Forensic Analysis and Therapeutic Monitoring of Psychotropic Drugs

Major efforts of clinical therapeutic monitoring aim at rapid finding and optimal adjustment of individual doses of appropriate psychotropic drugs for psychiatric patients, and include both, the clarification of side effects and surveying the patient's compliance. In contrast, forensic psychotropic drugs analysis becomes necessary in cases or events in which a psychiatric patient may stumble, violate or the law. Such offences may occur while driving under influence, in conflicts between individuals, or by committing crimes. As many times, the co-incidence psychic disturbances, psychopharmacological treatment and drug dependence is observed, the analysis and determination of therapeutic psychoactive compounds in blood or serum occurs in both, the clinical and in the forensic laboratory, in the latter often combined with illicit drug testing.

There is a major difference in the clinical and the forensic analytical approach: Especially, the forensic approach needs to be based on the chemical-analytical discovery and proof of the presence of any previously unknown drug or influence. For many psychoactive drugs and their metabolites, therefore, mass spectroscopy, especially the HPLC-MS-MS technique is preferred as analytical tool. In contrast, wherever the drug applied is known, and more serial determinations are necessary, less specific methods including acceptable quality measures may be regarded more cost-effective. Because of this inter-relation, the Society of Forensic and Toxicological Chemistry (GTFCh) organizes proficiency testing for forensic and clinical toxicology. Some results of recent ring tests and helpful efforts regarding methods validation will be presented.

Both, the therapeutic and forensic approach of drug analysis is based on or at least assumes a definite relationship between dose concentration and effect of psychoactive substances. Any assessment of such relationship is usually based on the detailed knowledge of pharmacokinetics, metabolism, pharmcogenomics, and especially, on careful observation of the pharmacodynamics of individual psychotropic drugs during therapy. Usually, target concentration ranges of individual psychotropic drugs have been figured out. Regarding clinical interpretation, it is well-known, that any formal tabulation of concentration ranges needs most careful usage. In forensic cases, such tabulation need to be used even more restricted. Reverse deducing drug effects from concentration measurements bares a high risk of misinterpretation. Finally, a road accident occurred under the influence of Citalopram will be presented.