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An in vitro study of the cytogenetic and cytotoxic effects of imatinib mesylate, STI571 on murine erythroleukemia GM-86 cells.

Imatinib mesylate, STI571, is a novel anticancer drug used to treat Philadelphia chromosome positive (Ph+) chronic myeloid leukemia. Studies have demonstrated the efficacy of imatinib mesylate in human cancers; however, its effects in murine cancer cell lines are not well documented. This study investigated the cytogenetic and cytotoxic effects of imatinib mesylate in vitro on virus-induced mouse erythroleukemia GM-86 cells. Cytogenetic studies revealed a noticeable increase in chromosomal abnormalities and multinucleation, as well as micro and macronuclei formation in treated cells. An increase in abnormalities such as condensed nuclei and nuclear and cytoplasmic degradations were also detected in cells treated with imatinib mesylate. It is suggested that the reduction in cell proliferation, mitotic index, and increase in cell damaging effects observed in imatinib mesylate-treated GM-86 cells were a result of the induced chromosomal and nuclear abnormalities.

Animals↗

Activation mutations of human c-KIT resistant to imatinib mesylate are sensitive to the tyrosine kinase inhibitor PKC412.

Constitutively activated forms of the transmembrane receptor tyrosine kinase c-KIT have been associated with systemic mast cell disease, acute myeloid leukemia, and gastrointestinal stromal tumors. Reports of the resistance of the kinase domain mutation D816V to the adenosine triphosphate (ATP)-competitive kinase inhibitor imatinib mesylate prompted us to characterize 14 c-KIT mutations reported in association with human hematologic malignancies for transforming activity in the murine hematopoietic cell line Ba/F3 and for sensitivity to the tyrosine kinase inhibitor PKC412. Ten of 14 c-KIT mutations conferred interleukin 3 (IL-3)-independent growth. c-KIT D816Y and D816V transformed cells were sensitive to PKC412 despite resistance to imatinib mesylate. In these cells, PKC412, but not imatinib mesylate, inhibited autophosphorylation of c-KIT and activation of downstream effectors signal transducer and transcriptional activator 5 (Stat5) and Stat3. Variable sensitivities to PKC412 or imatinib mesylate were observed among other mutants. These findings suggest that PKC412 may be a useful therapeutic agent for c-KIT-positive malignancies harboring the imatinib mesylate-resistant D816V or D816Y activation mutations.

Animals↗

Hematopathologic and cytogenetic findings in imatinib mesylate-treated chronic myelogenous leukemia patients: 14 months' experience.

Imatinib mesylate, an Abl kinase inhibitor, produces sustained complete hematologic responses (CHRs) in chronic myelogenous leukemia (CML) patients, but the sequence and timing of morphologic and cytogenetic changes in CML patients during prolonged imatinib mesylate treatment has not been described. In this report, we document sequential hematologic and bone marrow findings in 19 interferon-refractory/interferon-intolerant chronic phase CML patients on imatinib mesylate for at least 14 months. Patients treated at an effective oral dose (300 to 600 mg per day) were followed with peripheral blood (PB) counts, marrow examination, and cytogenetic studies at 0, 2, 5, 8, 11, and 14 months. By 2 months, 17 of 19 patients achieved CHR; 1 reached CHR by 5 months, and 1 at 11 months. Five of 19 patients developed cytopenias requiring treatment interruption and/or dose reduction, but all were able to continue in CHR on study. In contrast to interferon-alfa treatment, imatinib mesylate-treated CML patients achieved not only CHR but complete morphologic marrow response. Normalization of marrow lagged behind PB response; however, by 8 months, all marrows showed normal or reduced cellularity without morphologic evidence of CML. Eighteen of 19 patients continued in CHR and morphologic marrow remission at 14 months; 1 patient relapsed with chronic phase CML. Although hematologic and marrow responses were uniform, cytogenetic responses were variable. Complete cytogenetic responses occurred in 6 patients, with 4 also in remission by fluorescent in situ hybridization and/or reverse-transcription-polymerase chain reaction. Six of 19 had partial and 7 of 19 no cytogenetic response. Several patients acquired additional clonal cytogenetic abnormalities during therapy, a finding with significant implications for prognosis and laboratory monitoring in imatinib mesylate-treated CML patients.

