Determination of sumatriptan succinate in plasma and urine by high-performance liquid chromatography with electrochemical detection.

Methods are described for the determination of sumatriptan succinate (1) in plasma and urine. Prior to chromatography, plasma is subjected to liquid/liquid extraction and urine is diluted in pH 7 buffer without further pretreatment. Both procedures use reversed-phase high-performance liquid chromatography with electrochemical detection. The analytical range for the plasma assay is 1-30 ng/mL and that for the urine assay is 0.2-12 micrograms/mL. The assays are linear over the analytical ranges and specific with respect to endogenous interference and the major metabolite (2) of sumatriptan. For the plasma assay, intra-assay data (n = 6) indicate a maximum coefficient of variation (CV) and bias across the calibration range of 6.0 and 3.0%, respectively. The interassay CV (n = 4) is approximately 15% at the bottom of the calibration range, falling to 4% or less at 8 ng/mL and above. Bias is approximately 12% at the bottom, reducing to < 2% at 8 ng/mL and above. The urine intra-assay data indicate a maximum CV and bias of 8.9 and 8.3%, respectively. The interassay is CV 15% for the lowest calibrant, reducing steadily across the calibration range to < 2% for the top calibration value, and bias is < 7% across the range.