Drug-induced immune thrombocytopenia: pathogenesis, diagnosis, and management

Delayed allergic reaction from bupropion in a 27-year-old male with MDD: A case report and literature review

Introduction

Bupropion is an antidepressant approved for the treatment of major depressive disorder (MDD), seasonal affective disorder, and smoking cessation. Nausea, headache, tremor, and insomnia are well-known adverse effects of this medication. Less well-recognized adverse effects include delayed allergic reactions, which, in some cases, can appear 2 or more weeks after bupropion initiation.

Case Report

A 27-year-old male with recurrent MDD was referred for medication treatment at an outpatient mental health clinic and prescribed bupropion XL. On day 28 of treatment, he reported significant improvement in depressive symptoms and the development of itchiness and urticaria on his extremities and back. Bupropion was tapered over the course of 7 days, and he was given cetirizine 10 mg daily. He was transitioned to venlafaxine treatment and experienced complete resolution of hives and pruritus.

Discussion

Despite published reports on bupropion causing delayed hypersensitivity reactions, there remains limited clinical recognition of this side effect, and the risk of underrecognition may be greater when the onset of the reaction is more than 2 weeks after bupropion initiation.

Conclusion

Bupropion can cause delayed hypersensitivity reactions, including delayed pruritis and urticaria. The risk may be highest in males aged 17 to 40 years and those with a history of allergic reactions.

Pharmacokinetics and pharmacodynamics of the factor XIa-inhibiting antibody osocimab in healthy male East Asian volunteers: Results from two phase 1 studies

The pharmacokinetics, pharmacodynamics, immunogenicity, and safety of osocimab single doses in healthy Chinese and Japanese volunteers over 149 days were evaluated. Two phase 1 single-blinded, placebo-controlled studies with 27 Japanese and 50 Chinese participants were conducted. Osocimab was investigated with IV doses of 0.3, 1.25, and 2.5 mg/kg (Chinese study) and 0.3, 1.25, and 5.0 mg/kg (Japanese study), as well as SC doses of 3.0 and 6.0 mg/kg (Chinese study) and 6.0 mg/kg (Japanese study). The maximum plasma concentration was reached 1-3 h and 4-6 days after IV and SC administration, respectively. Osocimab exhibited a deviation from dose-proportional pharmacokinetics for AUC but not Cmax; higher doses had higher apparent clearance and disproportionately lower total exposure. A slightly lower exposure was observed in Japanese compared with Chinese volunteers after IV administration; conversely, relatively higher exposure in Japanese volunteers with SC dosing was identified. Osocimab was associated with a dose-dependent increase in activated partial thromboplastin time (aPTT). Maximal aPTT prolongations were observed 1-4 h and 2-6 days after IV and SC administration, respectively. Anti-drug antibodies of low titer were detected in 1/9 (11.1%) Japanese volunteers administered placebo and 26/40 (65.0%) Chinese volunteers administered osocimab. Adverse events were reported in 8/18 (44.4%) Japanese and 28/40 (70.0%) Chinese volunteers who received osocimab, as well as in 1/9 (11.1%) Japanese and 6/10 (60.0%) Chinese volunteers who received placebo. In conclusion, data did not suggest a clear dose-proportionality for osocimab within the investigated dose range. The effect of osocimab on aPTT was expected per its mechanism of action. Osocimab was generally well tolerated.

Teicoplanin-Induced Acute Thrombocytopenia in a Patient With Foot Osteomyelitis

This clinical case report explores the occurrence of acute thrombocytopenia following teicoplanin infusion in a patient with diabetic foot osteomyelitis. The patient, a 54-year-old male with a medical history of chronic kidney disease, hypertension, and type II diabetes mellitus, experienced a severe drop in platelet count during teicoplanin treatment. The article discusses the clinical presentation, diagnostic assessments, and management of teicoplanin-induced thrombocytopenia. Additionally, it delves into the broader context of drug-induced thrombocytopenia and emphasizes the importance of a systematic approach to understanding and managing this adverse reaction.

Penicillin Allergy: Mechanisms, Diagnosis, and Management

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

Rare cutaneous adverse reactions associated with GLP-1 agonists: a review of the published literature

Glucagon-like-peptide-1 (GLP-1) agonists are an emerging class of medications used to manage type 2 diabetes mellitus (T2DM) and weight loss, with demonstrated efficacy in reducing hemoglobin A1c levels, body mass index, and adverse cardiovascular events. While previous studies have reviewed notable cutaneous adverse effects with other antidiabetic medications, little is known about GLP-1 agonist-induced cutaneous reactions. Nevertheless, rare but significant cutaneous adverse reactions have been reported, including but not limited to dermal hypersensitivity reactions, eosinophilic panniculitis, bullous pemphigoid, and morbilliform drug eruptions. As GLP-1 induced cutaneous reactions are diverse, diagnosis requires clinical suspicion, thorough history-taking, and supportive histopathological findings when available. Management involves cessation of the offending agent with a tailored regimen to address inflammatory and/or immunogenic etiologies as well as irritative symptoms. This review aims to consolidate available information from case reports and case series regarding rare skin-related adverse outcomes due to GLP-1 use, aiming to provide a comprehensive overview of the presentation, pathogenesis, and management for dermatologists and other clinicians.

How I diagnose and treat thrombocytopenia in geriatric patients

ABSTRACT

Thrombocytopenia in older individuals is a common but diagnostically challenging condition that has variable clinical impact to those who are affected. Diagnostic approach requires evaluation of the preexisting clinical conditions, detailed review of medications, and assessment for disorders that warrant urgent treatment. In this article, we describe a systematic approach to diagnosis of thrombocytopenia and present a schematic review for management strategies. Three clinical scenarios are presented that are relevant for their prevalence and management challenges in an older adult population. The first scenario addresses primary immune thrombocytopenia (ITP) and reviews different treatment options. The second one addresses complications of thrombocytopenia in management of the myelodysplastic syndrome. The last one reviews diagnostic challenges of drug-induced ITP.

