Drug-induced thrombocytopenia: pathogenesis, evaluation, and management

Implementing evidence-based restrictive neonatal intensive care unit platelet transfusion guidelines

Platelet transfusions are life-saving treatments for specific populations of neonates. However, recent evidence indicates that liberal prophylactic platelet transfusion practices cause harm to premature neonates. New efforts to better balance benefits and risks are leading to the adoption of more restrictive platelet transfusion guidelines in neonatal intensive care units (NICU). Although restrictive guidelines have the potential to improve outcomes, implementation barriers exist. We postulate that as neonatologists become more familiar with the data on the harm of liberal platelet transfusions, enthusiasm for restrictive guidelines will increase and barriers to implementation will decrease. Thus, we focused this educational review on; (1) the adverse effects of platelet transfusions to neonates, (2) awareness of platelet transfusion "refractoriness" in thrombocytopenic neonates and its association with poor outcomes, and (3) the impetus to find alternatives to transfusing platelets from adult donors to NICU patients.

An Introduction to the Complete Blood Count for Clinical Chemists: Platelets

BACKGROUND

The most ordered laboratory test worldwide is the complete blood count (CBC).

CONTENT

In this primer, an introduction to platelet testing in the context of the CBC is provided with a discussion of the laboratory evaluation of platelet abnormalities including thrombocytopenia and thrombocytosis.

SUMMARY

As clinical chemists continue to be tasked to direct laboratories outside of the traditional clinical chemistry sections such as hematology, expertise must be developed. This primer is dedicated to that effort.

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.

Neonatal Intensive Care Unit Patients Receiving More Than 25 Platelet Transfusions

OBJECTIVE

A few patients in neonatal intensive care units (NICU) receive numerous platelet transfusions. These patients can become refractory, defined as transfusions of ≥10 mL/kg failing to increase the platelet count by at least 5,000/µL. Causes of, and best treatments for, platelet transfusion refractoriness in neonates have not been defined.

STUDY DESIGN

Multi-NICU multiyear retrospective analysis of neonates receiving >25 platelet transfusions.

RESULTS

Eight neonates received 29 to 52 platelet transfusions. All eight were blood group O. Five had sepsis, four were very small for gestational age, four had bowel resections, two Noonan syndrome, two had cytomegalovirus infection. All eight had some (19-73%) refractory transfusions. Many (2-69%) of the transfusions were ordered when the platelet count was >50,000/µL. Higher posttransfusion counts occurred after ABO-identical transfusions (p = 0.026). Three of the eight had late NICU deaths related to respiratory failure; all five survivors had severe bronchopulmonary dysplasia requiring tracheostomy for prolonged ventilator management.

CONCLUSION

Neonates who are high users of platelet transfusions appear to be at high risk for poor outcomes, especially respiratory failure. Future studies will examine whether group O neonates are more likely to develop refractoriness and whether certain neonates would have a higher magnitude of posttransfusion rise if they received ABO-identical donor platelets.

KEY POINTS

· Many of the platelet transfusions given in the NICU are given to a small subset of patients.. · Refractoriness to platelet transfusions is common among these very high recipients.. · Neonates who are high users of platelet transfusions appear to be at high risk for poor outcomes..

Valproic Acid-Induced Thrombocytopenia in Treatment-Resistant GABRB3 Genetic Epilepsy: A Case Report

Valproic acid (VPA) is utilized in the management of a variety of seizure and mood disorders. A rare side effect of this medication is dose-dependent thrombocytopenia. In this case, we report a patient with a treatment-resistant epilepsy GABRB3 genetic variant phenotype who was admitted for sepsis and found to have significant thrombocytopenia with clinical manifestations of epistaxis and easy bruising, which was found to be due to VPA use rather than secondary to other clinical pathologies. The patient's clinical condition improved with supportive treatment including fluid rehydration. Platelet counts normalized after a transfusion and holding of her valproate. She experienced breakthrough seizures despite the initiation of diazepam. The decision was made to restart VPA per Neurology consult recommendations for better seizure control. She had no breakthrough seizures reported after restarting VPA in the hospital. This case highlights the importance of monitoring antiseizure medication side effects, especially in populations at higher risk due to treatment resistance.

Tirofiban-induced thrombocytopenia

Tirofiban is a small non-peptide ligand-mimetic Glycoprotein (GP) IIb/IIIa inhibitor which can reversibly bind to the arginine-glycine-aspartic acid (RGD) recognition site of GP IIb/IIIa to prevent platelet aggregation. It reduces the incidence of thrombotic cardiovascular events in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Although generally considered safe, tirofiban has been reported to be associated with thrombocytopenia in several case reports and clinical trials. The pathogenesis for this adverse reaction is not entirely understood, is thought to be due to immune-mediated reaction. This side effect caused by tirofiban is especially concerning given how frequently it is used in the practice of contemporary cardiovascular care. The present review provides an overview of the pathophysiology, clinical presentation, management, and risk factors associated with tirofiban-induced thrombocytopenia.

