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Bordon KDCF, Cologna CT, Fornari-Baldo EC, Pinheiro-Júnior EL, Cerni FA, Amorim FG, Anjolette FAP, Cordeiro FA, Wiezel GA, Cardoso IA, Ferreira IG, de Oliveira IS, Boldrini-França J, Pucca MB, Baldo MA, Arantes EC. From Animal Poisons and Venoms to Medicines: Achievements, Challenges and Perspectives in Drug Discovery. Front Pharmacol 2020; 11:1132. [PMID: 32848750 PMCID: PMC7396678 DOI: 10.3389/fphar.2020.01132] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/13/2020] [Indexed: 12/16/2022] Open
Abstract
Animal poisons and venoms are comprised of different classes of molecules displaying wide-ranging pharmacological activities. This review aims to provide an in-depth view of toxin-based compounds from terrestrial and marine organisms used as diagnostic tools, experimental molecules to validate postulated therapeutic targets, drug libraries, prototypes for the design of drugs, cosmeceuticals, and therapeutic agents. However, making these molecules applicable requires extensive preclinical trials, with some applications also demanding clinical trials, in order to validate their molecular target, mechanism of action, effective dose, potential adverse effects, as well as other fundamental parameters. Here we go through the pitfalls for a toxin-based potential therapeutic drug to become eligible for clinical trials and marketing. The manuscript also presents an overview of the current picture for several molecules from different animal venoms and poisons (such as those from amphibians, cone snails, hymenopterans, scorpions, sea anemones, snakes, spiders, tetraodontiformes, bats, and shrews) that have been used in clinical trials. Advances and perspectives on the therapeutic potential of molecules from other underexploited animals, such as caterpillars and ticks, are also reported. The challenges faced during the lengthy and costly preclinical and clinical studies and how to overcome these hindrances are also discussed for that drug candidates going to the bedside. It covers most of the drugs developed using toxins, the molecules that have failed and those that are currently in clinical trials. The article presents a detailed overview of toxins that have been used as therapeutic agents, including their discovery, formulation, dosage, indications, main adverse effects, and pregnancy and breastfeeding prescription warnings. Toxins in diagnosis, as well as cosmeceuticals and atypical therapies (bee venom and leech therapies) are also reported. The level of cumulative and detailed information provided in this review may help pharmacists, physicians, biotechnologists, pharmacologists, and scientists interested in toxinology, drug discovery, and development of toxin-based products.
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Affiliation(s)
- Karla de Castro Figueiredo Bordon
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Camila Takeno Cologna
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | | | - Ernesto Lopes Pinheiro-Júnior
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Felipe Augusto Cerni
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Fernanda Gobbi Amorim
- Postgraduate Program in Pharmaceutical Sciences, Vila Velha University, Vila Velha, Brazil
| | | | - Francielle Almeida Cordeiro
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Gisele Adriano Wiezel
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Iara Aimê Cardoso
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Isabela Gobbo Ferreira
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Isadora Sousa de Oliveira
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | | | | | - Mateus Amaral Baldo
- Health and Science Institute, Paulista University, São José do Rio Pardo, Brazil
| | - Eliane Candiani Arantes
- Laboratory of Animal Toxins, Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
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Angeli F, Verdecchia P, Reboldi G. Non-inferiority Trial Design in Drug Development: A Primer for Cardiovascular Healthcare Professionals. Am J Cardiovasc Drugs 2020; 20:229-238. [PMID: 31650521 DOI: 10.1007/s40256-019-00378-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Noninferiority trials, in which a new treatment is compared with a standard active treatment, are becoming increasingly popular in cardiovascular medicine. A noninferiority trial seeks to test whether the effect of a new drug is not unacceptably worse than that of an active comparator by more than a predefined noninferiority margin. Noninferiority trials are typically used when a new drug is anticipated to have an efficacy profile similar to its comparator and offers advantages over the existing drug (better toxicity profile, less expensive, less invasive, simpler regimen, shorter treatment duration, different resistance profile). Given the high number of noninferiority trials, it is vital that clinicians fully understand the clinical impacts of the results. Nonetheless, assessing noninferiority in a trial is complex, in both the design and the analysis phases. The crucial issue in the design of a noninferiority trial is the definition of the noninferiority margin, accounting for both statistical (summarizing the historical evidence of the active comparator from randomized controlled trials) and clinical (choosing the fraction of the effect of the old drug that should be "preserved" by the new drug) considerations. We review the role of noninferiority trials in the development of new cardiovascular treatments and discuss a variety of key issues involved in the design and conduction of noninferiority trials, using some examples from real clinical trials in cardiovascular medicine.
