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Phillips E, Kornya M, Collier A, Barry M, Morrison K, Reggeti F. Presumptive phenobarbital-induced systemic lupus erythematosus in a domestic dog. J Vet Intern Med 2023; 37:2482-2487. [PMID: 37737539 PMCID: PMC10658473 DOI: 10.1111/jvim.16882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 09/11/2023] [Indexed: 09/23/2023] Open
Abstract
CASE DESCRIPTION We describe a case of presumptive acquired systemic lupus erythematosus secondary to phenobarbital administration in a dog, which resolved with withdrawal of the drug. CLINICAL FINDINGS A 3.5 year-old poodle presented to a veterinary teaching hospital for Tier 1 idiopathic epilepsy and was treated with phenobarbital. The dog experienced fever, multiple cytopenias, and proteinuria in conjunction with a positive antinuclear antibody (ANA) titer. DIAGNOSTICS Serial CBCs, urine protein : creatinine ratios, and sternal bone marrow aspirates were performed to evaluate improvement. TREATMENT AND OUTCOME Phenobarbital was withdrawn and levetiracetam initiated. All abnormalities resolved with supportive care, without initiation of immunosuppressive drugs. All cytopenias and proteinuria resolved and ANA test results became negative within 3 months. The patient recovered and did well clinically. CLINICAL RELEVANCE Systemic lupus erythematosus is a disease of multiple autoimmune syndromes occurring concurrently or sequentially in conjunction with the presence of circulating ANA. It has been well described in dogs as an idiopathic condition, but in human medicine may occur secondary to drug reactions (drug-associated lupus) including as a reaction to phenobarbital. The findings in our case are consistent with the criteria for drug-induced lupus in humans and we suggest it as the first report of phenobarbital-induced lupus in a dog.
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Affiliation(s)
- Erin Phillips
- Department of Clinical Studies, Ontario Veterinary CollegeUniversity of GuelphGuelphOntarioCanada
| | - Matthew Kornya
- Department of Clinical Studies, Ontario Veterinary CollegeUniversity of GuelphGuelphOntarioCanada
| | - Allison Collier
- Department of Clinical Studies, Ontario Veterinary CollegeUniversity of GuelphGuelphOntarioCanada
| | - Maureen Barry
- Department of Clinical Studies, Ontario Veterinary CollegeUniversity of GuelphGuelphOntarioCanada
| | - Katherine Morrison
- Department of Pathobiology, Ontario Veterinary CollegeUniversity of GuelphGuelphOntarioCanada
| | - Felipe Reggeti
- Animal Health Laboratories, Laboratory Services DivisionUniversity of GuelphGuelphOntarioCanada
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Addie DD, McDonald M, Audhuy S, Burr P, Hollins J, Kovacic R, Lutz H, Luxton Z, Mazar S, Meli ML. Quarantine protects Falkland Islands (Malvinas) cats from feline coronavirus infection. J Feline Med Surg 2012; 14:171-6. [PMID: 22314098 PMCID: PMC10822488 DOI: 10.1177/1098612x11429644] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Feline coronavirus (FCoV) causes feline infectious peritonitis (FIP). Since 2002, when 20 cats on the Falkland Islands were found to be FCoV seronegative, only seronegative cats could be imported. Between 2005-2007, 95 pet and 10 feral cats tested negative by indirect immunofluorescence antibody (IFA) analysis using two strains of type II FCoV, two transmissible gastroenteritis virus assays, an enzyme-linked immunosorbent assay and rapid immunomigration test. Twenty-four samples (23%) showed non-specific fluorescence, mostly attributable to anti-nuclear antibodies (ANA). The reason for ANA was unclear: reactive samples were negative for Erhlichia canis antibodies; seven were feline immunodeficiency virus positive, but 15 were negative. It was not possible to determine retrospectively whether the cats had autoimmune disease, hyperthyroidism treatment, or recent vaccination which may also cause ANA. The FCoV/ FIP-free status of the Falkland Islands cats should be maintained by FCoV testing incoming cats. However, ANA can complicate interpretation of IFA tests.
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Affiliation(s)
- Diane D Addie
- Institute Comparative Medicine, University of Glasgow Veterinary School, Glasgow, UK.
