New-onset acute thrombocytopenia in hospitalized patients: pathophysiology and diagnostic approach

Practical approach to thrombocytopenia in patients with sepsis: a narrative review

Thrombocytopenia frequently occurs in patients with sepsis. Disseminated intravascular coagulation (DIC) may be a possible cause of thrombocytopenia owing to its high prevalence and association with poor outcomes; however, it is important to keep the presence of other diseases in mind in sepsis practice. Thrombotic microangiopathy (TMA), which is characterized by thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (HUS), and complement-mediated HUS, is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ damage. TMA has become widely recognized in recent years because of the development of specific treatments. Previous studies have reported a remarkably lower prevalence of TMA than DIC; however, its epidemiology is not well defined, and there may be cases in which TMA is not correctly diagnosed, resulting in poor outcomes. Therefore, it is important to differentiate DIC from TMA. Nevertheless, differentiating between DIC and TMA remains a challenge as indicated by previous reports that most patients with TMA can be diagnosed as DIC using the universal coagulation scoring system. Several algorithms to differentiate sepsis-related DIC from TMA have been suggested, contributing to improving the care of septic patients with thrombocytopenia; however, it may be difficult to apply these algorithms to patients with coexisting DIC and TMA, which has recently been reported. This review describes the disease characteristics, including epidemiology, pathophysiology, and treatment, of DIC, TMA, and other diseases with thrombocytopenia and proposes a novel practical approach flow, which is characterized by the initiation of the diagnosis of TMA in parallel with the diagnosis of DIC. This practical flow also refers to the longitudinal diagnosis and treatment flow with TMA in mind and real clinical timeframes. In conclusion, we aim to widely disseminate the results of this review that emphasize the importance of incorporating consideration of TMA in the management of septic DIC. We anticipate that this practical new approach for the diagnostic and treatment flow will lead to the appropriate diagnosis and treatment of complex cases, improve patient outcomes, and generate new epidemiological evidence regarding TMA.

A Case of Ceftaroline-Associated Thrombocytopenia

Ceftaroline is a fifth-generation cephalosporin that can be used for the treatment of serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA). A rare adverse effect of ceftaroline therapy is thrombocytopenia. Our case involves a 45-year-old male with active intravenous drug usage who presented with persistent fever, lower back pain, and left elbow pain. His bloodcultures were found to be positive for MRSA. He was initially started on vancomycin; subsequently, the antibiotic was changed to daptomycin and ceftaroline, as vancomycin failed to clear the bacteremia. Seven days after initiation of ceftaroline, it was unintentionally discontinued by the electronic health record. Following its resumption two days later, the patient started having epistaxis accompanied by an acute drop in his platelet count from 422,000 cells/µL to less than 2,000 cells/µL. The ceftaroline therapy was discontinued, and he received a platelet transfusion. However, daptomycin was continued, resulting in successful resolution of his bacteremia. The patient's platelet count at discharge improved to 582,000 cells/µL. The patient was diagnosed with ceftaroline-induced thrombocytopenia, and it was added to his list of allergies.

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.

Characteristics of the post-surgical decrease in platelet counts in orthopedic surgery patients, observations and insights

INTRODUCTION

A reduced platelet count (PLT) is a frequent post-operative finding in orthopedic surgery patients. Despite its prevalence, the characteristics of post-surgical thrombocytopenia have not been well described.

METHODS

A retrospective chart review was conducted on patients who underwent a knee or hip replacement from 2012 to 2015. Patients who received heparin were excluded.

RESULTS

A total of 56 patients were analyzed on post-operative days 0 to 4. By day 1, 90.9% of the patients experienced a reduction in their platelet counts. The lowest mean platelet count (nadir) occurred on day 2 (201.3 × 109/L). The average decrease in the platelet count from the baseline was 24% (95%CI: 20.6 - 27.2). The change in the platelet count from the baseline ranged from a 49.6% drop to a 14.2% increase. A substantial portion of patients experienced thrombocytopenia, with 28% occurring on day 2. Platelet counts less than 100 × 109/L occurred only once. The percent decrease in the platelet count from the baseline to any other time point was significantly larger in patients aged > 65 years, compared to patients aged ≤ 65 years (p = 0.007). Specifically, the average drop in the platelet count at the nadir (day 2) relative to the baseline was 27.8% in patients aged > 65 years, compared to 19.5% in patients aged ≤ 65 years.

