Computerized Controlled-Substance Inventory Management in a Forensic Toxicology Laboratory: Practical Application of a State-Change Model

Efficient, accurate, secure, comprehensively audited, and legally defensible maintenance of an electronic chain-of-custody applied to a controlled-substance inventory system in a busy forensic toxicology lab (FTL) has been achieved with custom-written software which is based on a general state-change model. Prior to the use of this program we were unfortunately accustomed to being surprised by incomplete drug use documentation leading to pseudo-shortages, expired or uncertified lots, the lack of an adequate chain of custody, and the risk of legal challenges. This resulted in confusion, delays, and emergency orders, with the inevitable waste of time and money. The control strategy implemented in the INVEN subsystem of our main system, TOXLAB, is based on four principles. First, access to the drug inventory is strictly limited. Second, controlled drugs are dispersed to technical staff only when a computer-authorized request form is presented. Third, every request for addition/subtraction must be pre-authorized by the supervisor. Fourth, the program enforces a strict progression of requests and actions from one state to another and produces request, authorization and certification, and/or approval logs ready for signature at every step. This approach has given us a comprehensive, chronological record of all events involving drug inventory transactions and promises to improve resource utilization. Our system appears to fulfill the basic requirements for the legal adequacy of computer-resident data.