Drug-induced thrombocytopenia

An Updated Comprehensive Pharmacovigilance Study of Drug-Induced Thrombocytopenia Based on FDA Adverse Event Reporting System Data

Drug-induced thrombocytopenia (DIT) deserves both clinical and research attention for the serious clinical consequences and high prevalence of the condition. The current study aimed to perform a comprehensive pharmacovigilance analysis of DIT reported in the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database, with a particular focus on drugs associated with thrombocytopenia events. A disproportionality analysis of DIT was conducted using reports submitted to FARES from January 2004 to December 2022. Both the information component (IC) and reporting odds ratio (ROR) algorithms were applied to identify an association between target drugs and DIT events. A total of 15,940,383 cases were gathered in FAERS, 168,657 of which were related to DIT events. The top 50 drugs ranked by number of cases and ranked by signal strength were documented. The top 5 drugs ranked by number of cases were lenalidomide (10,601 cases), niraparib (3726 cases), ruxolitinib (3624 cases), eltrombopag (3483 cases), and heparin (3478 cases). The top 5 drugs ranked by signal strength were danaparoid (ROR 37.61, 95%CI 30.46-46.45), eptifibatide (ROR 34.75, 95%CI 30.65-39.4), inotersen (ROR 34.00, 95%CI 29.47-39.23), niraparib (ROR 30.53, 95%CI 29.42-31.69), and heparin (ROR 28.84, 95%CI 27.76-29.97). The top 3 involved drug groups were protein kinase inhibitors, antimetabolites, and monoclonal antibodies and antibody-drug conjugates. The current comprehensive pharmacovigilance study identified more drugs associated with thrombocytopenia. Although the mechanisms of DIT have been elucidated for some drugs, others still require further investigation.

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.

Maternal Coagulation Disorders and Postpartum Hemorrhage

Coagulation disorders are rare causes of postpartum hemorrhage. Disturbances in coagulation should be suspected in patients with a family history of coagulopathy, those with a personal history of heavy menstrual bleeding, and those with persistent bleeding despite correction of other causes. The coagulopathic conditions discussed include disseminated intravascular coagulation, platelet disorders, and disturbances of coagulation factors. These should not be overlooked in the evaluation of obstetric hemorrhage, as diagnosis and appropriate treatment may prevent severe maternal morbidity and mortality.

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.

Case Report: Simultaneously Induced Neutropenia and Hemolysis After a Single Metamizole Dose

BACKGROUND AND OBJECTIVE

Metamizole is a non-opioid ampyrone sulfonate compound with potent analgesic, antipyretic, and spasmolytic effects. Agranulocytosis is a rare life-threatening complication of metamizole.

CASE

Here, we present the case of a 62-year-old patient who developed agranulocytosis as well as hemolysis after a single administration of metamizole.

CONCLUSION

This case illustrates the inherent allergic potential of metamizole and its effects on different hematopoietic cell types.

Non-traumatic ecchymoses: A literature review from a medico-legal perspective

Ecchymosis, as a general term, refers to discoloration of the skin due to the presence of extravasated blood into the dermis and/or subcutaneous tissue. However, it can occasionally be observed without any trauma, as a symptom of disease, a clinical condition, or even during the course of treating a disease. It is extremely important that these non-traumatic lesions are known and recognized and can be distinguished from traumatic ecchymoses by both clinicians and forensic scientists. This review of the literature includes detailed descriptions of non-traumatic periorbital ecchymosis, Slapped Cheek Syndrome, Cullen's Sign, Grey Turner's Sign, Stabler's Sign, Ransohoff Sign, Bryant's Sign, postsacral ecchymosis, perianal ecchymosis, Fox's Sign, other lower leg ecchymosis, and ecchymosis on various body regions. In this article, it is emphasized that failure to correctly identify these findings may subject practitioners to malpractice lawsuits, and failure to correctly identify findings by forensic experts may result in unjust legal judgments against people or loss of rights. It is also this review encourages accurate diagnosis of non-traumatic ecchymoses.

Rapid Onset Severe Immune Thrombocytopenia following mRNA COVID-19 Vaccine in a Young Patient

The coronavirus disease 2019 (COVID-19) pandemic has affected millions of people around the world. Vaccination against COVID-19 has been approved for the following three vaccines in the United States: Pfizer-BioNTech, Moderna, and Janssen. Hematological complications of vaccination have been reported in the literature but remain as a rare phenomenon. We present the case of a patient who developed severe thrombocytopenia within twenty-four hours following the Pfizer-BioNTech vaccination. Commonly encountered differentials including heparin-induced thrombocytopenia and common viral etiologies were ruled out, and other causes such as drug reactions deemed unlikely as the etiology of this presentation after a broad workup. Nucleocapsid antibodies against COVID-19 were found to be positive which indicated that vaccination was at least the second encounter with this virus for our patient, which has been reported previously as the cause of immune thrombocytopenia (ITP), and this might be the culprit for sudden onset. He responded to the first-line ITP treatment with corticosteroids and intravenous immunoglobulin (IVIG) as evidenced by the fast recovery of platelet count and lack of recurrence of thrombocytopenia.

Pharmacists can improve diagnosis and help prevent diagnostic errors

We present two cases that highlight the role of pharmacists in the diagnostic process and illustrate how a culture of safety and teamwork between pharmacists and physicians can help prevent diagnostic errors.

