Prevalence of Antiphospholipid Antibodies and Association With Incident Cardiovascular Events

Importance

The prevalence of antiphospholipid antibodies (aPL) and their association with future atherosclerotic cardiovascular disease (ASCVD) risk has yet to be thoroughly investigated.

Objective

To determine the association between measurements of aPL at a single time point and ASCVD risk in a diverse population.

Design, Setting, and Participants

This cohort study measured 8 aPL (anticardiolipin [aCL] IgG/IgM/IgA, anti-beta-2 glycoprotein I [aβ2GPI] IgG/IgM/IgA, and antiphosphatidylserine/prothrombin [aPS/PT] IgG/IgM) by solid-phase assays in plasma from participants of the Dallas Heart Study (DHS) phase 2, a multiethnic, population-based cohort study. Blood samples were collected between 2007 and 2009. The median follow-up was 8 years. Statistical analysis was performed from April 2022 to January 2023.

Main Outcomes and Measures

Associations of aPL with future ASCVD events (defined as first nonfatal myocardial infarction, first nonfatal stroke, coronary revascularization, or death from cardiovascular cause) were assessed by Cox proportional hazards models, adjusting for known risk factors, medications, and multiple comparisons.

Results

Among the 2427 participants (mean [SD] age, 50.6 [10.3] years; 1399 [57.6%] female; 1244 [51.3%] Black, 339 [14.0%] Hispanic, and 796 [32.8%] White), the prevalence of any positive aPL tested at a single time point was 14.5% (353 of 2427), with approximately one-third of those detected at a moderate or high titer; aCL IgM had the highest prevalence (156 individuals [6.4%]), followed by aPS/PT IgM (88 [3.4%]), aβ2GPI IgM (63 [2.6%]), and aβ2GPI IgA (62 [2.5%]). The IgA of aCL (adjusted hazard ratio [HR], 4.92; 95% CI, 1.52-15.98) and aβ2GPI (HR, 2.91; 95% CI, 1.32-6.41) were independently associated with future ASCVD events. The risk further increased when applying a positivity threshold of at least 40 units (aCL IgA: HR, 9.01 [95% CI, 2.73-29.72]; aβ2GPI IgA: HR, 4.09 [95% CI, 1.45-11.54]). Levels of aβ2GPI IgA negatively correlated with cholesterol efflux capacity (r = -0.055; P = .009) and positively correlated with circulating oxidized LDL (r = 0.055; P = .007). aβ2GPI IgA-positive plasma was associated with an activated endothelial cell phenotype as evidenced by increased surface expression of surface E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1.

Conclusions and Relevance

In this population-based cohort study, aPL detectable by solid-phase assays were present in a substantial proportion of adults; positive aCL IgA and aβ2GPI IgA at a single time point were independently associated with future ASCVD events. Longitudinal studies with serial aPL measurements are needed to further explore these findings.

Health Literacy and Patient Activation in the Pediatric to Adult Transition in Systemic Lupus Erythematosus: Patient and Health Care Team Perspectives

Objective

Methods

Results

Conclusion

Therapeutic recreation camps for youth with childhood-onset systemic lupus erythematosus: perceived psychosocial benefits

BACKGROUND

The psychosocial burden of having a chronic disease can be substantial for adolescents with childhood-onset systemic lupus erythematosus (cSLE). Current literature is scarce on interventions that can improve psychosocial outcomes for this population. Therapeutic recreation camps have been proposed as a beneficial experience for chronically ill pediatric populations. However, their effective components have not been well characterized in patients with cSLE. In this study, we sought to understand the various components of the camp experience for adolescents with cSLE from both the patient and parent perspective.

METHODS

We recruited patients with cSLE who had participated in one or more annual, weekend-long recreational lupus camp(s) near Dallas, Texas. Semi-structured in-depth telephone interviews were conducted from March-June 2020 with both the patients and parents. Questions focused on overall patient experience, psychosocial impact of camp participation, coping skills gained, and opportunities to prepare for the transition from pediatric to adult care. Interviews were coded and analyzed using inductive thematic analysis.