CONCLUSIONS

A reduction in the platelet count is a frequent post-operative finding in orthopedic surgery patients, even after removing confounding factors, such as heparin exposure, but clinical thrombocytopenia is uncommon. Alternative etiologies should be considered when the platelet count is less than 100 × 109/L. Vigilance should also be considered regarding elderly patients.

Sulperazon-induced acute reactive thrombocytopenia during treatment of systemic lupus erythematosus: a case report

The purpose of this study is to report a patient who developed acute reactive thrombocytopenia while undergoing treatment with sulperazon for systemic lupus erythematosus (SLE). Sulperazon is a broad-spectrum antibiotic that can act against a wide range of microorganisms, but rarely causes severe thrombocytopenic events. We describe a 62-year-old man with new-onset acute reactive thrombocytopenia who experienced a precipitous fall in the platelet count from 168×109/L to 1×109/L within 29 hours after exposure to sulperazon. Sulperazon was immediately discontinued followed by administration of intravenous immunoglobulin for six consecutive days. The platelet count eventually recovered and petechiae at the injection sites improved. No complications secondary to acute reactive thrombocytopenia were observed except petechiae.

Only Acute but Not Chronic Thrombocytopenia Protects Mice against Left Ventricular Dysfunction after Acute Myocardial Infarction

BACKGROUND

Platelets are major players of thrombosis and inflammation after acute myocardial infarction (AMI). The impact of thrombocytopenia on platelet-induced cellular processes post AMI is not well defined.

METHODS

The left anterior descending artery was ligated in C57/Bl6 mice and in two thrombocytopenic mouse models to induce AMI.

RESULTS

Platelets from STEMI patients and from C57/Bl6 mice displayed enhanced platelet activation after AMI. This allows platelets to migrate into the infarct but not into the remote zone of the left ventricle. Acute thrombocytopenia by antibody-induced platelet depletion resulted in reduced infarct size and improved cardiac function 24 h and 21 days post AMI. This was due to reduced platelet-mediated inflammation after 24 h and reduced scar formation after 21 days post AMI. The collagen composition and interstitial collagen content in the left ventricle were altered due to platelet interaction with cardiac fibroblasts. Acute inflammation was also significantly reduced in Mpl-/- mice with chronic thrombocytopenia, but cardiac remodeling was unaltered. Consequently, left ventricular function, infarct size and scar formation in Mpl-/- mice were comparable to controls.

CONCLUSION

This study discovers a novel role for platelets in cardiac remodeling and reveals that acute but not chronic thrombocytopenia protects left ventricular function post AMI.

Piperacillin-Tazobactam Induced Rapid Severe Thrombocytopenia Without Known Exposure

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

Improving compliance with appropriateness of testing for heparin-induced thrombocytopaenia: a quality improvement report

Heparin-induced thrombocytopaenia (HIT) is a serious complication of heparin therapy. Evidence-based guidelines recommend the use of the 4Ts scoring system to calculate pretest probability of HIT. However, this scoring system is often underused, and inappropriate testing can lead to increased morbidity, medical costs and length of hospital stay. We identified that inappropriate testing for HIT was common at our institution and implemented structured multicomponent educational interventions to evaluate the impact of education on the appropriateness of HIT testing. The educational interventions led to a significantly increased rate of appropriateness of HIT testing (69% vs 35%; p=0.001). In addition, the 4Ts score documentation rate significantly improved following the intervention (52% vs 17%; p=0.001). The rates of discontinuation of heparin products and initiation of alternative anticoagulation increased, although not statistically significantly. Educational interventions can improve compliance with evidence-based guidelines on appropriateness of testing for HIT.

Association between basal platelet count and all-cause mortality in critically ill patients with acute respiratory failure: a secondary analysis from the eICU collaborative research database

BACKGROUND

Evidence regarding the correlation between platelet count and all-cause mortality in critically ill patients with acute respiratory failure (ARF) is limited. Therefore, the aim of the study was to evaluate whether platelet count was associated with all-cause mortality in critical patients with ARF by using the electronic intensive care unit (eICU) Collaborative Research Database (eICU-CRD).