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.

Immune Thrombocytopenic Purpura Following Pfizer-BioNTech COVID-19 Vaccine in an Elderly Female

Mass vaccination campaigns are being run all over the globe to combat the ongoing COVID-19 pandemic. There have been several reports of immune thrombocytopenic purpura (ITP) occurrence following COVID-19 vaccination. However, ITP due to the Pfizer-BioNTech vaccine has been rarely reported, and a causal link has not been identified. The pathophysiology behind immune thrombocytopenia is similar to heparin-induced thrombocytopenia. The management is also similar to other secondary immune thrombocytopenia. We present a case of a 67-year old female diagnosed with immune thrombocytopenia following Pfizer-BioNTech vaccination. The treatment was resistant to high-dose steroids, intravenous immunoglobulin (IVIG), and rituximab and eventually responded to a thrombopoietin-stimulating agent.

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.

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.

Secondary immune thrombocytopenia supposedly attributable to COVID-19 vaccination

Immune thrombocytopenia (ITP) has been widely reported as a complication of SARS-CoV-2 infection, but to our knowledge, there have been no reports on the association of the COVID-19 vaccine with thrombocytopenia. Here, we report a case of secondary ITP in a patient who was recently immunised with the messenger RNA COVID-19 vaccine BNT162b2 (Pfizer–BioNTech).

Vigilance regarding immune thrombocytopenic purpura after COVID-19 vaccine

INTRODUCTION

Based on the severity of thrombocytopenia, patients with immune thrombocytopenic purpura (ITP) are at an increased risk of mucocutaneous or major bleeding.

DISCUSSION

There has been an increased risk of ITP after administration of various vaccines like influenza, measles-mumps-rubella, hepatitis B, and diphtheria-tetanus-pertussis. The pathogenesis of vaccine-related thrombocytopenia is not completely clear and is probably caused by molecular mimicry. Till date, there have been few reported cases of thrombocytopenia in the pharmacovigilance databases after patients received the Pfizer and Moderna coronavirus disease-19 (COVID-19) vaccines.

CONCLUSION

Emergency physicians should be aware of the occurrence of vaccine-induced ITP in patients who present with bleeding manifestations, especially after the current boost in COVID-19 vaccination drive worldwide.

Aspirin "Allergy"-Induced Thrombocytopenia: A Case Report

Aspirin is clinically widely used to inhibit platelet aggregation after coronary intervention. Herein we describe a case of aspirin-induced thrombocytopenia that may be related to allergy to aspirin. A 47-year-old man developed a delayed hypersensitivity reaction to aspirin, with pruritus, purpura and thrombocytopenia, increased peripheral blood eosinophils and enlarged inguinal lymph node. All the symptoms disappeared in 2 years after stopping aspirin. Aspirin-induced thrombocytopenia related to allergy is rarely reported. Aspirin hypersensitivity should be taken into consideration in case of unexplained thrombocytopenia in patients taking aspirin. Aspirin "allergy"-induced thrombocytopenia may involve both aspirin related IgG and IgE antibodies.

Alcohol-induced thrombocytopenia: Current review

Thrombocytopenia is a decrease in the platelet count below 150,000 in a microliter of blood, i.e., below the lower limit of the reference range, which is 150,000-400,000/μL. The phenomenon of thrombocytopenia related to heavy drinking began to arouse interest in the 1960s and 1970s. It was initially described in case reports and clinical studies on small groups. In the following years, the phenomenon itself and the significance of alcohol-induced thrombocytopenia was studied. Many methodological difficulties inhibiting objective conclusions from research were encountered. Model pathological mechanisms of alcohol thrombocytopenia and the effects of alcohol on the structure and function of platelets were described. Furthermore, the phenomenon of rapid normalization of the number of platelets in people who stopped drinking was described. Relationships between alcohol use, its intensity and occurrence, and intensity of thrombocytopenia have been demonstrated. Predictive platelet counts for alcohol withdrawal syndrome complications have been proven and calculated. The risk of occurrence of withdrawal seizures or delirium tremens in alcohol withdrawal syndrome increases significantly when the platelet count is less than 119,000/μL. The knowledge of the nature of the phenomenon of alcohol-induced thrombocytopenia in a clinical environment allows decisions that are more rational. The attention of clinicians should be drawn to the importance of results of blood tests routinely collected on admission.

Drug-Induced Thrombocytopenia Secondary to Commonly Used Antibiotics in Total Joint Arthroplasty

Drug-induced thrombocytopenia secondary to antibiotic exposure is a rare complication more commonly associated with other medications. In this review, we present a case of antibiotic-induced thrombocytopenia and discuss the clinical picture and approach to identifying the complication. With increasing use of antibiotics that may be associated with drug-induced thrombocytopenia in perioperative prophylaxis protocols, surgeons need to be cognizant of this cause of thrombocytopenia in the postoperative patient. A delay in recognition and discontinuation of the offending agent can result in significant complications secondary to bleeding and superfluous testing.

