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Immunoassay of digoxin in hair
M Deveaux1, E Révuelta, E Mornay
1Institute of Legal Medicine, Lille, France.
Insights
Hair analysis can detect digoxin use before death, offering an alternative to blood tests in forensic cases. This study optimized methods for analyzing digoxin in hair samples.
Area of Science:
- Forensic Toxicology
- Cardiology
- Analytical Chemistry
Background:
- Blood digoxin analysis is crucial for therapeutic drug monitoring and assessing patient compliance.
- Postmortem blood analysis for digoxin is unreliable due to drug redistribution and endogenous digoxin-like factors.
- Autopsies often lack suitable biological fluids for drug analysis.
Purpose of the Study:
- To evaluate the efficacy of an immunological method for determining digoxin concentration in hair.
- To establish hair analysis as a viable method for confirming digoxin use prior to death.
- To optimize sample preparation techniques for digoxin extraction from hair.
Main Methods:
- Tested 35 elderly patients on long-term digoxin therapy.
- Compared two decontamination methods: dichloromethane vs. water/methanol.
- Evaluated three extraction techniques: ball mill (chloroform/acetone), crushing (methanol), and enzymatic digestion.
- Utilized microparticulate enzyme immunoassay for digoxin quantification.
Main Results:
- The optimal method involved water/methanol decontamination followed by enzymatic digestion.
- Hair digoxin concentrations ranged from 3.6 to 11.4 pg/mg.
- No significant correlation was observed between hair and blood digoxin levels.
- A forensic case demonstrated detectable hair digoxin (5 pg/mg).
Conclusions:
- Hair analysis, using optimized immunological methods, can provide valuable information on prior digoxin use.
- This technique offers a potential solution for drug monitoring in cases where blood analysis is compromised.
- Further research may refine hair analysis for routine forensic and clinical toxicology.
Abstract:
Digoxin analysis in blood is an essential tool for therapeutic drug monitoring in cardiology because compliance with the treatment is a critical issue for the patient. Unfortunately, in postmortem cases blood digoxin concentration is of poor quality because there is a possible drug redistribution in the corpse and because of digoxin-like factors present in some people's blood. On the other hand, no biological fluid can be obtained at the autopsy. The aim of the present study was to evaluate the ability of an immunological method to determine digoxin in hair, in order to confirm that hair analysis can provide information on digoxin use before death. We studied 35 elderly patients who had been taking digoxin (60-250 micrograms/day) for 1-5 years. Two decontamination procedures were tested: washing by dichloromethane or by water and methanol. Three extraction procedures were compared: crushing in a ball mill and chloroform/acetone: crushing and methanol; enzymatic digestion. Immunoassays were performed by a microparticulate enzyme immunoassay. Serum digoxin levels were also assayed when sampling hair. The best results were obtained after decontamination with water and methanol followed by enzymatic digestion. Hair digoxin concentrations range from 3.6 to 11.4 pg/mg. Those very low concentrations are probably due to low and narrow range serum digoxin levels (0.3-1.4 ng/ml). No correlation was found between hair and blood digoxin. A forensic case is presented with 5 pg/mg digoxin in hair.