Beyond the Norm: A Case of Multiorgan Injury Triggered by Ibuprofen

We report the case of a 71-year-old African American male with a history of chronic obstructive pulmonary disease (COPD), heart failure, vitiligo, penicillin allergy, and cocaine use, who presented with respiratory symptoms and was diagnosed with sepsis, COVID-19 pneumonia, exacerbation of COPD, and acute kidney injury (AKI). Treatment included antibiotics and high-dose steroids. The patient developed thrombocytopenia, autoimmune hemolytic anemia, acute liver failure, and interstitial nephritis associated with prolonged ibuprofen use. High-dose steroids and ibuprofen discontinuation led to significant improvement. This case highlights the rare occurrence of multiorgan injury from ibuprofen use, possibly aggravated by COVID-19, emphasizing the need for cautious non-steroidal anti-inflammatory drug (NSAID) use and close patient monitoring.

Vancomycin-Induced Thrombocytopenia in a 35-Year-Old Female With Pneumonia: A Case Report

Vancomycin is one of the most empirically used antibiotics in severely ill patients in hospitalized settings. Vancomycin-induced thrombocytopenia (VITP) is a rare and potentially life-threatening complication that requires immediate recognition. Platelet destruction is largely immune-mediated and results in a precipitous drop in the platelet count over a short period of time. Most cases of VITP are drug-dependent, as discontinuation of the offending agent frequently results in a timely return to baseline to pre-exposure platelet levels. Here, we present a case of severe vancomycin-induced thrombocytopenia in a 35-year-old female with a history of multiple comorbidities who presented with pneumonia. She was undergoing treatment with vancomycin and piperacillin-tazobactam and developed thrombocytopenia within 24 hours of hospitalization. The patient was on a loading dose of 1250 mg intravenous vancomycin every 24 hours and piperacillin-tazobactam 3.375 g intravenously every six hours for presumed community-acquired pneumonia. Her other medications included ondansetron, bupropion, sertraline, tamsulosin, pantoprazole, ergocalciferol, and insulin glargine. Additionally, the patient was placed on a prophylactic dose of enoxaparin while in-patient. The patient's thrombocytopenia resolved with discontinuation of vancomycin. Clinicians should be well-informed about which medications can trigger thrombocytopenia whenever starting a medication in such cases.

Safety Assessment of an Oral Therapeutic Dose of Firocoxib on Healthy Horses

Firocoxib is a non-steroidal anti-inflammatory drug specifically formulated for veterinary medicine and selectively acts on inhibiting the cyclooxygenase 2 enzyme (COX-2). This study evaluated the possible adverse effects of administering oral therapeutic firocoxib on gastric mucosa, hematological parameters, coagulation cascade, and hepatic and renal biochemistry in healthy horses. Nine clinically healthy Arabian horses, approximately 9 years old, received 0.1 mg/kg of oral firocoxib for 14 days. The gastroscopic examination was conducted 1 day before starting treatment (D0) and two days after the last blood collection (D23). Venous blood samples were obtained for laboratory tests on day 1, immediately prior to the initiation of treatment (D1), after 7 and 14 days of treatment (D7 and D14), and 7 days after the conclusion of treatment (D21. No changes were found in the gastroscopic and hematological tests. Coagulation and serum biochemistry levels remain between these species' average values. However, the increased activated partial thromboplastin time (aPTT) and prothrombin time (PT) indicate reduced blood coagulation capacity, which contradicts the expected effect of treatment with selective COX-2 inhibitors, as these drugs theoretically promote coagulation. Administering firocoxib to horses is safe as it does not cause significant adverse reactions. Therefore, it is a suitable option for managing inflammatory conditions in these animals with attention to an unexpected adverse anti-coagulopathy effect, and further study is warranted.

Calcium Channel Blocker-Induced Thrombocytopenia in the Intensive Care Unit: A Rare Presentation and Review of the Literature

Patients with thrombocytopenia may report easy bruising, abnormal bleeding, and fatigue. Drug-induced thrombocytopenia has been reported with a variety of medications, most commonly heparin products, sulphonamides, carbamazepine, nonsteroidal anti-inflammatory drugs, anti-epileptic drugs, and chemotherapy. We present the case of a 58-year-old female with severe thrombocytopenia attributed to a calcium channel blocker (CCB) overdose, a very rare cause of thrombocytopenia. We discuss the diagnostic work-up and management in the intensive care unit and perform a literature review.

Cryo-EM structures of full-length integrin αIIbβ3 in native lipids

Platelet integrin αIIbβ3 is maintained in a bent inactive state (low affinity to physiologic ligand), but can rapidly switch to a ligand-competent (high-affinity) state in response to intracellular signals ("inside-out" activation). Once bound, ligands drive proadhesive "outside-in" signaling. Anti-αIIbβ3 drugs like eptifibatide can engage the inactive integrin directly, inhibiting thrombosis but inadvertently impairing αIIbβ3 hemostatic functions. Bidirectional αIIbβ3 signaling is mediated by reorganization of the associated αIIb and β3 transmembrane α-helices, but the underlying changes remain poorly defined absent the structure of the full-length receptor. We now report the cryo-EM structures of full-length αIIbβ3 in its apo and eptifibatide-bound states in native cell-membrane nanoparticles at near-atomic resolution. The apo form adopts the bent inactive state but with separated transmembrane α-helices, and a fully accessible ligand-binding site that challenges the model that this site is occluded by the plasma membrane. Bound eptifibatide triggers dramatic conformational changes that may account for impaired hemostasis. These results advance our understanding of integrin structure and function and may guide development of safer inhibitors.

Immune Thrombocytopenia: A Rare Adverse Event of Vancomycin Therapy

Vancomycin, a glycopeptide antibiotic, is widely used for Gram-positive cocci or bacilli bacteria-induced serious infections. Although considered safe and effective, it still causes adverse events. Vancomycin-induced immune thrombocytopenia is a rarely reported adverse event, manifesting from asymptomatic thrombocytopenia to life-threatening bleeding. We underline a case of a 56-year-old male with a diabetic foot with an infected exudating purulent ulcer. He experienced a significant drop in platelet count after commencing vancomycin, and discontinuing vancomycin resulted in improved platelet count with positive vancomycin-induced anti-platelet antibodies. After ruling out other possible causes of thrombocytopenia, a presumptive diagnosis of vancomycin-induced thrombocytopenia was made.