Thrombocytopenia associated with clonidine in a case of clozapine-induced sialorrhea

Clozapine is approved by the US Food and Drug Administration for treatment-resistant schizophrenia and mitigation of suicidality in patients with schizophrenia or schizoaffective disorder. Clozapine requires monitoring of adverse events, such as hypotension, myocarditis, cardiomyopathy, seizures, severe neutropenia, and gastrointestinal hypomotility. Sialorrhea is another adverse event that can be bothersome for patients and result in nonadherence or the development of aspiration pneumonia. Clonidine, an α_2A adrenergic receptor agonist, is one medication option that can reduce or eliminate sialorrhea. Clonidine is generally well tolerated but can contribute to hypotension and sedation. One adverse event associated with clonidine not described in the literature is thrombocytopenia. Reported is a case of clonidine-associated thrombocytopenia when used for the treatment of clozapine-induced sialorrhea.

Prevalence of Adverse Events in Children With Congenital Hyperinsulinism Treated With Diazoxide

CONTEXT

Diazoxide, the only U.S. Food and Drug Administration-approved drug to treat hyperinsulinemic hypoglycemia, has been associated with several adverse events, which has raised concerns about the safety of this drug. Existing reports are limited to small studies and case reports.

OBJECTIVE

To determine prevalence of and clinical factors associated with adverse events in infants and children treated with diazoxide.

DESIGN

Retrospective cohort study of children with hyperinsulinism (HI) treated with diazoxide between 2003 and 2014.

SETTING

The Congenital Hyperinsulinism Center at the Children's Hospital of Philadelphia.

PATIENTS

Children and infants with laboratory-confirmed diagnosis of HI.

MAIN OUTCOME MEASURES

Prevalence of pulmonary hypertension (PH), edema, neutropenia, thrombocytopenia, and hyperuricemia was determined. Tests of association and logistic regression were used to identify potential risk factors.

RESULTS

A total of 295 patients (129 female) met inclusion criteria. The median age at diazoxide initiation was 29 days (interquartile range, 10 to 142 days; n = 226 available start dates); 2.4% of patients were diagnosed with PH after diazoxide initiation. Children with PH (P = 0.003) or edema (P = 0.002) were born at earlier gestational age and more frequently had potential PH risk factors, including respiratory failure and structural heart disease (P < 0.0001 and P = 0.005). Other adverse events included neutropenia (15.6%), thrombocytopenia (4.7%), and hyperuricemia (5.0%).

CONCLUSION

In this large cohort, PH occurred in infants with underlying risk factors, but no identifiable risk profile emerged for other adverse events. The relatively high prevalence of neutropenia, thrombocytopenia, and hyperuricemia suggests the value in proactively screening for these side effects in children treated with diazoxide.

Species-Specific Involvement of Integrin αIIbβ3 in a Monoclonal Antibody CH12 Triggers Off-Target Thrombocytopenia in Cynomolgus Monkeys

CH12 is a novel humanized monoclonal antibody against epidermal growth factor receptor variant III (EGFRvIII) for cancer treatment. Unfortunately, in pre-clinical safety evaluation studies, acute thrombocytopenia was observed after administration of CH12 in cynomolgus monkeys, but not rats. More importantly, in vitro experiments found that CH12 can bind and activate platelets in cynomolgus monkey, but not human peripheral blood samples. Cynomolgus monkey-specific thrombocytopenia has been reported previously; however, the underlying mechanism remains unclear. Here, we first showed that CH12 induced thrombocytopenia in cynomolgus monkeys through off-target platelet binding and activation, resulting in platelet destruction. We subsequently found that integrin αIIbβ3 (which is expressed on platelets) contributed to this off-target toxicity. Furthermore, three-dimensional structural modeling of the αIIbβ3 molecules in cynomolgus monkeys, humans, and rats suggested that an additional unique loop exists in the ligand-binding pocket of the αIIb subunit in cynomolgus monkeys, which may explain why CH12 binds to platelets only in cynomolgus monkeys. Moreover, this study supported the hypothesis that the minor differences between cynomolgus monkeys and humans can confuse human risk assessments and suggests that species differences can help the prediction of human risks and avoid losses in drug development.

Drug-induced thrombocytopenia: Focus on platelet apoptosis

Thrombocytopenia is a serious and potentially fatal complication of drug therapy that results either from a decrease in bone marrow platelet production or the excessive destruction of circulating platelets. Although multiple mechanisms are responsible for deregulated platelet clearance, the role of programmed platelet death (apoptosis) in drug-induced thrombocytopenia has been relatively under-investigated until recently. Here we review apoptotic signaling pathways in platelets, with a focus on current data that provide mechanistic insights into drug-induced apoptosis and thrombocytopenia.

Vancomycin-Induced Thrombocytopenia: A Narrative Review

Thrombocytopenia has been reported as an adverse reaction of numerous drugs. Vancomycin is often overlooked as a culprit but has been associated with several cases of thrombocytopenia that were not well described in the literature. A literature search was conducted to find reports of thrombocytopenia induced by vancomycin. Biomedical databases including 'PubMed', 'Scopus', and 'Web of Science' were searched using terms 'vancomycin', 'platelet', 'pancytopenia', 'thrombocytopenia', and 'bleeding'. English language articles published before July 2015 were included. Thirty-nine papers including 29 case reports (30 cases), five observational studies, two clinical trials, two letters, and one case series remained for final analysis. The main route of administration was intravenous infusion. This adverse reaction seems to be duration dependent with the mean time to platelet nadir count of 8 days in reported cases. The interval may be significantly shorter in re-exposure to the drug. Platelet nadir counts ranged from 2000 to 100,000/mL in patients who experienced bleeding. Vancomycin-specific antibodies were detected in 13 of 17 patients who were tested in the case reports. Based on the Naranjo Adverse Drug Reaction Probability Scale, reaction was 'definite', 'probable', and 'possible' in 1, 15, and 14 patients, respectively. Among 30 cases, vancomycin was discontinued in 29 patients and platelets returned to normal counts within 5-6 days in 17 of them; in one patient, vancomycin was not discontinued, but platelet count recovered 11 days after the nadir time. Transfusion might be recommended if severe thrombocytopenia and bleeding occurs. Intravenous immunoglobulins, corticosteroids, rituximab, and plasma exchange should be reserved for patients with resistant thrombocytopenia and severe bleeding as mentioned in a number of reports.