A case report of acute myocardial infarction with extremely severe thrombocytopenia after percutaneous coronary intervention

INTRODUCTION

The case report's purpose is to remind doctors a rare complication named thrombocytopenia of antithrombotic drugs. As a result, severe bleeding or even life-threatening situations may be avoided.

PATIENT CONCERNS

A specific case of a patient with acute myocardial infarction, a significant decrease in platelet count was observed after percutaneous coronary intervention.

DIAGNOSIS

After ruling out other potential causes, the medical team considered tirofiban-induced thrombocytopenia as a possible explanation.

INTERVENTIONS AND OUTCOMES

Through careful monitoring and adjustment of medication, the patient's platelet count eventually returned to normal.

CONCLUSION

To ensure patient safety, it is advised to regularly monitor platelet counts at intervals of 2 to 6 hours before and after administering tirofiban.

Recommendations for the Clinical Approach to Immune Thrombocytopenia: Spanish ITP Working Group (GEPTI)

Primary immune thrombocytopenia (ITP) is a complex autoimmune disease whose hallmark is a deregulation of cellular and humoral immunity leading to increased destruction and reduced production of platelets. The heterogeneity of presentation and clinical course hampers personalized approaches for diagnosis and management. In 2021, the Spanish ITP Group (GEPTI) of the Spanish Society of Hematology and Hemotherapy (SEHH) updated a consensus document that had been launched in 2011. The updated guidelines have been the reference for the diagnosis and management of primary ITP in Spain ever since. Nevertheless, the emergence of new tools and strategies makes it advisable to review them again. For this reason, we have updated the main recommendations appropriately. Our aim is to provide a practical tool to facilitate the integral management of all aspects of primary ITP management.

Primary and secondary immune thrombocytopenia (ITP): Time for a rethink

There are not many publications that provide a holistic view of the management of primary and secondary ITP as a whole, reflecting the similarities and differences between the two. Given the lack of major clinical trials, we believe that comprehensive reviews are much needed to guide the diagnosis and treatment of ITP today. Therefore, our review addresses the contemporary diagnosis and treatment of ITP in adult patients. With respect to primary ITP we especially focus on establishing the management of ITP based on the different and successive lines of treatment. Life-threatening situations, "bridge therapy" to surgery or invasive procedures and refractory ITP are also comprehensively reviewed here. Secondary ITP is studied according to its pathogenesis by establishing three major differential groups: Immune Thrombocytopenia due to Central Defects, Immune Thrombocytopenia due to Blocked Differentiation and Immune Thrombocytopenia due to Defective Peripheral Immune Response. Here we provide an up-to-date snapshot of the current diagnosis and treatment of ITP, including a special interest in addressing rare causes of this disease in our daily clinical practice. The target population of this review is adult patients only and the target audience is medical professionals.

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.

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.

Severe Acute Thrombocytopenia After Treatment with Tirofiban: A Case Series Approach

Glycoprotein IIb/IIIa inhibitors are an adjuvant therapy for the treatment of patients with acute coronary syndromes. The main adverse reactions are bleeding and thrombocytopenia in 1-2% of cases. A 66-year-old woman arrived at the emergency department with ST-elevation MI. The catheterisation lab was busy, so she received thrombolytic therapy. Coronary angiography revealed a 90% stenosis in the middle segment of the left anterior descending artery and Thrombolysis in MI 2 flow. Subsequent percutaneous coronary intervention showed abundant thrombus and a coronary dissection and it was necessary to insert five drug-eluting stents. Non-fractionated heparin and a tirofiban infusion were used. After the percutaneous coronary intervention, she developed severe thrombocytopenia, haematuria and gingivorrhagia, for which infusion of tirofiban was suspended. In follow-up, no major bleeding or subsequent haemorrhagic complications were identified. It is crucial to distinguish between heparin-induced thrombocytopenia and thrombocytopenia caused by other drugs. A high level of suspicion should be employed in these cases.

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.

Cross-reactivity between piperacillin-tazobactam and cefoperazone-sulbactam in drug-induced immune thrombocytopenia

Beta-lactam antibiotics commonly cause immune thrombocytopenia. Cross-reactivity in patients with drug-induced immune thrombocytopenia has rarely been reported. In this study, we describe the case of a 79-year-old man who developed thrombocytopenia after receiving piperacillin-tazobactam for an acute exacerbation of chronic obstructive pulmonary disease, and he was successfully treated with meropenem and cefotiam. However, thrombocytopenia recurred after cefoperazone-sulbactam administration. This indicated that cross-reactivity of platelet-specific antibodies occurred between piperacillin-tazobactam and cefoperazone-sulbactam. However, the responsible drug structures remain unknown, requiring further investigation. Likewise, chemical structure similarities among beta-lactam antibiotics must be examined to determine the risk of immune thrombocytopenia in the clinical setting.