Significance of Oral Manifestations in the Diagnosis of Severe Phenytoin-Induced Thrombocytopenia: A Rare Case

Phenytoin is a commonly used anticonvulsant drug for the prophylaxis of generalized tonic-clonic seizures, partial seizures, and neurosurgery-related seizure prevention. Phenytoin-induced thrombocytopenia is a rare but life-threatening condition. Close monitoring of blood counts may be necessary for patients receiving phenytoin, as delay in diagnosis or withdrawal of the drug can be life-threatening. Clinical manifestations of phenytoin-induced thrombocytopenia are usually reported within one to three weeks after drug initiation. In this article, we report a unique case of drug-induced thrombocytopenia that manifested as multiple hemorrhagic lesions in the oral mucous membrane three months after phenytoin initiation.

Applications of Artificial Intelligence in Thrombocytopenia

Thrombocytopenia is a medical condition where blood platelet count drops very low. This drop in platelet count can be attributed to many causes including medication, sepsis, viral infections, and autoimmunity. Clinically, the presence of thrombocytopenia might be very dangerous and is associated with poor outcomes of patients due to excessive bleeding if not addressed quickly enough. Hence, early detection and evaluation of thrombocytopenia is essential for rapid and appropriate intervention for these patients. Since artificial intelligence is able to combine and evaluate many linear and nonlinear variables simultaneously, it has shown great potential in its application in the early diagnosis, assessing the prognosis and predicting the distribution of patients with thrombocytopenia. In this review, we conducted a search across four databases and identified a total of 13 original articles that looked at the use of many machine learning algorithms in the diagnosis, prognosis, and distribution of various types of thrombocytopenia. We summarized the methods and findings of each article in this review. The included studies showed that artificial intelligence can potentially enhance the clinical approaches used in the diagnosis, prognosis, and treatment of thrombocytopenia.

Acute severe thrombocytopenia following iodinated radiographic contrast medium infusion: a case report

Acute contrast-induced thrombocytopenia is an unusual complication, and it is a rare event with the use of modern low-osmolarity iodinated contrast medium. There are only a few reports that exist in English literature.

Case presentation

The authors report the case of a 79-year-old male patient with severe, life-threatening thrombocytopenia after administration of intravenous nonionic low-osmolarity contrast medium. His platelet count dropped from 179×10⁹/l to 2×10⁹/l after 1 h of radiocontrast infusion. Which has returned gradually to normal level within days with corticosteroid administration and platelet transfusion.

Conclusion

Iodinated contrast-induced thrombocytopenia is a rare complication with an unknown causative mechanism. There is no definitive treatment for this condition, with corticosteroids being used in most cases. The platelet count normalizes within a few days regardless of any interventions, but supportive treatment is important to avoid any unwanted complications. Further studies are still needed for a better understanding of the exact mechanism of this condition.

Penicillin Allergy

Allergy to penicillin can occur via any of the 4 types of Gel-Coombs hypersensitivity reactions, producing distinct clinical histories and physical examination findings. Treatments include penicillin discontinuation, and depending on the type of reaction, epinephrine, antihistamines, and/or glucocorticoids. Most beta-lactams may be safely used in penicillin-allergic patients, with the possible exception of first-generation and second-generation cephalosporins. Penicillin testing includes skin testing, patch testing, and graded challenge. The selection of the type of testing depends on the clinical setting, equipment availability, and type of hypersensitivity reaction. Desensitization may be used in some cases where treatment with penicillins is essential.

A Possible Case of Nitrofurantoin-Associated Immune Thrombocytopenia in a Healthy 45-Year-Old Caucasian Female

Patients presenting with immune thrombocytopenia (ITP) may have an associated underlying medical condition or medication exposure serving as the cause of their disease, but oftentimes, ITP is due to an idiopathic, autoimmune cause. While molecular mimicry is recognized as the pathogenesis behind infectious-related causes of ITP, drug-induced ITP is likely due to hapten formation, leading to an inappropriate immune-mediated response. Several drugs are associated with the development of ITP. Nitrofurantoin, a commonly prescribed antibiotic for the treatment of uncomplicated urinary tract infections (UTIs), is a medication not previously associated with the development of ITP, with only one case reporting the development of thrombotic thrombocytopenic purpura (TTP) after nitrofurantoin use. Herein, we report a case of a middle-aged Caucasian female with a history of anxiety and hypothyroidism who developed ITP following exposure to nitrofurantoin three weeks prior to presentation. The patient presented with signs and symptoms consistent with ITP: an isolated low platelet count of 1 x 10⁹/L, petechia, fatigue, normal coagulation parameters, recurrent epistaxis, and melena. Subsequently, she was hospitalized for five days, receiving a total of four units of platelets during her stay. She was started on daily high-dose intravenous corticosteroids and received a one-time dose of intravenous immunoglobulin (IVIG). After achieving a platelet count greater than 30 x 10⁹/L, she was discharged from inpatient care, having responded well to corticosteroid treatment. Upon follow-up with outpatient hematology, her platelet levels were maintained above 150 x 10⁹/L, with full resolution of her acute illness. An autoimmune laboratory workup was negative except for an isolated, newly positive antinuclear antibody IgG with an elevated titer of 1:640, leading to the conclusion that an immunological response to nitrofurantoin had occurred. To our knowledge, this is the first report that describes an association between nitrofurantoin use and ITP. We hope this report aids clinicians in recognizing the various immune-mediated adverse reactions associated with nitrofurantoin.

Novel chemical-structure TPOR agonist, TMEA, promotes megakaryocytes differentiation and thrombopoiesis via mTOR and ERK signalings

BACKGROUND

Non-peptide thrombopoietin receptor (TPOR) agonists are promising therapies for the mitigation and treatment of thrombocytopenia. However, only few agents are available as safe and effective for stimulating platelet production for thrombocytopenic patients in the clinic.

PURPOSE

This study aimed to develop a novel small molecule TPOR agonist and investigate its underlying regulation of function in megakaryocytes (MKs) differentiation and thrombopoiesis.

METHODS

A potential active compound that promotes MKs differentiation and thrombopoiesis was obtained by machine learning (ML). Meanwhile, the effect was verified in zebrafish model, HEL and Meg-01 cells. Next, the key regulatory target was identified by Drug Affinity Responsive Target Stabilization Assay (DARTS), Cellular Thermal Shift Assay (CETSA), and molecular simulation experiments. After that, RNA-sequencing (RNA-seq) was used to further confirm the associated pathways and evaluate the gene expression induced during MK differentiation. In vivo, irradiation (IR) mice, C57BL/6N-TPOR^em1cyagen (Tpor^-/-) mice were constructed by CRISPR/Cas9 technology to examine the therapeutic effect of TMEA on thrombocytopenia.

