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Remofovir mesylate: a prodrug of PMEA with improved liver-targeting and safety in rats and monkeys.

Adefovir dipivoxil (Hepsera), a first-line therapy for chronic hepatitis B, is an esterase-activated prodrug of PMEA. Dose-limiting nephrotoxicity necessitates suboptimal dosing at 10 mg/day. Remofovir mesylate (MB06866Q) (Hepavir B) is a CYP3A4-activated prodrug of PMEA based on the HepDirect technology that targets PMEA to the liver. In a whole body autoradiography study in rats after oral dosing (30 mg/kg) of [14C]adefovir dipivoxil or [14C]remofovir mesylate, remofovir yielded 15 times higher concentrations of radioactivity in the liver than adefovir dipivoxil, but only one-third of the concentrations in the kidney. After oral dosing (4 mg/kg) of the same radiolabelled agents in cynomolgus monkeys, remofovir mesylate yielded 60 times higher levels of total radioactivity in the liver, but only two-thirds of total radioactivity levels in the kidney. Thus, remofovir mesylate may provide better efficacy and reduced nephrotoxicity. In portal vein-cannulated rats (30 mg/kg) after a single oral dose of [14C]adefovir dipivoxil or [14C]remofovir mesylate, no PMEA was detectable in rat portal plasma early after dosing, indicating that intestinal CYP3A4 does not play a role in conversion of remofovir mesylate to PMEA. The portal/systemic extraction ratio was quite high in both models, suggesting good liver-targeting properties. Portal and systemic remofovir/PMEA ratio indicates that the liver is the site of conversion of remofovir to PMEA. 28-Day toxicity studies demonstrated renal toxicity in rats at doses of 100 mg/kg or higher with no safety concerns at 30 mg/kg and acceptable safety in monkeys at doses up to 60 mg/kg. Thus, in rats and non-human primates, remofovir mesylate has liver-targeting properties and is safer than adefovir dipivoxil.

Adenine↗

Dual-specific Src and Abl kinase inhibitors, PP1 and CGP76030, inhibit growth and survival of cells expressing imatinib mesylate-resistant Bcr-Abl kinases.

The leukemogenic tyrosine kinase Bcr-Abl contains a highly conserved inhibitor-binding pocket (IBP), which serves as a binding site for imatinib mesylate. Mutations at the IBP may lead to resistance of the Abl kinase against imatinib mesylate. To examine the mechanisms of imatinib mesylate binding and resistance in more detail, we created several point mutations at amino acid positions 315 and 380 of Abl, blocking the access to the IBP and rendering Bcr-Abl imatinib mesylate-resistant. Moreover, introduction of a mutation destabilizing the inactive conformation of Abl (Asp276Ser/Glu279Ser) also led to imatinib mesylate resistance, suggesting that the inhibitor required inactivation of the kinase prior to binding. These Bcr-Abl mutants were then used to evaluate the binding mode and specificity of 2 compounds, PP1 and CGP76030, originally characterized as Src kinase inhibitors. Both compounds inhibited Bcr-Abl in a concentration-dependent manner by overlapping binding modes. However, in contrast to imatinib mesylate, PP1 and CGP76030 blocked cell growth and survival in cells expressing various inhibitor-resistant Abl mutants. Studies on the potential signaling mechanisms demonstrated that in cells expressing inhibitor-resistant Bcr-Abl mutants, PP1 and CGP76030 inhibited the activity of Src family tyrosine kinases and Akt but not signal transducer and activator of transcription-5 (STAT5) and JUN kinase (Jnk). The results suggest that the use of Src kinase inhibitors is a potential strategy to prevent or overcome clonal evolution of imatinib mesylate resistance in Bcr-Abl(+) leukemia.

Apoptosis↗

The third-generation bisphosphonate zoledronate synergistically augments the anti-Ph+ leukemia activity of imatinib mesylate.