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Affiliation(s)
- Fabio Angeli
- Department of Medicine and Surgery, University of Insubria, Varese, Italy
- Maugeri Care and Research Institute, IRCCS Tradate, Tradate, Italy
| | - Paolo Verdecchia
- Fondazione Umbra Cuore e Ipertensione-ONLUS and Division of Cardiology, Hospital S. Maria della Misericordia, Perugia, Italy
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Gómez-Outes A, Berto P, Prandoni P. Cost–effectiveness of bemiparin in the prevention and treatment of venous thromboembolism. Expert Rev Pharmacoecon Outcomes Res 2014; 6:249-59. [DOI: 10.1586/14737167.6.3.249] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Schmidt BJ, Papin JA, Musante CJ. Mechanistic systems modeling to guide drug discovery and development. Drug Discov Today 2012; 18:116-27. [PMID: 22999913 DOI: 10.1016/j.drudis.2012.09.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/17/2012] [Accepted: 09/05/2012] [Indexed: 01/24/2023]
Abstract
A crucial question that must be addressed in the drug development process is whether the proposed therapeutic target will yield the desired effect in the clinical population. Pharmaceutical and biotechnology companies place a large investment on research and development, long before confirmatory data are available from human trials. Basic science has greatly expanded the computable knowledge of disease processes, both through the generation of large omics data sets and a compendium of studies assessing cellular and systemic responses to physiologic and pathophysiologic stimuli. Given inherent uncertainties in drug development, mechanistic systems models can better inform target selection and the decision process for advancing compounds through preclinical and clinical research.
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Affiliation(s)
- Brian J Schmidt
- Department of Bioengineering, University of California at San Diego, La Jolla, CA 92093-0412, USA
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Dabigatran etexilate: an oral direct thrombin inhibitor for the management of thromboembolic disorders. Clin Ther 2012; 34:766-87. [PMID: 22444784 DOI: 10.1016/j.clinthera.2012.02.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2012] [Indexed: 12/30/2022]
Abstract
BACKGROUND Until recently, warfarin was the only oral anticoagulant available in the United States. Its narrow therapeutic index, interpatient variability in dose response, and drug and food interactions make it difficult to use. Dabigatran etexilate (DE) is a new oral direct thrombin inhibitor that was approved in the US and in Canada for the prevention of thromboembolic events in patients with atrial fibrillation (AF), as well as in Europe and Canada for the prevention of venous thromboembolism (VTE). OBJECTIVE To discuss the role of DE for the prevention and treatment of VTE, as well as for the prevention of stroke in patients with AF. METHODS Peer-reviewed clinical trials, review articles, and treatment guidelines were identified from MEDLINE and the Current Contents database (both 1966-February 15, 2012) using the search terms dabigatran, VTE, Afib, pharmacokinetics, pharmacodynamics, pharmacoeconomics, and cost-effectiveness. Citations from available articles were also reviewed for additional references. RESULTS For VTE prophylaxis, DE 150 or 220 mg orally daily has demonstrated either superiority or noninferiority to subcutaneous enoxaparin once daily in most studies. However, one study failed to demonstrate noninferiority to subcutaneous enoxaparin dosed BID in the composite end point of VTE, and all-cause mortality. For VTE treatment, DE 150 mg BID orally was shown to be noninferior to warfarin in preventing recurrent events. For AF, DE 150 mg BID orally is superior to warfarin in the prevention of thromboembolism, whereas 110 mg BID is noninferior to warfarin. Pharmacoeconomic analyses performed in the United Kingdom and Ireland found that DE can be cost-saving compared with enoxaparin in the prevention of VTE. Adverse effects of DE reported in clinical studies include dyspepsia (12%-13%) and bleeding (minor bleeding: 6%-22%). CONCLUSIONS DE exhibited a safety profile and efficacy comparable to enoxaparin for VTE prophylaxis; comparable safety profile and efficacy to warfarin for VTE treatment; and superiority (150 mg BID orally) in the prevention of stroke and systemic embolism compared with warfarin in patients with AF. The relative ease of oral administration, no need for routine monitoring, and lack of significant drug interactions, may favor use of DE over other anticoagulants. However, there is no antidote for DE currently available.