Impact of Comorbidity and Prescription Drugs on Haemorrhage in Cholecystectomy

Background

The purpose of the present study was to analyse the impact of patient-related risk factors and medication drugs on haemorrhagic complications following cholecystectomy.

Methods

All cholecystectomies registered in the Swedish population-based Register for Gallstone Surgery and ERCP (GallRiks) were identified. Risk factors for bleeding were assessed by linking data in the GallRiks to the National Patient Register and the Prescribed Drug Register, respectively. The risk of haemorrhage leading to intervention was determined by variable regression, and Kaplan–Meier analysis assessed survival rate following perioperative haemorrhage.

Results

A total of 94,557 patients were included between 2005 and 2015, of which 799 (0.8%) and 1192 (1.3%) patients were registered as having perioperative and post-operative haemorrhage, respectively. In multivariable analysis, an increased risk of haemorrhagic complications was seen in patients with cerebrovascular disease (p = 0.001), previous myocardial infarction (p = 0.001), kidney disease (p = 0.001), heart failure (p = 0.001), diabetes (p = 0.001), peripheral vascular disease (p = 0.004), and obesity (p = 0.005). Prescription of tricyclic antidepressant (p = 0.018) or dipyridamole (p = 0.047) was associated with a significantly increased risk of perioperative haemorrhage. However, this increase in risk did not remain significant following Bonferroni correction for mass significance. Perioperative haemorrhage increased the risk of death occurring within the first post-operative year [Hazard Ratio, (HR) 4.9, CI 3.52–6.93] as well as bile duct injury (OR 2.45, CI 1.79–3.37).

Conclusion

The increased risk of haemorrhage associated with comorbidity must be taken into account when assessing patients prior to cholecystectomy. Perioperative bleeding increases post-operative mortality and is associated with an increased risk of bile duct injury.

The impact of serious adverse drug reactions: a population-based study of a decade of hospital admissions in New South Wales, Australia

AIMS

Adverse drug reactions (ADRs) have major impacts on patients and the hospital system. Methods identifying ADRs from selected International Classification of Diseases-10th revision (ICD-10) diagnosis and external cause codes can be applied to population-level hospital admissions data, enabling the study of rare, yet serious ADRs. The present study aimed to use ICD10-based methods to identify four types of serious idiosyncratic ADRs in Australia, and to assess changes in incidence and their impact on length of stay (LOS), readmission and in-hospital mortality.

METHODS

The study used a census of hospital admission data from New South Wales between July 2000 and June 2012. Changes in incidence rates over time relative to a control group were estimated using log-linear regression. To assess impacts on LOS, readmission and mortality, each ADR case was matched with five controls, and cases were compared with controls via generalized linear models appropriate to each outcome.

RESULTS

The incidence of three ADR types showed a significant increase over time relative to controls, while the fourth type showed no evidence of change. All ADR types were significantly associated with an increase in LOS of between 22% and 328%. Significant increases in risk of readmission or death were only observed for some ADR types.

CONCLUSIONS

Reducing the incidence of idiosyncratic ADRs is challenging. ICD10-based methods support population-level analyses that can provide important insights into the effects and changes in ADRs over time. This, combined with strategies related to both patient care and drug monitoring pre- and post-commercial release, provides ways forward.

Rapid-Onset Thrombocytopenia Following Piperacillin-Tazobactam Reexposure

Drug-induced thrombocytopenia is a rare but serious adverse event that has been associated with multiple drugs including β-lactams. Although it mostly occurs with prolonged medication use, some cases of rapid-onset thrombocytopenia have been reported. We describe the case of a 69-year-old man who developed severe and immediate thrombocytopenia following reexposure to piperacillin-tazobactam in the critical care setting. He received a 6-day course of piperacillin-tazobactam for a possible pneumonia immediately after cardiac surgery. During this course of therapy, his platelet count decreased (fluctuating between 69 × 10(3) /mm(3) and 104 × 10(3) /mm(3) ) and then progressively increased after completion of the antibiotic to 340 × 10(3) /mm(3) on postoperative day 15. Ten days after the antibiotic course was completed (postoperative day 16), the patient developed new signs of infection (fever and neutrophilia), and piperacillin-tazobactam was restarted. Eight hours after reintroducing the antibiotic, his platelet count dropped from 317 × 10(3) /mm(3) to 7 × 10(3) /mm(3) . After reviewing all the medications administered to the patient as well as other potential causes of thrombocytopenia, and given the chronology of events, piperacillin-tazobactam was suspected as the most likely offending agent and was therefore replaced by meropenem on postoperative day 17. The patient's platelet count began to rise 2 days after discontinuation of piperacillin-tazobactam and reached 245 × 10(3) /mm(3) by postoperative day 30. No spontaneous bleeding or thrombosis occurred while the patient was thrombocytopenic. Use of the Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship (score of 6) between the patient's development of thrombocytopenia and piperacillin-tazobactam therapy. This case highlights the severity and swiftness in which drug-induced thrombocytopenia may present in the context of cardiac surgery.