RESULTS

A natural chemical-structure small molecule TMEA was predicted to be a potential active compound based on ML. Obvious phenotypes of MKs differentiation were observed by TMEA induction in zebrafish model and TMEA could increase co-expression of CD41/CD42b, DNA content, and promote polyploidization and maturation of MKs in HEL and Meg-01 cells. Mechanically, TMEA could bind with TPOR protein and further regulate the PI3K/AKT/mTOR/P70S6K and MEK/ERK signal pathways. In vivo, TMEA evidently promoted platelet regeneration in mice with radiation-induced thrombocytopenia but had no effect on Tpor^-/- and C57BL/6 (WT) mice.

CONCLUSION

TMEA could serve as a novel TPOR agonist to promote MKs differentiation and thrombopoiesis via mTOR and ERK signaling and could potentially be created as a promising new drug to treat thrombocytopenia.

Chemotherapy-induced thrombocytopenia: literature review

Chemotherapy-induced thrombocytopenia (CIT) is a common condition that frequently results in reduced chemotherapy dosages, postponed treatment, bleeding, and unfavorable oncological outcomes. At present, there is no clear suggestions for preventing or treating CIT. Thrombopoietin (TPO) replacement therapy has been invented and used to treat CIT to promote the production of megakaryocytes and stimulate the formation of platelets. However, this treatment is limited to the risk of immunogenicity and cancer progression. Therefore, an unmet need exists for exploring alternatives to TPO to address the clinical issue of CIT. Application of appropriate therapeutic drugs may be due to understanding the potential mechanisms of CIT. Studies have shown that chemotherapy significantly affects various cells in bone marrow (BM) microenvironment, reduces their ability to support normal hematopoiesis, and may lead to BM damage, including CIT in cancer patients. This review focuses on the epidemiology and treatment of cancer patients with CIT. We also introduce some recent progress to understand the cellular and molecular mechanisms of chemotherapy inhibiting normal hematopoiesis and causing thrombocytopenia.

Identification of subphenotypes in critically ill thrombocytopenic patients with different responses to therapeutic interventions: a retrospective study

Introduction

The causes of thrombocytopenia (TP) in critically ill patients are numerous and heterogeneous. Currently, subphenotype identification is a popular approach to address this problem. Therefore, this study aimed to identify subphenotypes that respond differently to therapeutic interventions in patients with TP using routine clinical data and to improve individualized management of TP.

Methods

This retrospective study included patients with TP admitted to the intensive care unit (ICU) of Dongyang People's Hospital during 2010-2020. Subphenotypes were identified using latent profile analysis of 15 clinical variables. The Kaplan-Meier method was used to assess the risk of 30-day mortality for different subphenotypes. Multifactorial Cox regression analysis was used to analyze the relationship between therapeutic interventions and in-hospital mortality for different subphenotypes.

Results

This study included a total of 1,666 participants. Four subphenotypes were identified by latent profile analysis, with subphenotype 1 being the most abundant and having a low mortality rate. Subphenotype 2 was characterized by respiratory dysfunction, subphenotype 3 by renal insufficiency, and subphenotype 4 by shock-like features. Kaplan-Meier analysis revealed that the four subphenotypes had different in-30-day mortality rates. The multivariate Cox regression analysis indicated a significant interaction between platelet transfusion and subphenotype, with more platelet transfusion associated with a decreased risk of in-hospital mortality in subphenotype 3 [hazard ratio (HR): 0.66, 95% confidence interval (CI): 0.46-0.94]. In addition, there was a significant interaction between fluid intake and subphenotype, with a higher fluid intake being associated with a decreased risk of in-hospital mortality for subphenotype 3 (HR: 0.94, 95% CI: 0.89-0.99 per 1 l increase in fluid intake) and an increased risk of in-hospital mortality for high fluid intake in subphenotypes 1 (HR: 1.10, 95% CI: 1.03-1.18 per 1 l increase in fluid intake) and 2 (HR: 1.19, 95% CI: 1.08-1.32 per 1 l increase in fluid intake).

Conclusion

Four subphenotypes of TP in critically ill patients with different clinical characteristics and outcomes and differential responses to therapeutic interventions were identified using routine clinical data. These findings can help improve the identification of different subphenotypes in patients with TP for better individualized treatment of patients in the ICU.

Pancytopenia in Carbamazepine Therapy: A Rare and Serious Entity with Simple Prevention

Carbamazepine is a commonly used drug in psychiatric settings used for indications such as partial seizures, generalized tonic-clonic seizures, mixed seizure patterns, pain associated with trigeminal neuralgia, acute manic, and mixed manic states. However, this drug comes with its own series of adverse effects such as nausea, vomiting, diarrhea, dizziness, hyponatremia, headaches, and dry mouth. One serious side effect which is rarely documented includes "carbamazepine-induced pancytopenia." In this case report, we wish to highlight a known case of schizophrenia, who was taking tablet carbamazepine as adjunctive treatment and subsequently developed pancytopenia. On removing the offending agent, her counts gradually returned to normal. By reporting this case, we wish to emphasize regarding the importance of regular monitoring of complete blood count, which often gets neglected. Furthermore, psychoeducating patients regarding regular blood monitoring and the importance of adherence holds considerable importance in enhancing their compliance. By ensuring such simple preventive measures, such serious and unusual side effects may be averted through early detection of warning signs.

Piperacillin-Tazobactam Induced Rapid Severe Thrombocytopenia Without Known Exposure

Thrombocytopenia is one of the commonly encountered laboratory abnormalities in the inpatient setting. The process of excluding life-threatening causes can be daunting and may result in overlooking iatrogenic sources such as medications. Antibiotics are known culprits; however, there are limited reports of rapid and severe onset thrombocytopenia following piperacillin-tazobactam (TZP) that were frequently observed in critically ill or immunocompromised patients with previous exposure to the antibiotic. This case describes a patient being treated for a soft tissue infection with vancomycin and TZP. Initiation of antimicrobial therapy resulted in severe thrombocytopenia and a platelet nadir of approximately 4,000 within 24 hours of the first doses. Thrombocytopenia resolved within three days of TZP withdrawal. To the best of our knowledge, there have not been any cases described of rapid drug-induced thrombocytopenia without previous exposure to the medication. Medications should always be reviewed when evaluating a patient with rapid and severe thrombocytopenia, which can obviate the need for unnecessary invasive or non-invasive treatments.

