Figure 4.

Memantine amount excreted in urine within each urine sampling period (ΔU/Δt) per hour vs memantine concentration in plasma at the midpoint of the same sampling period for the respective regimens A–D. (•) Regimen A: acidic urine pH, low urinary flow; (○) Regimen B: acidic urine pH, high urinary flow; (▪) Regimen C: alkaline urine pH, low urinary flow; (□) Regimen D: alkaline urine pH, high urinary flow. No dependence of CL_R on memantine plasma concentration could be detected, as the correlation of ΔU/Δtvs plasma concentration at the midpoint of the sampling period can be described by linear regression in accordance with first order kinetics.