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Ng W, Lobach AR, Zhu X, Chen X, Liu F, Metushi IG, Sharma A, Li J, Cai P, Ip J, Novalen M, Popovic M, Zhang X, Tanino T, Nakagawa T, Li Y, Uetrecht J. Animal Models of Idiosyncratic Drug Reactions. CURRENT CONCEPTS IN DRUG METABOLISM AND TOXICOLOGY 2012; 63:81-135. [DOI: 10.1016/b978-0-12-398339-8.00003-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Abstract
There are many autoimmune diseases recognized in humans; many of these have counterparts in companion animals. The diseases discussed in this article do not constitute the entire spectrum of autoimmune disease in these species. They are the common and better-described diseases of dogs and cats that have a well-documented autoimmune etiology. There are myriad autoimmune diseases that affect humans; similar diseases yet unrecognized in companion animals likely will be characterized in the future. The role of genetics in predisposition to autoimmunity is a common characteristic of these diseases in humans and animals. Likewise, the suggested role of environmental or infectious agents is another commonality between humans and their pets.
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Rottman JB, Willis CR. Mouse Models of Systemic Lupus Erythematosus Reveal a Complex Pathogenesis. Vet Pathol 2010; 47:664-76. [DOI: 10.1177/0300985810370005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The mammalian immune system is remarkable in that it can respond to an essentially infinite number of foreign antigens. The ability to mount a long-lasting (adaptive) immune response against foreign antigen requires the participation of cells selected from an enormously diverse population of B and T cells. Because the B and T cell receptors expressed by these cells are generated at random, a significant percentage of B and T cells are invariably directed against self-antigen. Under normal circumstances, autoreactive B and T cells are eliminated, reprogrammed, or inactivated in the primary and secondary lymphoid organs. Despite these checks and balances, a small but significant number of people and animals still develop autoimmune disease. One such autoimmune disease—systemic lupus erythematosus—is characterized by the loss of B- and T-cell tolerance to self-antigens (principally nuclear), culminating in multisystemic inflammation. Multiple genetic defects, drug exposure, infectious agents, and environmental factors can contribute to the pathogenesis of the disease. Loss of B- and T-cell tolerance precipitates activation of plasmacytoid and myeloid dendritic cells; collectively, these cells cooperate to form a complex positive feedback loop, continually stimulated by the persistence of self-antigen. Novel treatment strategies now focus on specific inhibition of various aspects of the feedback loop. These specific inhibitors have the potential to be more effective and lack the side effects associated with generalized immunosuppression.
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Affiliation(s)
- J. B. Rottman
- Pathology Department, Amgen Inc, Cambridge, Massachusetts
| | - C. R. Willis
- Inflammation Research, Amgen Inc, Seattle, Washington
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Pressler BM, Robarge ME, Anderson KI. Partial characterization of feline myeloperoxidase and investigation of its potential role as an autoantigen in hyperthyroid cats. Am J Vet Res 2009; 70:869-78. [PMID: 19566472 DOI: 10.2460/ajvr.70.7.869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To partially characterize the cDNA, amino acid sequence, and tertiary structure of feline myeloperoxidase, describe its cellular location in mature granulocytes, and determine whether hyperthyroid cats have anti-myeloperoxidase antibody. SAMPLE POPULATION Bone marrow RNA and whole blood from cats of various sources and feline serum samples submitted for measurement of total thyroxine concentration from September 2006 to July 2007. PROCEDURES Feline myeloperoxidase cDNA was amplified from bone marrow RNA; presumptive splice sites were determined by comparison with human sequences. Intracellular localization of myeloperoxidase in granulocytes was determined by use of immunofluorescence and electron microscopy, and molecular weight and partial tertiary structure were determined by use of immunoblotting of granulocyte lysates. Anti-human myeloperoxidase (hMPO) antibody was detected via ELISA. RESULTS A 2,493-bp sequence encompassing the 2,160-bp cDNA with presumably the same number and size of exons as hMPO was generated. Translation predicted 85% homology with hMPO. Feline myeloperoxidase was localized to neutrophil primary granules, and immunoblotting revealed heavy and light bands with molecular weights similar to those of hMPO. The prevalence of anti-hMPO antibody did not differ between nonhyperthyroid and hyperthyroid cats or among hyperthyroid cats subclassified by treatment modality. CONCLUSIONS AND CLINICAL RELEVANCE Moderate homology existed between feline myeloperoxidase and hMPO cDNA and protein. Although findings suggested a similar tertiary structure and function for the 2 proteins, they also suggested that inability to detect a high prevalence of anti-hMPO antibody in hyperthyroid cats may be attributable to antigenic differences between the human and feline proteins rather than a lack of autoantibody.
