Drug Dosing in Patients Undergoing Therapeutic Plasma Exchange

Minimal impact of low-density lipoprotein apheresis on vancomycin serum concentration: A case report

Low-density lipoprotein apheresis (LDL-A) is a blood purification therapy used to treat refractory ulcers in patients with arteriosclerosis obliterans. We describe a case of vancomycin treatment in a patient undergoing maintenance hemodialysis and LDL-A therapy and assess its impact on serum vancomycin concentration. The patient underwent LDL-A twice a week (Mondays and Fridays) and maintenance dialysis three times a week (Tuesdays, Thursdays, and Saturdays) for diabetic nephropathy associated with type 1 diabetes mellitus. Following the wound culture results, vancomycin was initiated with a 1.75 g administration post-dialysis. Serum vancomycin levels before and after LDL-A, measured on the subsequent day, exhibited only slight fluctuations within the intermeasurement variability range. Despite continuing vancomycin administration at the standard dose in patients undergoing hemodialysis, the serum concentration remained consistent, suggesting a minimal impact of LDL-A on vancomycin pharmacokinetics.

Neuromuscular Emergencies

OBJECTIVE

This article aims to familiarize the reader with the clinical approach, diagnostic considerations, and treatment strategies for patients presenting with abrupt-onset or acutely worsening weakness due to neuromuscular disorders.

LATEST DEVELOPMENTS

Neuromuscular weakness is often the result of an inflammatory process. In recent years, there has been growing recognition of pathologic antibodies that cause neuromuscular injury. This has allowed clinicians to make a more accurate diagnosis. Additionally, neuromuscular junction disorders and myopathies are increasingly identified as the adverse effects of novel anticancer therapies, namely immune checkpoint inhibitors. More data are being incorporated into frameworks for neuroprognostication after neuromuscular emergencies, especially for commonly encountered disorders such as Guillain-Barré syndrome.

ESSENTIAL POINTS

Care of patients with neuromuscular emergencies requires prompt attention to respiratory status. Once supportive measures are in place to protect the airway and facilitate effective ventilation, diagnostic considerations should hinge on appropriate neurologic localization. Aggressive immunosuppression is often required for immune-mediated neuromuscular disorders, and clinicians must be thoughtful in selecting a strategy that best aligns with each patient's risk factors and comorbidities.

Case report: A highly active refractory myasthenia gravis with treatment of telitacicept combined with efgartigimod

There is always a lack of effective treatment for highly active refractory generalized myasthenia gravis (GMG). Recently, telitacicept combined with efgartigimod significantly reduces circulating B cells, plasma cells, and immunoglobulin G, which brings promising therapeutic strategies. We report a case of a 37-year-old female patient with refractory GMG, whose condition got significant improvement and control with this latest treatment after multiple unsuccessful therapies of immunosuppressants. The new combination deserves further attention in the therapeutic application of myasthenia gravis.

Management of Bivalirudin Dosing and Replacement Fluid During Therapeutic Plasma Exchange in Children on Extracorporeal Membrane Oxygenation

The use of bivalirudin as the primary anticoagulant for children supported on extracorporeal membrane oxygenation (ECMO) is growing. Ideal management of bivalirudin dosing during therapeutic plasma exchange (TPE) on ECMO is unknown. We performed a single-center retrospective study of ECMO patients anticoagulated with bivalirudin who underwent TPE from January 2019 to December 2021. Therapeutic plasma exchange sessions were analyzed individually by bivalirudin dosing strategy (no change [NC] versus increased dose [dose change {DC} bivalirudin group]) and replacement fluid (all fresh-frozen plasma [FFP] versus all albumin or FFP and albumin [FFP/Albumin]). Primary outcomes included bleeding, coagulopathy, and circuit thrombosis within 24 hours of TPE. Secondary outcomes included change in bivalirudin dose and coagulation parameters following TPE. There were 60 unique TPE sessions. Bivalirudin dosing or replacement fluid strategies were not associated with bleeding, coagulopathy, or thrombosis post-TPE. All albumin or fresh frozen plasma and albumin combinations (FFP/Albumin) group had longer post-TPE thromboelastography (TEG) reaction time, clot time, and more acute angle. The FFP/Albumin group had increased post-TPE international normalization ratio (INR) and partial thrombin time (PTT). Therapeutic plasma exchange for children on ECMO and bivalirudin anticoagulation is feasible; however, optimal dosing during TPE requires further investigation. Replacement fluid with FFP/Albumin is associated with more coagulopathic laboratory parameters. Patients may benefit from all FFP fluid replacement strategy. Further investigation is needed to prove generalizability.

