A micromethod for the isolation of drugs from blood using amberlite XAD-2

Solid-phase extraction procedures in systematic toxicological analysis

In systematic toxicological analysis (STA) the substance(s) present is (are) not known at the start of the analysis. In such an undirected search the extraction procedure cannot be directed to a given substance but must be a general procedure where a compromise must be reached in that the substances of interest are isolated at a yield as high as possible and the interfering substances from the biological material are removed. When using solid-phase extraction (SPE) it is desirable to have procedures using just one column. An overview of screening procedures using diatomaceous earth, polystyrene-divinylbenzene copolymer and mixed-mode bonded silica as column material in SPE is given. The latter type of sorbent is most popular at the moment and the critical steps in the procedure are outlined in more detail. Recent developments of SPE disks look very promising for STA.

[A fatal monointoxication by flurazepam (Dalmadorm). Problems of the toxicological interpretation (author's transl)]

A death case following a suicidal overdose of flurazepam (Dalmadorm) is reported. The body was found after 3 month near a highway. The course of the intoxication is in question as benzodiazepines are believed to be relatively save drugs. The death might have occured rapidly because of the acute toxic actions of the drug overdose as well as after a protracted course involving additional complications like inflammatory alteration of the myocard or hypothermia during a coma. Flurazepam and its major metabolites were analysed in blood and urine. The toxic levels of flurazepam (0.51 mg/l), N1-desalkylflurazepam (0.14 mg/1) and N1-hydroxyethylflurazepam (9.0 mg/1) in the blood amounted to 20--50 times higher than therapeutic levels, with flurazepam and metabolites being in only slight altered relation to each other. The overdose is considered to have been above 2.4 g (80 tablets). The resorption of the drug was complete. The analytical findings in blood and urine as well as in the GI-tract are in satisfactory agreement. The analytical data of flurazepam and its metabolites are discussed in detail, taking metabolic and pharmacokinetic parameters, autopsy findings and case circumstances into consideration. A final decision about the course of the intoxication is not possible. This case shows however the fatal consequences of a flurazepam overdose although alcohol or other drugs were not involved.

[A screening radioimmunoassay for 1,4-benzodiazepines in human blood, serum, and urine using anti-oxazepam-hemisuccinate-antibodies (author's transl)]

A simple and specific radioimmunoassay (RIA) was developed for the determination of oxazepam and other 1,4-benzodiazepines in human blood serum and urine (e.g., diazepam, desmethyldiazepam, chlorazepate). For serum a 1:10 dilution, for urine a 1:100 dilution is recommended. Blood and hemolyzed samples need prior extraction by Amberlite XAD-2. The antisera were raised by immunizing "White New Zealand"-rabbits with an oxazepam-3-hemisuccinate bovine serum albumin conjugate. Using 0.1 ml serum dilution the sensitivity is 0.01 mg/l per tube. Especially higher concentrations show a tendency toward underestimation. Being not limited to a single 1,4-benzodiazepine derivative, the specificity of the antisera is also suitable for a screening analysis. Compared to thin-layer chromatographic analysis of urine this assay shows improved sensitivity (0.05--0.1 mg/l in 0.1 ml of a 1:100 dilution = 1 microliter of urine). For forensic investigations, an analysis in the sequence of urine-RIA, blood/serum-RIA, blood/serum-"electron-capture"-gas-liquid chromatography (ECD-GLC) seems to be a helpful approach. Blood levels of diazepam and desmethyldiazepam determined by RIA and GLC after extraction are in satisfactory agreement.

Isolation of drugs from blood and tissues with XAD-2 bags

Nylon bags containing 2-g portions of Amberlite XAD-2 resin were used for systematic analysis of drugs in biosamples. The procedure requires 10 or less grams of material, two XAD-2 bags, and enables rapid and economical isolation of most common drugs. The method was demonstrated on autopsy blood spiked withe 19 of the most common drugs, and was routinely used in cases of fatal and non-fatal poisoning. The eluates were clean and suitable for direct gas chromatographic and ultraviolet spectrophotometric analysis. The procedure used appeared more convenient than XAD-2 column extraction procedures. Classic solvent extraction methods were usually less efficient.