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Gulseth MP, Wittkowsky AK, Fanikos J, Spinler SA, Dager WE, Nutescu EA. Dabigatran Etexilate in Clinical Practice: Confronting Challenges to Improve Safety and Effectiveness. Pharmacotherapy 2011; 31:1232-49. [DOI: 10.1592/phco.31.12.1232] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Blommel ML, Blommel AL. Dabigatran etexilate: A novel oral direct thrombin inhibitor. Am J Health Syst Pharm 2011; 68:1506-19. [PMID: 21817082 DOI: 10.2146/ajhp100348] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Matthew L. Blommel
- West Virginia Center for Drug and Health Information, Morgantown, and Assistant Clinical Professor, Department of Clinical Pharmacy, School of Pharmacy, West Virginia University, Morgantown
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Baetz BE, Spinler SA. Dabigatran Etexilate: An Oral Direct Thrombin Inhibitor for Prophylaxis and Treatment of Thromboembolic Diseases. Pharmacotherapy 2008; 28:1354-73. [DOI: 10.1592/phco.28.11.1354] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Gulseth MP, Michaud J, Nutescu EA. Rivaroxaban: an oral direct inhibitor of factor Xa. Am J Health Syst Pharm 2008; 65:1520-9. [PMID: 18693206 DOI: 10.2146/ajhp070624] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE The mechanism of action, pharmacodynamics, pharmacokinetics, efficacy in clinical trials, interactions, adverse effects and toxicity, and place in therapy of rivaroxaban are reviewed. SUMMARY Rivaroxaban, the first oral, direct factor Xa (FXa) inhibitor to reach Phase III trials, inhibits thrombin generation by both the intrinsic and the tissue factor pathways. It has shown predictable, reversible inhibition of FXa activity, and it may have the ability to inhibit clot-bound FXa. Rivaroxaban is being evaluated for prevention of venous thrombosis in patients undergoing hip or knee arthroplasty, treatment of venous thrombosis, long-term use for secondary prevention of venous thrombosis, and prevention of stroke in atrial fibrillation. To date, only short-term trials have been reported, but rivaroxaban's safety and efficacy appear to be at least equivalent to those of traditional anticoagulants. The results of four studies of primary prevention of venous thrombosis in patients undergoing orthopedic surgery suggest that rivaroxaban 10 mg daily is a promising alternative to low-molecular-weight heparins. Rivaroxaban appears to have a low potential for drug-drug or drug-food interactions. It offers the advantages of a fixed oral dose, rapid onset of action, and predictable and consistent anticoagulation effect, precluding the need for routine monitoring of anticoagulation. CONCLUSION Rivaroxaban is a promising alternative to traditional anticoagulants for the prevention and treatment of venous thromboembolism and for stroke prevention in atrial fibrillation; it offers once-daily oral administration without the need for routine monitoring.
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Cvirn G, Cimenti C, Kutschera J, Ferstl U, Wagner T, Muntean W, Jurgens G, Gallistl S, Koestenberger M. Anticoagulant action of melagatran: a comparison between neonates and adults using calibrated automated thrombography (CAT). Eur J Pediatr 2007; 166:427-31. [PMID: 17047995 DOI: 10.1007/s00431-006-0253-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 07/13/2006] [Indexed: 11/29/2022]
Abstract
In the present study, we comparatively evaluated the anticoagulant efficacy of the new direct thrombin inhibitor melagatran in cord vs. adult plasma. In contrast to heparin, melagatran does not require antithrombin as a cofactor. Thus, anticoagulant treatment with melagatran is of special interest in neonatal patients, whose plasma is relatively deficient in antithrombin. We evaluated the anticoagulant action of increasing amounts of melagatran (0.1-2.0 micromol/l) in both cord and adult plasma by means of calibrated automated thrombography (CAT) with respect to the lag time until the onset of thrombin formation, time to thrombin peak maximum (TTP), endogenous thrombin potential (ETP), and thrombin peak height. Melagatran exhibited approximately the same ability to prolong lag times or TTPs in both cord and adult plasma. Similar concentrations (IC(50)) of melagatran were required to double the lag times (0.44+/-0.04 micromol/l vs. 0.52+/-0.05 micromol/l) or to double the TTPs (0.91+/-0.08 micromol/l vs. 1.06+/-0.09 micromol/l) in cord vs. adult plasma. Melagatran exhibited a higher ability to suppress ETPs or thrombin peak heights in cord vs. adult plasma. Markedly lower concentrations (IC(50)) of melagatran were required to suppress ETPs (0.27+/-0.03 micromol/l vs. 0.70+/-0.06 micromol/l) or thrombin peak heights by 50% (0.29+/-0.03 micromol/l vs. 0.53+/-0.04 micromol/l) in cord vs. adult plasma. We conclude that our results suggest a higher ability of melagatran to suppress thrombin formation in cord vs. adult plasma. Thus, lower amounts of melagatran might be required in neonates undergoing antithrombotic therapy.