Imatinib mesylate, a competitive inhibitor of Abl tyrosine kinase, is highly effective for the early stages of chronic myelogenous leukemia (CML), but remissions induced in advanced-phase CML and Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia tend to be relatively short-lived. Therefore, the search for agents that enhance the anti-Ph+ effect of imatinib mesylate is warranted. We investigated the combined effects of imatinib mesylate and the third-generation bisphosphonate zoledronate (ZOL) on Ph+ leukemias, because ZOL inhibited the prenylation of Ras-related proteins downstream of Bcr/Abl. First, we identified the potency of ZOL in vitro against human leukemic cell lines, including 2 Ph+ and a P-glycoprotein-overexpressing leukemic cell line. ZOL was also effective in vivo because as it prolonged the survival of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice who were given xenografts with Ph+ BV173 leukemic cells. Next, we showed the in vitro synergistic effects with ZOL and imatinib mesylate for Ph+ cell lines. ZOL combined with imatinib mesylate showed synergistic effects in vivo that prolonged the survival of mice inoculated with BV173. ZOL only minimally inhibited the growth of normal hematopoietic progenitors in vitro, and mice receiving ZOL or imatinib mesylate or both tolerated these treatments well. These findings indicate that ZOL is a potent antileukemic agent that augments synergistically the anti-Ph+ leukemia activity of imatinib mesylate.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

A novel mechanism for imatinib mesylate-induced cell death of BCR-ABL-positive human leukemic cells: caspase-independent, necrosis-like programmed cell death mediated by serine protease activity.

Caspase-independent programmed cell death can exhibit either an apoptosis-like or a necrosis-like morphology. The ABL kinase inhibitor, imatinib mesylate, has been reported to induce apoptosis of BCR-ABL-positive cells in a caspase-dependent fashion. We investigated whether caspases alone were the mediators of imatinib mesylate-induced cell death. In contrast to previous reports, we found that a broad caspase inhibitor, zVAD-fmk, failed to prevent the death of imatinib mesylate-treated BCR-ABL-positive human leukemic cells. Moreover, zVAD-fmk-preincubated, imatinib mesylate-treated cells exhibited a necrosis-like morphology characterized by cellular pyknosis, cytoplasmic vacuolization, and the absence of nuclear signs of apoptosis. These cells manifested a loss of the mitochondrial transmembrane potential, indicating the mitochondrial involvement in this caspase-independent necrosis. We excluded the participation of several mitochondrial factors possibly involved in caspase-independent cell death such as apoptosis-inducing factor, endonuclease G, and reactive oxygen species. However, we observed the mitochondrial release of the serine protease Omi/HtrA2 into the cytosol of the cells treated with imatinib mesylate or zVAD-fmk plus imatinib mesylate. Furthermore, serine protease inhibitors prevented the caspase-independent necrosis. Taken together, our results suggest that imatinib mesylate induces a caspase-independent, necrosis-like programmed cell death mediated by the serine protease activity of Omi/HtrA2.

Amino Acid Chloromethyl Ketones↗

Treatment of Philadelphia chromosome-positive acute lymphocytic leukemia with hyper-CVAD and imatinib mesylate.

Imatinib mesylate, an inhibitor of the Bcr-Abl tyrosine kinase, has modest activity in refractory/relapsed Philadelphia chromosome (Ph)-positive acute lymphocytic leukemia (ALL). Use of concurrent chemotherapy and imatinib mesylate in newly diagnosed Ph-positive ALL was explored. There were 20 patients who received hyper-CVAD (cyclophosphamide, vincristine, Adriamycin, and dexamethasone) and imatinib mesylate followed by imatinib mesylate-based consolidation/maintenance therapy. Of these patients, 11 had de novo disease, 4 were primary failures after induction (without imatinib mesylate), and 5 were in complete remission (CR) after induction (without imatinib mesylate). All 15 patients treated for active disease achieved CR. Within a median of 3.5 months in first CR, 10 patients underwent allogeneic stem cell transplantation (SCT). One patient relapsed after matched related SCT. The other 9 patients remained alive in CR with median follow-up of 12 months after SCT (range, 1+ to 17+ months). Among 10 patients ineligible for (no donor or older age) or refusing allogeneic SCT, 1 patient relapsed after one year. There were 5 patients who remained alive in continuous CR for a median of 20 months (range, 4+ to 24+ months), with 2 older patients dying in CR at 15 and 16 months of comorbid conditions. Molecular CRs were achieved in both groups (SCT or no SCT). Outcome with hyper-CVAD and imatinib mesylate appears better than with prior regimens; continued accrual and longer follow-up of the current cohort is needed.

