Bioequivalence and Bioavailability Forum

Hi Helmut,

I have a question on R, excuse me for being a novice.. I just started using it :)

❝ I tried to implement PK model I (one-compartment open, lag-time):

❝ parameter                  distribution  mean      CV(%)  truncation

❝ Volume of distribution     log-normal    1         10

...

❝ V.d    <- 1        # volume of distribution

❝ V.c    <- 0.1      # CV 10%, lognormal

...

❝   V      <- rlnorm(n=1, meanlog=log(V.d)-0.5*log(V.c^2+1),

In your program, is the mean of V from a log-normal distribution? If so, can't you just specify rlnorm statment as rlnorm(n=1, meanlog=V.d, ...) instead of rlnorm(n=1, meanlog=log(v.d)-0.5...)?

The reason I asked is because of the following I saw from an article on "PK Modeling and Simulation of Mixed Pellets" by Watanalumlerd et at. The author listed a table:

Parameter                Distribution        Mean+/-SD
...
lag time of emptying     Log-Normal          0.75+/-0.22

He wrote "A lognormal distribution was chosen ... because time cannot be negative"

In R, Does this mean the rlnorm statement will be:

rlnorm (n=1, mean=0.75, sdlog=0.22)?


Thanks

John