Clinical and Immunological Factors Associated with Recommended Trough Levels of Adalimumab and Infliximab in Patients with Crohn’s Disease

Introduction: Up to 40% of patients with Crohn’s disease do not respond to treatment with anti-TNF or lose response after the initial benefit. Low drug concentrations have been proposed as the main predictor of treatment failure. Our aim was to study the immunological profile and clinical evolution of patients with Crohn’s disease according to the anti-TNF dose and serum trough levels.Methods: Crohn’s disease patients in remission treated with infliximab or adalimumab at stable doses for at least for 3 months were included. Serum levels of anti-TNF, TNF-α, interferon-γ, and interleukin IL-12, IL-10, and IL-26 were determined in blood samples taken just before drug administration. Patients were classified according to anti-TNF levels below, within, or above the target level range and the use of intensified doses. Clinical evolution at 6 months was analyzed.Results: A total of 62 patients treated with infliximab (8 on intensified schedule) and 49 treated with adalimumab (7 on intensified schedule) were included. All infliximab-treated patients showed levels within the recommended range, but half of adalimumab-treated patients were below the recommended range. A significant negative relationship between body weight and adalimumab levels was observed, especially in patients treated with intensified doses. Patients with infliximab levels over 8 µg/ml presented higher median IL-10 than patients with in-range levels (84.0 pg/ml, interquartile range [IQR] 77.0–84.8 vs. 26.2 pg/mL, IQR 22.6–38.0; p < 0.001), along with lower values of interferon-γ (312.9 pg/ml, IQR 282.7–350.4 vs. 405.6 pg/ml, IQR 352.2–526.6; p = 0.005). Patients receiving intensified versus non-intensified doses of infliximab showed significantly higher IL-26 levels (91.8 pg/ml, IQR 75.6–109.5 vs. 20.5 pg/ml, IQR 16.2–32.2; p = 0.012), irrespective of serum drug levels. Patients with in-range levels of adalimumab showed higher values of IL-10 than patients with below-range levels (43.3 pg/ml, IQR 35.3–54.0 vs. 26.3 pg/ml, IQR 21.6–33.2; p = 0.001). Patients treated with intensified vs regular doses of adalimumab had increased levels of IL-12 (612.3 pg/ml, IQR 570.2–1353.7 vs. 516.4 pg/mL, IQR 474.5–591.2; p = 0.023). Four patients with low adalimumab levels (19%) and four treated with intensified doses were admitted to a hospital during a follow-up compared to none of the patients with levels within the range.Conclusion: Patients with Crohn’s disease treated with infliximab and adalimumab exhibit differences in serum levels of cytokines depending on the drug, dose intensification, and steady state trough serum levels.

Serum trough levels of infliximab are not associated with peripheral arthralgia activity in patients with inflammatory bowel disease

BackgroundInfliximab is an efficacious therapy for inflammatory bowel disease and may play a role in management of some extraintestinal manifestations. While higher trough levels of infliximab are associated with higher rates of disease remission, the association between trough levels of infliximab and arthralgia activity characterised as an extraintestinal manifestation has yet to be defined.ObjectiveWe aimed to assess the association between serum trough levels of infliximab and peripheral arthralgia activity in patients with inflammatory bowel disease.DesignIn this cross-sectional study, we identified patients with inflammatory bowel disease on infliximab therapy with known history of arthralgias attributed to an extraintestinal manifestation. Collected variables included disease phenotype, medications (such as thiopurines or methotrexate), Harvey Bradshaw Index, partial Mayo score, C reactive protein, trough levels of infliximab and anti-infliximab antibodies. The primary outcome was active patient-reported arthralgia.ResultsOut of 267 patients included, 65 (24.4%) had active arthralgias at the time the trough level of infliximab was measured. No significant differences in trough levels were seen between those patients with and without arthralgias. Patients on combination therapy with methotrexate or thiopurines or those with detectable anti-infliximab antibodies were not more likely to have inactive arthralgias (OR 0.99, 95% CI 0.57 to 1.74, p=0.99 and OR 1.94, 95% CI 0.9 to 4.1, p=0.09, respectively).ConclusionsThis study suggests that although therapeutic drug monitoring of infliximab can have a role in the management of Crohn’s disease and ulcerative colitis, it does not seem to be useful in managing arthralgias associated with inflammatory bowel disease.

