RE: steady state dosing

From: Jose Molto jmolto@ns.hugtip.scs.es Subject: [NMusers] RE: steady state dosing Date: Tuesday, April 13, 2004 2:52 AM Hello everyone, I am starting to work with NONMEM and I would appreciate very much some help from the forum. I am trying to build a pharmacokinetic model for an oral drug which is administered every 12 hours using a monocompartimental model (ADVAN2 TRANS2) Subjects are receiving the drug for at least 4 weeks (so steady state is assumed). Theoretically, they come to our unit in the morning, before taking any medication. A first blood sample is drawn just before taking the morning dose, and several blood samples are drawn during the following 12 hours (until the afternoon dose). I would like to have some opinions regarding several isues: 1. If the steady-state is assumed, the SS item in the drug administration events should be typed 1 or 2? 2. Blood samples are not drawn exactly 12 hours after the last dose (eg; a patient may take the last dose -the day before- at 22:00, the first sample is drawn at 8:00, and the morning dose is administered at 8:05). My question is: Is correct if I consider that both doses were at SS with an interdose interval (II) of 12 hours??? If not, how should I enter the data in the data file?. Thank you in advance, Jos Molt, MD "Lluita contra el Sida" Foundation HIV Unit. H. Germans Trias i Pujol Carretera de Canyet s/n 08916 Badalona. Barcelona Telf: +34 93 497 88 87 Fax: +34 93 465 76 02 E-mail: jmolto@ns.hugtip.scs.es