Adolescent↗

PD166326, a novel tyrosine kinase inhibitor, has greater antileukemic activity than imatinib mesylate in a murine model of chronic myeloid leukemia.

Imatinib mesylate is highly effective in newly diagnosed chronic myeloid leukemia (CML), but BCR/ABL (breakpoint cluster region/abelson murine leukemia)-positive progenitors persist in most patients with CML treated with imatinib mesylate, indicating the need for novel therapeutic approaches. In this study, we have used the murine CML-like myeloproliferative disorder as a platform to characterize the pharmacokinetic, signal transduction, and antileukemic properties of PD166326, one of the most potent members of the pyridopyrimidine class of protein tyrosine kinase inhibitors. In mice with the CML-like disease, PD166326 rapidly inhibited Bcr/Abl kinase activity after a single oral dose and demonstrated marked antileukemic activity in vivo. Seventy percent of PD166326-treated mice achieved a white blood cell (WBC) count less than 20.0 x 10(9)/L (20,000/microL) at necropsy, compared with only 8% of imatinib mesylate-treated animals. Further, two thirds of PD166326-treated animals had complete resolution of splenomegaly, compared with none of the imatinib mesylate-treated animals. Consistent with its more potent antileukemic effect in vivo, PD166326 was also superior to imatinib mesylate in inhibiting the constitutive tyrosine phosphorylation of numerous leukemia-cell proteins, including the src family member Lyn. PD166326 also prolonged the survival of mice with imatinib mesylate-resistant CML induced by the Bcr/Abl mutants P210/H396P and P210/M351T. Altogether, these findings demonstrate the potential of more potent Bcr/Abl inhibitors to provide more effective antileukemic activity. Clinical development of PD166326 or a related analog may lead to more effective drugs for the treatment of de novo and imatinib mesylate-resistant CML.

Animals↗

Severe hepatic injury caused by imatinib mesylate administered for the treatment of chronic myeloid leukemia and the efficacy of prednisolone for its management.

Imatinib mesylate is a specific inhibitor of BCR-ABL tyrosine kinase, which is now widely used for the treatment of chronic myeloid leukemia (CML) with a high efficacy. Although severe hepatic injury caused by imatinib mesylate is rare, such a side effect may force patients to discontinue taking imatinib mesylate. In the present paper, we report on the case of a 51-year-old woman with CML who experienced hepatic injury with severe hyperbilirubinemia caused by imatinib mesylate. The findings from a liver biopsy specimen and her clinical course suggested the hepatic injury to presumably have been caused by an allergic mechanism. The co-administration of prednisolone was thus tried, and she has been able to continue imatinib mesylate administration without any liver dysfunction and finally was able to obtain a complete cytogenetic response.We therefore recommend that prednisolone should be tried when severe hepatic injury caused by imatinib mesylate is observed, since it might enable such patients to continue imatinib mesylate treatment and thereby improve the prognosis in such cases.

Antineoplastic Agents↗

Imatinib mesylate: clinical results in Philadelphia chromosome-positive leukemias.

Targeted cancer therapy has long been sought by the oncology community as a potentially better approach than currently available therapies. One targeted therapy that has shown great success is the tyrosine kinase inhibitor imatinib mesylate (formerly STI571, [Gleevec]; Novartis Pharmaceuticals Corp, East Hanover, NJ) which was recently approved for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML). Basic scientific investigation into the molecular causes and pathogenesis of CML and encouraging preclinical investigations on the mechanism of action of imatinib mesylate led to the initiation of phase I clinical trials. Clinical development of imatinib mesylate continued with three large, multicenter, phase II trials. The majority (88%) of interferon-alpha-resistant or intolerant patients in chronic-phase CML achieved a complete hematologic response to imatinib mesylate. More importantly, approximately half of patients achieved a major cytogenetic response, a result historically associated with improved survival. Furthermore, 21% of patients in accelerated-phase CML and 13.5% of patients in blastic-phase CML (patient populations with typically poor prognosis before the advent of imatinib mesylate) achieved major cytogenetic responses. Results from ongoing studies will determine the durability of these responses and will evaluate ways to optimize treatment in advanced-stage patients using imatinib mesylate in combination with other therapies. Additional trials are planned to investigate the efficacy of imatinib mesylate to treat a variety of solid tumors whose pathogenesis is driven by the other tyrosine kinase targets, c-Kit and platelet-derived growth factor receptor.

