Quality control in therapeutic drug monitoring.

Quality control of routine drug assays, like most immunoassays, should mainly be the responsibility of each individual laboratory: intra-laboratory quality control. External quality assessment should direct its efforts in particular to non-routine methods and to new assays. However, it may sometimes also be very useful to have laboratory results of routine assays studied in external programmes, since vague requests or difficult interpretations of drug concentrations need discussion outside the individual laboratory.

A rapid method of determining serum levels of etomidate by gas chromatography with the aid of a nitrogen detector.

A rapid method of measuring etomidate in serum is described which is suitable for the determination of serum levels during and after surgical procedures. Etomidate with the added internal standard propoxate is extracted from serum using a hexane/ether mixture. The organic layer is evaporated and the residue dissolved in acetone and injected into an OV-17 column at 220 degrees C. Resulting concentrations are linear between 0.05 and 2.0 microgram/ml serum. There is 90% recovery and the detection limit is 0.03 microgram/ml. The other drugs normally present do not interfere with the estimation. Estimations can be carried out on 20 blood samples by one person with 3 hours.

A hemoperfusion column based on activated carbon granules coated with an ultrathin membrane of cellulose acetate.

A hemoperfusion system has been developed which makes use of activated carbon encapsulated with cellulose acetate. Studies have revealed that there are no stagnant flow regions in the column, there is minimal particle release and the coating is 30 A thick. The relationships between pore size, pore volume and surface area have been examined. Twenty-five patients in grade IV coma have been treated with the column for treatment of drug overdose or agricultural chemical poisoning; the clinical course of one meprobamate-poisoned patient is described in detail.