Pharmacogenomic Studies and Quantification of Tramadol and M1 in Human Post Mortem Samples

In recent years, there has been an increase of reported cases of abuse, addiction, or suicide by tramadol. Currently, only few studies have aimed to quantify tramadol and its active metabolite O-desmethyltramadol (M1) in post mortem samples and evaluate the relationship of M1 and polymorphisms with the cause of death. Therefore, this study was designed to validate an analytical technique of gas chromatography-ion trap mass spectrometry (GC-IT/MS) to quantify tramadol and M1 in post mortem cardiac and femoral blood. Also, pharmacogenomic studies were performed to better understand the role of genetic factors in tramadol and M1 pharmacokinetics.

Tramadol, M1 and internal standard were extracted by using Bond Elut® C18 cartridges. Derivatization was performed with ethyl acetate and bis(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane and then analytes were analyzed by GC-IT/MS. The method proved to be selective, accurate and precise. The regression analysis for tramadol and M1 was linear in the range of 5–1000 ng/mL with detection and quantification limits of 0.74 ng/mL and 0.56 ng/mL for tramadol and 2.24 ng/ml and 1.70 ng/ml for M1, respectively.

The proposed method was successfully applied to post mortem blood samples obtained from suspected fatal intoxications by tramadol, which were also genotyped for the presence of single nucleotide polymorphisms in the genes of cytochrome P4502D6, protein multidrug resistance 1. Results revealed the importance of genetics in the blood concentrations of tramadol and M1.

Comparisons between quantitative results and genetics will certainly help in the interpretation of forensic and clinical results.