Antineoplastic Agents↗

Effects of benztropine mesylate on haloperidol-induced prolactin secretion and serum haloperidol levels in rats.

The effects of benztropine mesylate on haloperidol-induced prolactin secretion and serum haloperidol levels were investigated in 240 rats. Animals were pretreated with benztropine mesylate or saline 20 min prior to receiving haloperidol or saline. Serum prolactin and haloperidol levels were analyzed at six time periods over 150 min. There was no significant difference in prolactin levels of control animals, i.e., saline pretreated/saline treated rats compared to benztropine mesylate pretreated/saline treated rats. Haloperidol caused a significant rise (p less than 0.0001) in serum prolactin compared with controls. The prolactin concentration for the 30-150-min sampling period was significantly higher when the rats received benztropine mesylate prior to haloperidol (p less than 0.05). There was a significant correlation (r = 0.57, p less than 0.001) between serum haloperidol levels and serum prolactin levels in haloperidol-treated animals pretreated with either saline or benztropine mesylate. Additionally, serum haloperidol levels were not significantly different in animals pretreated with benztropine mesylate compared with those pretreated with saline. Thus, the enhancement of prolactin levels by benztropine mesylate was independent of any effect of haloperidol metabolism. This study appears to indicate that in the rat, cholinergic mechanisms exert a weak inhibitory effect on prolactin secretion under conditions of dopamine blockade.

Animals↗

Selective inhibition of human mast cell tryptase by gabexate mesylate, an antiproteinase drug.

Gabexate mesylate is a non-antigenic synthetic inhibitor of trypsin-like serine proteinases that is therapeutically used in the treatment of pancreatitis and disseminated intravascular coagulation and as a regional anticoagulant for hemodialysis. Considering the structural similarity between gabexate mesylate and arginine-based inhibitors of trypsin-like serine proteinases, the effect of gabexate mesylate on human and bovine mast cell tryptase action was investigated. Values of the inhibition constant (K(i)) for gabexate mesylate binding to human and bovine tryptase were 3.4 x 10(-9) M and 1.8 x 10(-7) M (at pH 7.4 and 37.0 degrees ), respectively. Furthermore, gabexate mesylate inhibited the fibrinogenolytic activity of human tryptase. On the basis of the available x-ray crystal structure of human tryptase, the possible binding mode of gabexate mesylate to human and bovine tryptase was analyzed. Human tryptase inhibition by gabexate mesylate may account for the reported prevention of inflammation, erosion, and ulceration of skin and mucosae.

Animals↗

Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone-insulin-like growth factor I axis in growth hormone-deficient children.

Ibutamoren mesylate (MK-0677), an orally active nonpeptide growth hormone (GH) secretagogue, stimulates GH release through a pituitary and hypothalamic receptor that is different from the GH-releasing hormone receptor. We evaluated the safety and tolerability and the GH-insulin-like growth factor (IGF) responses to two dosages of oral ibutamoren mesylate given to children with GH deficiency for 7 to 8 days. The patients, 18 prepubertal children (15 male, 3 female) with idiopathic GH deficiency, had a chronologic age of 10.6 +/- 0.8 years (mean +/- SD), bone age of 7.4 +/- 0.7 years, growth velocity < 10th percentile for age, height < 10th percentile for age, and a maximum GH response of < or = 10 microg/L to two different GH stimulation tests. The children were assigned as follows to one of three treatment groups with ibutamoren mesylate: 0.2 mg/kg per day for 7 days (days 1-7 or 8-14) and matching placebo for the alternate 7 days (groups I and II, respectively) or 0.8 mg/kg per day for 7 days (days 8-14, group III). On day 15 all patients received an 0.8-mg/kg dose of ibutamoren mesylate. Patients in groups I and II were studied first to assess safety at the low dose before advancement to the high dose. Hormonal profiles were evaluated on day -1 (baseline) and day 15, and the results were expressed as the change from baseline within each group. After administration of ibutamoren mesylate 0.8 mg/kg for 8 days (group III), the median increases (on day 15) from baseline were as follows: 3.8 microg/L (range, 0 to 34.3) for serum GH peak concentration (P = .001), 4.3 microg x h/L (range, 1.3 to 35.6) for the GH area under the concentration-time curve from time zero to 8 hours (AUC(0-8)) (P < .001), 12 microg/L (range, -4 to 116) for serum IGF-I (P = .01), and 0.4 microg/L (range, -0.9 to 1.5) for serum IGF-binding protein 3 (IGFBP-3) (P = .01). There was no change in serum prolactin, glucose, triiodothyronine, thyroxine, thyrotropin, peak serum cortisol, and insulin concentrations or 24-hour urinary free cortisol after administration of 0.8 mg/kg per day of ibutamoren mesylate for 8 days. We conclude that short-term administration of ibutamoren mesylate can increase GH, IGF-I, and IGFBP-3 levels in some children with GH deficiency. Thus this compound is applicable for testing its effect on growth velocity.