RESULTS

We interviewed 9 current and former campers (ages 16-24), including a current camp counselor, and 3 of their parents separately. Reported benefits included a positive impact on social support through peer bonding, opportunities to develop coping mechanisms through structured activities and peer/medical staff interactions, opportunities for education about the cSLE disease experience, improved adherence through peer modeling, overall increase in self-efficacy, and better parental insight into the patient experience. Participants also provided suggestions for expansion and improvement in program development to optimize educational opportunities for both campers and parents. In addition, they advocated for longitudinal social support and community building.

CONCLUSIONS

In this qualitative study, in which cSLE patients and their parents reflected on their experiences with therapeutic recreation camps, we found several perceived benefits impacting the patient and parent experience. Participants expressed a desire for more educational opportunities that could contribute to their successful transition from pediatric to adult care. Further studies are needed to demonstrate the effects of therapeutic recreation camps on the psychosocial health of this population.

A Medical Records Review Study Assessing Safety of Zoster Vaccine Recombinant, Adjuvanted in Patients With Rheumatic Disease

OBJECTIVE

Patients with rheumatic disease are at increased risk for herpes zoster infection. Because of limited safety data in this population and concerns over vaccine-precipitated flares, there are no guidelines for vaccination with the zoster vaccine recombinant, adjuvanted (ZRA). We evaluated self-reported adverse events (AEs) and disease activity after ZRA administration in adults with rheumatic disease.

METHODS

In this medical records review study at our large academic center, patients who had received at least 1 dose of ZRA from January 1, 2018 to March 11, 2020 were assessed. Self-reported AEs and disease activity were monitored 3 months after each ZRA administration. Measures of disease activity were reviewed 6 months before ZRA in those who received both doses, or 3 months before ZRA in those who received 1 dose.

RESULTS

We identified 65 patients, of whom 34 (52.3%) received both doses of ZRA. Four patients (6.2%) self-reported AEs after receiving ZRA, all of which were minor and systemic. Three patients (9.2%) developed a flare after receiving ZRA, compared with 8 (12.3%) who experienced a flare in the baseline period. There was no significant change in flare incidence or disease activity after vaccination. Subgroup analysis of those on biologic and nonbiologic disease-modifying antirheumatic drugs revealed no differences in frequency of postvaccination AEs, flares, or disease activity.

CONCLUSIONS

In our cohort, disease activity seemed stable when comparing disease markers before and after ZRA administration. In addition, ZRA was well-tolerated with minor AEs. Further studies are needed to guide formal vaccination recommendations.

"You Just Have to Keep Going, You Can't Give Up": Coping mechanisms among young adults with lupus transferring to adult care

INTRODUCTION

Coping mechanisms and emotional regulation are important contributors to psychosocial health during stressful life events. We sought to describe the coping and emotional responses of persons with childhood-onset systemic lupus erythematosus during the transfer from pediatric to adult healthcare.

METHODS

Semi-structured in-depth one-on-one interviews were conducted with 13 young women aged 18-24 of minority background who had transferred to adult care in a public hospital system. Thematic analysis was used to identify themes motifs from the data.

RESULTS

Participants described the use of (1) problem-focused coping such as the use of clear communication and self-education, (2) adaptive emotion-focused coping such as cognitive reframing and acceptance, (3) social coping including support-seeking, (4) meaning-making coping including positive religious framing and viewing events as learning opportunities for growth, and (5) disengaged coping including denial and social isolation. A range of emotional responses associated with the transfer were described including fear, anger, loss, and feelings of empowerment and excitement.

CONCLUSION

Effective coping and emotional regulation are modifiable factors that may impact transfer-related outcomes and psychosocial health. Addressing coping mechanisms is relevant to the optimized transfer to adult care.

Predictors of Adverse outcomes in patients with systemic lupus erythematosus transitioning to adult care

BACKGROUND

The transition from pediatric to adult care is a vulnerable period for individuals with chronic diseases. We sought to identify risk factors associated with poor outcomes in patients with childhood-onset systemic lupus erythematosus (cSLE) who have transitioned to adult care.