Scoping Review on Epigenetic Mechanisms in Primary Immune Thrombocytopenia

Immune Thrombocytopenia (ITP) is an autoimmune blood disorder that involves multiple pathways responsible for the homeostasis of the immune system. Numerous pieces of literature have proposed the potential of immune-related genes as diagnostic and prognostic biomarkers, which mostly implicate the role of B cells and T cells in the pathogenesis of ITP. However, a more in-depth understanding is required of how these immune-related genes are regulated. Thus, this scoping review aims to collate evidence and further elucidate each possible epigenetics mechanism in the regulation of immunological pathways pertinent to the pathogenesis of ITP. This encompasses DNA methylation, histone modification, and non-coding RNA. A total of 41 studies were scrutinized to further clarify how each of the epigenetics mechanisms is related to the pathogenesis of ITP. Identifying epigenetics mechanisms will provide a new paradigm that may assist in the diagnosis and treatment of immune thrombocytopenia.

Platelet transfusion in adults: An update

Many patients worldwide receive platelet components (PCs) through the transfusion of diverse types of blood components. PC transfusions are essential for the treatment of central thrombocytopenia of diverse causes, and such treatment is beneficial in patients at risk of severe bleeding. PC transfusions account for almost 10% of all the blood components supplied by blood services, but they are associated with about 3.25 times as many severe reactions (attributable to transfusion) than red blood cell transfusions after stringent in-process leukoreduction to less than 10⁶ residual cells per blood component. PCs are not homogeneous, due to the considerable differences between donors. Furthermore, the modes of PC collection and preparation, the safety precautions taken to limit either the most common (allergic-type reactions and febrile non-hemolytic reactions) or the most severe (bacterial contamination, pulmonary lesions) adverse reactions, and storage and conservation methods can all result in so-called PC "storage lesions". Some storage lesions affect PC quality, with implications for patient outcome. Good transfusion practices should result in higher levels of platelet recovery and efficacy, and lower complication rates. These practices include a matching of tissue ABH antigens whenever possible, and of platelet HLA (and, to a lesser extent, HPA) antigens in immunization situations. This review provides an overview of all the available information relating to platelet transfusion, from donor and donation to bedside transfusion, and considers the impact of the measures applied to increase transfusion efficacy while improving safety and preventing transfusion inefficacy and refractoriness. It also considers alternatives to platelet component (PC) transfusion.

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.

The Clinical Challenge of Refractory Octreotide-Induced Thrombocytopenia in Active Gastrointestinal Bleeding: A Case Report

The association between octreotide and thrombocytopenia has been documented in the literature but it remains a rare finding. We are reporting a 59-year-old female patient with alcoholic liver cirrhosis who presented with the gastrointestinal tract (GIT) bleeding secondary to esophageal varices. Initial management involved fluid and blood products resuscitation and initiation of both octreotide and pantoprazole infusion. However, the abrupt onset of severe thrombocytopenia was evident within a few hours of admission. Platelet transfusion and discontinuation of pantoprazole infusion failed to correct the abnormality prompting the holding off of octreotide. However, this also failed to control the decline in platelet count and prompted intravenous immunoglobulin (IVIG). This case helps to remind clinicians to closely monitor platelet count once octreotide is initiated. This allows early detection of the rare entity of octreotide-induced thrombocytopenia, which can be life-threatening with extremely low platelet count nadir.

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.

Immune-Mediated Adverse Drug Reactions (IM-ARDs) in the Form of Drug-Induced Immune Thrombocytopenia and Cutaneous Adverse Drug Reactions (CARD) Due to Clindamycin in an Human Immunodeficieny Virus (HIV) Patient

BACKGROUND Many drugs have been reported to cause immune-mediated adverse drug reactions (IM-ADRs) in human immunodeficiency virus (HIV) patients; the most common is cutaneous adverse drug reaction (CADR). Immune thrombocytopenia purpura (ITP) is frequent in HIV patients, and it can be caused HIV, opportunistic infections, or drugs. Although drugs can cause immune thrombocytopenia, termed drug-induced immune thrombocytopenia (DIIT), there has been no study on DIIT in HIV patients. CASE REPORT A 33-year-old male patient was admitted to our hospital with pruritic skin lesion over the entire body, which started 7 days before. He was diagnosed with HIV infection, brain toxoplasmosis, and pulmonary tuberculosis 2 weeks before admission, and was given trimethoprim sulphamethoxazole, isoniazid, rifampicin, pyrazinamide, and ethambutol. Clindamycin was added 10 days before admission. Skin examination revealed generalized erythematous macules with palpable petechiae and purpura. The platelet count was 141 000/µL when he was diagnosed with HIV, and it was 2000/µL at the time of admission. Clindamycin was discontinued and he was given steroids and platelet transfusion. The skin lesions improved along with an increased platelet count. He was discharged on the 10th day of admission, with platelet count of 42 000/µL. When he returned to the outpatient clinic on the 15th day, his platelet was 54 000/µL. The skin lesions had resolved completely and become hyperpigmented, and no purpura or petechiae were seen. CONCLUSIONS We present a case of an HIV patient with IM-ADR in the form of DIIT in conjunction with CADR that might have been caused by clindamycin.