METHODS

In this retrospective multicenter cohort study, the data of 26961 patients with ARF hospitalized in ICUs between 2014 and 2015 were collected. The independent variable was log2 basal platelet count, and the dependent variables were all-cause in-hospital and ICU mortality. Covariates including demographic data, Acute Physiology and Chronic Health Evaluation (APACHE) IV score, supportive treatment, and comorbidities were collected.

RESULTS

In the fully adjusted model, log2 basal platelet count was negatively associated with all-cause mortality both in hospital [RR: 0.87, 95% CI: 0.84-0.91] and in ICU [RR: 0.87, 95% CI: 0.83-0.92]. A non-linear relationship between log2 basal platelet count and all-cause in-hospital and ICU mortality was identified by the nonlinearity test. The inflection points we got were 6.83 and 6.86 respectively (after inverse log2 logarithmic conversion, the platelet counts were 114×10⁹/L and 116×10⁹/L, respectively). On the right side of the inflection point, however, no association was observed between blood platelets and all-cause in-hospital (RR: 0.96, 95% CI: 0.88-1.03) and ICU mortality (RR: 0.97, 95% CI: 0.91-1.04).

CONCLUSIONS

For patients with ARF in ICU, platelet count was negatively associated with all-cause in-hospital and ICU mortality when the platelet count was less than 114×10⁹/L and 116×10⁹/L respectively, but when the platelet count was higher, we failed to observe a correlation between them. The safe ranges of platelet count for hospital stay and ICU stay were 78×10⁹/L-145×10⁹/L and 89×10⁹/L-147×10⁹/L respectively.

Magnitude and Associated Factors of Thrombocytopenia among Pregnant Women Attending Antenatal Care Clinics at Dessie Comprehensive Specialized Hospital, Northeast Ethiopia

BACKGROUND

Thrombocytopenia is a common hematological abnormality during gestation. Pregnant women with severe thrombocytopenia may be associated with a higher risk of excessive bleeding during or after delivery. Therefore, the main aim of this study was to assess the magnitude and associated factors of thrombocytopenia among pregnant women attending antenatal care services at Dessie comprehensive and specialized hospital, Northeast Ethiopia.

METHODS

An institution-based cross-sectional study was conducted from February to March 2021. Using a systematic random sampling technique, a total of 294 pregnant women were enrolled in the study. Structured interviewer-administered questionnaires were used to collect socio-demographic and clinical data of study participants. Four ml of venous blood were collected from each pregnant woman and a complete blood count was determined using DIRUI BF 6500 automated hematology analyzer. Data were entered into Epidata version 4.6.0 and then exported into SPSS version 24.0. Multivariate logistic regression was used to assess the association between dependent and independent variables. P-value < 0.05 was considered to be statistically significant.

RESULTS

A total of 294 pregnant women who visited antenatal care services at Dessie comprehensive specialized hospital were included. The mean (±SD) age of the study participants was 29.7 (±6.1) years. The prevalence of thrombocytopenia among pregnant women was 9.9% (95% CI: 6.5, 13.6). A mild type of thrombocytopenia is the major type and accounted for 72.4% whereas moderate thrombocytopenia and severe thrombocytopenia accounted for 17.2% and 10.4% respectively among pregnant women. Multivariate logistic regression showed that urban residents (AOR: 0.206,95% CI, 0.055-0.748), gestational ages within the first trimester (AOR: 0.183, 95% CI, 0.057-0.593) and gestational ages within the second trimester (AOR = 0.264, 95% CI, 0.092-0.752) were significantly associated and independent predictors of thrombocytopenia in pregnant women.

CONCLUSION

In this study, the prevalence of thrombocytopenia was 9.9% and the mild type of thrombocytopenia (72.4%) was higher than the other type of thrombocytopenia among pregnant women. In multivariate logistic regression analysis, residence and gestational age (trimester) were significantly associated with thrombocytopenia. Therefore, the platelet count should be routinely determined during the antenatal care visit for proper diagnosis and to minimize bleeding during and or after childbirth.

