Re: PK data from individuals who vomited after drug ingestion

Kok-Seng, I would not use a mixture model because you already have the information about which group vomited. I am surprised you describe the elimination of ethanol with a half-life. If you gave an ethanol dose big enough to induce vomiting I would expect you to describe elimination with a mixed order (saturable) elimination process. Best wishes, Nick Seng Kok Yong wrote: > Dear NM-users, > > I have a question regarding NONMEM modeling of PK data from individuals who vomited after drug ingestion. Basically, I have a set of data from about 150 subjects (about 5 measurements per subject) who orally ingested alcohol at time = 0 h. However, about 15% of this group vomited more than 1 h post-dose. Based on NONMEM modeling of PK data from subjects who did not vomit during the study, the mean elimination half-life is about 30 min. > > May I ask if I should model vomiting incidence (a “yes” or a “no”) as a categorical covariate for analysis of all the data? I have demographic covariate information at hand. Or, should I introduce a mixture model during NONMEM modeling? I would expect the vomiting subgroup to display different values for Vd, Ka etc as compared to the non-vomiting subgroup. > > Thank you very much for your time and kind advice. > > Best wishes, > > Kok-Yong Seng, PhD > > DSO National Laboratories > > Republic of Singapore -- Nick Holford, Professor Clinical Pharmacology Dept Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand [email protected] tel:+64(9)923-6730 fax:+64(9)373-7090 mobile: +64 21 46 23 53 http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford