Prophylactic infusion of calcium gluconate to prevent a symptomatic fall in plasma ionized calcium during therapeutic plasma exchange: A comparison of two methods

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.

Basic principles of therapeutic plasma exchange

Therapeutic plasma exchange is a method of treatment for clinical conditions that represent diverse fields of medicine. The rationale for this mode of therapy is based on sound mathematical modeling of the synthesis and removal of large molecules, usually proteins, from the circulation. The basic assumptions underlying therapeutic plasma exchange are that a clinical illness is caused by, or related to, a pathogenic substance in the plasma, and that removing that substance from the plasma will alleviate the patient's illness. This approach has proven applicable to a wide variety of clinical conditions. Therapeutic plasma exchange is largely a safe procedure in experienced hands. The principal adverse effect, the hypocalcemic reaction, is readily ameliorated or prevented.

Effect of Admission Serum Calcium Levels and Length of Stay in Patients with Acute Pancreatitis: Data from the MIMIC-III Database

Objective. We retrospectively investigated the effect of admission serum calcium levels on length of stay (LOS) in patients hospitalized with acute pancreatitis (AP). Methods. Clinical data for 3156 patients diagnosed with AP were obtained from the Multiparametric Intelligent Monitoring in Intensive Care III (MIMIC-III) database. Restricted cubic spline curve (RCS) functions of dose-response analysis curves and logistic regression analysis were used to analyze the relationship between admission serum calcium levels and the LOS. Results. All patients were divided into 2 groups (<8.5 mg/dl group and ≥8.5 mg/dl group) based on RCS analysis. RCS showed a significant nonlinear negative correlation between blood calcium levels and the LOS ( $p<0.001$ ). In addition, compared with patients with blood calcium <8.5 mg/dl, multivariate logistic regression analysis showed that patients with blood calcium ≥8.5 mg/dl had a reduced risk of the LOS >2 days (aOR = 0.653; 95% CI 0.507–0.842; $p=0.001$ ), a reduced risk of the LOS >5 days (aOR = 0.589; 95% CI 0.503–0.689; $p<0.001$ ), and a reduced risk of the LOS >7 days (aOR = 0.515; 95% CI 0.437–0.609; $p<0.001$ ). And similar results were found in the subgroup analysis. Conclusion. Our findings suggest that low blood calcium increases the LOS in patients with AP. More attention is needed for patients with combined low blood calcium levels (<8.5 mg/dl) in hospitalized AP patients.

Impact of Changes in Serum Calcium Levels on In-Hospital Mortality

Background and objectives: Calcium concentration is strictly regulated at both the cellular and systemic level, and changes in serum calcium levels can alter various physiological functions in various organs. This study aimed to assess the association between changes in calcium levels during hospitalization and mortality. Materials and Methods: We searched our patient database to identify all adult patients admitted to our hospital from January 1st, 2009 to December 31st, 2013. Patients with ≥2 serum calcium measurements during the hospitalization were included. The serum calcium changes during the hospitalization, defined as the absolute difference between the maximum and the minimum calcium levels, were categorized into five groups: 0–0.4, 0.5–0.9, 1.0–1.4, 1.5–1.9, and ≥2.0 mg/dL. Multivariable logistic regression was performed to assess the independent association between calcium changes and in-hospital mortality, using the change in calcium category of 0–0.4 mg/dL as the reference group. Results: Of 9868 patients included in analysis, 540 (5.4%) died during hospitalization. The in-hospital mortality progressively increased with higher calcium changes, from 3.4% in the group of 0–0.4 mg/dL to 14.5% in the group of ≥2.0 mg/dL (p < 0.001). When adjusted for age, sex, race, principal diagnosis, comorbidity, kidney function, acute kidney injury, number of measurements of serum calcium, and hospital length of stay, the serum calcium changes of 1.0–1.4, 1.5–1.9, and ≥2.0 mg/dL were significantly associated with increased in-hospital mortality with odds ratio (OR) of 1.55 (95% confidence interval (CI) 1.15–2.10), 1.90 (95% CI 1.32–2.74), and 3.23 (95% CI 2.39–4.38), respectively. The association remained statistically significant when further adjusted for either the lowest or highest serum calcium. Conclusion: Larger serum calcium changes in hospitalized patients were progressively associated with increased in-hospital mortality.

Gluconate suppresses seizure activity in developing brains by inhibiting CLC-3 chloride channels

Neonatal seizures are different from adult seizures, and many antiepileptic drugs that are effective in adults often fail to treat neonates. Here, we report that gluconate inhibits neonatal seizure by inhibiting CLC-3 chloride channels. We detect a voltage-dependent outward rectifying Cl⁻ current mediated by CLC-3 Cl⁻ channels in early developing brains but not adult mouse brains. Blocking CLC-3 Cl⁻ channels by gluconate inhibits seizure activity both in neonatal brain slices and in neonatal animals with in vivo EEG recordings. Consistently, neonatal neurons of CLC-3 knockout mice lack the outward rectifying Cl⁻ current and show reduced epileptiform activity upon stimulation. Mechanistically, we demonstrate that activation of CLC-3 Cl⁻ channels alters intracellular Cl⁻ homeostasis and enhances GABA excitatory activity. Our studies suggest that gluconate can suppress neonatal seizure activities through inhibiting CLC-3 Cl⁻ channels in developing brains.