Furosemide-Induced Thrombotic Thrombocytopenic Purpura: A Report of a Rare Case

Drug-induced immune thrombocytopenia (DITP) refers to drug-dependent, antibody-mediated platelet destruction. Although several drugs have been implicated as the cause of DITP, the most commonly encountered are heparin, sulfonamides, quinine, vancomycin, and beta-lactam antibiotics. However, furosemide has been rarely reported as the cause of thrombocytopenia. We present a unique case of furosemide-induced thrombotic thrombocytopenia in a 64-year-old female referred by her primary care provider for low platelets, rash, and bleeding. She was recently started on oral furosemide for diastolic heart failure two weeks before this presentation. She was admitted to the intensive care unit and was worked up for new-onset thrombocytopenia. Labs revealed anemia, thrombocytopenia, elevated lactate dehydrogenase, and low haptoglobin with normal serum creatinine. Peripheral smear showed schistocytes, low platelets, and ADAMTS13 level was 0.03. The patient was diagnosed with thrombotic thrombocytopenic purpura and treated with steroids, rituximab, and plasmapheresis, which led to rapid recovery of the platelet count to normal. Based on this case report, clinicians should consider furosemide as one of the drugs potentially causing thrombotic thrombocytopenia. Early detection and prompt management can be lifesaving.

Linezolid induced thrombocytopenia in critically ill patients: Risk factors and development of a machine learning-based prediction model

INTRODUCTION

Linezolid is an antimicrobial with broad activity against Gram-positive bacteria. Thrombocytopenia is one of its most common side effects often leading to severe complications. The aim of this study is to identify factors related with development of this condition in critically ill patients and to develop and evaluate a predictive machine learning-based model considering easy-to-obtain clinical variables.

METHODS

Data was obtained from the Medical Information Mart for Intensive Care III. Patients who received linezolid for over three days were considered, excluding those under 18 years and/or lacking laboratory data. Thrombocytopenia was considered as a platelet decrease of at least 50% from baseline.

RESULTS

Three hundred and twenty patients met inclusion criteria of which 63 developed thrombocytopenia and presented significant greater duration of treatment, aspartate-aminotransferase, bilirubin and international normalized ratio; and lower renal clearance and platelet count at baseline. Thrombocytopenia development was associated with a worse outcome (30 days mortality [OR: 2.77; CI95%: 1.87-5.89; P < .001], 60 days mortality [OR: 3.56; CI95%: 2.18-7.26; P < .001]). Thrombocytopenia was also correlated with higher length of hospital stays (35.56 [20.40-52.99] vs 22.69 [10.05-38.61]; P < .001). Median time until this anomaly was of 23 days (CI95%:19.0-NE). Two multivariate models were performed. Accuracy, sensitivity, specificity and AUROC obtained in the best of them were of 0.75, 0.78, 0.62 and 0.80, respectively.

CONCLUSION

Linezolid associated thrombocytopenia entails greater mortality rates and hospital stays. Although the proposed predictive model has to be subsequently validated in a real clinical setting, its application could identify patients at risk and establish screening and surveillance strategies.

Evaluation and management of platelet transfusion refractoriness

Platelet transfusion refractoriness (PTR), in which platelet counts do not increase after transfusion, occurs in many patients receiving platelet transfusions. PTR is a clinical condition that can harm patients. The causes of PTR can be divided into two types: immune and non-immune. Most cases of PTR are non-immune. Among immune causes, the most common is human leukocyte antigen (HLA) class I molecules. PTR caused by anti-HLA antibodies is usually managed by transfusing HLA-matched platelets. Therefore, it is important, especially for hemato-oncologists who frequently perform transfusion, to accurately diagnose whether the cause of platelet transfusion failure is alloimmune or non-immunological when determining the treatment direction for the patient. In this review, we discuss the definitions, causes, countermeasures, and prevention methods of PTR.

Acute drug-induced immune thrombocytopenia - A work of articaine

Background

Drug‐induced immune thrombocytopenia (DITP) is a rare, but serious complication to a wide range of medications. Upon suspicion, one should do a thorough clinical evaluation following proposed diagnostic criteria and seek laboratory confirmation. If confirmed, it is important to ensure avoidance of the drug in the future.

Study design and methods

Herein, we describe a young adult male who experienced two bouts of severe thrombocytopenia following dental treatment. The thrombocytopenia was acknowledged due to unexpected hemorrhaging during the procedures. On both occasions, he was exposed to four different drugs, none commonly associated with DITP. After the second episode of severe procedural‐related thrombocytopenia, an investigation into the cause was initiated. We describe the clinical approach to elucidate which of the four implicated drugs was responsible for thrombocytopenia and the laboratory work‐up done to confirm that the reaction was antibody‐mediated and identify the antibody's drug: glycoprotein specificity. An alternative drug was tested both in vivo and in vitro, to identify an option for future procedures.

Results

Sequential exposure revealed the local anesthetic substance articaine to induce thrombocytopenia. Laboratory work‐up confirmed drug‐dependent antibodies (DDAbs) with specificity for the glycoprotein Ib/IX complex, swiftly identified by a bead‐based Luminex assay. Further investigations by monoclonal antibody immobilization of platelet antigens assay (MAIPA) revealed a probable GPIb binding site. An alternative local anesthetic, lidocaine, was deemed safe for future procedures.

Conclusion

Articaine can induce rapid‐onset, severe immune‐mediated thrombocytopenia causing bleeding complications. A modified bead‐based Luminex platelet antigen assay proved a useful addition in the DITP‐investigation.

Risk Assessment in Drug Hypersensitivity: Detecting Small Molecules Which Outsmart the Immune System

Drug hypersensitivity (DH) reactions are clinically unusual because the underlying immune stimulations are not antigen-driven, but due to non-covalent drug-protein binding. The drugs may bind to immune receptors like HLA or TCR which elicits a strong T cell reaction (p-i concept), the binding may enhance the affinity of antibodies (enhanced affinity model), or drug binding may occur on soluble proteins which imitate a true antigen (fake antigen model). These novel models of DH could have a major impact on how to perform risk assessments in drug development. Herein, we discuss the difficulties of detecting such non-covalent, labile and reversible, but immunologically relevant drug-protein interactions early on in drug development. The enormous diversity of the immune system, varying interactions, and heterogeneous functional consequences make it to a challenging task. We propose that a realistic approach to detect clinically relevant non-covalent drug interactions for a new drug could be based on a combination of in vitro cell culture assays (using a panel of HLA typed donor cells) and functional analyses, supplemented by structural analysis (computational data) of the reactive cells/molecules. When drug-reactive cells/molecules with functional impact are detected in these risk assessments, a close clinical monitoring of the drug may reveal the true incidence of DH, as suppressing but also enhancing factors occurring in vivo can influence the clinical manifestation of a DH.