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Affiliation(s)
- Barrak M Pressler
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
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Uetrecht JP. Section Review Pulmonary-Allergy, Dermatological, Gastrointestinal & Arthritis: Drug-induced lupus: Possible mechanisms and their implications for prediction of which new drugs may induce lupus. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.5.7.851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Radioiodine is considered the treatment of choice for hyperthyroidism, but in some situations, methimazole therapy is preferred, such as in cats with preexisting renal insufficiency. Unfavorable outcomes from methimazole are usually attributable to side effects, such as gastrointestinal upset, facial excoriation, thrombocytopenia, neutropenia, or liver enzyme elevations. Because restoration of euthyroidism can lead to a drop in glomerular filtration rate, all cats treated with methimazole should be monitored with blood urea nitrogen and creatinine levels in addition to serum thyroxine (T(4)) and a complete blood cell count. Transdermal methimazole is associated with fewer gastrointestinal side effects and can be used in cats with simple vomiting or inappetence from oral methimazole. Hypertension may not resolve immediately when serum T(4) is normalized, and moderate to severe hypertension should be treated concurrently with atenolol, amlodipine, or an angiotensin-converting enzyme inhibitor.
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Affiliation(s)
- Lauren A Trepanier
- Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive, Madison, WI 53706-1102, USA.
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Abstract
Radioiodine is considered the treatment of choice for hyperthyroidism, but in some situations, methimazole therapy is preferred, such as in cats with pre-existing renal insufficiency. Methimazole blocks thyroid hormone synthesis, and controls hyperthyroidism in more than 90% of cats that tolerate the drug. Unfavorable outcomes are usually due to side effects such as gastrointestinal (GI) upset, facial excoriation, thrombocytopenia, neutropenia, or liver enzyme elevations; warfarin-like coagulopathy or myasthenia gravis have been reported but are rare. Because restoration of euthyroidism can lead to a drop in glomerular filtration rate, all cats treated with methimazole should be monitored with BUN and creatinine, in addition to serum T4, complete blood count, and liver enzymes. Transdermal methimazole is associated with fewer GI side effects, and can be used in cats with simple vomiting or inappetance from oral methimazole. Hypertension may not resolve immediately when serum T4 is normalized, and moderate to severe hypertension should be treated concurrently with-atenolol, amlodipine, or an ACE inhibitor. Alternatives to methimazole include carbimazole, propylthiouracil, or iodinated contrast agents.
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Affiliation(s)
- Lauren A Trepanier
- Department of Medical Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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Uetrecht J. Role of animal models in the study of drug-induced hypersensitivity reactions. AAPS JOURNAL 2006; 7:E914-21. [PMID: 16594644 PMCID: PMC2750961 DOI: 10.1208/aapsj070489] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Drug-induced hypersensitivity reactions (DHRs) are a major problem, in large part because of their unpredictable nature. If we understood the mechanisms of these reactions better, they might be predictable. Their unpredictable nature also makes mechanistic studies very difficult, especially prospective clinical studies. Animal models are vital to most biomedical research, and they are almost the only way to test basic hypotheses of DHRs, such as the involvement of reactive metabolites. However, useful animal models of DHRs are rare because DHRs are also unpredictable in animals. For example, sulfonamide-induced DHRs in large-breed dogs appear to be valid because they are very similar to the DHRs that occur in humans; however, the incidence is only approximately 0.25%, and large-breed dogs are difficult to use as an animal model. Two more practical models are penicillamine-induced autoimmunity in the Brown Norway rat and nevirapine-induced skin rash in rats. The toxicity in these models is clearly immune mediated. In other models, such as amodiaquine-induced agranulocytosis/hepatotoxicity and halothane-induced hepatotoxicity, the drug induces an immune response but there is no clinical toxicity. This finding suggests that regulatory mechanisms usually limit toxicity. Many of the basic characteristics of the penicillamine and nevirapine models, such as memory and tolerance, are quite different suggesting that the mechanisms are also significantly different. More animal models are needed to study the range of mechanisms involved in DHRs; without them, progress in understanding such reactions is likely to be slow.
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Affiliation(s)
- Jack Uetrecht
- Department of Pharmacology, Clinical Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.
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Abstract
Antinuclear antibodies in domestic animal species have been commonly detected for many years, with the greatest frequency occurring in dogs as well as horses and cats. Most commonly, the assay used in diagnostic laboratories is indirect immunofluorescence on HEP-2 cells, similar to that used in human medicine, but with the exception that species-specific antiglobulin reagents are used instead of antihuman immunoglobulin. To a lesser extent, the Crithidia luciliae test for antibodies to double-stranded DNA has been used. Several research groups have used other assays.