Vancomycin-induced nephrotoxicity in non-intensive care unit pediatric patients

Previous data suggested several risk factors for vancomycin-induced nephrotoxicity (VIN), including higher daily dose, long-term use, underlying renal disease, intensive care unit (ICU) admission, and concomitant use of nephrotoxic medications. We conducted this study to investigate the prevalence and risk factors of VIN and to estimate the cut-off serum trough level for predicting acute kidney injury (AKI) in non-ICU pediatric patients. This was a retrospective, observational, single-center study at Samsung Medical Center tertiary hospital, located in Seoul, South Korea. We reviewed the medical records of non-ICU pediatric patients, under 19 years of age with no evidence of previous renal insufficiency, who received vancomycin for more than 48 h between January 2009 and December 2018. The clinical characteristics were compared between patients with AKI and those without to identify the risk factors associated with VIN, and the cut-off value of serum trough level to predict the occurrence of VIN was calculated by the Youden’s index. Among 476 cases, 22 patients (4.62%) developed AKI. The Youden’s index indicated that a maximum serum trough level of vancomycin above 24.35 μg/mL predicted VIN. In multivariate analysis, longer hospital stay, concomitant use of piperacillin-tazobactam and serum trough level of vancomycin above 24.35 μg/mL were associated independently with VIN. Our findings suggest that concomitant use of nephrotoxic medication and higher serum trough level of vancomycin might be associated with the risk of VIN. This study suggests that measuring serum trough level of vancomycin can help clinicians prevent VIN in pediatric patients.

Possible inhibitory effects of terbinafine on aripiprazole metabolism: Two case reports

Aripiprazole, an atypical antipsychotic, is a metabolic substrate for cytochrome P450 (CYP)3A4 and 2D6. Terbinafine, an antifungal agent used for onychomycosis, is a CYP2D6 inhibitor and could theoretically reduce the metabolism of aripiprazole. However, there are no published reports describing this interaction. We present 2 female patients hospitalized in a psychiatric unit who were both taking aripiprazole 15 mg daily and terbinafine 250 mg daily prior to admission. The first patient was a 58-year-old female who was prescribed aripiprazole and terbinafine concomitantly for approximately 5 months prior to admission. A commercial pharmacogenetic testing platform classified this patient as a normal metabolizer for CYP3A4 and 2D6. The first patient's serum trough aripiprazole concentration at steady-state concentration (Css) was 207.5 ng/mL. The second patient was a 43-year-old female who was taking aripiprazole and terbinafine concomitantly for approximately 2 weeks prior to admission who had a Css aripiprazole concentration of 278.9 ng/mL. Aripiprazole has a wide therapeutic range (100 to 350 ng/mL) and a reference dose-related drug concentration of 11.7 (mean) ± 5.6 (SD) ng/mL/mg/d. Our patients had Css aripiprazole concentrations 18% and 59% higher than guideline-supported dose-related drug concentrations. Through the use of therapeutic drug monitoring, pharmacogenetic data, electronic pharmaceutical claims data, and the Drug Interaction Probability Scale, we suggest terbinafine possibly increases aripiprazole concentrations 18% to 59%. Further reports are needed to confirm these findings prior to using this information in clinical practice.

Levetiracetam Therapeutic Drug Monitoring in a Large Cohort of Korean Epileptic Patients

Levetiracetam is a new antiepileptic drug (AED) used for treating and preventing partial or generalized seizures. The usefulness of levetiracetam therapeutic drug monitoring (TDM) is related to inter- or intra-individual pharmacokinetic variability, drug interactions, and patient noncompliance. We aimed to investigate the levetiracetam TDM status in Korean epilepsy patients. Serum trough levetiracetam concentrations were measured using liquid chromatography–tandem mass spectrometry in 710 samples from 550 patients. The median (range) daily and weight-adjusted levetiracetam doses were 1500 (20–5000) mg and 25.5 (3.03–133.0) mg/kg, respectively. Patients on levetiracetam monotherapy constituted only 19.5% of the population, while 30.1% were on co-medication with valproate and 56.0% with enzyme-inducing AEDs (EIAEDs). Observed levetiracetam concentrations were widely distributed, ranging 0.8–95 mg/L, with a median of 17.3 mg/L. Levetiracetam concentrations were therapeutic, supra-therapeutic, and sub-therapeutic in 58.5% (n = 393), 11.6% (n = 78), and 29.9% (n = 201) of samples, respectively. There was a strong correlation between weight-adjusted levetiracetam dosage and concentrations (ρ = 0.6896, p < 0.0001). In this large-scale clinical study, a large inter-individual difference in levetiracetam pharmacokinetics was observed, and levetiracetam concentrations were influenced by EIAEDs. For individual dose adjustments and monitoring compliance, routine levetiracetam TDM is needed in epilepsy patients.