Postinfluenza Vaccination Idiopathic Thrombocytopenic Purpura in Three Elderly Patients

The etiologies of secondary idiopathic thrombocytopenic purpura (ITP) include infection, autoimmune disease, and immunodeficiency. We report the cases of three elderly patients who developed ITP after receiving influenza vaccinations. The platelet count of an 81-year-old woman fell to 27,000/μL after she received an influenza vaccination. A 75-year-old woman developed thrombocytopenia (5,000 platelets/μL) after receiving an influenza vaccination. An 87-year-old woman whose laboratory test values included a platelet count of 2,000/μL experienced genital bleeding after receiving an influenza vaccination. After Helicobacter pylori (HP) eradication or corticosteroid treatment, all of the patients' platelet counts increased. Influenza vaccination is an underlying etiology of ITP in elderly patients. HP eradication or corticosteroid treatment is effective for these patients. Clinicians should be aware of the association between ITP and influenza vaccinations.

Platelet transfusion for patients with cancer

BACKGROUND

Platelet transfusion is a critical and often necessary aspect of managing cancer. Low platelet counts frequently lead to bleeding complications; however, the drugs used to combat malignancy commonly lead to decreased production and destruction of the very cell whose function is essential to stop bleeding. The transfusion of allogeneic platelet products helps to promote hemostasis, but alloimmunization may make it difficult to manage other complications associated with cancer.

METHODS

The literature relating to platelet transfusion in patients with cancer was reviewed.

RESULTS

Platelet storage, dosing, transfusion indications, and transfusion response are essential topics for health care professionals to understand because many patients with cancer will require platelet transfusions during the course of treatment. The workup and differentiation of non-immune-mediated compared with immune-mediated platelet refractoriness are vital because platelet management is different between types of refractoriness.

CONCLUSIONS

A combination of appropriate utilization of platelet inventory and laboratory testing coupled with communication between those caring for patients with cancer and those providing blood products is essential for effective patient care.

A rare case of acyclovir-induced thrombocytopenia

Acyclovir is used for its potent antiviral properties for the mucocutaneous herpes, herpes zoster, herpes encephalitis, and genital herpes simplex. The drug has a very wide distribution involving almost every organ of the body, with excretion into the urine. Urine analysis, kidney function, liver function, and complete blood counts are some of the monitoring parameters. The active triphosphate form of the drug inhibits DNA synthesis and viral replication by competing with deoxyguanosine triphosphate for viral DNA polymerase and being incorporated into viral DNA. Because the drug is only absorbed by the cells that are virus infected, acyclovir has minimal side effects at therapeutic doses. However, at high intravenous infusions, severe central nervous system (malaise), gastrointestinal (nausea/vomiting), renal (elevated blood urea nitrogen/creatinine), hepatic (elevated liver enzymes), and skin dyscrasias have been found to occur. There have been few case reports of bone marrow suppression and only one case report so far of acyclovir-related isolated thrombocytopenia. Whether there is any further association between acyclovir and thrombotic thrombocytopenic purpura/hemolytic uremic syndrome is the next dilemma if such an association is established. Here, the authors present a case report of a 58-year-old man with acquired immune deficiency syndrome on highly active antiretroviral therapy who went into severe thrombocytopenia on starting acyclovir.

Drug-induced immune-mediated thrombocytopenia in the intensive care unit

A 62-year-old woman with prosthetic mitral valve was admitted for explant of an infected prosthetic knee. Perioperatively, she was bridged with heparin and started on empiric vancomycin and piperacillin-tazobactam. Platelet counts dropped precipitously within 2 days reaching a nadir of 6000/μL, without any bleeding. Decline persisted despite substituting heparin with bivalirudin. Antiplatelet factor 4 and anti-PLA1 antigen were negative. Schistocytes were absent. Antibiotics were substituted with daptomycin for suspected drug-induced thrombocytopenia. Pulse dose of intravenous immunoglobulin was initiated with rapid normalization of platelet count. She tested positive for IgG antiplatelet antibodies to vancomycin and piperacillin-tazobactam thereby confirming the diagnosis. Drug-induced immune-mediated thrombocytopenia is an underrecognized cause of thrombocytopenia in the intensive care units. Clinicians should be cognizant of this entity, and a definitive diagnosis should be sought if feasible.