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Affiliation(s)
- Laurel J Gershwin
- Department of Pathology, Microbiology, and Immunology, 2019 Haring Hall, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Lusson D, Billiemaz B, Chabanne JL. Circulating lupus anticoagulant and probable systemic lupus erythematosus in a cat. J Feline Med Surg 1999; 1:193-6. [PMID: 11919034 DOI: 10.1016/s1098-612x(99)90208-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An adult domestic short hair cat was presented in a critical condition with icterus. Various investigations demonstrated the presence of haemolytic anaemia and hepatic abnormalities, as well as significant coagulation defects. Systemic lupus erythematosus (SLE) was suggested as a possible cause.
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Affiliation(s)
- D Lusson
- 360 ave de la lere DLF, 83220 Le Pradet, France
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Escobar-Morreale HF, Bravo P, García-Robles R, García-Laraña J, de la Calle H, Sancho JM. Methimazole-induced severe aplastic anemia: unsuccessful treatment with recombinant human granulocyte-monocyte colony-stimulating factor. Thyroid 1997; 7:67-70. [PMID: 9086574 DOI: 10.1089/thy.1997.7.67] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Aplastic anemia is a rare but severe complication of thionamide therapy. Although colony-stimulating factors have been used extensively in thionamide-induced agranulocytosis with good results, the same might not apply to aplastic anemia. We present a case of a patient with methimazole-induced aplastic anemia in which, as administration of recombinant human granulocyte-monocyte colony-stimulating factor for a week did not result in an increase in peripheral blood cell count, standard immunosuppressive treatment was needed to restore normal hematopoiesis. The clinical characteristics of this patient are compared with those of previous cases of thionamide-induced aplastic anemia, especially with the only other reported patient in which colony-stimulating factors were used.
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Abstract
Prognosis in aplastic anemia is usually linked to the degree of hypoplasia in the bone marrow and pancytopenia in the blood. The authors were, therefore, intrigued when a patient with methimazole-associated aplastic anemia who satisfied criteria for severe disease recovered rapidly and completely once her drug was withdrawn. Review of the English language literature revealed ten fully documented cases of aplastic anemia associated with use of the antithyroid drugs methimazole, carbimazole, and propylthiouracil. Analysis of the ten and of an eleventh case presented here indicated that the disorder is typically characterized by severe pancytopenia and profound marrow hypoplasia, yet surprisingly good prognosis, ie, minimum survival of more than 70% with partial or complete recovery from symptoms and cytopenias in survivors within 2-5 weeks. The only deaths, both in the 1950s, were from brain hemorrhage in patients who were not transfused with platelets. The discrepancy between the clinical and laboratory severity of antithyroid drug-associated aplasia, on the one hand, and its relatively good prognosis and short term course, on the other, should be kept in mind when considering these patients for bone marrow transplantation or for therapy with antithymocyte globulin.
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Uetrecht J. Metabolism of drugs by activated leukocytes: implications for drug-induced lupus and other drug hypersensitivity reactions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1991; 283:121-32. [PMID: 2068978 DOI: 10.1007/978-1-4684-5877-0_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Despite their importance, little is known about the mechanism of idiosyncratic reactions, many such reactions have characteristics that suggest an immune-mediated mechanism. This is particularly true of drug-induced lupus which is an autoimmune syndrome. Certain functional groups are associated with a high incidence of idiosyncratic reactions, probably reflecting the ease with which they are metabolized to reactive metabolites. Although the liver is the principal organ of drug metabolism, most reactive metabolites generated in the liver would not reach other organs in significant concentrations. Because of the function of leukocytes, especially monocytes, in the induction of an immune response, the generation of reactive metabolites by monocytes would seem likely to lead to an immune-mediated adverse reaction. We have found that drugs that are associated with drug-induced lupus are oxidized to reactive metabolites by the myeloperoxidase system of monocytes. The initial step in drug-induced lupus could be haptenization of a protein on the surface of monocytes by these reactive metabolites. Other types of idiosyncratic drug reactions may involve a similar mechanism and the same drugs that induce lupus are usually associated with a high incidence of other types of idiosyncratic reactions. for example, procainamide, which causes the highest incidence of drug-induced lupus, also causes a relatively high incidence of agranulocytosis. Even some of the therapeutic effects of drugs may involve the production of reactive metabolites by myeloperoxidase or thyroid peroxidase.
