library(ggplot2)
des2CMTbolus <- function(t,y,p){
  with(as.list(c(p,y)), {
    V1  <- 1 / (C1 + C2)
    K21 <- (C1 * L2 + C2 * L1) / (C1 + C2)
    K10 <- L1 * L2 / K21
    K12 <- L1 + L2 - K21 - K10

    DADT1 = A2 * K21 - A1 * (K10 + K12)
    DADT2 = A1 * K12 - A2 * K21

    CP     <- A1/V1
    list(c(DADT1,DADT2),c(CP=CP))
  })
}
pars   <- c(C1=10,L1=1,C2=2,L2=0.2)
init   <- c(A1=0,A2=0)
events <- dose_func(cmt=1,value=10,times=0)
times  <- seq(0,24,length.out=200)
out    <- as.data.frame(deSolve::lsoda(init,times,des2CMTbolus, pars,events=list(data=events)))
out    <- reshape2::melt(out,id='time')
ggplot(out,aes(time,value)) + geom_line() + facet_wrap(~variable,scales='free')
