RESUMEN
AIMS: Previously, we have reported an association between clozapine use and elevated FL3 neutrophil fluorescence, a flow-cytometric parameter for cell viability. Here, we developed and evaluated a pharmacokinetic-pharmacodynamic model relating FL3-fluorescence to clozapine exposure and derived a nomogram for estimation of long-term adherence. METHODS: Data from 27 patients initiating clozapine were analysed using nonlinear mixed effects modelling. A previously described pharmacokinetic model for clozapine was coupled to a FL3 fluorescence model. For this, an effect compartment with clozapine concentrations as input and a first order decay rate as output was linked with an Emax model to FL3-fluorescence. FL3-fluorescence was simulated for clozapine doses of 50, 150 and 400 mg daily (n = 10 000) to establish the nomogram. Finally, true simulated adherence (% of daily doses taken over 100 days) was compared to nomogram-estimated adherence to evaluate the performance of the nomogram. RESULTS: The half-life of FL3-fluorescence was estimated at 228 h (coefficient of variation 35%). Median absolute prediction errors of the nomogram in case of fully random adherence for 50, 150 and 400 mg ranged from -0.193% to -0.525%. The nomogram performed slightly worse in case of nonrandom adherence (median prediction error up to 5.19%), but was still clinically acceptable. Compliance patterns containing longer drug holidays revealed that the nomogram adequately estimates compliance over approximately the last 3 weeks prior to FL3-measurement. CONCLUSION: Our nomogram could provide information regarding long-term adherence based on prescribed clozapine dose and FL3-fluorescence. Future studies should further explore the clinical value of this biomarker and nomogram.
Asunto(s)
Antipsicóticos/uso terapéutico , Clozapina/uso terapéutico , Monitoreo de Drogas/métodos , Cumplimiento de la Medicación , Neutrófilos/efectos de los fármacos , Nomogramas , Adolescente , Adulto , Antipsicóticos/farmacocinética , Clozapina/farmacocinética , Bases de Datos Factuales , Femenino , Citometría de Flujo , Humanos , Masculino , Modelos Biológicos , Dinámicas no Lineales , Valor Predictivo de las Pruebas , Factores de Tiempo , Adulto JovenRESUMEN
BACKGROUND: The long-term impact of pneumococcal conjugate vaccines on pneumonia hospitalizations in all age-groups varies between countries. In the Netherlands, the 7-valent pneumococcal conjugate vaccine (PCV7) was implemented for newborns in 2006 and replaced by PCV10 in 2011. We assessed the impact of PCVs on community-acquired pneumonia (CAP) hospitalization rates in all age-groups. METHODS: A time series analysis using Poisson regression was performed on 155,994 CAP hospitalizations. Hospitalization rates were calculated using the total number of hospitalizations as denominator. The time trend in the pre-PCV period (1999-2006) was extrapolated to predict the hospitalization rate in the post-PCV period (2006-2014) if PCV had not been implemented. Rate ratios over time were calculated by comparing observed and predicted time trends. RESULTS: In children <5â¯years of age, the observed hospitalization rates during the post-PCV period were significantly lower than predicted if PCV had not been implemented (0-6â¯months: 0.62, 95% CI: 0.41-0.96; 6â¯months - 1â¯year: 0.67, 95% CI: 0.50-0.90; 2-4â¯years: 0.78, 95% CI: 0.61-0.97). In all other age-groups, rate ratios declined over time but did not reach statistical significance. CONCLUSIONS: After introduction of PCV, CAP hospitalizations declined in young children but no clear impact of PCV on CAP hospitalizations was seen in other age-groups.