Administration, Oral↗

Effects of the lazaroid, tirilazad mesylate, on sepsis-induced acute lung injury in minipigs.

OBJECTIVE: To assess the effects of the lazaroid, tirilazad mesylate, a potent lipid peroxidation inhibitor, in an animal model of Pseudomonas sepsis. DESIGN: Comparison of four experimental groups: a) saline control; b) Pseudomonas sepsis control; c) tirilazad mesylate control; and d) sepsis with tirilazad mesylate pre treatment. SETTING: University animal laboratory. SUBJECTS: Hanford minipigs (20 to 25 kg), anesthetized with pentobarbital and mechanically ventilated on an FIO2 of 0.4. INTERVENTIONS: Sepsis was induced by infusing Pseudomonas aeruginosa at 1 x 10(6) colony-forming units/kg/min over 120 mins. The tirilazad mesylate-treated group received a 5-mg/kg bolus 30 mins before, and a 3-mg/kg bolus 3 hrs after, the onset of sepsis. Hemodynamics, PaO2, and neutrophil counts were measured for 6 hrs. Thiobarbituric acid reactive material (TBARM) in tissue (lung, liver, and intestine), lung wet/dry weight ratio, lung myeloperoxidase activity, plasma tumor necrosis factor (TNF)-alpha concentrations, protein content, and percent neutrophils in bronchoalveolar lavage fluid were evaluated at the time the animals were killed (6 hrs). MEASUREMENTS AND MAIN RESULTS: Sepsis induced significant systemic hypotension, pulmonary hypertension, hypoxemia, and neutropenia. Sepsis also significantly increased TBARM content, lung wet/dry weight ratio, myeloperoxidase activity, plasma TNF-alpha concentrations, and bronchoalveolar lavage neutrophil percentage. Treatment with tirilazad mesylate significantly attenuated hypoxemia and decreased TBARM content, lung wet/dry weight ratio, myeloperoxidase activity, bronchoalveolar lavage protein, and bronchoalveolar lavage neutrophil percentage, but did not affect sepsis-induced hemodynamics, including systemic hypotension and pulmonary hypertension, plasma TNF-alpha concentrations, or neutropenia. CONCLUSIONS: Pretreatment with the tirilazad mesylate did not change P. aeruginosa sepsis-induced hemodynamic consequences. However, tirilazad mesylate attenuated sepsis-induced acute lung injury.

Animals↗

Single-blind study of the effects of intravenous dolasetron mesylate versus ondansetron on electrocardiographic parameters in normal volunteers.