The important role of non-covalent drug-protein interactions in drug hypersensitivity reactions

Drug hypersensitivity reactions (DHR) are heterogeneous and unusual immune reactions with rather unique clinical presentations. Accumulating evidence indicates that certain non-covalent drug-protein interactions are able to elicit exclusively effector functions of antibody reactions or complete T-cell reactions which contribute substantially to DHR. Here, we discuss three key interactions; (a) mimicry: whereby soluble, non-covalent drug-protein complexes ("fake antigens") mimic covalent drug-protein adducts; (b) increased antibody affinity: for example, in quinine-type immune thrombocytopenia where the drug gets trapped between antibody and membrane-bound glycoprotein; and (c) p-i-stimulation: where naïve and memory T cells are activated by direct binding of drugs to the human leukocyte antigen and/or T-cell receptors. This transient drug-immune receptor interaction initiates a polyclonal T-cell response with mild-to-severe DHR symptoms. Notable complications arising from p-i DHR can include viral reactivations, autoimmunity, and multiple drug hypersensitivity. In conclusion, DHR is characterized by abnormal immune stimulation driven by non-covalent drug-protein interactions. This contrasts DHR from "normal" immunity, which relies on antigen-formation by covalent hapten-protein adducts and predominantly results in asymptomatic immunity.

Bioactive Molecules Derived from Snake Venoms with Therapeutic Potential for the Treatment of Thrombo-Cardiovascular Disorders Associated with COVID-19

As expected, several new variants of Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2) emerged and have been detected around the world throughout this Coronavirus Disease of 2019 (COVID-19) pandemic. Currently, there is no specific developed drug against COVID-19 and the challenge of developing effective antiviral strategies based on natural agents with different mechanisms of action becomes an urgent need and requires identification of genetic differences among variants. Such data is used to improve therapeutics to combat SARS-CoV-2 variants. Nature is known to offer many biotherapeutics from animal venoms, algae and plant that have been historically used in traditional medicine. Among these bioresources, snake venom displays many bioactivities of interest such as antiviral, antiplatelet, antithrombotic, anti-inflammatory, antimicrobial and antitumoral. COVID-19 is a viral respiratory sickness due to SARS-CoV-2 which induces thrombotic disorders due to cytokine storm, platelet hyperactivation and endothelial dysfunction. This review aims to: (1) present an overview on the infection, the developed thrombo-inflammatory responses and mechanisms of induced thrombosis of COVID-19 compared to other similar pathogenesis; (2) underline the role of natural compounds such as anticoagulant, antiplatelet and thrombolytic agents; (3) investigate the management of coagulopathy related to COVID-19 and provide insight on therapeutic such as venom compounds. We also summarize the updated advances on antiviral proteins and peptides derived from snake venoms that could weaken coagulopathy characterizing COVID-19.

Statin-Induced Thrombocytopenia in a Young Female: A Case Report and Literature Review

The causal relationship of thrombocytopenia with statin intake has been described in many research articles. Our case discusses the refractory nature of thrombocytopenia in a 22-year-old female, one month following a daily intake of 20 mg atorvastatin. This is the first case ever of drug-induced refractory thrombocytopenia reported in a young patient. We will also discuss previously reported cases of drug-induced thrombocytopenia (DIT) in our manuscript.

Consensus guidelines for the management of adult immune thrombocytopenia in Australia and New Zealand

Introduction

The absence of high quality evidence for basic clinical dilemmas in immune thrombocytopenic purpura (ITP) underlines the need for contemporary guidelines relevant to the local treatment context. ITP is diagnosed by exclusions, with a hallmark laboratory finding of isolated thrombocytopenia.

Main recommendations

Bleeding, family and medication histories and a review of historical investigations are required to gauge the bleeding risk and possible hereditary syndromes. Beyond the platelet count, the decision to treat is affected by individual bleeding risk, disease stage, side effects of treatment, concomitant medications, and patient preference. Treatment is aimed at achieving a platelet count > 20 × 10⁹/L, and avoidance of severe bleeding. Steroids are the standard first line treatment, with either 6‐week courses of tapering prednisone or repeated courses of high dose dexamethasone providing equivalent efficacy. Intravenous immunoglobulin can be used periprocedurally or as first line therapy in combination with steroids.

Changes in management as a result of this statement

There is no consensus on choice of second line treatments. Options with the most robust evidence include splenectomy, rituximab and thrombopoietin receptor agonists. Other therapies include azathioprine, mycophenolate mofetil, dapsone and vinca alkaloids. Given that up to one‐third of patients achieve a satisfactory haemostatic response, splenectomy should be delayed for at least 12 months if possible. In life‐threatening bleeding, we recommend platelet transfusions to achieve haemostasis, along with intravenous immunoglobulin and high dose steroids.

Immune checkpoint inhibitor-related thrombocytopenia: incidence, risk factors and effect on survival

INTRODUCTION

Immune checkpoint inhibitors (ICI) are associated with unique immune-related adverse events (irAEs). Immune-related thrombocytopenia (irTCP) is an understudied and poorly understood toxicity; little data are available regarding either risk of irTCP or the effect of irTCP on clinical outcomes of patients treated with ICI.

METHODS

We conducted a retrospective review of sequential cancer patients treated with ICI between 2011 and 2017 at our institution. All patients who received ICI alone or in combination with other systemic therapy in any line of treatment were included; those with thrombocytopenia ≥ grade 3 at baseline were excluded. We calculated the incidence of ≥ grade 3 irTCP and overall survival (OS). Patient factors associated with irTCP were assessed.