Cefazolin-Induced Thrombocytopenia in a Patient with Polycythemia Vera Following Coronary Artery Bypass

Cefazolin is an antibiotic that is commonly administered perioperatively to reduce the risk of surgical site infections. Cephalosporins have a well-established safety profile, but have been associated with thrombocytopenia and neutropenia due to their myelosuppressive effects. While this effect may be benign in healthy patients undergoing minor surgery, it can be detrimental in patients with underlying hematologic disorders presenting for open-heart surgery. Herein, we discuss the first case in the literature of cefazolin-induced thrombocytopenia and severe coagulopathy in a patient with polycythemia vera (PCV) during a coronary artery bypass-grafting surgery.

Approach to the Hospitalized Patient With Thrombocytopenia

During the 2020 JADPRO Live Virtual conference, Laura J. Zitella, MS, RN, ACNP-BC, AOCN®, educated the audience on the most important causes of thrombocytopenia in hospitalized patients and diagnostic approaches to employ.

Comparison of linezolid step-down therapy to standard parenteral therapy in methicillin-resistant Staphylococcus aureus bloodstream infections

Data supporting oral step-down therapy in methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) are sparse; linezolid offers potential in this setting. This study aimed to determine the effectiveness and safety of oral step-down linezolid compared with standard parenteral therapy (SPT) in MRSA-BSI. This was a retrospective cohort performed in adults receiving step-down/outpatient linezolid or SPT (vancomycin, daptomycin) for MRSA-BSI from 2011-2019. Primary outcome was 90-day infection-related re-admission (IRR) from clinical worsening/relapse or infection recurrence. 215 patients included (54 linezolid, 161 SPT). Infection sources were skin (34%), bone/joint (15%), endocarditis (13%), other (32%), multiple (6%). Patients receiving SPT more commonly had complicated bacteraemia (72% vs. 41%; P < 0.0001) and metastatic foci (45% vs. 20%; P = 0.001). 90-day IRR occurred in 17% and 26% of linezolid and SPT groups, respectively (P = 0.159). When accounting for disease severity, linezolid use was not independently associated with 90-day IRR (adjOR, 1.0, 95% CI 0.24-4.3; P = 0.986). There were no differences in all-cause 90-day mortality (4% vs. 6%, P = 0.487) or overall incidence of drug-related adverse events (AEs) (17% vs. 16%; P = 0.843) between the groups. More patients in the SPT group developed an AE requiring re-hospitalisation (12% vs. 2%; P = 0.024), most commonly line-related complications. Oral step-down linezolid demonstrated similar clinical and safety outcomes compared with SPT for MRSA-BSI, except linezolid was associated with fewer AEs requiring re-hospitalisation. Additional research is needed exploring step-down linezolid in MRSA-BSI, particularly in patients requiring shorter durations of outpatient therapy.

Severe Thrombocytopenia Associated With Black Seed Oil and Evening Primrose Oil

We report the case of a 69-year-old female with stage IIIB endometrial adenocarcinoma who developed an acute thrombocytopenia with greater than 90% decrease from her baseline value in platelets one day after a laparoscopic hysterectomy. Subsequently, the patient was found to have bilateral subsegmental pulmonary emboli and a right atrial thrombus. The thrombocytopenia reached a nadir of 31,000/mL3 from a baseline of 410,000/mL3 and resolved without intervention. Prior to the surgery, the patient was taking black seed oil, which is commonly used for its anti-carcinogenic effects, and evening primrose oil daily for approximately one month. A literature review revealed that black seed oil contains thymoquinone, which is a compound related to quinine. Evening primrose oil is also known to reduce platelet aggregation and has anti-thrombotic properties. We believe the patient's thrombocytopenia was caused by a consumptive coagulopathy due to the formation of multiple thrombi and exacerbated by the use of herbal supplements, namely black seed and evening primrose oil.

Thrombocytopenia and platelet course on hospital mortality in neurological intensive care unit: a retrospective observational study from large database

BACKGROUND

Thrombocytopenia (TP) has been shown to be an independent predictor of mortality in the intensive care unit (ICU) patients. Studies are lacking in the neurological ICU (NICU) population. The aim was to evaluate the incidence of TP in NICU and the relationship between TP and outcomes.

METHODS

We conducted a retrospective multicenter study of prospectively collected data of all patients admitted to the NICU between 2014 and 2015 from a large database (eICU Collaborative Research Database). The main exposure was TP at admission and TP developed during NICU stay. Multivariable logistic regression and Cox proportional hazard models were used to evaluate the relationship of TP at admission and platelet course with hospital mortality. The primary outcome was hospital mortality.

