No abstract

A sensitive and robust ultra-high-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for the quantification of acetaminophen, dexchlorpheniramine, caffeine, cotinine and salicylic acid in postmortem blood samples from children younger than 4 years. The sample was prepared by a protein precipitation with ice-cold methanol/acetonitrile mixture (85:15, v/v). The organic phase was evaporated to dryness and the residue was dissolved in the mobile phase. Separation, with gradient elution and an acidic mobile phase, was achieved on an Acquity UPLC® HSS T3 column. The compounds were quantified using a multiple reaction-monitoring mode. Two transitions were monitored for each compound and one for the deuterated internal standards. The mass spectrometric detection in the positive ion mode was performed for all the compounds except salicylic acid which was detected in the negative ionization mode. The limits of quantification were as follows: acetaminophen 0.30 mg/L, dexchlorpheniramine 0.0050 mg/L, caffeine 0.099 mg/L, cotinine 0.00035 mg/L and salicylic acid 1.3 mg/L. Between-assay and within-assay precisions were ≤15% (biases: -10% to 26%) and ≤10%, respectively. Extraction recoveries varied from 93% to 137%. The matrix effects in blood, corrected with deuterated internal standards, were 100% ± 10% for all compounds except dexchlorpheniramine (111%) and caffeine (138%).

An elderly man with decreased kidney function was admitted to hospital with gastrointestinal bleeding. After remaining stable for 2 days in hospital, he became haemodynamically unstable and an adverse effect of dabigatran was suspected, but efforts to treat the patient failed and the following morning he passed away. In conjunction with the autopsy, blood samples from his hospital stay were analysed for dabigatran, revealing the highest concentration (6400 ng/mL) apparently reported to date. Supra-therapeutic dosing was, however, never suspected. Dabigatran is largely excreted through the kidneys. A possible cause of the high dabigatran concentrations could be a rapid decrease in kidney function that seemingly occurred over a period of 2 months, sometime between his initiation of treatment (eGFR 51-55 mL/min/1.73 m ) and subsequent hospital admission (eGFR 31 mL/min/1.73 m ). The increasing dabigatran concentrations in the patient was, however, not apparent to the prescribing doctor, as therapeutic drug monitoring of dabigatran is not recommended in current guidelines and no such analyses were performed. There may be a need to evaluate blood concentrations of dabigatran, in the light of the reported differences in interindividual concentrations, along with the increased risks of thromboembolic events with lower concentrations and major bleeding events with higher concentrations. Functional assays to assess concentrations of dabigatran in blood have been developed and are available in some hospitals to be used in suspected overdoses or before emergency surgeries. Methods to determine concentrations of dabigatran specifically have also been developed and can additionally be used for therapeutic drug monitoring in an outpatient setting, especially in high-risk individuals.