Re: trough time same as dosing time

Thanks for the input from James and Leonid! This drug was given orally to the volunteers. Nevertheless, I did code the trough record prior to the dosing record in the dataset. The same control stream and dataset were then run in NONMEM V. The minimization was successful with covariance matrix reported. The theta and omega are the same as those generated from NONMEM VI, of which the minimization was terminated. This discrepancy didn't surprise me as it happens occasionally... Ying. Leonid Gibiansky wrote: > Should not be a problem for oral administration. If IV, make sure that trough observation records are before the dosing records (time can be the same, but they should be ordered correctly). > > Leonid > > Ying HONG wrote: > > > Dear NMusers, > > > > A single-dose of drug was given to healthy volunteers and a PK model incorporating Michaelis-Menten distribution nicely captured the concentration-time profile. > > > > The same drug was given to healthy volunteers once daily for consecutive 7 days. The same PK model developed on the single-dose data were fitted to multiple-dose data, however, nonmem minimization was terminated. In the dataset, the time of trough sample is coded exactly same as the time for next dose according to the study protocol, for example, the time for trough on day 1 and time for dosing on day 2 is 24 hr. Actually, it will never be the case in the real clinical setting. My gut feeling is coding in this way may cause numerical errors. Can someone shed light on it so that I can request the clock time for dosing and sampling? > > > > Thank you very much! Ying -- Ying HONG, PhD Department of Pharmaceutical Sciences University at Buffalo, SUNY C237 Cooke Hall, Buffalo, NY 14260 Tel: 716 645 2828 ext 275 Fax: 716 645 3693 E-mail: [EMAIL PROTECTED]