METHODS

A retrospective analysis of cSLE patients was performed. Outcomes of interest were development of end-stage renal disease (ESRD) or death and time to first hospitalization following final pediatric rheumatology visit. Multivariable logistic and Cox regression models were used.

RESULTS

Of 190 patients with cSLE, 21 (11%) developed ESRD and 9 (5%) died following the final pediatric rheumatology visit. In logistic regression, public insurance, history of Child Protective Services involvement, and an unscheduled hospitalization during the final year in pediatric care were predictive of ESRD or death (odds ratio (95% confidence intervals (CI)) 6.7 (1.5-30.7), 6.6 (2.3-19.1), and 3.2 (1.3-8.3), respectively). Among 114 patients with healthcare utilization data, 53% had a hospitalization in adult care. In Cox regression analysis, a pediatric outpatient opioid prescription was associated with shorter time to adult hospitalization and White or Asian race was associated with longer time to adult hospitalization (hazard ratio (CI) 3.5 (1.7-7.0) and 0.1 (0.03-0.4), respectively).

CONCLUSIONS

Risks factors associated with poor outcomes in adult care amongst patients with cSLE include public insurance, history of Child Protective Services involvement, unscheduled care utilization in pediatric care, pediatric outpatient opioid prescription, Black race and Hispanic ethnicity. Efforts to improve long-term outcomes among patients with cSLE should focus on these populations.

Clinical Team Perspectives on the Psychosocial Aspects of Transition to Adult Care for Patients With Childhood-Onset Systemic Lupus Erythematosus

OBJECTIVE

The transition from pediatric to adult care for youth with childhood-onset systemic lupus erythematosus (SLE) is a vulnerable period. Adverse outcomes during this transition include gaps in care, unscheduled health care utilization, loss of insurance, and high disease activity. The objective of this study was to examine the clinical care teams' perspective on the psychosocial factors associated with transition outcomes, which are poorly understood in this population.

METHODS

We conducted in-depth interviews with clinical care team members who interact with childhood-onset SLE patients during transfer from pediatric to adult rheumatology. A semistructured interview guide was used to prompt participants' perspectives about the psychosocial factors associated with the transition process for patients with childhood-onset SLE. Audio recordings were transcribed and analyzed using the constant comparative method. We stopped conducting interviews once thematic saturation was achieved.

RESULTS

Thirteen in-depth interviews were conducted. Participants included pediatric rheumatologists (n = 4), adult rheumatologists from both academic and private practice settings (n = 4), nurses (n = 2), a nurse practitioner, a social worker, and a psychologist. We identified several themes deemed by clinical care teams as important during the transition, including the impact of the family, patient resilience and coping mechanisms, the role of mental health and emotional support, and the need for education, peer support, and social connectedness.

CONCLUSION

We identified several psychosocial themes that clinical team members believe impact the transition of patients with childhood-onset SLE into adult care. The role of parental modeling, youth resilience, mental health and emotional care, improved childhood-onset SLE education, and structured peer support and social connectedness are highlighted, which may be amenable to interventions.

SARS-CoV-2 Antibody Responses Do Not Predict COVID-19 Disease Severity

OBJECTIVES

Initial reports indicate adequate performance of some serology-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assays. However, additional studies are required to facilitate interpretation of results, including how antibody levels impact immunity and disease course.

METHODS

A total of 967 subjects were tested for IgG antibodies reactive to SARS-CoV-2, including 172 suspected cases of SARS-CoV-2, 656 plasma samples from healthy donors, 49 sera from patients with rheumatic disease, and 90 specimens from individuals positive for polymerase chain reaction (PCR)-based respiratory viral panel. A subgroup of SARS-CoV-2 PCR-positive cases was tested for IgM antibodies by proteome array method.

RESULTS

All specificity and cross-reactivity specimens were negative for SARS-CoV-2 IgG antibodies (0/795, 0%). Positive agreement of IgG with PCR was 83% of samples confirmed to be more than 14 days from symptom onset, with less than 100% sensitivity attributable to a case with severe immunosuppression. Virus-specific IgM was positive in a higher proportion of cases less than 3 days from symptom onset. No association was observed between mild and severe disease course with respect to IgG and IgM levels.