Adult↗

Imatinib mesylate (STI571) therapy for Philadelphia chromosome-positive chronic myelogenous leukemia in blast phase.

Molecular abnormalities caused by the hybrid Bcr-Abl gene are causally associated with the development and progression of Philadelphia chromosome-positive (Ph(+)) chronic myelogenous leukemia (CML). Imatinib mesylate (STI571), a specific Bcr-Abl tyrosine-kinase signal-transduction inhibitor, has shown encouraging activity in phase I and II studies of CML. Here, we describe the use of imatinib mesylate to treat 75 patients in blast-phase CML (median age, 53 years; 65 with nonlymphoid and 10 with lymphoid blasts), and compare the results with those of a historical control group treated with standard cytarabine-based therapy. Imatinib mesylate was given as oral doses at 300 to 1000 mg per day and was the first salvage therapy for 47 patients. The objective response rate was 52% (39 of 75 patients: 16 had complete and 3 had partial hematologic response; 12 had hematologic improvement; 7 returned to second chronic phase; and 1 had a complete response in extramedullary blastic disease). Response rates were not different between nonlymphoid and lymphoid groups. The cytogenetic response rate was 16% (12 patients: 5 complete, 3 partial [Ph(+) below 35%], and 4 minor [Ph(+), 34% to 90%]). The estimated median overall survival was 6.5 months; the estimated 1-year survival was 22%. Response to therapy (landmark analysis at 8 weeks) was associated with survival prolongation. Compared with standard cytarabine combinations, imatinib mesylate therapy was less toxic and produced a higher response rate (55% versus 29%, P =.001), longer median survival (7 versus 4 months, P =.04), and lower 4-week induction mortality (4% versus 15%, P =.07). Imatinib mesylate is currently being tested in combination with other drugs to improve the prognosis for blast-phase CML.

Adult↗

Molecular targeting of platelet-derived growth factor B by imatinib mesylate in a patient with metastatic dermatofibrosarcoma protuberans.

PURPOSE: Dermatofibrosarcoma protuberans is caused by activation of the platelet-derived growth factor B (PDGFB) receptor, a transmembrane tyrosine kinase. We investigated the response of dermatofibrosarcoma protuberans to the tyrosine kinase inhibitor imatinib mesylate. PATIENTS AND METHODS: A patient with unresectable, metastatic dermatofibrosarcoma protuberans received imatinib mesylate (400 mg bid). Response to therapy was assessed by [18F]fluorodeoxyglucose (FDG) positron emission tomography, magnetic resonance imaging, and histopathologic and immunohistochemical evaluation. RESULTS: The patient was treated for 4 months with imatinib mesylate. The hypermetabolic uptake of FDG fell to background levels within 2 weeks of treatment, and the tumor volume shrank by over 75% during the 4 months of therapy, allowing for resection of the mass. There was no residual viable tumor in the resected specimen, indicating a complete histologic response to treatment with imatinib mesylate. CONCLUSION: Imatinib mesylate is highly active in dermatofibrosarcoma protuberans. The dramatic response seen in this patient demonstrates that inhibition of PDGFB receptor tyrosine kinase activity can significantly impact viability of at least one type of solid tumor.

Adult↗

Effects of 17-allylamino-17-demethoxygeldanamycin (17-AAG) on pediatric acute lymphoblastic leukemia (ALL) with respect to Bcr-Abl status and imatinib mesylate sensitivity.