Carvedilol-Induced Thrombocytopenia: A Case Report

Thrombocytopenia is a commonly encountered complication of hospitalized patients, and can be caused by many factors including infections, surgery, and medications. Drug-induced thrombocytopenia (DITP) should be considered when a patient presents with an unexpected occurrence of thrombocytopenia. Many drugs can induce thrombocytopenia either as a direct effect on thrombopoiesis within the bone marrow or by drug-dependent antibody-mediated destruction of platelets within the circulation. We present the case of a 44-year-old female who presented with 2 weeks of nausea, vomiting, and headaches occurring with her hemodialysis sessions. On admission she was found to be thrombocytopenic with a platelet count of 35 K/µL. Her last known normal platelet count was 299 K/µL from 2 months prior. A thorough work up of her thrombocytopenia was found to be unremarkable. Her newly started carvedilol was thought to be the most likely cause based on the rapid platelet recovery upon drug discontinuation and negative workup of other potential causes.

Thrombocytopenia Induced by Direct Oral Anticoagulants: a Clinical Case and Literature Review

The last decade has dramatically changed the strategy of anticoagulant therapy in patients with atrial fibrillation. Direct oral anticoagulants have replaced vitamin K antagonists: either direct thrombin blockers (dabigatran) or factor IIa blockers (apixaban, rivaroxaban, edoxaban). According to the regulatory domestic and foreign documents, the use of direct oral anticoagulants in patients with atrial fibrillation has priority in comparison with vitamin K antagonists, since they have a predictable anticoagulant effect, the possibility of taking fixed doses without the need for routine anticoagulant monitoring, rapid onset and termination of action, relatively low potential for food and drug interactions. Direct oral anticoagulants are used for the prevention of thromboembolic complications in patients with atrial fibrillation, for the prevention of deep vein thrombosis in patients who have undergone surgery on the knee or hip joints, for emergency treatment and secondary prevention of deep vein thrombosis and pulmonary embolism. Alertness to side effects tends to focus on the likelihood of bleeding, with the possibility of other side effects of direct oral anticoagulants receiving less attention or going unnoticed. These mainly include liver damage, kidney damage and a number of other rare adverse reactions. The finding of isolated thrombocytopenia in patients taking direct oral anticoagulants may be associated with a high risk of life-threatening bleeding. The article analyzes published data on the occurrence of thrombocytopenia associated with the intake of direct oral anticoagulants, and presents a clinical case of thrombocytopenia while taking apixaban.

Eptifibatide-Induced Severe Thrombocytopenia After ST-Elevation Myocardial Infarction (STEMI): A Case Report

Eptifibatide is a platelet glycoprotein (GP) IIb/IIIa inhibitor that is used in certain cases of acute coronary syndrome, including those with high thrombus burden or with no-reflow. It can rarely be associated with severe thrombocytopenia, which brings up a dilemma in managing those patients who require antiplatelet therapy. We discuss a patient who had ST-elevation myocardial infarction (STEMI) and developed severe thrombocytopenia after eptifibatide infusion. He was managed with platelet transfusion, stopping eptifibatide, and interrupting dual antiplatelet therapy (DAPT).

Serum protein and electrolyte imbalances are associated with chemotherapy induced neutropenia

Introduction

Cancer and its treatment using various chemotherapeutic agents can have many adverse side effects. These side effects often result in significant changes in haematological and biochemical composition of blood. As a result, the regular monitoring of serum biochemical and haematological changes plays an important role in management of disease. The present study aimed to determine the relationship between haematological and biochemical changes in neutropenic cancer patients following chemotherapy. Specifically we evaluated the association between neutrophil count and serum proteins and electrolytes.

Methods

For this purpose we analysed retrospectively collected laboratory results from two independent patient cohorts. Each cohort was divided into a control group consisting of patients with normal haematological parameters and a study group which included patients with reduced neutrophil counts. Neutropenic patients (study group) were cancer patients on chemotherapy.

Results and conclusion

Blood samples of cancer patients in study group showed reduction in haemoglobin, neutrophils and platelets. Neutropenic group showed a significant reduction in serum albumin, total protein, calcium, and potassium. Our results show that patients with severe neutropenia had pronounced changes in serum protein and electrolytes and increased incidence of abnormal serum protein and electrolyte level. The changes in the neutrophil counts showed a positive correlation with the changes in serum protein and electrolyte levels. A similar trend was seen in both the patient cohorts: the discovery set (176 patients) and the validation set (200 patients). Taken together our results suggest that chemotherapy-induced neutropenia is associated with dysregulation in haemoglobin, platelets, serum proteins and electrolytes.