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Affiliation(s)
- Gerhard Cvirn
- Institute of Physiological Chemistry, Center of Physiological Medicine, Medical University of Graz, Harrachgasse 21/II, 8010, Graz, Austria.
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Rogers F, Rebuck JA, Sing RF. Venous thromboembolism in trauma: an update for the intensive care unit practitioner. J Intensive Care Med 2007; 22:26-37. [PMID: 17259566 DOI: 10.1177/0885066606295291] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Venous thromboembolism (VTE) in trauma patients is a capricious problem that continues to plague trauma surgeons and critical care physicians alike. Pharmacologic preventions of VTE with anticoagulants are often contraindicated in the trauma patient because of risk of bleeding diathesis. Mechanical prophylaxis in the form of venous compression boots often cannot be placed because of external fixators, swelling, and so forth. Providing effective VTE prophylaxis, while at the same time providing definitive care for the trauma patient, can be a nightmare. This review will first discuss the incidence and prevalence of VTE, as well as investigate the condition's diagnosis and treatment. Solutions to frequently encountered clinical dilemmas in managing VTE in trauma patients are considered in the form of frequently asked questions. Diagnostic techniques such as magnetic resonance venography, D-dimer, and various computed tomography methods are evaluated. Recent literature on preventive pharmacologic therapies is explored. The authors also consider whether vena cava filters prevent pulmonary embolism in trauma patients.
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Cimenti C, Koestenberger M, Leschnik B, Haidl H, Muntean W. The respective and combined anticoagulant effects of recombinant human activated protein C, melagatran and heparins using CAT. Thromb Res 2007; 119:361-7. [PMID: 16712904 DOI: 10.1016/j.thromres.2006.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 03/07/2006] [Accepted: 03/07/2006] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Combinations of anticoagulants might be beneficial in some patients with sepsis, but most anticoagulants require specific clotting assays for monitoring. Thrombin generation assay, however, is a global function test of hemostasis. MATERIALS AND METHODS We performed an in vitro investigation of the respective effects of recombinant human activated protein C (rhAPC) alone and in combination with either melagatran (a new direct thrombin inhibitor), unfractionated heparin (UH) or low molecular weight heparin (LMWH) in varying concentrations on the thrombin generation (TG) using the calibrated automated thrombography. RESULTS RhAPC, UH, LMWH and melagatran dose-dependently prolonged the lag time and the time to peak, and significantly suppressed the endogenous thrombin potential (ETP). Combined application of rhAPC with either melagatran, UH or LMWH induced an additive prolongation of the lag time; this effect was more pronounced in a combination of rhAPC with UH or LMWH. CONCLUSION In our in vitro study adding either melagatran, UH or LMWH augmented the capacity of rhAPC to suppress thrombin generation in human plasma. These findings suggest that patients with severe sepsis might benefit from a treatment with combinations of anticoagulant agents.
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Affiliation(s)
- Christina Cimenti
- Ludwig Boltzmann Research Institute for Pediatric Hemostasis and Thrombosis at the Department of Pediatrics, Medical University of Graz, Auenbruggerplatz 30, 8036 Graz, Austria.
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Yoshida WB, El Dib RP, Yoshida RDA, Maffei FHDA. Ximelagatran versus warfarin for prophylaxis of venous thromboembolism in major orthopedic surgery: systematic review of randomized controlled trials. SAO PAULO MED J 2006; 124:355-61. [PMID: 17322960 DOI: 10.1590/s1516-31802006000600012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 10/23/2006] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Ximelagatran has been recently studied for prophylaxis in surgical orthopedic cases. PURPOSE We proposed to establish whether interventions involving ximelagatran, as compared with warfarin, would increase thromboembolic prophylaxis in patients undergoing major orthopedic knee surgery. DATA SOURCE Studies with random assignment were identified by an electronic search of the medical literature up to 2006. Data were double-entered into the Review Manager software, version 4.2.5. DATA SYNTHESIS We included three well-conducted clinical trials involving 4,914 participants. Sub-groups with two dosages of ximelagatran (24 mg and 36 mg, b.i.d.), were defined. Ximelagatran showed significantly lower frequency of total venous thromboembolism (VTE) than warfarin, but only with the 36-mg dosage (risk relative, RR: 0.72; 95% confidence interval, CI: 0.64-0.81; p < 0.00001). For the 24-mg subgroup, total VTE frequency was similar (RR: 0.86; 95% CI: 0.73-1.01; p = 0.06). No significant differences were shown with either ximelagatran dosage for deep vein thrombosis (DVT), pulmonary embolism, any bleeding or severe bleeding. At the end of the treatment, alanine aminotransferase (ALT) elevation was less frequent in the 24-mg ximelagatran sub-group (RR: 0.33; 95% CI: 0.12-0.91; p = 0.03], but during the follow-up period, the ALT elevation rate was greater in the 36-mg ximelagatran group (RR: 6.97; 95% CI: 1.26-38.50; p = 0.03]. CONCLUSIONS Ximelagatran appears to be more effective than warfarin when used in higher dosages (36 mg b.i.d.), but at the expense of increased frequency of ALT elevation during the follow-up period.