CONCLUSIONS

The studied SARS-CoV-2 IgG assay had 100% specificity and no adverse cross-reactivity. Measures of IgG and IgM antibodies did not predict disease severity in our patient population.

Ethnic Disparities in Atherosclerotic Cardiovascular Disease Incidence and Prevalence Among Rheumatoid Arthritis Patients in the United States: a Systematic Review

Objective

Rheumatoid arthritis (RA) is associated with increased atherosclerotic cardiovascular disease (ASCVD). General population cohorts have shown African American individuals to have greater and Hispanic Americans to have lower cardiovascular disease prevalence when compared with non‐Hispanic white individuals; however, the reasons for these findings are not clear. This systematic review seeks to describe the incidence and prevalence of ASCVD stratified by race/ethnicity within the US RA population.

Methods

MEDLINE, Embase, and Cochrane databases were searched for studies that reported incidence or prevalence of ASCVD (including, but not limited to, fatal and nonfatal stroke, myocardial infarction, and cardiovascular death) in those with RA. Abstracts and full texts were screened separately for inclusion by two reviewers, with a third reviewer to resolve discrepancies.

Results

We screened 2625 abstracts and fully reviewed 138 manuscripts. Twenty‐one were included that cited at a minimum the percentage of non‐Hispanic whites in their population. No publication meeting entry criteria initially stratified ASCVD by race/ethnicity. The average prevalent ASCVD in RA is 46.9% (95% CI: 46.8–47) (range of prevalent ASCVD: 30%‐47%). The average incident ASCVD is 8.2% (95% CI: 8.14–8.25) (range of incident ASCVD 1%–46%).

Conclusion

In this systematic review, we found a paucity of data on racially/ethnically diverse RA patients and ASCVD outcomes. Future studies should report the prevalence of ASCVD in various races/ethnicities with RA in the United States. These data would help inform clinicians on how best to manage cardiovascular disease risk in RA.

Inflammatory myositis in systemic lupus erythematosus

BACKGROUND

The coexistence of inflammatory myositis in systemic lupus erythematosus (SLE) has not been extensively studied. In this study, we describe the incidence, distinct types of inflammatory myositis, and risk factors for this finding in a cohort of pediatric and adult SLE patients.

METHODS

We identified SLE patients with coexisting myositis followed between 2010 and 2019 at two pediatric hospitals and one adult hospital. Demographic, clinical, laboratory, and pathological features of myositis were collected, and descriptive statistics were applied.

RESULTS

A total of 1718 individuals were identified as having SLE (451 pediatric and 1267 adult patients). Of these, 108 were also diagnosed with inflammatory myositis (6.3%). People of black race had a significantly higher prevalence of inflammatory myositis, as did those with childhood-onset SLE compared to adult-onset disease. In the majority of patients (68%), SLE and inflammatory myositis presented concurrently. Overlapping features of systemic sclerosis occurred in 48%, while dermatomyositis-specific rashes were present in a third. Arthralgias and inflammatory arthritis were seen in >90%. Thrombotic events and significant pregnancy-related morbidity were present in more than a third of patients. Lymphopenia, hypocomplementemia, and a positive RNP were the most common laboratory features noted. Myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) were present in >40% of patients. A review of 28 muscle biopsy reports revealed a wide array of pathological features, including nonspecific changes, dermatomyositis, polymyositis, and necrotizing auto-immune myopathy.

CONCLUSION

In our SLE patient population, 6.3% presented with concurrent inflammatory myositis. Dermatomyositis-specific rashes, clinical features of systemic sclerosis, arthralgias and arthritis, and cytopenias were common coexisting clinical manifestations. A high frequency of RNP, MSA, and MAA were found. People of black race and with childhood-onset disease had a higher prevalence of myositis. Our findings suggest that SLE patients of black race, with childhood-onset SLE, and who possess MSA or MAA should be routinely screened for myositis.