Severe Thrombocytopenia Caused by Vancomycin in the Intensive Care Unit: A Case Report

Thrombocytopenia can cause substantial morbidity and mortality in critically ill patients. There are multiple etiology factors and various mechanisms associated with thrombocytopenia, of which drug-induced thrombocytopenia (DITP) deserves attention. Herein, we describe a case of severe thrombocytopenia during intensive care unit (ICU) hospitalization that was likely to be associated with vancomycin. By revealing the process of identifying this case of DITP and reviewing relevant clinical studies, a risk alert of vancomycin-related severe hematotoxicity should be considered.

Drug-Induced Immune Thrombocytopenia Toxicity Prediction Based on Machine Learning

Drug-induced immune thrombocytopenia (DITP) often occurs in patients receiving many drug treatments simultaneously. However, clinicians usually fail to accurately distinguish which drugs can be plausible culprits. Despite significant advances in laboratory-based DITP testing, in vitro experimental assays have been expensive and, in certain cases, cannot provide a timely diagnosis to patients. To address these shortcomings, this paper proposes an efficient machine learning-based method for DITP toxicity prediction. A small dataset consisting of 225 molecules was constructed. The molecules were represented by six fingerprints, three descriptors, and their combinations. Seven classical machine learning-based models were examined to determine an optimal model. The results show that the RDMD + PubChem-k-NN model provides the best prediction performance among all the models, achieving an area under the curve of 76.9% and overall accuracy of 75.6% on the external validation set. The application domain (AD) analysis demonstrates the prediction reliability of the RDMD + PubChem-k-NN model. Five structural fragments related to the DITP toxicity are identified through information gain (IG) method along with fragment frequency analysis. Overall, as far as known, it is the first machine learning-based classification model for recognizing chemicals with DITP toxicity and can be used as an efficient tool in drug design and clinical therapy.

A Data-Driven Medical Decision Framework for Associating Adverse Drug Events with Drug-Drug Interaction Mechanisms

Adverse drug events (ADEs) occur when multiple drugs interact within an individual, thus causing effects that were not initially predicted. Such toxic interactions lead to morbidity and mortality. Contemporary research surrounding ADEs has tended to focus on the detection of potential ADEs without great concern for elucidating the associations of drug-drug interaction (DDI) mechanisms that can predict potential adverse drug reactions (ADRs). Such associations are of great practical importance for everyday pharmacovigilance efforts. This study presents a data-driven framework for conducting knowledge-driven data analysis that combines a semantic inference system and enrichment analysis in order to identify potential ADE mechanisms. The framework was used to rank mechanisms according to their relevance for DDIs and also to categorize ADEs based on the number of DDI mechanism associations identified through enrichment analysis. Its validity is demonstrated through using both commercial and publicly available DDI resources. The results of this study solidly prove the framework's effectiveness and highlight potential for future research by way of incorporating additional and broader data to deepen and expand its capabilities.

Pantoprazole-induced Thrombocytopenia: Unresponsive to Corticosteroid and Thrombocyte Concentrate Transfusion

INTRODUCTION

Pantoprazole is a proton pump inhibitor (PPI) class drug that is widely used in the treatment of SRMD (stress-related mucosal disease in critical ill patients. PPI are one class of drugs used commonly both for treatment and prophylactic therapy for stress ulcers in intensive care unit (ICU).

CASE

We report a case of a 51-year old male who was referred to PKU Hospital. He was admitted to ICU with diagnosis of Hyperosmolar Hyperglymic State and bronchopneumonia. Thrombocytopenia was noted in admission. There was more than 70% decrease in platelet count after initiation of pantoprazole. Patient received Thrombocyte Concentrate (TC) transfusion and corticosteroid iv for several days, but only had minor increase in platelet count. The platelets recovered after stopping pantoprazole.

DISCUSSION

In the present case report, another exposures to parenteral pantoprazole in a dose of 40 mg once daily reproduced the same adverse drug reaction. In comparison to lansoprazole, thrombocytopenia from pantoprazole is more severe that necessitate TC transfusion and corticosteroid trial. However, in the present case, TC transfusion and corticosteroid fail to escalate platelet count. This finding suggests probability of non-immune mechanism of pantoprazole-induced thrombocytopenia.

CONCLUSION

Pantoprazole may induce thrombocytopenia with new features that were immediately developed, resulting a decrease in platelet count >70%. The mechanism found in this case may be non-immune. Drug-induced thrombocytopenia is one of the rare complications that has to be kept in mind with the use of pantoprazole.

Detection of Drug-Induced Thrombocytopenia Signals in Children Using Routine Electronic Medical Records

Background: Drug-induced thrombocytopenia (DITP) is a severe adverse reaction and a significantly under-recognized clinical problem in children. However, for post-marketing pharmacovigilance purposes, detection of DITP signals is crucial. This study aimed to develop a signal detection model for DITP using the pediatric electronic medical records (EMR) data.