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Affiliation(s)
- J Uetrecht
- Faculty of Pharmacy, University of Toronto, Canada
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Chapter 19. Chemical Basis for Immune Mediated Idiosyncratic Drug Hypersensitivity. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1991. [DOI: 10.1016/s0065-7743(08)61206-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Rubin RL, Tang FL, Tsay G, Pollard KM. Pseudoautoimmunity in normal mice: anti-histone antibodies elicited by immunization versus induction during graft-versus-host reaction. CLINICAL IMMUNOLOGY AND IMMUNOPATHOLOGY 1990; 54:320-32. [PMID: 2295157 DOI: 10.1016/0090-1229(90)90093-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Native preparations of evolutionarily conserved intracellular macromolecules are generally nonimmunogenic when injected in soluble form. However, vigorous immune responses were observed when common autoantigens such as histones, DNA or Sm antigen, or homologous liver homogenate were noncovalently coupled to latex beads prior to injection into mice. Antibody response to histone beads displayed immunologic memory and required a functional thymus, suggesting that T-helper cells were involved. However, bead-elicited autoantibodies could be distinguished from true autoantibodies in that they reacted with denatured, minor, or foreign components of the preparations or to regions unexposed in the native form of the immunogen. This response contrasted with spontaneously arising autoantibodies accompanying graft-versus-host (GVH) disease in the same strain of mice which preferred native nucleoprotein conformations within nuclei, chromatin, or DNA-histone complexes. Histone beads elicited antihistone antibodies displaying a sustained IgM isotype in contrast to spontaneously arising autoantibodies in GVH disease which were predominantly IgG. These studies demonstrate that immunization with autoantigens does not usually elicit true autoantibodies and suggest that lymphocyte populations responsible for pseudoautoimmune responses are different from autoantibody-producing cells. We speculate that if autoimmunity is driven by particulate forms of in vivo self-materials, additional factors are required for breaking the natural tolerance to native conformations within the immunogen.
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Affiliation(s)
- R L Rubin
- W. M. Keck Autoimmune Disease Center, Department of Molecular and Experimental Medicine, Scripps Clinic and Research Foundation, La Jolla, California 92037
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19
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Uetrecht J. Drug metabolism by leukocytes and its role in drug-induced lupus and other idiosyncratic drug reactions. Crit Rev Toxicol 1990; 20:213-35. [PMID: 2178625 DOI: 10.3109/10408449009089863] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This review presents a unifying hypothesis that provides a connection between several types of hypersensitivity reactions associated with several types of drugs and explains some of the therapeutic effects (antiinflammatory activity and antithyroid effects) of these same drugs. This hypothesis centers on the oxidation of these drugs to chemically reactive metabolites by peroxidases. The drugs of interest have functional groups that are easily oxidized. The major peroxidase involved in this hypothesis is MPO because of its critical location in leukocytes which play a key role in the function of the immune system. However, thyroid peroxidase can probably also oxidize many of the same drugs to reactive metabolites, and this may be responsible for the thyroid autoimmunity observed in connection with some hypersensitivity reactions. Peroxidases have also been described in the skin and in platelets, and their presence may be responsible for the high incidence of skin reactions in the hypersensitivity response and the occurrence of immune-mediated thrombocytopenia, respectively. Involvement of other peroxidases, such as prostaglandin peroxidase, may also be important for antiinflammatory effects of drugs. In addition, leukocytes contain prostaglandin synthetase, and the activation of leukocytes leads to the release of arachidonic acid and the production of prostaglandins. This process may also lead to the metabolism of drugs to reactive metabolites. In studies of the metabolism of procainamide and dapsone, aspirin and indomethacin did not inhibit the formation of the hydroxylamine by neutrophils and mononuclear leukocytes. This is evidence against the involvement of prostaglandin synthetase in these oxidation; however, preliminary studies with other drugs suggest that prostaglandin synthetase may contribute to the metabolism of some drugs by leukocytes. Furthermore, the metabolism of phenylbutazone, phenytoin, and tenoxicam, as well as our preliminary work with other drugs such as carbamazepine, suggests that the range of drugs that are metabolized to reactive metabolites by peroxidases may be broader than initially suspected. There are several other drugs that do not fit into the functional group classes covered in this review but have similar properties. A good example is alpha-methyldopa, which is associated with drug-induced lupus, immune-mediated hemolytic anemia, and other hypersensitivity reactions. Such drugs may also be metabolized to reactive metabolites by peroxidases. Another aspect of the hypothesis is that an infection, or other inflammatory condition, may be an important risk factor for a hypersensitivity reaction because such a stimulus leads to activation of leukocytes which can lead to formation of reactive metabolites from certain drugs.(ABSTRACT TRUNCATED AT 400 WORDS)
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