Bioequivalence and Bioavailability Forum

Calculation of time above MIC [🇷 for BE/BA]

posted by Aceto81 – Belgium, 2008-06-30 17:50 (5768 d 14:26 ago) – Posting: # 1988
Views: 33,097

Hi HS,

the time above MIC was calculated during the Steady State, which goes from 12 hours to 120 hours. That's why the results differs. (I was struggling with this part as well ).

Here the updated code:
time <- c(0.5, 1, 3, 5, 8, 12, 24, 36, 48, 60,
          72, 84, 96, 108, 120, 122, 124)
conc <- c(0.64, 0.7, 1.39, 1.35, 0.67, 1.48, 0.32, 2.08, 0.87, 0.93,
          1.09, 0.59, 1.01, 0.47, 0.99, 0.62, 0.13)
dat  <- data.frame(time, conc)

f <- function(dat, th) {
  under <- 0
  for (i in which(dat$conc < th)) {
      if (!is.na(dat$conc[i-1])) {
        y <- dat$conc[c(i-1,i)]
        x <- dat$time[c(i-1,i)]
        slope <- coef(lm(y~x))[2]
        under <- under + x[2]-x[1]-(th-y[1])/slope
      }
      if (!is.na(dat$conc[i+1])) {
        y <- dat$conc[c(i,i+1)]
        x <- dat$time[c(i,i+1)]
        slope <- coef(lm(y~x))[2]
        under <- under + (th-y[1])/slope
      }
    }
  return(under)
}

th    <- 0.517
first <- 12
last  <- 120
occupancy <- last-first - f(dat[dat$time >=first & dat$time <=last, ], th)
coverage  <- 100*occupancy/(last-first)
cat(" Time point interval:",first,"-",last,"\n",
    "Occupancy time:",occupancy,"\n",
    "Coverage:",coverage,"%\n")

Thanks for your valuable input

Ace

Complete thread:

• Calculation of time above MIC Aceto81 2008-06-26 16:31 [🇷 for BE/BA] 
  • Calculation of time above MIC Helmut 2008-06-26 18:58
    • Calculation of time above MIC Aceto81 2008-06-26 21:50
      • Calculation of time above MIC Helmut 2008-06-27 00:18
      • Calculation of time above MIC Helmut 2008-06-29 02:24
        • Calculation of time above MICAceto81 2008-06-30 15:50
          • Therapeutic Occupancy Time / MEC Helmut 2008-06-30 16:45
    • Time above MIC (WinNonlin 5.2.1) Helmut 2008-08-08 20:38
      • Time above MIC (WinNonlin 5.2.1) Aceto81 2008-08-12 09:56
        • Time above MIC (WinNonlin 5.2.1) Helmut 2008-08-12 12:32
          • Time above MIC (R function) Aceto81 2008-08-13 11:19
            • Time above MIC (R function) Helmut 2008-08-13 13:18
              • Time above MIC (R function) Aceto81 2008-08-13 15:35
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            • Phoenix-WinNonlin 6.0 Helmut 2009-06-04 11:57
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