Different assays for different studies

Dear all, I am involved in a project, where data from several different studies are pooled and a PK model is being developed. The studies were conducted over a period of time and the bioanalytical assay was improved during this period. Hence, 2 of these studies have a LOQ of 1 ng/mL, while the others have a LOQ of 20 ng/mL. This results in all samples, including the very early ones, showing detectable levels of the compound for the 2 studies, while the others indicate an apparent lag-time, since the older bioanalysis was not sensitive to detect the low concentrations at the beginning of the dosing. Any comments on how to deal with this situation? Toufigh Toufigh Gordi, PhD President, PK/PD and Clinical Pharmacology Services Rosa & Co. LLC: www.rosaandco.com E-mail: [email protected] Tel.: 408-480-7314 Fax: 408-370-9810 The information contained in this e-mail message, e-mail message sequence, and/or any enclosures is confidential, and it may be privileged and protected from unauthorized use and/or disclosure. If you are not the intended recipient, any use, dissemination, distribution, or copying is strictly prohibited. If you received this e-mail in error, PLEASE NOTIFY THE SENDER immediately and destroy this message, any enclosures, and any copies of the message and/or the enclosures. Thank you.