A single-blind, randomized, five-way cross-over, safety and tolerability trial was conducted to determine whether intravenous (i.v.) dolasetron mesylate at varying single doses induces changes in ECG intervals in healthy volunteers and to compare these changes with a single intravenous dose of ondansetron or placebo. Thirty healthy male volunteers received 1.2, 1.8, and 2.4 mg/kg i.v. dolasetron mesylate, 32 mg i.v. ondansetron, and placebo on 5 separate days. ECGs were recorded at intervals during the 24 h after study drug administration. The changes in ECG intervals observed after dolasetron mesylate or ondansetron were acute, transient, and asymptomatic. Dolasetron mesylate resulted in slight but statistically significant dose-related increases in heart rate (HR) and PR and QRS intervals (between h 0 and 4). A statistically significant increase in QTc interval was detected with both dolasetron mesylate (2.4 mg/kg) and ondansetron. Ondansetron also produced a slight but statistically significant increase in JT interval and a decrease in HR. These changes in ECG intervals were usually observed between h 0 and 4; all parameters returned to baseline within 8 h of treatment. The results demonstrate that both dolasetron mesylate and ondansetron prolong the QTc interval. However, dolasetron mesylate predominantly altered ECG parameters indicative of ventricular depolarization (QRS duration), whereas ondansetron predominantly affected ventricular repolarization as measured by a prolongation in the JT interval. Both dolasetron and ondansetron were well tolerated. The adverse event (AE) rate was 13.3% (4 of 30); all AE were of mild or moderate severity and were distributed across all dose arms.

Adult↗

Effects of intravenous high dose co-dergocrine mesylate ('Hydergine') in elderly patients with severe multi-infarct dementia: a double-blind, placebo-controlled trial.

A double-blind, placebo-controlled trial was carried out in 40 patients affected by multi-infarct dementia to see if a daily intravenous infusion of 3 mg co-dergocrine mesylate ('Hydergine') over 14 days would improve severely deteriorated elderly patients and shorten the latent period (3 months) which is observed when the drug is given orally. All the patients had severe mental impairment, psychological deficit or altered consciousness. A Hachinski score of 7 or more, and a cumulative score of at least 12 points on SCAG scale Items 1, 2 and 4 (anxiety/depression) and/or Items 5, 6 and 8 (alertness/confusion) were required for admission. After 1 week of intravenous infusion of placebo, patients were randomly allocated to treatment with co-dergocrine mesylate or placebo, from Day 1 to Day 14. The solutions were infused over a period of 2 hours. During the follow-up period from Day 15 to Day 21, the patients did not receive any treatment. Thirty-six patients (17 on co-dergocrine mesylate, 19 on placebo) completed the study. The results, as rated on the SCAG scale, indicated significant improvements, in favour of co-dergocrine mesylate, in cognitive dysfunction, mood depression, withdrawal and overall impression. Furthermore, the factor fatigue on the Nowlis scale and clinical global assessments by physicians also showed significant advantages of the co-dergocrine mesylate group over placebo. Nine out of 17 co-dergocrine mesylate patients complained of side-effects, usually experienced during infusion; they consisted mainly of nausea (6 patients), gastric discomfort (2 patients), and tremor, nasal congestion, flushing, hypotension and hypertension (1 patient each). Despite the appearance of side-effects, general tolerability was rated as 'good' by both physicians and patients. It is concluded, therefore, that intravenous high dose co-dergocrine mesylate treatment has a fast and clinically relevant effect on the key clinical symptoms of multi-infarct dementia.

Aged↗

Inhibitory effect of deferoxamine mesylate and low iron diet on the 13762NF rat mammary adenocarcinoma.

The iron chelator deferoxamine mesylate has been shown to inhibit the growth of a variety of human malignant cell lines and the rat 13762NF mammary adenocarcinoma cell line. In vivo studies in mice have also demonstrated that an iron deficiency induced by either feeding a low iron diet or injecting the iron chelator deferoxamine mesylate decreases tumor growth. In this study Fisher rats were transplanted with the 13762NF mammary adenocarcinoma and divided into four groups: normal diet, normal diet plus deferoxamine mesylate treatment, low iron diet and low iron diet plus deferoxamine mesylate treatment. The measurements of tumor size and body weight were recorded weekly. We found that treatment with either deferoxamine mesylate or a low iron diet decreased rat tumor growth, but the greatest inhibitory effect on tumor growth occurred when the rats were treated with deferoxamine mesylate injections plus fed a low iron diet. These treatments did not significantly inhibit the weight gain of the rats. At the end of the experiments measurement of serum iron proved that these treatments caused iron deficiency, but there was no significant treatment related alteration in blood hematocrit. We therefore concluded that deferoxamine mesylate may be a useful chemotherapeutic agent in the treatment of breast cancer, when used in combination with standard chemotherapeutic regiments or with other agents that interfere with iron metabolism, and further that the restricting of iron intake should be considered when planning chemotherapy for all cancer patients.

