Pharmacokinetic-pharmacodynamic modelling and simulation of methotrexate dosing in patients with rheumatoid arthritis.

AIMS: To develop a non-linear mixed-effects population pharmacokinetic and pharmacodynamic (PK-PD) model describing the change in the concentration of methotrexate polyglutamates in erythrocytes (ery-MTX-PGn with "n" number of glutamate, representing PK component) and how this relates to modified 28-joint Disease Activity Score incorporating erythrocyte sedimentation rate (DAS-28-3) for rheumatoid arthritis (RA), representing PD component. METHODS: An existing PK model was fitted to data from a study consisting of 117 RA patients. The estimation of population PK-PD parameters was performed using stochastic approximation expectation maximisation algorithm in Monolix 2021R2. The model was used to perform Monte Carlo simulations of a loading dose regimen (50mg subcutaneous methotrexate as loading doses, then 20mg weekly oral methotrexate) compared to a standard dosing regimen (10mg weekly oral methotrexate for 2 weeks, then 20mg weekly oral methotrexate). RESULTS: Every 40 nmol/L increase in ery-MTX-PG3-5 total concentration correlated with 1-unit reduction in DAS-28-3. Significant covariate effects on the therapeutic response of methotrexate included the use of prednisolone in the first 4 weeks (positive use correlated with 25% reduction in DAS-28-3 when other variables were constant) and patient age (every 10-year increase in age correlated with 3.4% increase in DAS-28-3 when other variables were constant). 4 methotrexate loading doses led to a higher percentage of patients achieving a good/moderate response compared to the standard regimen (Week 4: 87.6% vs. 39.8%; Week 10: 64.7% vs. 57.0%). CONCLUSIONS: A loading dose regimen was more likely to achieve higher ery-MTX-PG concentration and better therapeutic response after 4 weeks of methotrexate treatment.

Comparative Risk of Gout Flares When Initiating or Escalating Various Urate-Lowering Therapy: A Systematic Review With Network Meta-Analysis.

OBJECTIVE: We systematically examined comparative gout flare risk after initiation or escalation of different urate-lowering therapies (ULTs), comparative flare risk with and without concomitant flare prophylaxis, adverse event rates associated with flare prophylaxis, and optimal duration of flare prophylaxis. METHODS: We searched the Medline, Embase, Web of Science, and Cochrane databases and clinical trial registries from inception to November 2021 for trials investigating adults with gout initiating or escalating ULT. We performed random effects network meta-analyses and calculated risk ratios (RRs) between treatments. Bias was assessed using the revised Cochrane risk-of-bias tool. RESULTS: We identified 3,775 records, of which 29 publications (27 trials) were included. When compared to placebo plus prophylaxis, the RR of flares ranged from 1.08 (95% confidence interval [CI] 0.87-1.33) for febuxostat 40 mg plus prophylaxis to RR 2.65 [95% CI 1.58-4.45] for febuxostat 80 mg plus lesinurad 400 mg plus prophylaxis. Compared to ULT alone, the RR of flares was lower for ULT plus rilonacept 160 mg (RR 0.35 [95% CI 0.25-0.50]), ULT plus rilonacept 80 mg (RR 0.43 [95% CI 0.31-0.60]) and ULT plus colchicine (RR 0.50 [95% CI 0.35-0.72]). There was limited evidence for other flare prophylaxis and on prophylaxis harms and optimal duration. Primarily because of missing outcome data and bias in the selection of reported results, 71.4% and 63.4% of studies were assessed as high risk of bias for flares and adverse events, respectively. CONCLUSION: The RR of flares when introducing ULT varies depending on ULT drug and dosing strategies. There were limited data on ULT escalation. Flare prophylaxis with colchicine and rilonacept reduces flare incidence. More research is required on the harms and optimal duration of prophylaxis.

Barriers and Enablers in the Use of Parenteral Methotrexate in Rheumatoid Arthritis Patients: A Scoping Review.

OBJECTIVE: Methotrexate (MTX) is effective in controlling disease activity in rheumatoid arthritis (RA). Parenteral MTX may have benefits over oral MTX, but it is rarely used in practice. To better understand this low usage rate, it is necessary to explore the barriers and enablers of therapy from the perspective of RA patients. The objectives of this scoping review were to describe RA patients' perspectives on the barriers and enablers in the use of parenteral MTX and to identify the research gaps in this field. METHODS: The search was performed in Medline, Embase, Scopus, and Cochrane Library from inception to May 2021. Data synthesis was conducted using the Theoretical Framework of Acceptability. This scoping review included any type of study that explored the use of parenteral MTX by adult RA patients from the patients' perspective, written in English. RESULTS: Fifteen studies were included; findings related to the constructs "affective attitude," "burden," "intervention coherence," and "self-efficacy" were explored the most, while some were rarely ("opportunity cost" and "perceived effectiveness") or not ("ethicality") reported. RA patients were generally satisfied with MTX injections ("affective attitude"). From the burden construct, the requirement for dexterity for administering MTX by injection was considered a barrier, whereas the lack of significant pain from MTX injection was considered an enabler. CONCLUSION: The findings suggested that patients generally preferred parenteral MTX formulations with attributes that facilitate self-administration. However, much of the identified research focused on prefilled pen devices, and significant gaps were identified, such as a lack of qualitative research.

The Association between Proton Pump Inhibitors and Myocardial Infarction: What Do Food and Drug Administration Data Tell Us?

OBJECTIVE: There is limited and conflicting evidence on the association between proton pump inhibitors (PPIs) and myocardial infarction (MI). This study aims to examine the occurrence of MI associated with PPI use from the Food and Drug Administration (FDA) Adverse Event Reporting System database. METHODS: This is a cross-sectional study using data from the FDA dated from December 2013 to April 2018. Standard descriptive statistics were used to describe demographic information. Logistic regression analyses were performed to investigate the association between the independent variables and MI. FINDINGS: Among the 52,443 individuals who were taking a PPI and experienced an adverse event which was registered on the FDA database, 726 (1.38%) experienced MI. Of all the PPIs, esomeprazole had the largest proportion of users experiencing MI (1.81%). Compared to other PPIs, esomeprazole was associated with a significantly higher rate of MI (odds ratio [OR] =1.53, P < 0.001), whereas lansoprazole was associated with a lower rate of MI (OR = 0.74, P = 0.03). CONCLUSION: Among the PPIs, esomeprazole appeared to have the highest risk of MI. Although the observed associations do not infer causality, this study highlighted a need for further studies to determine if a PPI, especially esomeprazole, can indeed cause MI.