Distribution of clomipramine, citalopram, midazolam and metabolites in skeletal tissue after chronic dosing in rats

In recent years, the usage of skeletal tissue as alternative matrix in forensic toxicology has grown new interest. In cases where extreme decomposition has taken place, analysis of skeletal tissue is often the only option left. In this paper, a fully validated method is presented and the distribution of clomipramine, citalopram, midazolam and metabolites after chronically administration is examined within skeletal tissue. Rats were chronically dosed with respectively clomipramine, citalopram or midazolam. Extracts were quantitatively analyzed using LC-ESI-MS/MS. Clomipramine, citalopram and metabolites, respectively desmethylclomipramine and desmethylcitalopram are shown to be detectable in all bone types sampled. Midazolam and its metabolite OH-midazolam could not be detected. The absence of midazolam in extracts gives an indication that drugs with pKa values under physiological pH are badly or not incorporated in bone tissue. Bone and post-mortem blood concentrations were compared. A range of different bone types were compared and showed that the concentration is strongly dependent on the bone type. In concordance with previous publications, the humerus shows the highest drug levels. Found skeletal tissue concentrations ranged from 1.1 – 587.8 ng/g. Comparison of the same bone type between the different rats showed high variances. However, the ratio of drugs/metabolite proved to have lower variances (