, such as lack of parkinsonian side effects and tardive dyskinesia, suggests that carbamazepine does not act by blocking dopamine receptors. To assess the effects of carbamazepine on dopamine mechanisms, we measured the dopamine metabolite homovanillic acid (HVA) in the cerebrospinal fluid of affectively ill patients before and after treatment. Carbamazepine did not alter basal concentrations of HVA, but decreased probenecid-induced accumulations of HVA, paralleling results in animal studies. In 25 patients, lower baseline cerebrospinal fluid HVA levels were related to subsequent better acute antidepressive responses to carbamazepine. While the precise mechanism of carbamazepine's effects on dopaminergic systems remains to be determined, this study provides further evidence that carbamazepine does not have a biochemical profile typical of neuroleptics.

Adult↗
PubMed1978

Therapy of gonorrhea. Comparison of trimethoprim-sulfamethoxazole and ampicillin.

Eighty-nine men with gonococcal urethritis were randomly treated with trimethoprim-sulfamethoxazole, four tablets (trimethoprin, 320 mg, and sulfamethoxazole, 1,600 mg) twice daily for two days, or ampicillin, 3.5 g, plus probenecid, 1 g, in a single dose. Forty-one (95.3%) of 43 patients who received trimethoprin-sulfamethosazole and 41 (97.6%) of 42 given ampicillin were cured. Neither drug caused major side effects. All isolates of Neisseria gonorrhoeae were susceptible in vitro to trimethoprim-sulfame-thoxazole, and all but one were inhibited by ampicillin. The ampicillin-resistant strain (minimum inhibitory concentration, 4 micrograms/ml) produced penicillinase and was reovered from a patient who responded to treatment with trimethoprim-sulfamethoxazole. There was no significant correlation between the minimum inhibitory concentrations of trimethoprim-sulfamethoxazole and ampicillin. It is concluded that trimethoprim-sulfamethoxazole is as efficacious and safe as ampicillin in the therapy of gonococcal urethritis.

Ampicillin↗
PubMed1997

Possible role of the multidrug resistance-associated protein (MRP) in chemoresistance of human melanoma cells.

Human malignant melanoma is characterised by unresponsiveness to conventional chemotherapy. Melanoma-derived cell lines are often markedly chemoresistant, suggesting that cellular mechanisms mediate the multidrug resistance (MDR) phenotype. The multidrug resistance-associated protein (MRP) is a drug transporter protein associated with resistance to a broad spectrum of lipophilic drugs. To investigate whether MRP is involved in intrinsic drug resistance of human melanoma, we analysed expression and functional activity of MRP as well as its impact on chemoresistance in 40 melanoma cell lines (35 established by us from primary and metastatic lesions and 5 obtained from international sources), as well as in one dysplastic naevus-derived cell line and in normal melanocytes. By reverse transcriptase-polymerase chain reaction various levels of MRP mRNA were detected in all melanoma cell lines, and by immunoblot the corresponding protein in a high percentage of them. Functional activity of MRP was assayed by analysing cellular accumulation of 3H-daunomycin (3H-DM) and calcein in response to MRP-modulators by beta-spectrometric and fluorescence-activated cell sorter analysis, respectively. Probenecid (PRO), N-ethylmaleimide (NEM) and benzbromarone (BB) moderately (< or = 1.43-fold) but significantly enhanced intracellular accumulation of MRP substrate probes corresponding to MRP expression. Moreover, the sensitivity of melanoma cell lines to daunomycin (DM) and doxorubicin (DOX), but not to vinblastine (VBL), etoposide (VP-16) and cisplatin (CDDP), analysed by an MTT-based survival assay, were inversely correlated with MRP-gene expression. Our results imply that MRP may be a component of the intrinsic chemoresistance phenotype characteristic of human malignant melanoma.

ATP-Binding Cassette Transporters↗
PubMed1998

Detection of P-glycoprotein in the Golgi apparatus of drug-untreated human melanoma cells.

The intracellular location of the MDR1 gene product, known as P-glycoprotein (P-gp), has been detected by flow cytometry in 3 stabilized human melanoma cell lines which had never undergone cytotoxic drug treatment and did not express P-gp on the plasma membrane. In addition, MDR1 mRNA expression was revealed by RT-PCR in the same cell lines. Immunofluorescence microscopy, performed by using the same 2 monoclonal antibodies (MM4.17 and MRK-16) as employed in the flow-cytometric analysis, revealed the presence of P-gp intracytoplasmically, in a well-defined perinuclear region. Double immunofluorescence labelling and immunoelectron microscopy strongly suggested the location of the transporter molecule in the Golgi apparatus. The same observations have been obtained on a primary culture from a metastasis of human melanoma. Analysis of the expression of another membrane transport protein, the multidrug-resistance-related protein (MRP1), showed that it was present in the cytoplasm of all the melanoma cell lines examined. MRP1 also showed Golgi-like localization. The study by laser scanning confocal microscopy on the intracellular localization of the anti-tumoral agent doxorubicin (DOX) during the drug-uptake and -efflux phases, indicated the Golgi apparatus as a preferential accumulation site for the anthracyclinic antibiotic. P-gp function modulators (verapamil and cyclosporin A) were able to modify DOX intracytoplasmic distribution and to increase drug intracellular concentration and cytotoxic effect in melanoma cells. On the contrary, MRP1 modulators (probenecid and genistein) did not significantly influence either DOX efflux and distribution or the sensitivity of melanoma cells to the cytotoxic drug.

ATP Binding Cassette Transporter, Subfamily B, Mem↗