Methods: This study used the electronic medical records collected at Beijing Children’s Hospital between 2009 and 2020. A two-stage modeling method was developed to detect the signal of DITP. In the first stage, we calculated the crude incidence by mining cases of thrombocytopenia to select the potential suspected drugs. In the second stage, we constructed propensity score–matched retrospective cohorts of specific screened drugs from the first stage and estimated the odds ratio (OR) and 95% confidence interval (CI) using conditional logistic regression models. The novelty of the signal was assessed by current evidence.

Results: In the study, from a total of 839 drugs, 21 drugs were initially screened as potentially inducing thrombocytopenia. In total, we identified 18 positive DITP associations. Of these, potential DITP risk of nystatin (OR: 1.75, 95% CI: 1.37–2.22) and latamoxef sodium (OR: 1.61, 95% CI: 1.38–1.88) were two new DITP signals in both children and adults. Six associations between thrombocytopenia and drugs including imipenem (OR: 1.69, 95% CI: 1.16–2.45), teicoplanin (OR: 4.75, 95% CI: 3.33–6.78), fusidic acid (OR: 2.81, 95% CI: 2.06–3.86), ceftizoxime sodium (OR: 1.83, 95% CI: 1.36–2.45), ceftazidime (OR: 2.16, 95% CI: 1.58–2.95), and cefepime (OR: 5.06, 95% CI: 3.77–6.78) were considered as new signals in children.

Conclusion: This study developed a two-stage algorithm to detect safety signals of DITP and found eighteen positive signals of DITP, including six new signals in a pediatric population. This method is a promising tool for pharmacovigilance based on EMR data.

Immune Thrombocytopenia Exacerbation After COVID-19 Vaccination in a Young Woman

The coronavirus disease 2019 (COVID-19) pandemic is one of the greatest health concerns worldwide. Safe and effective COVID-19 vaccines are urgently needed and have been rapidly approved. COVID-19 vaccine-induced thrombocytopenia was reported as a rare adverse effect in the Vaccine Adverse Events Reporting System. A 25-year-old woman, who was previously diagnosed with immune thrombocytopenia (ITP, stage I), had exacerbated severe thrombocytopenia (platelet count of 6,000/μL) with a headache, joint pain, general fatigue, and bleeding tendency three days after receiving her second dose of the Pfizer BioNTech COVID-19 vaccine. Pulsed high-dose dexamethasone therapy rapidly ameliorated the ITP. Although it is difficult to confirm a causal association between Pfizer BioNTech COVID-19 vaccination and ITP exacerbation, abrupt onset of ITP exacerbation after vaccination suggests that the ITP may be vaccination-induced thrombocytopenia exacerbation. Rare but severe adverse events such as ITP may be observed, depending on increased numbers of individuals who receive COVID-19 vaccines worldwide. Further investigation is needed to clarify the mechanisms of COVID-19 vaccine-induced ITP.

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.

Acute Profound Thrombocytopenia Induced by Eptifibatide Causing Diffuse Alveolar Hemorrhage

Background

Eptifibatide is a glycoprotein IIb/IIIa (GP IIb/IIIa) receptor inhibitor which prevents platelet activation. The mechanism in which eptifibatide causes profound thrombocytopenia is poorly understood. One hypothesis suggests antibody-dependent pathways which cause thrombocytopenia upon subsequent reexposure to eptifibatide. This case reports acute profound thrombocytopenia (platelets < 20 × 10³/mm³) within 24 hours of administration. Alveolar hemorrhage occurred during a second eptifibatide infusion 5 days after initial asymptomatic eptifibatide treatment. Case Presentation. A 50-year-old male presenting with a STEMI was treated with eptifibatide during cardiac catheterization. Twelve hours posttreatment, the patient encountered profound thrombocytopenia and hemoptysis. The patient was briefly intubated for airway protection. The patient was stabilized after receiving platelet transfusion and fully recovered.

Conclusion

This is one of several cases reported on eptifibatide causing acute profound thrombocytopenia and subsequent alveolar hemorrhage. This case supports the theory in which antibodies contribute to eptifibatide-induced thrombocytopenia.

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.

A Novel Case of Leflunomide-Induced Thrombotic Thrombocytopenic Purpura

Leflunomide has not been previously associated with thrombotic thrombocytopenic purpura (TTP), a rare life-threatening clinical syndrome characterized by thrombotic microangiopathy (TMA) due to inability to cleave ADAMTS13. Here, we present the first case of leflunomide-induced TTP. Our patient developed encephalopathy, thrombocytopenia, anemia and hyperbilirubinemia 2 months after starting leflunomide. Schistocytes were noted on peripheral smear and ADAMTS13 activity was low (< 5%), consistent with acquired TTP. He received therapeutic plasma exchange, corticosteroids, rituximab and caplacizumab with normalization of hemolysis labs and ADAMTS13 activity. However, pancytopenia persisted, raising the suspicion for leflunomide toxicity. Oral cholestyramine treatment was empirically started before teriflunomide (a leflunomide metabolite) level was found to be elevated. Blood counts normalized after cholestyramine and have remained normal at last follow-up over a year later. This is the first reported case of TTP precipitated by leflunomide. Our case highlights the importance of recognizing drugs as an etiology of TMA and adds leflunomide to this list.