Segmental Arterial Mediolysis: A Vasculitis Mimic

Background Segmental arterial mediolysis (SAM) is a rare noninflammatory vasculopathy. The purpose of this report is to describe the clinical data of six patients diagnosed with SAM, discuss key elements for diagnosis, and highlight the differences between SAM and vasculitis. We also propose a modification to the criteria developed by Kalva et al for the diagnosis of SAM.

Methods This is a retrospective study approved by the Institutional Review Board and included patients diagnosed with SAM between January 2008 and December 2016. Eleven patients were identified, of whom six (four males with a median age of 59.5 years) had complete data per the guidelines proposed by Kalva et al and were thus included. Data on patient’s clinical presentation, laboratory and imaging findings, and outcomes were collected.

Results Presenting symptoms included abdominal pain, flank pain, and bloody stools. Five patients had negative antinuclear antibodies (ANAs) and one had positive ANAs with negative subserologies. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were normal except for an elevated CRP in two patients with organ infarction. The superior mesenteric and renal arteries were most commonly involved. The most common vascular abnormalities were dissection, pseudoaneurysm, thrombosis, and wall thickening. Two patients received endovascular repair for hepatic artery aneurysms. During the follow-up (range: 3–36 months), two patients developed a new aneurysm or dissection.

Conclusion The long-term prognosis of SAM appears to be favorable. Vascular intervention is only needed for patients with impending vascular compromise. We propose that the criteria developed by Kalva et al could be modified to include patients with elevated ANA but negative subserologies and elevated CRP and ESR in the presence of organ infarction.

Body Mass Index, Weight Loss, and Cause-Specific Mortality in Rheumatoid Arthritis

OBJECTIVE

To examine associations of body mass index (BMI) and weight loss with cause-specific mortality in rheumatoid arthritis (RA).

METHODS

A cohort of US veterans with RA was followed until death or through 2013. BMI was categorized as underweight, normal, overweight, and obese. Weight loss was calculated as the 1) annualized rate of change over the preceding 13 months, and 2) cumulative percent. Vital status and cause of death were obtained from the National Death Index. Multivariable competing-risks regression models were utilized to assess the time-varying associations of BMI and weight loss with cause-specific mortality.

RESULTS

Among 1,600 participants and 5,789 patient-years of followup, 303 deaths occurred (95 cardiovascular, 74 cancer, and 46 respiratory). The highest weight-loss rate and weight-loss percent were associated with a higher risk of cardiovascular mortality (rate: subdistribution hazard ratio [sHR] 2.27 [95% confidence interval (95% CI) 1.61-3.19]; percent: sHR 2.31 [95% CI 1.06-5.01]) and cancer mortality (rate: sHR 2.36 [95% CI 1.11-5.01]; percent: sHR 1.90 [95% CI 1.00-3.62]). Overweight BMI was protective of cardiovascular mortality (sHR 0.59 [95% CI 0.38-0.91]), while underweight BMI was associated with a near 3-fold increased risk of respiratory mortality (sHR 2.93 [95% CI 1.28-6.67]). Incorporation of time-varying BMI and weight loss in the same models did not substantially alter individual associations for cardiovascular and cancer mortality, but an association between weight-loss percentage and respiratory mortality was attenuated after BMI adjustment.

CONCLUSION

Both BMI and weight loss are predictors of cause-specific mortality in RA. Weight loss is a strong predictor of cardiovascular and cancer mortality, while underweight BMI is a stronger predictor of respiratory mortality.

Associations of Circulating Cytokines and Chemokines With Cancer Mortality in Men With Rheumatoid Arthritis

OBJECTIVE

To examine the potential of circulating cytokines and chemokines as biomarkers of cancer mortality risk in patients with rheumatoid arthritis (RA).

METHODS

Male participants in the Veterans Affairs RA registry were followed up from the time of enrollment until death or December 2013. Cytokines and chemokines were measured in banked serum obtained at the time of enrollment, using a bead-based multiplex assay, and a previously developed cytokine score was calculated. Vital status and cause of death were determined through the National Death Index. Associations of cytokines with cancer mortality were examined using multivariable competing-risks regression.

