Comparison of capillary electrophoresis with HPLC for diagnosis of factitious hypoglycemia.
BACKGROUND
The diagnosis of "factitious hypoglycemia" is essentially based on the disclosure of hypoglycemic agents in blood or urine. The aim of this study was to evaluate the performance of capillary electrophoresis (CE) as a quantitative method for determination of chlorpropamide, tolbutamide, glipizide, gliclazide, and glibenclamide in serum.


METHODS
Serum samples (1 mL), with internal standard added, were purified by solid-phase extraction on OASIS(TM) HLB cartridges (Waters), dried under reduced pressure, and reconstituted with 30-60 microL of acetonitrile:H(2)O. Analysis was carried out by micellar electrokinetic capillary chromatography in 5 mmol/L borate, 5 mmol/L phosphate, 75 mmol/L sodium cholate, pH 8.5, containing 25 mL/L methanol. Separation was accomplished in a 20 cm x 50 microm (i.d.) silica capillary at 25 degrees C and a constant voltage of +10 kV. Pharmacokinetics of gliclazide (80-mg tablet) in a diabetic patient were assayed by both HPLC and CE. Two hypoglycemic patients positive by HPLC analysis for unreported gliclazide and tolbutamide overdose were also screened by CE.


RESULTS
Separation of six drugs (including the internal standard) was accomplished in 5 min plus 5 min rinsing. The between-day CV of the ratio of the areas of the sulfonylurea drugs to internal standard was <1% (n = 10). Linearity (r(2) > or =0.998) and recovery (> or =80%) were good for all sulfonylurea drugs tested. Pharmacokinetic curves for gliclazide by CE and HPLC were superimposable. CE analysis confirmed the HPLC diagnosis of surreptitious abuse of gliclazide and tolbutamide.


CONCLUSIONS
CE is a useful tool in the clinical chemistry and toxicology laboratory for drug monitoring and pharmacokinetic investigations.
Paroni
R
R
Laboratory of Separative Techniques, IRCCS Ospedale San Raffaele, 20132 Milano, Italy. paroni.rita@hsr.it
Comuzzi
B
B
Arcelloni
C
C
Brocco
S
S
de Kreutzenberg
S
S
Tiengo
A
A
Ciucci
A
A
Beck-Peccoz
P
P
Genovese
S
S
D000328:Adult; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy; D062787:Drug Overdose; D019075:Electrophoresis, Capillary; D005260:Female; D005907:Gliclazide / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics; D006801:Humans; D007003:Hypoglycemia / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis*; D007004:Hypoglycemic Agents / Q000009:adverse effects / Q000097:blood* / Q000493:pharmacokinetics; D008875:Middle Aged; D015203:Reproducibility of Results; D013453:Sulfonylurea Compounds / Q000009:adverse effects / Q000097:blood* / Q000493:pharmacokinetics; D014044:Tolbutamide / Q000009:adverse effects / Q000097:blood
D007004:Hypoglycemic Agents; D013453:Sulfonylurea Compounds; D014044:Tolbutamide; D005907:Gliclazide