Eptifibatide-induced profound thrombocytopaenia: a rare complication

Drug-induced immune thrombocytopaenia (DITP) is a type of thrombocytopaenia caused by medications. It is one of the common causes of unexplained thrombocytopaenia. It is caused by the formation of autoantibodies against a particular drug and is commonly observed with medications like heparin and beta-lactam antibiotics. One of the rare causes of DITP is eptifibatide, a widely used antiplatelet agent for pretreatment in cardiac catheterisation. These patients can be asymptomatic or develop complications like skin bruising, epistaxis and even intracranial haemorrhage. We present a case of a 64-year-old man who developed eptifibatide-induced profound thrombocytopaenia leading to extensive skin bruising. He was treated with platelet transfusions followed by prompt improvement in platelet count.

Comparison of Clinical Scoring Tools to Predict Heparin-Induced Thrombocytopenia in Cardiac Surgery

The 4Ts and HIT-Expert Probability (HEP) scoring tools for heparin-induced thrombocytopenia (HIT) have not been validated in cardiac surgery patients, and the reported sensitivity and specificity of the Post-Cardiopulmonary Bypass (CPB) scoring tool vary widely in the 2 available analyses. It remains unclear which of the available scoring tools most accurately predicts HIT in this population. Forty-nine HIT-positive patients who underwent on-pump cardiac surgery within a 6-year period were loosely matched to 98 HIT-negative patients in a 1:2 case-control design. The 4Ts, HEP, and CPB scores were calculated for each patient. Sensitivity and specificity of each tool were calculated using standard cut-offs. The Youden method was utilized to determine optimal cut-offs within receiver operating characteristic (ROC) curves of each score, after which sensitivities and specificities were recalculated. Using standard cut-offs, the sensitivities for the CPB, HEP, and 4Ts scores were 100%, 93.9%, and 69.4%, respectively. Specificities were 51%, 49%, and 71.4%, respectively. The AUC of the scoring tool ROC curves were 0.961 for the CPB score, 0.773 for the HEP score, and 0.805 for the 4Ts score. Using the Youden method-derived optimal cut-off of  ≥3 points on the CPB score, sensitivity remained 100% with improved specificity to 88.9%. The CPB score is the preferred HIT clinical scoring tool in adult cardiac surgery patients, whereas the 4Ts score performed less effectively. A cut-off of ≥ 3 points on the CPB score could increase specificity while preserving high sensitivity, which should be validated in a prospective evaluation.

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.

A Rare Cause of Drug-Induced Pancytopenia: Trimethoprim-Sulfamethoxazole-Induced Pancytopenia

Pancytopenia is a decrease across cellular hematological lines. Many different etiologies can cause this clinical picture including viral and bacterial infections, chemicals, malignancy, and medications. Particular attention should be paid to the onset, timing, and severity as they can indicate the underlying cause. In cases of iatrogenic-induced pancytopenia, the offending agent should be stopped immediately and the patient should be monitored for recovery of cell lines. While not well reported in the literature, trimethoprim-sulfamethoxazole (TMP-SMX) is a cause of pancytopenia. We present a case of drug-induced pancytopenia secondary to TMP-SMX that resolved quickly with cessation of use.

Autoimmune heparin-induced thrombocytopenia: a rare manifestation of COVID-19

We describe the case of a 65-year-old male who presented to an outside hospital for shortness of breath, nausea and vomiting 8 days after testing positive for COVID-19. Initial workup revealed massive bilateral pulmonary emboli and thrombocytopenia. The patient was then admitted to our hospital, received an inferior vena cava filter and initially started on argatroban for autoimmune heparin-induced thrombocytopenia (HIT) prophylaxis. On hospital stay day 6, labs revealed a diagnosis of HIT in the setting of COVID-19. This case highlights the rare occurrence of a patient developing HIT without heparin exposure and in the setting of a novel infectious agent, COVID-19.

Panitumumab-Associated Drug-Induced Immune Thrombocytopenia in a Patient with Colorectal Cancer

Severe thrombocytopenia is a rare adverse event of panitumumab. Here, we report the first patient with metastatic colorectal cancer who developed severe thrombocytopenia, diagnosed as panitumumab-associated drug-induced immune thrombocytopenia (DITP). A clinical diagnosis of DITP can be obtained by excluding other causes of thrombocytopenia and is confirmed by the recovery of thrombocytopenia after the discontinuation of the suspected drug. Treatment includes permanent discontinuation of the suspected drug. Re-exposure should be avoided. It should be kept in mind that panitumumab can induce DITP in the case of a new, sudden, unexpected, and isolated drop in platelet count after excluding other causes of thrombocytopenia.