RESULTS

7450 patients in NICU from 17 hospitals were included. Hospital mortality was 9%. TP at admission was present in 20% of patients, TP developed during NICU stay was present in 13.2% of patients. TP at admission was not associated with hospital mortality after adjusting for confounders (OR 1.14 [95% CI 0.92-1.41, p = 0.237]). Hospital mortality of continuous TP during NICU stay was 15% while hospital mortality of recovery from TP at admission was 6% (p < 0.001). Patients with TP developed during NICU stay had higher odds ratio for hospital mortality (OR 1.65 [95% CI 1.3-2.09, p < 0.001]).

CONCLUSIONS

Thrombocytopenia is common in NICU and patients who have thrombocytopenia not resolving have increased mortality. Patients' recovery from thrombocytopenia may predict a good prognosis.

Etiologies of Thrombocytopenia in the Community Hospital: The Experience of 1 Hematologist

BACKGROUND

Thrombocytopenia in hospitalized patients is a common cause for hematologic consultation. Our experience in the community hospital setting can inform treating physicians of the causes for and need to treat thrombocytopenia. Here we describe our clinical experience from 2 community hospitals over a 22-month period, wherein a single hematologist was consulted for 97 cases of thrombocytopenia in 93 patients.

METHODS

Referred patients underwent history, physical, review of old records and imaging, relevant laboratory testing, review of the peripheral smear, and a bone marrow aspirate and biopsy if clinically indicated.

RESULTS

Thirty-five patients had a primary hematologic cause for their thrombocytopenia. Fifty-one had secondary causes for thrombocytopenia. Eleven patients had no discernible etiology for their thrombocytopenia. The most common hematologic diagnoses were immune thrombocytopenia purpura (n = 12), heparin-induced thrombocytopenia (n = 6), in vitro platelet clumping (n = 4), quite remarkably acute progranulocytic leukemia (n = 4), and thrombotic thrombocytopenia purpura (n = 3). The latter 3 were immediately diagnosed by reviewing the peripheral smear, which led to appropriate therapy. The most common nonhematologic etiologies were liver disease (n = 21), bacterial sepsis (n = 12), and oral medication (n = 7). Although the thrombocytopenia was mostly nonacute, immediate hematologic interventions were needed for 21 patients. Four patients died, none from complications of thrombocytopenia.

CONCLUSIONS

Thrombocytopenia in hospitalized patients requires consideration of multiple etiologies and review of the peripheral smear. Liver disease is often overlooked as a cause for thrombocytopenia.

A Sudden Onset of Severe Thrombocytopenia While Using Evolocumab

A 72-year-old man with a 10-year history of coronary heart disease started evolocumab treatment once a month after developing excess myalgia due to therapy with a 3-hydroxy-methylglutaryl CoA reductase inhibitor. No side effects such as myalgia symptoms had been reported during the first 14 months of evolocumab treatment; however, he suddenly presented with acute severe thrombocytopenia following the 14th treatment. His platelet count continued to decrease to a nadir of 1,000/μL. His platelet-associated immunoglobulin G level had elevated to 790 ng/10⁷ cells. He started receiving a combination of steroid therapy, high-dose immunoglobulin therapy, and platelet transfusions, but the first-line therapy was ineffective. He was subsequently treated with a thrombopoietin receptor agonist, and his platelet count recovered to 250,000/μL.

Thrombocytopenia during intravenous valproic acid therapy in the neurological intensive care unit

WHAT IS KNOWN AND OBJECTIVE

Thrombocytopenia is a common laboratory abnormality among critically ill patients under neurological intensive care unit (NCU) care. Valproic acid (VPA), a widely used antiepileptic drug, is one of the common causes of drug-induced thrombocytopenia. The purpose of this study was to estimate the incidence and risk factors of thrombocytopenia after intravenous VPA therapy among the patients admitted to NCU.

METHODS

We retrospectively reviewed the medical records of patients who were treated with intravenous VPA during their NCU stay between January 2014 and December 2018. We studied the frequency of thrombocytopenia and further evaluated the risk of thrombocytopenia in these patients.

