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High‐dose (HD) methotrexate (MTX) is a critical component of treatment for hematologic malignancies in children and young adults. Therapeutic drug monitoring is necessary due to substantial interindividual variation in MTX clearance. Common function‐altering polymorphisms in SLCO1B1 (encodes OATP1B1, which transports MTX) may contribute to clearance variability. We performed pharmacokinetic modeling using data for 106 children and young adults treated with HD MTX for hematologic malignancies; of 396 total courses of HD MTX, 360 consisted of 5 g/m2 over 24 hours. We evaluated the contribution of clinical covariates and SLCO1B1 genotype (388A>G and 521T>C) to MTX clearance variability. Of the clinical covariates studied, patient weight improved the pharmacokinetic model most significantly (P < 0.001). The addition of the SLCO1B1 variants individually further improved the model (P < 0.05 for each). An interaction between these variants was suggested when both were included (P = 0.017). SLCO1B1 genotype should be considered in efforts to personalize HD MTX dosing. [ABSTRACT FROM AUTHOR]

Objective: This study was undertaken to investigate the hypothesis that a genetic predisposition toward rheumatoid arthritis (RA) increases the risk of 10 cardiometabolic and autoimmune disorders previously associated with RA in epidemiologic studies, and to define new genetic pleiotropy present in RA. Methods: Two approaches were used to test our hypothesis. First, we constructed a weighted genetic risk score (wGRS) and then examined its association with 10 prespecified disorders. Additionally, a phenome‐wide association study (PheWAS) was carried out to identify potential new associations. Second, inverse variance–weighted regression (IVWR) meta‐analysis was used to characterize the association between genetic susceptibility to RA and the prespecified disorders, with the results expressed as odds ratios (ORs) and 95% confidence intervals (95% CIs). Results: The wGRS for RA was significantly associated with type 1 diabetes mellitus (DM) (OR 1.10 [95% CI 1.04–1.16]; P = 9.82 × 10−4) and multiple sclerosis (OR 0.82 [95% CI 0.77–0.88]; P = 1.73 × 10−8), but not with other cardiometabolic phenotypes. In the PheWAS, wGRS was also associated with an increased risk of several autoimmune phenotypes including RA, thyroiditis, and systemic sclerosis, and with a decreased risk of demyelinating disorders. In the IVWR meta‐analyses, RA was significantly associated with an increased risk of type 1 DM (P = 1.15 × 10−14), with evidence of horizontal pleiotropy (Mendelian Randomization–Egger intercept estimate P = 0.001) likely driven by rs2476601, a PTPN22 variant. The association between type 1 DM and RA remained significant (P = 9.53 × 10−9) after excluding rs2476601, with no evidence of horizontal pleiotropy (intercept estimate P = 0.939). RA was also significantly associated with type 2 DM and C‐reactive protein levels. These associations were driven by variation in the major histocompatibility complex region. Conclusion: This study presents evidence of pleiotropy between the genetic predisposition to RA and associated phenotypes found in other autoimmune and cardiometabolic disorders, including type 1 DM. [ABSTRACT FROM AUTHOR]

Chronic kidney disease (CKD) is often complicated by difficult-to-control hypertension, in part due to chronic overactivation of the sympathetic nervous system (SNS). CKD patients also exhibit a greater increase in arterial blood pressure for a given increase in sympathetic nerve activation, suggesting an augmented vasoconstrictive response to SNS activation (i.e., neurovascular transduction). One potential mechanism of increased sympathetic neurovascular transduction is heightened sensitivity of the vascular α1-adrenergic receptors (α1ARs), the major effectors of vasoconstriction in response to norepinephrine release at the sympathetic nerve terminals. Therefore, we hypothesized that patients with CKD have increased vascular α1AR sensitivity. We studied 32 patients with CKD stages III and IV (age 59.9 ± 1.3 yr) and 19 age-matched controls (CON, age 63.2 ± 1.6 yr). Using a linear variable differential transformer (LVDT), we measured change in venoconstriction in response to exponentially increasing doses of the selective α1AR agonist phenylephrine (PE) administered sequentially into a dorsal hand vein. Individual semilogarithmic PE dose-response curves were constructed for each participant to determine the PE dose at which 50% of maximum venoconstriction occurred (ED50), reflecting α1AR sensitivity. In support of our hypothesis, CKD patients had a lower PE ED50 than CON (CKD = 2.23 ± 0.11 vs. CON = 2.63 ± 0.20, P = 0.023), demonstrating increased vascular α1AR sensitivity. Additionally, CKD patients had a greater venoconstrictive capacity to PE than CON (P = 0.015). Augmented α1AR sensitivity may contribute mechanistically to enhanced neurovascular transduction in CKD and may explain, in part, the greater blood pressure reactivity exhibited in these patients. [ABSTRACT FROM AUTHOR]