RESULTS

We identified 1,038 patients that met eligibility criteria. Overall, 89 (8.6%) patients developed grade ≥ 3 thrombocytopenia; eighteen were attributed to ICI (1.73% overall). Patients who developed grade ≥ 3 irTCP had worse overall survival compared to those whose thrombocytopenia was unrelated to ICI (4.17 vs. 10.8 month; HR. 1.94, 95% CI 1.13, 3.33; log-rank p = 0.0164). Patients with grade ≥ 3 irTCP also had worse survival compared to those without thrombocytopenia (4.17 vs. 13.31 months; HR 2.22, 95% CI 1.36, 3.62; log-rank p = 0.001). The incidence of irTCP appeared lowest among those treated with PD-1/L1 monotherapy (p = 0.059) and was not associated with cancer type, smoking status, age, gender, race, or line of therapy.

CONCLUSIONS

Unlike other irAEs, we found that irTCP was associated with worse overall survival. The incidence of irTCP appeared lowest among those treated with PD-1/L1 monotherapy.

Emerging therapeutic opportunities for integrin inhibitors

Integrins are cell adhesion and signalling proteins crucial to a wide range of biological functions. Effective marketed treatments have successfully targeted integrins αIIbβ3, α4β7/α4β1 and αLβ2 for cardiovascular diseases, inflammatory bowel disease/multiple sclerosis and dry eye disease, respectively. Yet, clinical development of others, notably within the RGD-binding subfamily of αv integrins, including αvβ3, have faced significant challenges in the fields of cancer, ophthalmology and osteoporosis. New inhibitors of the related integrins αvβ6 and αvβ1 have recently come to the fore and are being investigated clinically for the treatment of fibrotic diseases, including idiopathic pulmonary fibrosis and nonalcoholic steatohepatitis. The design of integrin drugs may now be at a turning point, with opportunities to learn from previous clinical trials, to explore new modalities and to incorporate new findings in pharmacological and structural biology. This Review intertwines research from biological, clinical and medicinal chemistry disciplines to discuss historical and current RGD-binding integrin drug discovery, with an emphasis on small-molecule inhibitors of the αv integrins.

Integrins are key signalling molecules that are present on the surface of subsets of cells and are therefore good potential therapeutic targets. In this Review, Hatley and colleagues discuss the development of integrin inhibitors, particularly the challenges in developing inhibitors for integrins that contain an αv-subunit, and suggest how these challenges could be addressed.

Meropenem-induced thrombocytopenia: a paediatric case

Meropenem is a broad-spectrum carbapenem widely used to treat both Gram-positive and negative bacterial infections, including extended-spectrum beta-lactamase-producing microbes. We describe the occurrence of thrombocytopenia and hypersensitivity in a boy receiving intravenous meropenem for intra-abdominal sepsis secondary to perforated appendicitis. The patient developed a pruritic maculopapular rash with occasional petechiae, associated with severe thrombocytopenia, after 7 days of meropenem administration. Investigations for other causes of thrombocytopenia, including possible line sepsis, were unfruitful, and the thrombocytopenia did not resolve until cessation of meropenem. Drug-induced reactions should be considered in children receiving meropenem who present with a rash and thrombocytopenia.

Point-of-care microvolume cytometer measures platelet counts with high accuracy from capillary blood

Background

Point-of-care (PoC) testing of platelet count (PLT) provides real-time data for rapid decision making. The goal of this study is to evaluate the accuracy and precision of platelet counting using a new microvolume (8 μL), absolute counting, 1.5 kg cytometry-based blood analyzer, the rHEALTH ONE (rHEALTH) in comparison with the International Society of Laboratory Hematology (ISLH) platelet method, which uses a cytometer and an impedance analyzer.

Methods

Inclusion eligibility were healthy adults (M/F) ages 18–80 for donation of fingerprick and venous blood samples. Samples were from a random N = 31 volunteers from a single U.S. site. Samples were serially diluted to test thrombocytopenic ranges. Interfering substances and conditions were tested, including RBC fragments, platelet fragments, cholesterol, triglycerides, lipids, anti-platelet antibodies, and temperature.

Results

The concordance between the rHEALTH and ISLH methods had a slope = 1.030 and R² = 0.9684. The rHEALTH method showed a correlation between capillary and venous blood samples (slope = 0.9514 and R² = 0.9684). Certain interferents changed platelet recovery: RBC fragments and anti-platelet antibodies with the ISLH method; platelet fragments and anti-platelet antibodies on the rHEALTH; and RBC fragments, platelets fragments, triglycerides and LDL on the clinical impedance analyzer. The rHEALTH’s precision ranged from 3.1–8.0%, and the ISLH from 1.0–10.5%.

Conclusions

The rHEALTH method provides similar results with the reference method and good correlation between adult capillary and venous blood samples. This demonstrates the ability of the rHEALTH to provide point-of-care assessment of normal and thrombocytopenic platelet counts from fingerprick blood with high precision and limited interferences.

Common and Rare Hematological Manifestations and Adverse Drug Events during Treatment of Active TB: A State of Art

Background: Tuberculosis (TB) can seriously affect the hematopoietic system, with involvement of both myeloid and lymphoid cell lines as well as plasma components. These hematological changes act as a marker for the diagnosis, prognosis and response to therapy. Methods: We searched PubMed, Scopus, Google Scholar, EMBASE, Cochrane Library and WHO websites from 1950 to May 2021 for papers on the interaction between TB and common and rare hematological manifestation. Results: Hematological reactions in patients with TB are possible in both young and old women and men but seem more frequent in the elderly, and they can be predictors of both diagnosis and worse outcome for TB, regardless of whether it is pulmonary, extra pulmonary or miliary. Even anti-TB therapies can cause hematological adverse events, among which some are serious and rare and can compromise the patient’s recovery pathway to completing treatment. Conclusion: Hematological screening and follow-up, including complete blood count and coagulation, are always necessary both at the diagnosis of TB and during antitubercular treatment in order to monitor hematological parameters. Short therapy regimens for multidrug-resistant TB (MDR-TB) may also be useful for reducing hematological toxicity, especially in contexts where this cannot be monitored. Close monitoring of drug interactions and hematological adverse events is always recommended.

Spontaneous bleeding from orbital haemangioma in drug-induced thrombocytopaenia

An 81-year-old woman, a drug-induced thrombocytopaenia (DITP) patient, presented with a case of spontaneous bleeding from an orbital haemangioma manifesting as a sudden onset of ocular pain, proptosis and limited eye movement. Image studies revealed an extraconal, cystic lesion with haemorrhage. The ophthalmopathy was caused by the bleeding of the orbital haemangioma and it was resolved after embolisation of the feeding vessels. Spontaneous bleeding of orbital haemangioma is rare. This case emphasises that DITP may be the cause of spontaneous bleeding of orbital haemangioma by precipitating the inflammatory reactions within the tumour, which further cause the haemodynamic disturbances and ultimate spontaneous bleeding.