Preclinical models of nicotinamide phosphoribosyltransferase inhibitor-mediated hematotoxicity and mitigation by co-treatment with nicotinic acid

Nicotinamide adenine dinucleotide (NAD) is an essential co-factor in glycolysis and is a key molecule involved in maintaining cellular energy metabolism. Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the rate-limiting step of an important salvage pathway in which nicotinamide is recycled into NAD. NAMPT is up-regulated in many types of cancer and NAMPT inhibitors (NAMPTi) have potential therapeutic benefit in cancer by impairing tumor metabolism. Clinical trials with NAMPTi APO-866 and GMX-1778, however, failed to reach projected efficacious exposures due to dose-limiting thrombocytopenia. We evaluated preclinical models for thrombocytopenia that could be used in candidate drug selection and risk mitigation strategies for NAMPTi-related toxicity. Rats treated with a suite of structurally diverse and potent NAMPTi at maximum tolerated doses had decreased reticulocyte and lymphocyte counts, but no thrombocytopenia. We therefore evaluated and qualified a human colony forming unit-megakaryocyte (CFU-MK) as in vitro predictive model of NAMPTi-induced MK toxicity and thrombocytopenia. We further demonstrate that the MK toxicity is on-target based on the evidence that nicotinic acid (NA), which is converted to NAD via a NAMPT-independent pathway, can mitigate NAMPTi toxicity to human CFU-MK in vitro and was also protective for the hematotoxicity in rats in vivo. Finally, assessment of CFU-MK and human platelet bioenergetics and function show that NAMPTi was toxic to MK and not platelets, which is consistent with the clinically observed time-course of thrombocytopenia.

Amoxicillin/Clavulanic Acid-induced thrombocytopenia

INTRODUCTION AND OBJECTIVE

Drug-induced thrombocytopenia is a common adverse effect reported in the literature. Typically patients present with a low platelet count with signs and symptoms ranging from bruising to bleeding, and major organ damage. Penicillin-induced thrombocytopenia previously reported in the literature is explained primarily through the hapten-dependent antibody process. The goal of this report is to present a case of an amoxicillin/clavulanic acid-induced thrombocytopenia.

CASE PRESENTATION

A 23-year-old male presented to the emergency department with bruises on his arms and legs after completing a full course of amoxicillin/clavulanic acid of 625 mg twice a day for 5 days for tonsillitis. After several tests, the patient was diagnosed with thrombocytopenia induced by amoxicillin/clavulanic acid. The patient was treated with a corticosteroids taper regimen for 3 weeks. He was discharged after 3 days of inpatient treatment with instructions to avoid physical activity for 2 weeks. Two weeks post discharge, the follow-up showed that the platelet count had increased.

DISCUSSION

Penicillin-induced thrombocytopenia has been previously reported in the inpatient setting where bleeding was observed. However, the patient in this case report presented with bruises on his arms and legs. The diagnosis was made by the process of elimination; not all possible tests were conducted. The patient was prescribed corticosteroids that are not indicated for drug-induced thrombocytopenia. The Naranjo scale showed that this is a probable adverse event of amoxicillin/clavulanic acid.

CONCLUSION

This is a unique case where amoxicillin/clavulanic acid was reported to be a probable cause of thrombocytopenia in an outpatient setting without signs of bleeding and without concomitant medications.

Acute thrombocytopenia after initiating anticoagulation with rivaroxaban

A 75-year-old man with paroxysmal atrial fibrillation developed a traumatic intracranial hemorrhage during warfarin treatment. The administration of warfarin was stopped and rivaroxaban therapy, a novel oral anticoagulant (NOAC), was started. Immediately, his platelet count decreased to 3.7×10(4) /μL. The platelet count recovered rapidly after cessation of rivaroxaban administration. Development of thrombocytopenia and its rapid recovery was observed again after another administration, and subsequent cessation, of the drug. A diagnosis of rivaroxaban-induced thrombocytopenia was made. The incidence of thrombocytopenia due to NOACs is rare. Careful attention to thrombocytopenia, which is associated with a higher risk for life-threatening bleeding, is therefore necessary during treatment with NOACs.

Drug-induced immune thrombocytopenia: incidence, clinical features, laboratory testing, and pathogenic mechanisms

Drug-induced immune thrombocytopenia (DIIT) is a relatively uncommon adverse reaction caused by drug-dependent antibodies (DDAbs) that react with platelet membrane glycoproteins only when the implicated drug is present. Although more than 100 drugs have been associated with causing DIIT, recent reviews of available data show that carbamazepine, eptifibatide, ibuprofen, quinidine, quinine, oxaliplatin, rifampin, sulfamethoxazole, trimethoprim, and vancomycin are probably the most frequently implicated. Patients with DIIT typically present with petechiae, bruising, and epistaxis caused by an acute, severe drop in platelet count (often to <20,000 platelets/pL). Diagnosis of DIIT is complicated by its similarity to other non-drug-induced immune thrombocytopenias, including autoimmune thrombocytopenia, posttransfusion purpura, and platelet transfusion refractoriness, and must be differentiated by temporal association of exposure to a candidate drug with an acute, severe drop in platelet count. Treatment consists of immediate withdrawal of the implicated drug. Criteria for strong evidence of DIIT include (1) exposure to candidate drug-preceded thrombocytopenia; (2) sustained normal platelet levels after discontinuing candidate drug; (3) candidate drug was only drug used before onset of thrombocytopenia or other drugs were continued or reintroduced after resolution of thrombocytopenia, and other causes for thrombocytopenia were excluded; and (4) reexposure to the candidate drug resulted in recurrent thrombocytopenia. Flow cytometry testing for DDAbs can be useful in confirmation of a clinical diagnosis, and monoclonal antibody enzyme-linked immunosorbent assay testing can be used to determine the platelet glycoprotein target(s), usually GPIIb/IIIa or GPIb/IX/V, but testing is not widely available. Several pathogenic mechanisms for DIIT have been proposed, including hapten, autoantibody, neoepitope, drug-specific, and quinine-type drug mechanisms. A recent proposal suggests weakly reactive platelet autoantibodies that develop greatly increased affinity for platelet glycoprotein epitopes through bridging interactions facilitated by the drug is a possible mechanism for the formation and reactivity of quinine- type drug antibodies.