As more and more effective targeted therapeutics have been developed to treat adults with cancer, it is of critical importance to devise appropriate in vitro experimental models to study their use in pediatric patients. Acute lymphoblastic leukemia (ALL) with Bcr-Abl translocation is one of the most difficult to treat and deadly diseases in children. The targeted kinase inhibitor imatinib mesylate has been shown to induce an initial response but resistance often develops. Recently, the geldanamycin family of antibiotics has been found to induce apoptosis in many malignant cells, including adult CML and AML. We describe experiments in which 17-allylamino-17-demethoxygeldanamycin (17-AAG) was evaluated in the context of Bcr-Abl and resistance to imatinib mesylate. Pediatric ALL cell lines with varying Bcr-Abl status and imatinib mesylate sensitivity were generated and their growth inhibition by 17-AAG was studied in vitro. Western blots were used to follow the changes in proteins that correlate with cell survival. Results show that apoptosis was induced in all lines with an increased 50% inhibitory concentration (IC50) for Bcr-Abl positive but imatinib mesylate-resistant cells. Addition of 17-AAG greatly increased imatinib sensitivity in vitro. A decrease in p53, survivin, Her2/neu, and WT1 was seen in cells that expressed these proteins. With some notable exceptions, when combined with 17-AAG, the IC50 of most of the common chemotherapeutic agents decreased. We describe an experimental approach to investigate the complex interaction between Bcr-Abl status, imatinib mesylate sensitivity, and 17-AAG in pediatric ALL. Information from such an approach will provide means to devise combined treatment approaches and to follow their effectiveness in vitro.

Adult↗

Co-dergocrine mesylate. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic use in age-related cognitive decline.

Co-dergocrine mesylate is a combination of the mesylated forms of dihydroergocornine, dihydroergocristine, dihydro-alpha-ergocryptine and dihydro-beta-ergocryptine. In animal models and healthy elderly volunteers the compound improves indices of cognitive function such as memory and learning. The mechanism(s) behind such action remains under investigation. Nonetheless, it has been proposed that co-dergocrine mesylate has a dual effect on central monoaminergic neurotransmitter systems, compensating for both hyperactivity and deficits of the adrenergic, serotoninergic and dopaminergic systems. The compound also appears to have a normalising effect on the power of electroencephalogram frequencies, and may improve cerebral metabolism. Results from controlled studies of elderly patients with age-related cognitive decline have established that co-dergocrine mesylate is well tolerated and, in some studies, had statistically significant positive effects on symptoms of cognitive dysfunction. However, there is considerable controversy over the clinical relevance of these results as there was wide variability in the number and type of cognitive and neuropsychological assessments used in individual studies and there may have been considerable overlap in diagnosis of patients with varying degrees of dementia. In addition, the drug has not been compared with most other, more recently developed, centrally active agents. Thus, the specific place of co-dergocrine mesylate in the treatment of age-related cognitive decline remains undetermined, despite many years of clinical use.

Aging↗

A Phase II study of intravenous exatecan mesylate (DX-8951f) administered daily for 5 days every 3 weeks to patients with metastatic breast carcinoma.

BACKGROUND: The objective of the current study was to determine the antitumor activity, safety, and pharmacokinetic (PK) profile of exatecan mesylate in patients with anthracycline-resistant and taxane-resistant, metastatic breast carcinoma. METHODS: All patients had clinical evidence of metastatic breast carcinoma; disease resistance or progression after chemotherapy that included anthracyclines and taxanes; no prior chemotherapy with camptothecin derivatives; and bidimensionally measurable disease. The starting dose of exatecan mesylate was either 0.5 mg/m(2) per day or 0.3 mg/m(2) per day, depending on prior chemotherapy exposure. PK blood samples were collected from each patient during the first course of therapy. RESULTS: Thirty-nine patients received a total of 172 courses of therapy (median, 4 courses; range, 1-16 courses). Three patients (7.7%) had a partial response, and 20 patients (51.3%) had either a minor response or stable disease. Approximately 20% of patients had stable disease for 6 months or longer. The median time to disease progression was 3 months, and the median survival was 14 months. The most frequent severe adverse event was neutropenia. The most frequent severe (Grade 3-4) nonhematologic toxicities were fatigue, nausea, headache, myalgia, constipation, emesis, and paresthesias in 28%, 10%, 10%, 8%, 8%, 5%, and 5% of patients, respectively. Exatecan mesylate displayed linear PK characteristics at the doses administered. The average plasma clearance, total volume of distribution, and terminal elimination half-life were approximately 1.4 L per hour per m(2), 12 L/m(2), and 8 hours, respectively. CONCLUSIONS: Exatecan mesylate had moderate activity in patients with anthracycline-refractory and taxane-refractory, metastatic breast carcinoma. The toxicity profile of exatecan mesylate was acceptable, and it appeared to have linear PK characteristics on the basis of multiple dose administration.