Clozapine-Induced Severe Toxicity: Exploring the Pharmacokinetic Profile of Clozapine and Its Significance in Hemodynamic Instability - A Case Report

Hemodynamic instability in patients with clozapine intoxication can indirectly reflect the serum concentration of clozapine.We have described a case of a 32-year-old pregnant woman who developed life-threatening clozapine toxicity at 28 weeks of gestation. The levels of clozapine and norclozapine in the serum were high. We initiated hemoperfusion(HP) and other detoxification therapies to remove the drug. The patient had severely dilated peripheral blood vessels, which led to cardiac symptoms such as fatal hypotension and uncontrollable tachycardia, resulting in very high cardiac output and elevated Central venous oxygen saturation (ScvO2). Pharmacological intervention significantly improved the hemodynamics.In light of our observations in the ongoing case, we posit that evaluating hemodynamic parameters before and after blood detoxification could serve as a valuable means to gauge effectiveness and provide guidance for treatment.

Therapeutic Plasma Exchange Versus FcRn Inhibition in Autoimmune Disease

Therapeutic plasma exchange (TPE or PLEX) is used in a broad range of autoimmune diseases, with the goal of removing autoantibodies from the circulation. A newer approach for the selective removal of immunoglobulin G (IgG) antibodies is the use of therapeutic molecules targeting the neonatal Fc receptor (FcRn). FcRn regulates IgG recycling, and its inhibition results in a marked decrease in circulating autoantibodies of the IgG subtype. The difference between FcRn inhibition and PLEX is often questioned. With anti-FcRn monoclonal antibodies (mAbs) and fragments only recently entering this space, limited data are available regarding long-term efficacy and safety. However, the biology of FcRn is well understood, and mounting evidence regarding the efficacy, safety, and potential differences among compounds in development is available, allowing us to compare against nonselective plasma protein depletion methods such as PLEX. FcRn inhibitors may have distinct advantages and disadvantages over PLEX in certain scenarios. Use of PLEX is preferred over FcRn inhibition where removal of antibodies other than IgG or when concomitant repletion of missing plasma proteins is needed for therapeutic benefit. Also, FcRn targeting has not yet been studied for use in acute flares or crisis states of IgG-mediated diseases. Compared with PLEX, FcRn inhibition is associated with less invasive access requirements, more specific removal of IgG versus other immunoglobulins without a broad impact on circulating proteins, and any impacts on other therapeutic drug levels are restricted to other mAbs. In addition, the degree of IgG reduction is similar with FcRn inhibitors compared with that afforded by PLEX. Here we describe the scientific literature regarding the use of PLEX and FcRn inhibitors in autoimmune diseases and provide an expert discussion around the potential benefits of these options in varying clinical conditions and scenarios.

The effect of plasma exchange on serum levels of lacosamide: A case report

PURPOSE

We describe the case of a 22-year-old male who developed thyroid storm necessitating therapeutic plasma exchange (TPE). The patient's past medical history was complicated by epilepsy, for which he took lacosamide. Little evidence was available to guide lacosamide dosing during TPE. Because of an exacerbation of the patient's underlying epilepsy in the context of the thyroid storm, we conducted therapeutic medication monitoring of lacosamide concentrations to guide management.

SUMMARY

We arranged for measurement of the lacosamide concentration immediately before TPE (5.1 μg/mL) and 2.5 hours after the initial measurement (3.4 μg/mL) to determine the amount of lacosamide removed by TPE. Utilizing population pharmacokinetic parameters, we calculated the expected concentration and compared this to the measured concentration. The difference between these values was used to determine the percentage removed via TPE compared to the expected post-TPE concentration. We found that one TPE session removed an additional 20% of serum lacosamide.

CONCLUSION

TPE appeared to remove an additional 20% of lacosamide when compared to the expected post-TPE concentration.

Plasma exchange as a tool for removal of bevacizumab: Highlighting application for urgent surgery

Background

Bevacizumab is commonly used to manage cerebral edema associated with brain tumors. However, its long half-life poses challenges for patients requiring urgent surgery due to wound complications. We present a case of utilizing therapeutic plasma exchange (TPE) to remove bevacizumab in a patient with recurrent glioblastoma requiring urgent surgery.

Methods

A 58-year-old male with recurrent glioblastoma, IDH-wildtype, presented with clinical and radiographic concern for ventriculitis requiring urgent wound washout only 4 days after his last bevacizumab infusion. TPE was performed for 3 sessions after surgery using a centrifugation-based cell separator. Replacement fluids included normal serum albumin, normal saline, and fresh frozen plasma. Bevacizumab levels were quantified using an enzyme-linked immunoabsorbent assay before and after each TPE session.

Results

TPE effectively removed bevacizumab, enabling safe surgery without new complications. Plasma bevacizumab levels decreased from 1087.63 to 145.35 ng/mL (13.4% of original) by the end of the last TPE session. This decline is consistent with nearly 3 half-lives, which compares favorably to the expected timeline of natural decline given the 21-day half-life.

Conclusions

We report a complex clinical scenario of a patient requiring urgent wound washout 4 days after last bevacizumab infusion for CNS infection. Surgery was successfully performed without new complications with use of TPE to remove bevacizumab immediately following surgery. This case highlights the feasibility of this approach, which may be utilized effectively in patients requiring surgery after having recently received bevacizumab.