RESULTS

Among 1,190 men with RA, 60 cancer deaths (30 of which were attributable to lung cancer) occurred over 5,307 patient-years of follow-up. The patients had a mean age of 64.5 years, had established disease (median duration 8.7 years), were seropositive for rheumatoid factor (81%) or anti-cyclic citrullinated peptide antibody (77%), and frequently had a history of smoking (82% current or former). Seven of 17 analytes examined were individually associated with cancer mortality. The cytokine score was associated with overall cancer (subhazard ratio [SHR] 1.42, 95% confidence interval [95% CI] 1.08-1.85) and lung cancer (SHR 1.86, 95% CI 1.57-2.19) mortality in multivariable analyses. Those in the highest quartile of cytokine scores had a >2-fold increased risk of overall cancer mortality (P = 0.039) and a 6-fold increased risk of lung cancer mortality (P = 0.028) relative to the lowest quartile. A synergistic interaction between current smoking and high cytokine score was observed.

CONCLUSION

Serum cytokines and chemokines are associated with cancer and lung cancer mortality in men with RA, independent of multiple factors including age, smoking status, and prevalent cancer.

Vascular calcifications on hand radiographs in rheumatoid arthritis and associations with autoantibodies, cardiovascular risk factors and mortality

OBJECTIVE

To examine whether vascular calcifications on hand films in RA might aid in determining mortality risk.

METHODS

Hand radiographs from 906 RA patients were scored as positive or negative for vascular calcifications. Patient characteristics associated with vascular calcifications were assessed using multivariable logistic regression, and associations with mortality were examined using Cox proportional hazards regression. Cytokines and multiplex ACPA were measured in both groups.

RESULTS

A total of 99 patients (11%) demonstrated radiographic vascular calcifications. Factors independently associated with vascular calcifications included diabetes [odds ratio (OR) 2.85; 95% CI 1.43, 5.66], cardiovascular disease at enrolment (OR 2.48; 95% CI 1.01, 6.09), prednisone use (OR 1.90; 95% CI 1.25, 2.91), current smoking (OR 0.06; 95% CI 0.01, 0.23) and former smoking (OR 0.36; 95% CI 0.27, 0.48) vs never smoking. In cytokine and ACPA subtype analysis, IL-4 and anti-citrullinated apolipoprotein E were significantly increased in patients with vascular calcifications in fully adjusted multivariable models. After multivariable adjustment, vascular calcifications were associated with an increase in all-cause mortality (hazard ratio 1.41; 95% CI 1.12, 1.78; P = 0.004).

CONCLUSION

Vascular calcifications on hand radiographs were independently associated with increased all-cause mortality in RA. Mechanisms underpinning the associations of IL-4 and select ACPA with vascular calcifications and their utility as biomarkers predictive of cardiovascular disease risk in RA merit further study.

Laboratory evaluation of skin refrigerants used in dermabrasion

Six skin refrigerants were evaluated for maximum cooling temperature. The temperatures produced correlated well with the chemical components and also the gelatin freeze-thaw times. Freon 114 and Freon 114-ethyl chloride mixtures are time-tested, safe skin refrigerants. Some of the newer skin refrigerants are pure sources of Freon 12 or mixtures of Freon 12 and Freon 11. These newer, colder products have the potential to damage the skin and represent a hazard to successful dermabrasion.