Adult↗

Lack of a pharmacokinetic/pharmacodynamic interaction between nimodipine and tirilazad mesylate in healthy volunteers.

The potential interaction between tirilazad mesylate, a membrane lipid peroxidation inhibitor, and nimodipine, a calcium-channel antagonist, was assessed in 12 healthy male volunteers. Subjects received 60 mg nimodipine orally, 2.0 mg/kg tirilazad mesylate as a 10-minute intravenous infusion, and a combination of the two treatments according to a balanced 3-way crossover design. No significant effects of nimodipine on tirilazad mesylate pharmacokinetic parameters were observed (P > .05). Values for tirilazad mesylate clearance (34.9 +/- 8.96 L/hr) and half-life (29 +/- 7.83 hr) were consistent with previous studies. Nimodipine pharmacokinetic parameters exhibited substantial variability, and mean AUC was approximately 25% below the range of previously published values. However, no significant differences in nimodipine pharmacokinetics were observed between treatments. Nimodipine administration increased heart rate slightly without a change in blood pressure, which was not observed after tirilazad administration and was not altered when tirilazad and nimodipine were coadministered. Thus, no significant interaction between tirilazad mesylate and nimodipine is detectable after single-dose administration.

Administration, Oral↗

Pharmacokinetic study of the interaction between rifampin and delavirdine mesylate.

OBJECTIVE: To study the effect of rifampin (INN, rifampicin), a potent inducer of cytochrome P450, on the steady-state pharmacokinetics of delavirdine. METHODS: Twelve patients who were positive for human immunodeficiency virus, with CD4 counts ranging from 110 to 483/mm3, were randomized to two groups and studied in parallel. Both the control group (n = 5) and the rifampin group (n = 7) received 400 mg delavirdine mesylate every 8 hours for 30 days; subjects in the rifampin group took a 600 mg once-daily dose of rifampin on days 16 through 30. Harvested plasma from serial blood samples collected after dosing on days 15, 16, and 30 was assayed for delavirdine and its N-desalkyl metabolite concentrations with a reversed-phase HPLC method. Blood samples obtained on days 16 and 30 were also assayed for rifampin by HPLC. RESULTS: Delavirdine mesylate alone and in combination with rifampin was well tolerated. On day 30, statistically significant differences between groups were observed for all delavirdine pharmacokinetic parameters (p < 0.049). In the rifampin group, delavirdine oral clearance increased by about 27-fold (p = 0.022), resulting in virtually negligible (< 0.09 mumol/L) steady-state through drug concentrations in all patients after 2 weeks of concurrent dosing of delavirdine mesylate and rifampin. The ratio of metabolite formation to elimination clearance for desalkyldelavirdine was significantly higher (3.9 +/- 1.2 versus 0.23 +/- 0.10) and delavirdine elimination half-life was significantly shorter (1.7 +/- 1.4 versus 4.3 +/- 1.3 hours) when delavirdine mesylate was taken with rifampin. Rifampin pharmacokinetic parameters on days 16 and 30 were similar to those previously reported for normal volunteers. CONCLUSIONS: The findings of this study indicate that rifampin induces the metabolism of delavirdine. Therefore therapy with rifampin is contraindicated in patients receiving delavirdine mesylate.

Adult↗

Prophylaxis of ERCP-related pancreatitis: a randomized, controlled trial of somatostatin and gabexate mesylate.