Personalized antiseizure medication therapy in critically ill adult patients

Precision medicine has the potential to have a significant impact on both drug development and patient care. It is crucial to not only provide prompt effective antiseizure treatment for critically ill patients after seizures start but also have a proactive mindset and concentrate on epileptogenesis and the underlying cause of the seizures or seizure disorders. Critical illness presents different treatment issues compared with the ambulatory population, which makes it challenging to choose the best antiseizure medications and to administer them at the right time and at the right dose. Since there is a paucity of information available on antiseizure medication dosing in critically ill patients, therapeutic drug monitoring is a useful tool for defining each patient's personal therapeutic range and assisting clinicians in decision-making. Use of pharmacogenomic information relating to pharmacokinetics, hepatic metabolism, and seizure etiology may improve safety and efficacy by individualizing therapy. Studies evaluating the clinical implementation of pharmacogenomic information at the point-of-care and identification of biomarkers are also needed. These studies may make it possible to avoid adverse drug reactions, maximize drug efficacy, reduce drug-drug interactions, and optimize medications for each individual patient. This review will discuss the available literature and provide future insights on precision medicine use with antiseizure therapy in critically ill adult patients.

State of the Evidence: Drug Removal via Apheresis

Therapeutic apheresis refers to a diversity of procedures in which specific hematologic components (e.g., plasma, erythrocytes, leukocytes, etc.) with pathological associations are removed from circulation (with possible replacement) in order to treat a variety of disease processes. As pharmacologic agents also circulate with these components, their removal is sometimes incidental, or in the scenario of drug toxicity, a therapeutic goal. The corpus of published manuscripts on this subject has grown immensely over the past few decades; however, the breadth of diseases, methods, and drugs that co-exist in this space make it challenging to generate generalizable evidence regarding drug removal via apheresis. This review discusses factors worth considering when interpreting literature-reported data on drug removal by apheresis with examples from several notable studies and highlights topics in need of evidential improvement and growth as our palette of therapeutic agents continues to expand.

Treatment of comatose patient from cyclobenzaprine overdose with therapeutic plasma exchange

We present a case of a 15-year-old female who was admitted in a comatose state with no spontaneous respiratory effort and absence of brainstem reflexes after cyclobenzaprine ingestion. Due to severe presentation and recent ingestion of high plasma protein binding medication with long half-life, therapeutic plasma exchange (TPE) was performed and resulted in full neurological recovery. This case explores the role of TPE as an effective treatment option for life-threatening cyclobenzaprine overdose. TPE is generally beneficial for drugs that have a low volume of distribution and high plasma protein binding. Cyclobenzaprine is known to have a relatively high volume of distribution. However, in the case of drug intoxication with relatively high-volume distribution, high protein binding, and long half-life, TPE could be effective if it is conducted promptly.

Phenytoin Pharmacokinetics During Venoarterial Extracorporeal Membrane Oxygenation and Plasma Exchange

Currently, there is minimal guidance to antiepileptic dose adjustment for a patient requiring either venoarterial (VA) extracorporeal membrane oxygenation (ECMO) or plasma exchange (PLEX) therapy, and to our knowledge, there are rare guidances for a patient requiring both. Given the dangers with non-therapeutic concentrations of phenytoin, it is critical for the intensive care unit (ICU) practitioner to understand how the pharmacokinetic parameters of phenytoin change in critically ill patients requiring extracorporeal support. This case study presents a 41-year-old female transferred to the cardiovascular ICU requiring VA ECMO and PLEX for the treatment of systemic lupus erythematosus (SLE)-induced catastrophic antiphospholipid syndrome (CAPS). Free phenytoin concentrations were measured to assess the removal of phenytoin. There was no significant decrease in the free phenytoin concentrations post-PLEX and while on ECMO. Free phenytoin concentrations are not influenced in the setting of PLEX and while on ECMO.

Best practices and recommendations for drug regimens and plasma exchange for immune thrombotic thrombocytopenic purpura

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ injury. TTP pathophysiology is based on a severe ADAMTS13 deficiency, and is a medical emergency with fatal outcome if appropriate treatment is not initiated promptly.

AREAS COVERED

Authors will review the best options currently available to minimize mortality, prevent relapses, and obtain the best clinical response in patients with immune TTP (iTTP). Available bibliography about iTTP treatment has been searched in Library's MEDLINE/PubMed database from January 1990 until April 2021.

EXPERT OPINION

The generalized use of plasma exchange marked a paradigm in the management of iTTP. In recent years, strenuous efforts have been done for a better understanding of the pathophysiology of this disease, improve diagnosis, optimize treatment, reduce mortality, and prevent recurrences. The administration of front-line rituximab and, more recently, the availability of caplacizumab, the first targeted therapy for iTTP, have been steps toward a further reduction in early mortality and for the prevention of relapses.