Delayed thrombocytopenia following administration of abciximab: Pharmacovigilance survey and literature review

BACKGROUND

Abciximab (ABX) is used for acute coronary syndrome and unstable angina. Thrombocytopenia is a frequent adverse effect described as occurring in the first 24hours. The aim of this study was to evaluate, in a context of pharmacovigilance survey, the occurrence of delayed thrombocytopenia following ABX infusion in pharmacovigilance database reports and in the literature.

METHODS

Individual case safety reports (ICSRs) of delayed thrombocytopenia-between 3 and 30 days - with ABX presented as a single suspect were selected in VigiBase®, the WHO global database of ICSRs. The French cases were then extracted from the French national pharmacovigilance database. In addition, a literature review of published cases was performed using PubMed.

RESULTS

Among the 84 ICSRs selected from VigiBase®, 43 were also reported in the FPVD. Mean age was 60.1±12.3 years with a majority of male patients (77.4%). The average time to onset (TTO) was 8.9±5.2 days. Thrombocytopenia regressed in 5.1±2.7 days. Haemorrhagic complications were reported in 15% of ICSRs. In the French cases, the median nadir of platelet count was 28×10⁹/L (range 1-110) with a majority of grade 4 thrombocytopenia (39.5%). The literature review identified 42 cases and provided additional information on administered therapies, which include platelet units, corticosteroids, and IV immunoglobulins. GPIIb/IIIa-ABX complex antibodies were described in 26 published cases.

CONCLUSION

Delayed thrombocytopenia, probably due to immune reaction, is a possible life-threatening adverse effect of ABX with a mean TTO of 9 days, supporting the recommendation of a platelet count monitoring during at least two weeks. This recommendation was added to the abcximab SmPC in 2019.

Regorafenib-induced exacerbation of chronic immune thrombocytopenic purpura in remission: A case report

Regorafenib is an oral multi-kinase inhibitor which targets tumor angiogenesis, the tumor microenvironment and oncogenesis. Based on this mode of action, regorafenib has a broad spectrum of toxicities. However, at present, few reports have focused on autoimmune adverse events. We report a first case of regorafenib-induced exacerbation of chronic immune thrombocytopenic purpura in remission during treatment for the patients with heavily treated advanced colorectal cancer. This case report highlights the need for caution with regard to regorafenib treatment in patients with cancer with concomitant immune thrombocytopenic purpura.

Acute Severe Thrombocytopenia Event Associated with Trimethoprim/Sulfamethoxazole Use

OBJECTIVE

To report a case of life-threatening thrombocytopenia associated with the use of trimethoprim/sulfamethoxazole (TMP/SMX) therapy.

REPORT OF THE CASE

50-year-old woman with no significant past medical history who presented with one day of petechial rash on her arms, chest and legs. Patient reports that she had just completed a 7- day course of TMP/SMX (1-double strength tablet twice a day) for uncomplicated UTI by her PMD. On admission, the patient was hemodynamically stable, and complete blood cell count revealed a platelet count of 2000/uL. TMP/SMX was believed to be the most likely cause of thrombocytopenia. After discontinuation of TMP/SMX and treatment with 2 units of platelets, 1gm intravenous immunoglobulin (IVIG) and oral dexamethasone, repeat CBC showed a stable platelet count of 90,000/uL. Patient was successfully discharged on hospital day 3 with outpatient follow up with the hematology clinic for further monitoring.

CONCLUSION AND DISCUSSION

Differential diagnosis of severe thrombocytopenia include drug induced thrombocytopenia (DITP), thrombotic thrombocytopenic purpura (TTP), post transfusion purpura (PTP), immune thrombocytopenic purpura (ITP), heparin induced thrombocytopenia (HIT), or catastrophic antiphospholipid antibody syndrome (APS). Drug-dependent antibodies are an unusual class of antibodies that bind firmly to specific epitopes on platelet surface glycoproteins only in the presence of the sensitizing drugs. DITP typically has an abrupt onset of severe thrombocytopenia, usually less than 20,000/uL. Thrombocytopenia usually begins to recover within 1-2 days after the offending drug is discontinued and platelet levels usually normalize within one week as demonstrated in our case report. Pharmacological treatment can include platelet transfusions in case of severe, overt bleeding, corticosteroids or IVIG administration. In most cases, however, discontinuation of the offending drug is sufficient.

Plexus Slim®-Induced Immune Thrombocytopenic Purpura

Primary immune thrombocytopenic purpura (ITP) is a common cause of thrombocytopenia. Due to the many possible precipitating factors, the diagnostic approach can be complex in nature. Much of the published literature on drug-induced ITP (DITP) report on quinine-induced thrombocytopenia. Here we present a case of the proposed dietary cause of DITP by the weight loss supplement Plexus® which contains two potential thrombocytopenia-causing compounds, garcinia cambogia fruit extract, and chromium polynicotinate. This case highlights how a thorough patient history, including evaluation of supplement use and dietary habits, can be of the utmost importance in the workup of ITP.