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Affiliation(s)
- Winston Bonetti Yoshida
- Department of Surgery and Orthopedics, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil, CEP 18618-970.
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Koestenberger M, Gallistl S, Bettina L, Cimenti C, Kutschera J, Cvirn G. Effects of melagatran on activated partial thromboplastin time and on ecarin clotting time in cord versus adult plasma. Blood Coagul Fibrinolysis 2006; 17:677-80. [PMID: 17102656 DOI: 10.1097/01.mbc.0000252604.63142.e0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Melagatran is the active form of the oral direct thrombin inhibitor ximelagatran. Melagatran does not require antithrombin as a cofactor. Its administration is therefore of special interest in neonatal patients, whose plasma is relatively deficient in antithrombin. We investigated the effects of increasing amounts of melagatran (0.05-1 micromol/l) on the activated partial thromboplastin time (APTT) and ecarin clotting time (ECT) in cord versus adult plasma. Both the APTT and ECT were dose-dependently prolonged in the presence of increasing amounts of melagatran. Furthermore, the ECT revealed a higher susceptibility of cord plasma to addition of melagatran than adult plasma. Whereas similar amounts of melagatran were required in cord and adult plasma samples to double the APTT (IC(50), 0.47 vs 0.46 micromol/l), significantly less melagatran was required in cord versus adult plasma to double the ECT (IC(50), 0.26 vs 0.56 micromol/l). Based on APTT measurements, similar plasma levels of melagatran might be required in neonates and in adults to treat thromboembolic complications. The APTT, however, is relatively insensitive to plasma melagatran concentrations. When the sensitive indicator ECT is used, results suggest that lower amounts of melagatran might be required in neonates than in adults. This has to be scrutinized in future clinical studies.
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Chang JJY, Parikh CR. HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: When Heparin Causes Thrombosis: Significance, Recognition, and Management of Heparin-Induced Thrombocytopenia in Dialysis Patients. Semin Dial 2006; 19:297-304. [PMID: 16893407 DOI: 10.1111/j.1525-139x.2006.00176.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is characterized by thrombocytopenia and paradoxical hypercoagulability. HIT occurs when an antibody ("HIT antibody") produced against the complex of heparin and platelet factor 4 (PF4) causes systemic platelet consumption and activation. Nephrologists encounter HIT in the care of end-stage renal disease (ESRD) patients because heparin is a routine anticoagulant in hemodialysis. The incidence of HIT in ESRD appears to be lower than in other clinical settings. However, HIT is equally life threatening in ESRD patients and therefore demands the same prompt recognition and aggressive treatment. Diagnosing HIT requires the detection of HIT antibodies. A functional assay (e.g., [(14)C] serotonin release assay) relies on the patient's HIT antibodies to activate donor platelets at pharmacologic heparin concentrations. The more common antigen assay (e.g., enzyme-linked immunosorbent assay [ELISA]) detects the binding of the patient's HIT antibodies to antigens (e.g., heparin-PF4 complex) in a microtiter well and does not involve platelets. The moment HIT is suspected, heparin should be stopped and an alternative anticoagulant initiated immediately, even before the result of a serologic test becomes available. The advent of several new anticoagulants in the last decade, especially argatroban and bivalirudin, has expanded treatment options for HIT in dialysis patients. This review discusses the epidemiology, pathogenesis, clinical features, diagnosis, and treatment of HIT, with special emphasis on concepts relevant to the care of dialysis patients.
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Affiliation(s)
- John Jae Young Chang
- Section of Nephrology, Clinical Epidemiology Research Center, VA Connecticut Health Care System and Yale University, West Haven, Connecticut 06516, USA
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Affiliation(s)
- E Arbit
- Emisphere Technologies, Tarrytown, NY, USA
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