BACKGROUND & AIMS: It still is debated whether post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis can be prevented by administering either somatostatin or gabexate mesylate. The aim of the study is to assess the efficacy of a 6.5-hour infusion of somatostatin or gabexate mesylate in preventing ERCP-related complications. METHODS: In a double-blind multicenter trial, 1127 patients undergoing ERCP were randomly assigned to intravenous administration of somatostatin (750 microg; n = 351), gabexate mesylate (500 mg; n = 381), or placebo (saline; n = 395). The drug infusion started 30 minutes before and continued for 6 hours after endoscopy. Patients were evaluated clinically, and serum amylase levels were determined at 4, 24, and 48 hours after endoscopy. RESULTS: No significant differences in incidences of pancreatitis, hyperamylasemia, or abdominal pain were observed among the placebo (4.8%, 32.6%, and 5.3%, respectively), somatostatin (6.3%, 26.8%, and 5.1%, respectively), and gabexate mesylate groups (5.8%, 31.5%, and 6.3%, respectively). Univariate analysis of patient characteristics and endoscopic maneuvers showed that a Freeman score >1 (P < 0.0001), >/=3 pancreatic injections (P < 0.00001), and precut sphincterotomy (P = 0.01) were significantly associated with post-ERCP pancreatitis. At multiple logistic regression analysis, >/=3 pancreatic injections (odds ratio [OR], 1.95; 95% confidence interval [CI], 1.45-2.63) and a Freeman score >1 (OR, 1.47; 95% CI, 1.11-1.94) retained their predictive power. CONCLUSIONS: Long-term (6.5-hr) administration of either somatostatin or gabexate mesylate is ineffective for the prevention of post-ERCP pancreatitis. Pancreatic injury seems to be related to difficulty in common bile duct access.

Aged↗

Preparation of Chiral Allenylmetal Reagents from Enantioenriched Allenyl Iodides and Propargylic Mesylates. A Comparison of Indium, Bismuth, and Tin Derivatives.

Chiral allenylmetal halides were prepared starting from enantioenriched ( approximately 95% ee) 1-octyn-3-ol mesylate (1) and 3-butyn-2-ol mesylate (7). Addition of these transient metallo species to aldehydes in situ afforded mainly anti homopropargylic alcohol adducts of varying ee. Three approaches were explored. In the first, the mesylates were converted to allenylstannanes with Bu(3)SnLi.CuBr and the allenylmetal halide was prepared from the resulting enantioenriched allenylstannane by transmetalation with InBr(3), BiBr(3), and SnCl(4) in the presence of cyclohexanecarboxaldehyde. The configurational stability of the transient allenylmetal halide was estimated from the ee of the derived adduct. The second approach involved metalation of the allenyl iodides prepared from mesylates 7 and 1 through S(N)2' displacement with LiCuI(2). From these experiments, it was determined that allenylindium bromides and allenyltin bromides are configurationally stable under the reaction conditions. The adduct obtained from the allenylbismuth bromide was nearly racemic. A superior procedure was developed in which the propargylic mesylates 7 and 1 were converted to allenylindium iodide intermediates through treatment with InI and 5 mol % of a Pd(0) dppf catalyst in THF-HMPA, THF-DMSO, or THF-DMPU. Under these conditions, alpha-branched aldehydes were converted to anti adducts ( approximately 95:5 anti/syn) of >90% ee. Additions to unbranched aldehydes were less diastereoselective, but afforded adducts of high ee. Additions of enantiomeric allenylindium iodide reagents to (R)-beta-ODPS-alpha-methylpropanal (13) afforded diastereomeric adducts (anti,anti and anti,syn) 14, 15 and 18, 19 with excellent diastereoselectivity indicative of a high degree of reagent control. A convenient procedure for the preparation of InI from In and I(2) is also described.

Journal Article↗

Clinical pharmacology of adinazolam and N-desmethyladinazolam mesylate after single oral doses of each compound in healthy volunteers.

The tolerance, pharmacokinetics, and pharmacodynamics of adinazolam and N-desmethyladinazolam (NDMAD) were assessed after single oral doses of 10, 30, and 50 mg adinazolam mesylate, NDMAD mesylate, and placebo. Within doses, six healthy male volunteers received these treatments in a double-blind crossover design. No clinically significant changes were observed in blood pressure, pulse, respiration, or clinical laboratory test results. Untoward effects were typical of benzodiazepines. Adinazolam and NDMAD kinetics were dose independent. Greater than 95% of the adinazolam dose was metabolized to NDMAD. Adinazolam and NDMAD mesylate produced dose-related increases in uric acid clearance and decreases in plasma uric acid. Both adinazolam and NDMAD mesylate administration resulted in dose-related sedation and decrements in psychomotor performance. Within doses, decrements produced by adinazolam and NDMAD were quantitatively similar. These results suggest that both adinazolam and NDMAD possess uricosuric activity and support the hypothesis that NDMAD primarily mediates benzodiazepine-like effects of adinazolam mesylate.

