Under Task 19, the Contractor shall conduct, as directed by the COR, special in vivo or in vitro toxicology, safety or pharmacokinetic studies, the details of which cannot be specified in advance of the contract award. These studies may necessitate the development and characterization of a model that is amenable to the evaluation of potential pharmacotherapeutic agents. The objective of this study is to determine the safety of a test article in combination with an interaction article, for example, an abused substance, such as morphine, on respiratory parameters measured by whole body plethysmography. For purposes of cost estimation only, assume the following. A test article or its vehicle will be administered by the oral route and an interaction article, e.g., morphine or its vehicle, will be administered by the intravenous route, via an implanted jugular vein cannula, to 45 male and to 45 female Sprague Dawley rats, 200-250 g body weight. The following parameters shall be measured: respiratory rate (f); tidal volume (TVp); minute volume (MVb); inspiratory time (Ti); expiratory time (Te); end inspiratory pause (EIP); end expiratory pause (EEP); chamber temperature (Tc) and relative humidity (RH). The following apnea parameters may also be measured: sigh count (Nsigh); number of apneas (Napnea); apnea percentage (Papnea); and average apnea duration (Tapnea). After being placed in the plethysmograph, these parameters would be recorded continuously for 1 hour prior to the test article/vehicle dose and reported at 1, 2, 5, 10, 15, 30 and 60 min; for 2 hours after the test article/vehicle dose and reported at 0, 1, 2, 5, 10, 15, 30, 60, 90 and 120 min post dosing and for 4 hours after the interaction article/vehicle dose and reported at 0, 1, 2, 5, 10, 15, 30, 60, 90, 120, 150, 180, 210 and 240 min post dosing in tables and as time course graphs using 1 min bins. Clinical signs shall be recorded every 30 min whilst in the plethysmograph. There shall be a mock dosing session to acclimate the animals to handling and the plethysmography chambers. The animals will be humanely sacrificed after the last post interaction article recording. Test article and interaction article dosing solutions shall be assayed for stability and to verify identity and concentration. There may be up to 2 studies. NIDA requires a complete report for each study. Report content and format shall conform to GLP guidelines.