Assessment of a modified 4T scoring system for heparin-induced thrombocytopenia in critically ill patients

PURPOSE

The purpose of the study is to determine if a modified 4T (m4T) scoring system, which omits clinical evaluation of other thrombocytopenic etiologies, is different from the 4T scoring system's probability to predict a positive heparin-induced thrombocytopenia (HIT) laboratory test in the intensive care unit.

MATERIALS AND METHODS

This is a single-centered retrospective analysis of critically ill adults who had an enzyme-linked immunosorbent assay antiplatelet factor 4 antibody (ELISA anti-PF4 Ab) ordered. Patients were identified as HIT positive (optical density, ≥0.40) or HIT negative (optical density, <0.40) based on the ELISA anti-PF4 Ab. Both 4T and m4T scores were calculated, and the diagnostic accuracy was compared using paired receiver operating characteristic curves.

RESULTS

A total of 1487 adult intensive care unit patients with an ELISA anti-PF4 Ab ordered between January 2007 and December 2009 were eligible for study enrollment. Application of exclusion criteria and random selection yielded a total of 232 patients included for analysis (58 HIT-positive and 174 HIT-negative patients). The area under the curve for the 4T and m4T scores were 0.683 (95% confidence interval, 0.604-0.762) and 0.680 (95% confidence interval, 0.600-0.759), respectively (P=.065).

CONCLUSION

This study does not show a difference in the probability of the m4T and 4T scoring systems to predict a positive ELISA anti-PF4 Ab test in the critically ill patient population. Further prospective studies are needed to validate the m4T scoring system.

Adverse reactions to targeted and non-targeted chemotherapeutic drugs with emphasis on hypersensitivity responses and the invasive metastatic switch

More than 100 drugs are used to treat the many different cancers. They can be divided into agents with relatively broad, non-targeted specificity and targeted drugs developed on the basis of a more refined understanding of individual cancers and directed at specific molecular targets on different cancer cells. Individual drugs in both groups have been classified on the basis of their mechanism of action in killing cancer cells. The targeted drugs include proteasome inhibitors, toxic chimeric proteins and signal transduction inhibitors such as tyrosine kinase (non-receptor and receptor), serine/threonine kinase, histone deacetylase and mammalian target of rapamycin inhibitors. Increasingly used targeted vascular (VEGF) and platelet-derived endothelial growth factor blockade can provoke a range of pathological consequences. Many of the non-targeted drugs are cytotoxic, suppressing haematopoiesis as well as provoking cutaneous eruptions and vascular, lung and liver injury. Cytotoxic side effects of the targeted drugs occur less often and usually with less severity, but they show their own unusual adverse effects including, for example, a lengthened QT interval, a characteristic papulopustular rash, nail disorders and a hand-foot skin reaction variant. The term hypersensitivity is widely used across a number of disciplines but not always with the same definition in mind, and the terminology needs to be standardised. This is particularly apparent in cancer chemotherapy where anti-neoplastic drug-induced thrombocytopenia, neutropenia, anaemia, vascular disorders, liver injury and lung disease as well as many dermatological manifestations sometimes have an immune basis. The most insidious of all adverse consequences of targeted therapies, however, are tumour adaptation, increased malignancy and the invasive metastatic switch seen with anti-angiogenic drugs that inhibit the VEGF-A pathway. Adverse reactions to 44 non-targeted and 33 targeted, frequently used, chemotherapeutic drugs are presented together with discussions of diagnosis, premedications, desensitizations and importance of understanding the mechanisms underlying the various drug-induced reactions. There is need for wide-ranging acceptance of what constitutes a hypersensitivity reaction and for allergists to be more involved in the diagnosis, treatment and prevention of chemotherapeutic drug-induced hypersensitivity reactions.

The potential of antimicrobials to induce thrombocytopenia in critically ill patients: data from a randomized controlled trial

BACKGROUND

Antimicrobial-induced thrombocytopenia is frequently described in the literature among critically ill patients. Several antimicrobials have been implicated, although experimental evidence to demonstrate causality is limited. We report, using a randomized trial, the potential of antimicrobials to induce thrombocytopenia.

METHODS

Randomized trial allocated patients to antimicrobial treatment according to standard- of-care (SOC group) or drug-escalation in case of procalcitonin increases (high-exposure group). Patients were followed until death or day 28. Thrombocytopenia defined as absolute (platelet count ≤ 100 x 109/L) or relative (≥ 20% decrease in platelet count). Analyses were performed in the two randomized groups and as a merged cohort.