RESULTS

Among the 283 patients (181 male [64.0%], mean age: [61.0 ± 14.9] years) who were treated with intravenous VPA, thrombocytopenia was observed in 104 patients (36.7%). Thrombocytopenia was associated with several risk factors, including lower baseline platelet counts (<200 × 10⁹ /L); aetiologies other than intracranial or subarachnoid haemorrhage; longer use of VPA (more than 3 days); higher daily dose of VPA (more than 1000 mg/d); concurrent use of VPA with other antiepileptic drugs; infection; and the use of mechanical ventilation. Multivariate analysis found several independent risk factors of thrombocytopenia with intravenous VPA therapy, including lower baseline platelet counts, aetiologies other than intracranial or subarachnoid haemorrhage, use of VPA for more than 3 days and infection.

WHAT IS NEW AND CONCLUSION

Thrombocytopenia is common in NCU patients. Because several clinical and laboratory factors are associated with thrombocytopenia, careful use of VPA should be considered in patients with these risk factors.

The Use of High Dose Eltrombopag in the Management of Sepsis-Associated Thrombocytopenia in Critically Ill Patients

Introduction

Sepsis is a life-threatening condition, and sepsis-associated thrombocytopenia (SAT) is a common consequence of the disease where platelet count falls drastically within a very short time. Multiple key factors may cause platelet over-activation, destruction and reduction in platelet production during the sepsis. Eltrombopag is a thrombopoietin receptor agonist and is the second-line drug of choice in the treatment of chronic immune thrombocytopenia (ITP).

Aim of the study

The objective of this study was to observe the therapeutic outcome of high dose eltrombopag in SAT management in critically ill patients.

Material and Methods

This 6-month-long single group, observational study was conducted on seventeen ICU patients with SAT. Eltrombopag 100 mg/day in two divided doses was given to each patient. Platelet counts were monitored. A low platelet blood count returning to 150 K/μL or above, is taken as indicative of a successful reversal of a thrombocytopenia event.

Results

The mean Apache II score of patients (n= 17) was 18.71 (p-value: >0.05). No eltrombopag-induced adverse event was observed among the patients during the study period. Thrombocytopenia events were reversed successfully in 64.71% of patients (11; n= 17) within eight days of eltrombopag therapy.

Conclusions

The therapeutic potentiality of high dose eltrombopag regime in the management of sepsis-associated thrombocytopenia was found clinically significant in over two-thirds of critically ill adult patients enrolled in the study. These data may point to a new strategy in the management of acute type of thrombocytopenia in septic patients.

A Case of Confirmed Ceftriaxone-induced Immune Thrombocytopenia

Drug-induced immune thrombocytopenia (DITP) is a rare, but potentially fatal cause of isolated thrombocytopenia. DITP is thought to occur when drug-dependent antibodies bind to the platelet membrane glycoproteins to activate platelet consumption signaling. Common implicated drugs include quinine/quinidine, penicillamines, valproic acid and cotrimoxazole. Ceftriaxone is a rare culprit with only six reported cases since 1991, of which only three were confirmed with drug-dependent antiplatelet antibodies. We describe a case of antibody confirmed ceftriaxone-induced immune thrombocytopenia after initiation of empiric antibiotic therapy for acute bacterial meningitis.

Hepatotoxicity of Herbal Supplements Mediated by Modulation of Cytochrome P450

Herbal supplements are a significant source of drug-drug interactions (DDIs), herb-drug interactions, and hepatotoxicity. Cytochrome P450 (CYP450) enzymes metabolize a large number of FDA-approved pharmaceuticals and herbal supplements. This metabolism of pharmaceuticals and supplements can be augmented by concomitant use of either pharmaceuticals or supplements. The xenobiotic receptors constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) can respond to xenobiotics by increasing the expression of a large number of genes that are involved in the metabolism of xenobiotics, including CYP450s. Conversely, but not exclusively, many xenobiotics can inhibit the activity of CYP450s. Induction of the expression or inhibition of the activity of CYP450s can result in DDIs and toxicity. Currently, the United States (US) Food and Drug Administration does not require the investigation of the interactions of herbal supplements and CYP450s. This review provides a summary of herbal supplements that inhibit CYP450s, induce the expression of CYP450s, and/or whose toxicity is mediated by CYP450s.