Therapeutic drug monitoring of anti-epileptic drugs - a clinical verification of volumetric absorptive micro sampling.

Background Therapeutic drug monitoring (TDM) of antiepileptic drugs (AEDs) can serve as a valuable tool in optimising and individualising epilepsy treatment, especially in vulnerable groups such as pregnant women, the elderly and children. Unfortunately, TDM is often performed suboptimally due to limitations in blood collection. Therefore, we investigated volumetric absorptive micro sampling (VAMS) - a new home-sampling technique. We aimed to evaluate VAMS to determine and quantify the different AEDs and concentrations of 16 different AEDs in whole blood collected by VAMS. Methods Patient blood samples (n = 138) were collected via venepunctures at the Academic Centre for Epileptology Kempenhaeghe. AED concentrations were determined, and these concentrations were used to compare the VAMS method (whole blood) with the conventional method (serum). In addition, the recovery was examined as well as the impact of haematocrit. Finally, AED-spiked blood was used to test the stability of the AEDs inside the micro-sampler devices over a period of time and whether temperature had an effect on the stability. Results VAMS allows for an accurate detection of 16 different AEDs within 2 days after sampling. Deviation in recovery was less than 10% and high correlations were found between VAMS and conventional sampling. Moreover, haematocrit does not have an effect with values between 0.3 and 0.5 (L/L). Finally, although storage temperature of VAMS does affect some AEDs, most are unaffected. Conclusions VAMS enables an accurate detection of a wide variety of AEDs within 2 days after sampling.

Similar alterations of lymphocyte subpopulations in type I and type II diabetes.

Peripheral blood lymphocytes of diabetes mellitus patients were analyzed by flow-cytometry using monoclonal antibodies directed against cell surface markers present in T- and B-cells, monocytes and natural killer cells. The lymphocyte subsets were quantified and expressed in an absolute amount. The study included 17 patients with type I (insulin-dependent), 21 patients with type II (non-insulin-dependent) diabetes and 40 age-matched control subjects. Quantification of the cells present within different lymphocyte subsets revealed a general increase in both patient groups compared to their controls, with the exception of activated T-cells. However, no significant difference was found in the relative amount of T-helper cells and T-suppressor/cytotoxic cells of the diabetes patients when they were compared with their control groups. The fact that we found similar changes in lymphocyte subsets in both type I and type II diabetes suggests that the altered immunological state is secondary to the diabetes mellitus in general.

A time-resolved fluoroimmuno assay of the IgM-rheumatoid factor.

A time-resolved fluoroimmuno assay of the IgM-rheumatoid factor is described. Aggregated rabbit IgG was coated to microtitre plates to serve as the target protein. F(ab')2-fragments from antibodies, raised in rabbits against human IgM, were labelled with Eu3+ and used in the assay to mark the bound IgM-rheumatoid factor. The labelling procedure is easy to perform, and there is no need for special equipment. The shelf life of the label at -20 degrees C is at least one year. The lower detection limit of the assay is 1.3 x 10(3) IU/l. The range over which the IgM-rheumatoid factor can be measured at a within-run precision of less than 5% without varying the dilution (working range) is 5-1200 x 10(3) IU/l. Linearity in serum dilutions is good. There is good correlation with existing methods for the assay of IgM-rheumatoid factor. This correlation is better with an assay using rabbit IgG as the target than with one using human IgG. Comparison of methods shows that standardization, despite the use of the WHO Reference Preparation as the first calibrator, remains problematic. The 95th percentile in normal bloodbank donors is 8 x 10(3) IU/l. The costs for the reagents were about 0.5 Dutch florin (ca 0.30 US-$) per well. In conclusion, the method described here is analytically at least comparable with other methods, in precision, linearity, working range etc. Finally, it is easy to perform.