RESULTS

Of the 1147 patients with platelet data available, 18% had absolute thrombocytopenia within the first 24 hours after admission to intensive care unit and additional 17% developed this complication during follow-up; 57% developed relative thrombocytopenia during follow-up. Absolute and relative thrombocytopenia day 1-4 was associated with increased mortality (HR: 1.67 [95% CI: 1.30 to 2.14]; 1.71 [95% CI: 1.30 to 2.30], P<0.0001, respectively). Patients in the high-exposure group received more antimicrobials including piperacillin/tazobactam, meropenem and ciprofloxacin compared with the SOC group, whereas cefuroxime was used more frequently in the SOC group (p<0.05). Risk of absolute and relative thrombocytopenia (RR: 0.9 [0.7-1.3], p=0.7439; 1.2 [1.0-1.4], p=0.06; respectively), as well as absolute platelet count (daily difference, high-exposure vs. SOC -1.7 [-3.8-0.5], p=0.14) was comparable between groups. In observational analyses, use of ciprofloxacin and piperacillin/tazobactam predicted risk of relative thrombocytopenia (vs. cefuroxime, RR: 2.08 [1.48-2.92]; 1.44 [1.10-1.89], respectively), however only ciprofloxacin were associated with a reduction in absolute platelet count (p=0.0005).

CONCLUSION

High exposure to broad-spectrum antimicrobials does not result in a reduction in thrombocytopenia in critically ill patients. However, single use of ciprofloxacin, and less so piperacillin/tazobactam, may contribute to a lower platelet count.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00271752 http://clinicaltrials.gov/ct2/show/NCT00271752.

Adverse events to monoclonal antibodies used for cancer therapy: Focus on hypersensitivity responses

Fifteen monoclonal antibodies (mAbs) are currently registered and approved for the treatment of a range of different cancers. These mAbs are specific for a limited number of targets (9 in all). Four of these molecules are indeed directed against the B-lymphocyte antigen CD20; 3 against human epidermal growth factor receptor 2 (HER2 or ErbB2), 2 against the epidermal growth factor receptor (EGFR), and 1 each against epithelial cell adhesion molecule (EpCAM), CD30, CD52, vascular endothelial growth factor (VEGF), tumor necrosis factor (ligand) superfamily, member 11 (TNFSF11, best known as RANKL), and cytotoxic T lymphocyte-associated protein 4 (CTLA4). Collectively, the mAbs provoke a wide variety of systemic and cutaneous adverse events including the full range of true hypersensitivities: Type I immediate reactions (anaphylaxis, urticaria); Type II reactions (immune thrombocytopenia, neutopenia, hemolytic anemia); Type III responses (vasculitis, serum sickness; some pulmonary adverse events); and Type IV delayed mucocutaneous reactions as well as infusion reactions/cytokine release syndrome (IRs/CRS), tumor lysis syndrome (TLS), progressive multifocal leukoencephalopathy (PML) and cardiac events. Although the term "hypersensitivity" is widely used, no common definition has been adopted within and between disciplines and the requirement of an immunological basis for a true hypersensitivity reaction is sometimes overlooked. Consequently, some drug-induced adverse events are sometimes incorrectly described as "hypersensitivities" while others that should be described are not.

A case of thrombocytopenia caused by rifampicin and pyrazinamide

A 32-year-old male patient was diagnosed as having pulmonary tuberculosis and put on category II antitubercular regime since he had a history of antituberculosis treatment 10 years ago. Within 3 weeks, patient presented with ulcers in mouth, and blood picture confirmed thrombocytopenia. Rifampicin-induced thrombocytopenia was suspected and antitubercular treatment stopped. Patient improved and was re-exposed to the drugs one by one. After re-exposure with pyrazinamide, the platelet count decreased drastically and oral mucosal ecchymoses reappeared, while with rifampicin, thrombocytopenia was accompanied with petechiae on legs and forearms. Isoniazid, ethambutol, and streptomycin were continued.

Only severe thrombocytopenia results in bleeding and defective thrombus formation in mice

Hemostasis, thrombosis, and ischemic brain infarction efficiently occur at unexpectedly low platelet counts in mice. The threshold platelet count required for occlusive thrombus formation differs between thrombosis models.

Simvastatin and amlodipine induced thrombocytopenia in the same patient: double trouble and a literature review

WHAT IS KNOWN AND OBJECTIVE

Drug-induced thrombocytopenia (DITP) may be a fatal adverse reaction to many drugs. It is often misdiagnosed as primary immune thrombocytopenia (ITP), and thus diagnosis can be delayed and patients can be treated inappropriately. Amlodipine a calcium-channel blocker, and simvastatin, a statin, have very rarely been implicated in DITP. We report on an investigation of the causal relationship of amlodipine and simvastatin with thrombocytopenia occurring in the same patient, and review the literature.

CASE SUMMARY

We present the case of a 78-year-old female hypertensive diabetic patient with three successive DITPs. The first attack of acute severe thrombocytopenia occurred after a 2-week course of amlodipine, and was initially misdiagnosed as ITP. Her platelet count normalized after the amlodipine was discontinued. The second attack followed her restarting simvastatin 3 weeks later. She had stopped it 2 months earlier having previously taken it for over 5 years. Again, she recovered once the simvastatin was discontinued. The third DITP attack occurred when she accidently took a single dose of amlodipine 9 months later.

WHAT IS NEW AND CONCLUSION

We provide clear evidence of a causal association of amlodipine with thrombocytopenia, and probable evidence of a causal association of simvastatin with thrombocytopenia. This is the first reported case of DITPs occurring with two of the most widely prescribed drugs in the same patient. Many hypertensive patients need to take multiple drugs in order to achieve their treatment goals and this increases their risk of drug-induced adverse reactions and makes identification of the causal drug (or drugs) extremely difficult.