Administration, Oral↗

Effect of endotoxin on tirilazad mesylate (U74006F) pharmacokinetic parameters in neonatal calves.

The pharmacokinetics of the 21-aminosteroid tirilazad mesylate (U74006F) were studied in both healthy and endotoxin-challenged neonatal calves. Group I calves received a 3-h intravenous (i.v.) infusion of sterile saline (250 ml) and tirilazad mesylate (1.5 mg/kg i.v.) 1 h after the start of the saline infusion. Group II calves received tirilazad mesylate 1 h after the start of a 3-h endotoxin (3.25 micrograms/kg) infusion. The data obtained indicate that tirilazad mesylate follows a biexponential equation in neonatal calves. The area-derived volume of distribution (Vdarea) was 9.68 +/- 0.759 l/kg in healthy calves and 6.53 +/- 1.20 l/kg in endotoxin-challenged calves (P < 0.05). Similarly, significant (P < 0.05) decreases in steady-state volume of distribution (Vdss) and central volume (Vc) were observed in endotoxin-challenged calves (5.32 +/- 0.979 l/kg and 1.68 +/- 0.189 l/kg, respectively) compared to healthy calves (7.58 +/- 0.834 l/kg and 2.43 +/- 0.452 l/kg, respectively). A and B were significantly larger in endotoxin-challenged calves than in healthy calves (P < 0.05). Rate constants and their associated half-lives, area under the curve and clearance were not significantly altered by endotoxin challenge. Serum thromboxane generation (ex vivo) was evaluated as a marker of the drug's physiologic activity. There was no significant difference in thromboxane generation during clotting of blood from healthy and endotoxemic calves treated with tirilazad mesylate.

Animals↗

A controlled long-term study with ergoloid mesylates (Hydergine) in healthy, elderly volunteers: results after three years.

A long-term clinical comparison of the effects of ergoloid mesylates and placebo on 148 healthy elderly volunteers of both sexes was analyzed after three years of study. At that point, 99 subjects (53 receiving ergoloid mesylates and 46, placebo) were still being treated under double-blind conditions, while the remainder either had dropped out or continued to participate under open conditions. Many subjects in both groups were healthier after the three years than they had been at the onset of the study: subjective symptoms such as tiredness and dizziness were reduced, performances on tests of intelligence were improved, and some abnormal laboratory values had normalized. Blood pressures increased on the average during the investigational period and pulse rates became slower. The ergoloid mesylate regimen was well tolerated objectively and subjectively. Additional medical and psychologic improvements were noted in the group treated with ergoloid mesylates concerning cardiovascular parameters, cholesterol levels, subjective symptoms, and performances on tests of intelligence. These intermediate findings are interpreted as showing a preventive effect of ergoloid mesylates against some of the debilitating physical and psychologic concomitants of aging.

Aged↗

Safety, tolerance, and pharmacokinetics of atevirdine mesylate (U-87201E) in asymptomatic human immunodeficiency virus-infected patients.