Roxithromycin-Associated Acute Thrombocytopenia

Patient: Female, 78-year-old

Final Diagnosis: Acute autoimmune thrombocytopenia

Symptoms: Petechial lesions of the palate • two hematomas of the tongue and purpuric macules with central crust in the abdomen and in the left lower limb

Medication: —

Clinical Procedure: —

Specialty: Hematology • Pharmacology and Pharmacy

Updated Understanding of Platelets in Thrombosis and Hemostasis: The Roles of Integrin PSI Domains and their Potential as Therapeutic Targets

Platelets are small blood cells known primarily for their ability to adhere and aggregate at injured vessels to arrest bleeding. However, when triggered under pathological conditions, the same adaptive mechanism of platelet adhesion and aggregation may cause thrombosis, a primary cause of heart attack and stroke. Over recent decades, research has made considerable progress in uncovering the intricate and dynamic interactions that regulate these processes. Integrins are heterodimeric cell surface receptors expressed on all metazoan cells that facilitate cell adhesion, movement, and signaling, to drive biological and pathological processes such as thrombosis and hemostasis. Recently, our group discovered that the plexin-semaphorin-integrin (PSI) domains of the integrin β subunits exert endogenous thiol isomerase activity derived from their two highly conserved CXXC active site motifs. Given the importance of redox reactions in integrin activation and its location in the knee region, this PSI domain activity may be critically involved in facilitating the interconversions between integrin conformations. Our monoclonal antibodies against the β3 PSI domain inhibited its thiol isomerase activity and proportionally attenuated fibrinogen binding and platelet aggregation. Notably, these antibodies inhibited thrombosis without significantly impairing hemostasis or causing platelet clearance. In this review, we will update mechanisms of thrombosis and hemostasis, including platelet versatilities and immune-mediated thrombocytopenia, discuss critical contributions of the newly discovered PSI domain thiol isomerase activity, and its potential as a novel target for anti-thrombotic therapies and beyond.

Drug-induced immune-mediated thrombocytopenia secondary to durvalumab use

Immunotherapy is an expanding area of cancer treatment with significant promise. Despite their efficacy, checkpoint inhibitors are associated with a number of immune-related adverse events; here, we described thrombocytopenia secondary todurvalumab.

Perioperative thrombocytopenia

PURPOSE OF REVIEW

In this review, we discuss recent developments and trends in the perioperative management of thrombocytopenia.

RECENT FINDINGS

Large contemporary data base studies show that preoperative thrombocytopenia is present in about 8% of asymptomatic patients, and is associated with increased risks for bleeding and 30-day mortality. Traditionally specific threshold platelet counts were recommended for specific procedures. However, the risk of bleeding may not correlate well with platelet counts and varies with platelet function depending on the underlying etiology. Evidence to support prophylactic platelet transfusion is limited and refractoriness to platelet transfusion is common. A number of options exist to optimize platelet counts prior to procedures, which include steroids, intravenous immunoglobulin, thrombopoietin receptor agonists, and monoclonal antibodies. In addition, intraoperative alternatives and adjuncts to transfusion should be considered. It appears reasonable to use prophylactic desmopressin and antifibrinolytic agents, whereas activated recombinant factor VII could be considered in severe bleeding. Other options include enhancing thrombin generation with prothrombin complex concentrate or increasing fibrinogen levels with fibrinogen concentrate or cryoprecipitate.

SUMMARY

Given the lack of good quality evidence, much research remains to be done. However, with a multidisciplinary multimodal perioperative strategy, the risk of bleeding can be decreased effectively.

A practical approach to evaluating postoperative thrombocytopenia

Identifying the cause(s) of postoperative thrombocytopenia is challenging. The postoperative period includes numerous interventions, including fluid administration and transfusion of blood products, medication use (including heparin), and increased risk of organ dysfunction and infection. Understanding normal thrombopoietin physiology and the associated expected postoperative platelet count changes is the crucial first step in evaluation. Timing of thrombocytopenia is the most important feature when differentiating causes of postoperative thrombocytopenia. Thrombocytopenia within 4 days of surgery is commonly caused by hemodilution and increased perioperative platelet consumption prior to thrombopoietin-induced platelet count recovery and transient platelet count overshoot. A much broader list of possible conditions that can cause late-onset thrombocytopenia (postoperative day 5 [POD5] or later) is generally divided into consumptive and destructive causes. The former includes common (eg, infection-associated disseminated intravascular coagulation) and rare (eg, postoperative thrombotic thrombocytopenic purpura) conditions, whereas the latter includes such entities as drug-induced immune thrombocytopenia or posttransfusion purpura. Heparin-induced thrombocytopenia is a unique entity associated with thrombosis that is typically related to intraoperative/perioperative heparin exposure, although it can develop following knee replacement surgery even in the absence of heparin exposure. Very late onset (POD10 or later) of thrombocytopenia can indicate bacterial or fungal infection. Lastly, thrombocytopenia after mechanical device implantation requires unique considerations. Understanding the timing and severity of postoperative thrombocytopenia provides a practical approach to a common and challenging consultation.

Rifampicin-Induced Thrombocytopenia: A Case Report and Short Review of the Literature

Thrombocytopenia may be associated with a variety of conditions and risks depending on its severity, ranging from mild epistaxis to life-threating bleeding. Many drugs or herbal remedies can cause thrombocytopenia by either inhibiting platelet production and/or enhancing their destruction from the peripheral blood mediated via an immunological mechanism implicating drug-dependent antibodies. The latter entity is called drug-induced immune thrombocytopenia: a life-threatening, under-recognised condition, which is often a diagnostic challenge. Rifampicin is a widely used, well-tolerated, and effective bactericidal drug. Adverse events, except for gastrointestinal effects, headache, skin rash, and pruritus, are uncommon. The authors herein report on a patient with isolated thrombocytopenia with a recent medical history of brucellosis on rifampicin and doxycycline. Thrombocytopenia was proved to be rifampicin-induced. Also presented is a short review of the literature on this rare subject, which should be of great importance to clinicians.