Background Although evidence from animal and human studies indicates opioid analgesics increase susceptibility to infections, it is unclear whether the risk varies by specific opioid. We compared the risk of serious infection among patients initiating long-acting opioid analgesics with and without previously reported immunosuppressive properties. Methods We conducted a retrospective cohort study of Tennessee Medicaid enrollees age ≥18 years initiating long-acting opioids (1995–2015). Hospitalizations for serious infection were identified using validated coding algorithms. We used multivariable Poisson regression models to calculate adjusted incidence rate ratios (aIRR) and 95% confidence intervals (CI) to compare the infection risk among patients using long-acting opioids with known immunosuppressive properties (morphine, fentanyl, methadone) to the infection risk among patients using long-acting opioids without known immunosuppressive properties (oxycodone, oxymorphone, tramadol) accounting for demographics, opioid dose, comorbidities and pain conditions, medication use, frailty indicators, and healthcare encounter history using exposure propensity scores. We further compared users of individual long-acting opioids to long-acting morphine users (considered the prototypical immunosuppressive opioid). Results Among the 61 240 patients initiating opioids with immunosuppressive properties and 22 811 patients initiating opioids without immunosuppressive properties, we identified 1906 serious infections. Nonimmunosuppressive opioid users had a lower rate of infections than immunosuppressive opioid users (aIRR:0.78 [CI: 0.66–0.91]). Among individual opioids, oxycodone users had a lower rate of infection than morphine users (aIRR:0.73 [CI: 0.60–0.89]). There were no significant differences in the infection risk between other opioids and morphine. Conclusion The risk of serious infections among long-acting opioid users varies by opioid type. Providers should carefully consider the risk of serious infections when making pain management decisions. [ABSTRACT FROM AUTHOR]

Tizanidine, a widely used muscle relaxant that can lower blood pressure, is metabolized by the cytochrome P450 1A2 (CYP1A2). We studied 1,626 patients prescribed tizanidine and 5,012 prescribed cyclobenzaprine concurrently with a strong CYP1A2 inhibitor. The primary outcome was severe hypotension, defined as systolic blood pressure (SBP) ≤ 70 mmHg during periods of drug co‐exposure. Severe hypotension occurred more often in the tizanidine group (2.03%; n = 33) than the cyclobenzaprine group (1.28%; n = 64); odds ratio (OR) = 1.60; P = 0.029. This difference remained statistically significant after adjustment for a log‐transformed propensity score that included age, sex, race, Charlson's comorbidity index, and concurrent use of antihypertensive medications (OR = 1.57; P = 0.049). A sensitivity analysis that defined hypotension as SBP < 90 mmHg also yielded higher rates of hypotension among patients prescribed tizanidine. In conclusion, CYP1A2 inhibition increases the risk of hypotensive episodes associated with the use of tizanidine in routine clinical practice. [ABSTRACT FROM AUTHOR]

Purpose Despite significant growth of opioid prescriptions, only limited data are available regarding the comparative safety of long‐acting opioids for chronic non‐cancer pain. Recent data suggest that transdermal fentanyl and oxycodone CR may have greater toxicity than morphine SR in patients with non‐cancer pain. Thus, we compared the risk of out‐of‐hospital deaths in patients with non‐cancer pain filling prescriptions for transdermal fentanyl or oxycodone CR with that for morphine SR. Methods: We conducted a retrospective cohort study in 50 658 patients enrolled in Tennessee Medicaid who filled prescriptions for transdermal fentanyl (n = 8717), oxycodone CR (n = 14 118), or morphine SR (n = 27 823) between 1999 and 2011. We excluded individuals with cancer or other life‐threatening diagnoses and used propensity scores to adjust for multiple potential confounders. The primary outcome was out‐of‐hospital mortality. Results: During 44 385 person‐years of follow‐up, 689 patients died. The out‐of‐hospital mortality rate among all study subjects was 155/10 000 patient‐years. Contrary to earlier data suggesting greater risk, mortality was not significantly different in patients filling prescriptions for transdermal fentanyl compared with morphine SR (adjusted HR = 0.96, 95% C.I.: 0.77‐1.21); moreover, patients filling prescriptions for oxycodone CR had lower mortality risk compared with those filling prescriptions for morphine SR (adjusted HR = 0.79, 95% C.I. 0.66‐0.95). Conclusion: In the study population, long‐acting opioids for non‐cancer pain were associated with high out‐of‐hospital mortality rates. We found comparable out‐of‐hospital mortality risks associated with transdermal fentanyl and morphine SR. The risk of out‐of‐hospital death for oxycodone CR was lower than that for morphine SR. [ABSTRACT FROM AUTHOR]

