Postmortem investigation of lamotrigine concentrations.

Lamotrigine is a relatively new anticonvulsant. Therapeutic plasma concentrations generally range from 1 to 4 mg/L, although several studies have shown that good control of epilepsy has been achieved with concentrations reaching 10 mg/L generally, with little toxicity. In overdose, however, the drug has been linked to ECG changes that may suggest a possible arrythmogenic effect and hence cardiac toxicity. Lamotrigine has also been shown to cause encephalopathy and thus neurotoxicity. There is no information concerning postmortem lamotrigine concentrations and their interpretation. We describe lamotrigine concentrations in postmortem specimens including blood, liver, bile, vitreous humour, and urine from eight cases. A high performance liquid chromatography (HPLC) method is described with extraction procedures for the various tissues. Two possible groups were identified. The first being the "broader therapeutic" group with blood concentrations ranging from 0.9 to 7.2 mg/L and corresponding liver concentrations ranging from 16 to 36 mg/kg. The second being a "supratherapeutic" group with blood concentrations ranging from 20 to 39 mg/L and corresponding liver concentrations ranging from 53 to 350 mg/kg. Although none of the eight cases described were attributed to overdose by lamotrigine alone, the cause of death for one of the three cases in the "supratherapeutic" group was given as mixed drug toxicity. Cause of death for the remaining two cases in this group was reported as epilepsy. However, both these cases showed elevated concentrations of lamotrigine and both were co-medicated with valproic acid. Such co-administration has been shown in the literature to lead to elevated lamotrigine concentrations and a reduction in lamotrigine dose has been recommended. With such data, we highlight the importance of monitoring lamotrigine concentrations in cases co-medicated, particularly with valproic acid.

Postmortem clomipramine: therapeutic or toxic concentrations?

Postmortem blood and liver concentrations of clomipramine were determined in ten cases by high performance liquid chromatography (HPLC). Blood concentrations ranged from 0.21 to 4.9 mg/L, and liver concentrations from 7.0 to 320 mg/kg. Two cases associated with clomipramine toxicity were clearly differentiated from other cases by the analysis of liver. The concentrations of clomipramine in these two cases were 3.3 and 1.8 mg/L in blood, and 280 and 320 mg/kg in liver. The liver concentrations were 10 to 30 fold greater in the deaths associated with drug toxicity compared with the other cases. One case, where cardiac blood was collected in place of femoral blood, showed a high blood concentration (4.9 mg/L), but an arguably therapeutic liver concentration (13 mg/kg). The analysis of femoral blood together with liver provides the best guide as to the significance of post-mortem clomipramine concentrations.

Dual ultraviolet wavelength high-performance liquid chromatographic method for the forensic or clinical analysis of seventeen antidepressants and some selected metabolites.

A sensitive method suitable for the determination of tricyclic and other antidepressants in postmortem and clinical specimens is presented. The procedure, which utilizes reversed-phase HPLC combined with dual ultraviolet wavelength detection, enables the separation of 17 commonly prescribed antidepressants and some selected metabolites in a single extraction. Peak purity was confirmed using absorbance ratios at 220 nm and 254 nm wavelengths and revealed little interference from other eluting analytes. The blood detection limit for most antidepressants was 50 ng/ml. The most commonly observed antidepressants in 281 forensic cases analysed over a two-year period with the described method were dothiepin, amitriptyline, nortriptyline and doxepin.