Adenocarcinoma↗

Clinical efficacy of tirilazad mesylate for treatment of endotoxemia in neonatal calves.

The clinical efficacy of the lazaroid, tirilazad mesylate, a new therapeutic agent for prophylaxis and treatment of endotoxemia, was evaluated in 24 neonatal Holstein calves. Endotoxemia was induced by IV infusion of commercial Escherichia coli lipopolysaccharide (3.25 micrograms/kg of body weight) over 3 hours. Group-1 calves were given endotoxin alone; group-2 calves were given an infusion of 0.9% sterile saline solution, then were treated with tirilazad mesylate (1.5 mg/kg) 1 hour after the infusion was started. Group-3 calves were treated with tirilazad mesylate 1 hour after the start of the endotoxin infusion, and group-4 calves were given tirilazad mesylate 1 hour before the start of the endotoxin infusion. Clinical signs of endotoxemia were mitigated by tirilazad mesylate. In addition, tirilazad mesylate protected calves from endotoxin-induced hyperglycemia; treatment after endotoxin infusion decreased the severity of hypoglycemia and prevented lactic acidosis. Treatment with tirilazad mesylate after initiation of endotoxin infusion was as protective as was pretreatment.

Animals↗

[Effect of co-dergocrine mesylate on catecholamines and prolactin in elderly hypertensive patients].

The antihypertensive efficacy of co-dergocrine mesylate (a mixture of dihydroergocornine mesylate, dihydroergocristine mesylate, and alpha- and beta-dihydroergocryptine mesylates; Hydergin) and its effects on heart rate, plasma catecholamines, catecholamine excretion and plasma prolactin was tested in 12 elderly hypertensive patients. Co-dergocrine mesylate (6 mg or 12 mg, 1 or 2 tablets once a day) caused a significant reduction of the blood pressure during rest and under physical stress without a reactive increase of the heart rate. Plasma norepinephrine and prolactin as well as urinary excretion of norepinephrine and epinephrine were not affected by co-dergocrine mesylate. The therapeutic advantage of co-dergocrine mesylate for the treatment of hypertension in the elderly is discussed.

Aged↗

Imatinib-mesylate blocks recombinant T-type calcium channels expressed in human embryonic kidney-293 cells by a protein tyrosine kinase-independent mechanism.

The 2-phenylaminopyrimidine derivative imatinib-mesylate, a powerful protein tyrosine kinase (PTK) inhibitor that targets abl, c-kit, and the platelet-derived growth factor receptors, is rapidly gaining a relevant role in the treatment of several types of neoplasms. Because first generation PTK inhibitors affect the activity of a large number of voltage-dependent ion channels, the present study explored the possibility that imatinib-mesylate could interfere with the activity of T-type channels, a class of voltage-dependent Ca2+ channels that take part in the chain of events elicited by PTK activation. The effect of the drug on T-type channel activity was examined using the whole-cell patch-clamp technique with Ba2+ (10 mM) as the permeant ion in human embryonic kidney-293 cells, stably expressing the rat Ca(V)3.3 channels. Imatinib-mesylate concentrations, ranging from 30 to 300 microM, reversibly decreased Ca(V)3.3 current amplitude with an IC(50) value of 56.9 microM. By contrast, when imatinib-mesylate (500 microM) was intracellularly dialyzed with the pipette solution, no reduction in Ba2+ current density was observed. The 2-phenylaminopyrimidine derivative modified neither the voltage dependence of activation nor the steady-state inactivation of Ca(V)3.3 channels. The decrease in extracellular Ba2+ concentration from 10 to 2 mM and the substitution of Ca2+ for Ba2+ increased the extent of 30 microM imatinib-mesylate-induced percentage of channel blockade from 25.9 +/- 2.4 to 36.3 +/- 0.9% in 2 mM Ba2+ and 44.2 +/- 2.3% in 2 mM Ca2+. In conclusion, imatinib-mesylate blocked the cloned Ca(V)3.3 channels by a PTK-independent mechanism. Specifically, the drug did not affect the activation or the inactivation of the channel but interfered with the ion permeation process.

Benzamides↗