This cohort study assesses the association of diltiazem with risk of serious bleeding compared with metoprolol in older adults with atrial fibrillation receiving apixaban or rivaroxaban. Key Points: Question: Do patients with atrial fibrillation receiving apixaban or rivaroxaban and concurrently treated for ventricular rate control with diltiazem have greater risk of serious bleeding than those treated with metoprolol? Findings: In this cohort study of 204 155 patients aged 65 years or older, those treated with diltiazem had a significantly greater risk of serious bleeding compared with those treated with metoprolol. Meaning: Among older adults with atrial fibrillation receiving apixaban or rivaroxaban, treatment with diltiazem was associated with increased risk of serious bleeding compared with metoprolol. Importance: Diltiazem, a commonly prescribed ventricular rate–control medication for patients with atrial fibrillation, inhibits apixaban and rivaroxaban elimination, possibly causing overanticoagulation. Objective: To compare serious bleeding risk for new users of apixaban or rivaroxaban with atrial fibrillation treated with diltiazem or metoprolol. Design, Setting, and Participants: This retrospective cohort study included Medicare beneficiaries aged 65 years or older with atrial fibrillation who initiated apixaban or rivaroxaban use and also began treatment with diltiazem or metoprolol between January 1, 2012, and November 29, 2020. Patients were followed up to 365 days through November 30, 2020. Data were analyzed from August 2023 to February 2024. Exposures: Diltiazem and metoprolol. Main Outcomes and Measures: The primary outcome was a composite of bleeding-related hospitalization and death with recent evidence of bleeding. Secondary outcomes were ischemic stroke or systemic embolism, major ischemic or hemorrhagic events (ischemic stroke, systemic embolism, intracranial or fatal extracranial bleeding, or death with recent evidence of bleeding), and death without recent evidence of bleeding. Hazard ratios (HRs) and rate differences (RDs) were adjusted for covariate differences with overlap weighting. Results: The study included 204 155 US Medicare beneficiaries, of whom 53 275 received diltiazem and 150 880 received metoprolol. Study patients (mean [SD] age, 76.9 [7.0] years; 52.7% female) had 90 927 person-years (PY) of follow-up (median, 120 [IQR, 59-281] days). Patients receiving diltiazem treatment had increased risk for the primary outcome (RD, 10.6 [95% CI, 7.0-14.2] per 1000 PY; HR, 1.21 [95% CI, 1.13-1.29]) and its components of bleeding-related hospitalization (RD, 8.2 [95% CI, 5.1-11.4] per 1000 PY; HR, 1.22 [95% CI, 1.13-1.31]) and death with recent evidence of bleeding (RD, 2.4 [95% CI, 0.6-4.2] per 1000 PY; HR, 1.19 [95% CI, 1.05-1.34]) compared with patients receiving metoprolol. Risk for the primary outcome with initial diltiazem doses exceeding 120 mg/d (RD, 15.1 [95% CI, 10.2-20.1] per 1000 PY; HR, 1.29 [95% CI, 1.19-1.39]) was greater than that for lower doses (RD, 6.7 [95% CI, 2.0-11.4] per 1000 PY; HR, 1.13 [95% CI, 1.04-1.24]). For doses exceeding 120 mg/d, the risk of major ischemic or hemorrhagic events was increased (HR, 1.14 [95% CI, 1.02-1.27]). Neither dose group had significant changes in the risk for ischemic stroke or systemic embolism or death without recent evidence of bleeding. When patients receiving high- and low-dose diltiazem treatment were directly compared, the HR for the primary outcome was 1.14 (95% CI, 1.02-1.26). Conclusions and Relevance: In Medicare patients with atrial fibrillation receiving apixaban or rivaroxaban, diltiazem was associated with greater risk of serious bleeding than metoprolol, particularly for diltiazem doses exceeding 120 mg/d. [ABSTRACT FROM AUTHOR]