Successful Treatment of Invasive MRSA Infections in Children Using Area Under the Vancomycin Concentration-Time Curve Divided by the Minimum Inhibitory Concentration (AUC/MIC) to Measure Vancomycin Exposure

Background: Vancomycin is the treatment of choice for invasive methicillin-resistant Staphylococcus aureus (MRSA) infections. Previous guidelines issued by the Infectious Diseases Society of America (IDSA) recommended targeting vancomycin serum trough concentrations of 15–20 mg/L; however, troughs <15 mg/L are also associated with increased odds of renal toxicity. To minimize toxicity, recently updated ASHP/IDSA/PIDS vancomycin dosing guidelines recommend the use of an area under the vancomycin concentration-time curve divided by the minimum inhibitory concentration (AUC/MIC) pharmacodynamic index to measure vancomycin exposure, with an AUC/MIC ratio >400 correlating with clinical efficacy. However, data on vancomycin therapeutic drug monitoring (TDM) in children are limited. Our institutional practice since January 2009 has been to use AUC/MIC, rather than serum trough concentrations, to guide vancomycin dosing. In this study, we describe clinical outcomes in vancomycin-treated children with invasive MRSA infections using this dosing method. Methods: We performed a retrospective chart review of children hospitalized with invasive MRSA infections between 2006 and 2019 at Rady Children’s Hospital in San Diego, California. Clinical, microbiologic, and pharmacologic data including the site of MRSA infection, clinical failure or cure, occurrence of acute kidney injury (AKI), vancomycin MIC, vancomycin AUC, and serum trough concentrations were collected. Results: In total, 61 invasive MRSA cases were reviewed: 20 were admitted January 2016 through December 2008, and 41 were admitted January 2009 through June 2019 (Figure 1). Most patients did not have medical comorbidities. The most common types of infections were primary bacteremia (34%) and osteomyelitis (32%). Of 61 children, 50 (82%) had positive clinical outcomes regardless of vancomycin dosing method. Of 20 patients, 8 (40%) admitted prior to January 2009 developed AKI, compared with 5 (12%) of 41 patients admitted after January 2009. Conclusions: In our retrospective review, most patients had clinically successful outcomes regardless of which dosing strategy was used. We found higher rates of renal toxicity in patients who were admitted prior to 2009, with TDM based on measuring peak and trough concentrations, compared with those using AUC/MIC for TDM. Our findings suggest that AUC/MIC TDM for invasive MRSA infections may be associated with lower rates of renal toxicity.Funding: NoDisclosures: None

Efficacy of Everolimus Low-Dose Treatment for Cardiac Rhabdomyomas in Neonatal Tuberous Sclerosis: Case Report and Literature Review

Background: Cardiac rhabdomyomas (CRs) are the most common cardiac tumors in newborns. Approximately 80–90% of cases are associated with tuberous sclerosis complex (TSC). In selective cases, Everolimus has resulted in a remarkable tumoral regression effect in children with TS. The optimal dosage for neonates is still unknown. Case presentation: We describe the use of Everolimus in a neonate with multiple biventricular CRs, causing subaortic obstruction, in which a low-dose treatment (0.1 mg/die), in an effort to maintain serum trough levels of 3–7 ng/mL, was successfully used off-label, without adverse effects. Conclusions: We showed that a low-dose Everolimus regimen may be an effective and safe treatment for CR regression in TS neonates, when the minimum therapeutic range was maintained.

#50: Vancomycin Doses and Trough Concentrations in Pediatric Patients

Background Vancomycin serum trough concentrations are monitored to reduce nephrotoxicity and optimize therapeutic efficacy. Vancomycin pharmacokinetics and trough levels used in pediatric patients are extrapolated from the adult population. The pediatric dosing strategies are empirical and there is limited evidence to suggest that these doses result in the recommended steady-state trough concentrations. The objective of the study was to determine the association between vancomycin dosing regimens and trough concentrations levels of 10 to 20 μg/mL in pediatric patients with complicated infections. Methods Retrospective cohort, 505 trough vancomycin serum concentrations of patients of 1 month to 18 years from hospital wards and the Intensive Care Unit of the Instituto Nacional de Salud del Niño San Borja during December 2015 to April 2019. It included only the first vancomycin trough level measured 30 minutes before the fourth doses and serum trough concentrations of 10 to 20 μg/mL were considered as therapeutic levels. A multinomial logistic regression model to estimate the relative risk ratio (RRR) with a 95% confidence interval was used, the comparator group was therapeutic vancomycin levels and it was adjusted by glomerular filtration rate, age group, hospital room, dose interval, and weight. Results Five hundred and five vancomycin dosages were analyzed. Infants and children were 43.12% and 39.22%, respectively, 45.17% were women. 56.77% had a high glomerular filtration rate and only 28.02% of the patients obtained therapeutic trough levels of vancomycin. The RRR of having sub-therapeutic levels in patients with low glomerular filtration rates compared with normal filtration rates was 0.31 (P = 0.049) and the RRR of having sub-therapeutic levels in patients from 2 to 12 years compared with patients under 2 years old was 2.38 (P = 0.007). There was no difference in having therapeutic levels using doses equal or greater than 60 mg/kg/day vs. less than 40 mg/kg/day comparing sub-therapeutic levels (P = 0.655) and supratherapeutic levels (P = 0.264). Conclusions The empirical vancomycin regimens used in pediatric patients did not reach the recommended therapeutic trough levels of 10 to 20 μg/mL. Patients of 2 to 12 years and low glomerular filtration rates were associated to have sub-therapeutic trough levels.