Plasma and red blood cell concentrations of amiodarone during chronic therapy

Amiodarone and a metabolite, desethylamiodarone, were measured in plasma of 55 patients and in both plasma and red blood cell (RBC) in 28 patients who received chronic amiodarone treatment. The assay for amiodarone and desethylamiodarone was performed by high-pressure liquid chromatography. During chronic treatment, median plasma concentration of amiodarone was 2.80 micrograms/ml and desethylamiodarone was 2.20 micrograms/ml. In matched samples, plasma amiodarone concentration exceeded RBC amiodarone concentration (p less than 0.001) and the RBC-to-plasma concentration ratio averaged 0.31. The plasma desethylamiodarone concentration was not significantly different from its RBC concentration, and the RBC-to-plasma concentration ratio averaged 1.29. There was a linear correlation between plasma concentrations of amiodarone and desethylamiodarone (r = 0.82) and between RBC concentrations of drug and metabolite (r = 0.71). Drug or metabolite concentrations in plasma and RBCs correlated directly with daily dosage of amiodarone. Adverse side effects during chronic amiodarone therapy were related most strongly to RBC drug and metabolite concentrations. The group with adverse side effects had a significantly higher RBC concentration of amiodarone, 150 vs 0.75 micrograms/ml (p less than 0.001), than did patients free of adverse effects. After dosage reduction, side effects abated and plasma and RBC concentrations of drug and metabolite decreased. These data indicate that there is an expected range of amiodarone and desethylamiodarone concentrations during chronic treatment and that adverse side effects correlate best with RBC concentrations of drug and metabolite. Red cell concentrations may reflect the amount of unbound, free amiodarone and desethylamiodarone in plasma.

Monitoring drug concentrations in a case of combined overdosage with primidone and methsuximide

We describe a case of fatal overdosage with primidone and methsuximide. During the early phase of the patient's hospital course we found concentrations of methsuximide, N-desmethylmethsuximide, and primidone in serum that far exceeded the usual therapeutic concentrations, as determined by gas-liquid chromatography. Determination of N-desmethylmethsuximide in peritoneal fluid demonstrated concentrations comparable to those in serum. This led to the therapeutic decision to manage the patient by dialysis. Subsequently, serum samples collected during the course of hospitalization were analyzed quantitatively by gas-liquid chromatography for methsuximide, N-desmethylmethsuximide, primidone, phenobarbital, and diphenylhydantoin. Selected serum specimens were also analyzed by gas chromatography-mass spectrometry, and N-methyl-2-hydroxymethyl-2-phenylsuccinimide, a metabolite of methsuximide not previously described in human serum, was identified by analysis of its mass spectrum.

Monitoring drug concentrations in a case of combined overdosage with primidone and methsuximide

We describe a case of fatal overdosage with primidone and methsuximide. During the early phase of the patient's hospital course we found concentrations of methsuximide, N-desmethylmethsuximide, and primidone in serum that far exceeded the usual therapeutic concentrations, as determined by gas-liquid chromatography. Determination of N-desmethylmethsuximide in peritoneal fluid demonstrated concentrations comparable to those in serum. This led to the therapeutic decision to manage the patient by dialysis. Subsequently, serum samples collected during the course of hospitalization were analyzed quantitatively by gas-liquid chromatography for methsuximide, N-desmethylmethsuximide, primidone, phenobarbital, and diphenylhydantoin. Selected serum specimens were also analyzed by gas chromatography-mass spectrometry, and N-methyl-2-hydroxymethyl-2-phenylsuccinimide, a metabolite of methsuximide not previously described in human serum, was identified by analysis of its mass spectrum.

Gas-chromatographic determination of an antifibrinolytic drug, epsilon-aminocaproic acid

We describe a modified method for assay of epsilon-aminocaproic acid. Serum or cerebrospinal fluid is deproteinized, followed by cation-exchange column-chromatography, and N-trifluoroacetyl-n-butyl derivatives of amino acids are formed and separated by gas chromatography. Tranexamic acid, a nonprotein amino acid, was used as an internal standard. The assay is sensitive and precise, and results correlate adequately with those obtained with an automated amino acid analyzer (ion-exchange chromatography).

Gas-chromatographic determination of an antifibrinolytic drug, epsilon-aminocaproic acid

We describe a modified method for assay of epsilon-aminocaproic acid. Serum or cerebrospinal fluid is deproteinized, followed by cation-exchange column-chromatography, and N-trifluoroacetyl-n-butyl derivatives of amino acids are formed and separated by gas chromatography. Tranexamic acid, a nonprotein amino acid, was used as an internal standard. The assay is sensitive and precise, and results correlate adequately with those obtained with an automated amino acid analyzer (ion-exchange chromatography).