Atevirdine mesylate (U-87201E) is a new nonnucleoside (bisheteroarylpiperazine) inhibitor of human immunodeficiency virus type 1 reverse transcriptase. In a double-blind, escalating single-dose study the safety, tolerance, and pharmacokinetics of atevirdine mesylate were investigated in 24 asymptomatic human immunodeficiency virus-seropositive male patients. Each patient received one single oral dose of atevirdine mesylate and placebo separated by an interval of 1 to 3 weeks. For each dose level (400, 800, 1,200, and 1,600 mg) six patients received drug and placebo on separate occasions. Blood samples were collected before dosing and at intervals afterward for safety evaluation and estimation of atevirdine and metabolite levels. The concentrations of atevirdine and its principal metabolite (U-89255) in serum were determined by high-performance liquid chromatography. The results of the study showed that atevirdine mesylate is well tolerated at all dose levels. No clinically significant effects on vital signs, electrocardiograms, or laboratory tests were observed. Occasional headache and nausea were reported both in the drug group and in the placebo group. The times to peak values were relatively short (0.5 to 1.0 h), suggesting a rapid absorption. The maximum concentrations of drug in serum were 1.4 microM (400 mg), 4.2 microM (800 mg), 7.3 microM (1,200 mg), and 5.8 microM (1,600 mg). The values of the pharmacokinetic parameters for atevirdine were found to have relatively large intersubject variabilities, and consequently, the study had little power to detect dose-dependent changes in the values of the pharmacokinetic parameters. The oral clearance of atevirdine tended to increase by 90% as the atevirdine mesylate doses increased from 400 to 1,600 mg, but this change in oral clearance was not statistically significant. The values of the pharmacokinetic parameters determined in the study were similar to those found in a previous single-dose study in healthy volunteers.

Adult↗

The role of c-kit and imatinib mesylate in uveal melanoma.

BACKGROUND: Uveal melanoma (UM) is the most common primary intraocular tumor in adults, leading to metastasis in 40% of the cases and ultimately to death in 10 years, despite local and/or systemic treatment. The c-kit protein (CD117) is a membrane-bound tyrosine kinase receptor and its overexpression has been observed in several neoplasms. Imatinib mesylate is a FDA approved compound that inhibits tyrosine quinase receptors, as well as c-kit. Imatinib mesylate controls tumor growth in up to 85% of advanced gastrointestinal stromal tumors, a neoplasia resistant to conventional therapy. METHODS: Fifty-five specimens of primary UM selected from the archives of the Ocular Pathology Laboratory, McGill University, Montreal, Canada, were immunostained for c-kit. All cells displaying distinct immunoreactivity were considered positive. Four human UM cell lines and 1 human uveal transformed melanocyte cell line were tested for in vitro proliferation Assays (TOX-6) and invasion assay with imatinib mesylate (concentration of 10 microM). RESULTS: The c-kit expression was positive in 78.2% of the UM. There was a statistical significant decrease in the proliferation and invasion rates of all 5 cell lines. CONCLUSION: The majority of UM expressed c-kit, and imatinib mesylate does decrease the proliferation and invasion rates of human UM cell lines. These results justify the need for a clinical trial to investigate in vivo the response of UM to imatinib mesylate.

Journal Article↗

Safety pharmacology of sibutramine mesylate, an anti-obesity drug.

Sibutramine mesylate is a new anti-obesity drug. It is a crystalline salt of sibutramine developed to improve the solubility of sibutramine hydrochloride. Methanesulfonic acid was used as a salt-forming acid instead of hydrochloric acid, resulting in a greatly improved solubility of 1000 mg/mL in water. Sibutramine mesylate was administered orally to ICR mice, Sprague-Dawley rats, and beagle dogs at dose levels of 1.15, 3.45, and 11.50 mg/kg to measure its effects on the central nervous system (CNS), general behaviour, cardiovascular-respiratory system and the other organ systems. Following administration of sibutramine mesylate, spontaneous locomotor activity was significantly increased from 120 min to 24 hours at 3.45 mg/kg and from 30 min to 24 hours at 11.50 mg/kg. Furthermore, there were a decrease in hexobarbital-induced sleep time, an increase in respiratory rate at 120 min, increases in intestinal transport capacity and gastric pH at 11.50 mg/kg, and decreases in gastric volume and total acidity at 3.45 and 11.50 mg/kg. However sibutramine mesylate caused no effects on general behaviour, motor coordination, body temperature, analgesia, convulsion, blood pressure, heart rate, electrocardiogram, cardiac functions of the isolated rat heart, isolated smooth muscles and renal function. Based on the above results, it was concluded that sibutramine mesylate caused effects on the spontaneous locomotor activity, hexobarbital-induced sleep time, respiration, gastrointestinal transport, and gastric secretion at a dose level of 3.45 mg/kg or greater but caused no effects on other general pharmacological reactions.

Administration, Oral↗