Novel liquid chromatographic assay for the low-level determination of apomorphine in plasma

• Published in: Journal of chromatography. B, Biomedical applications Biomedical applications, 1996-05, Vol.681 (1), p.161-167
• Main Authors: Priston, Melanie J., Sewell, Graham J.
• Format: Article
• Language: English
• Subjects: Antioxidants - analysis; Apomorphine; Apomorphine - blood; Apomorphine - chemistry; Apomorphine - pharmacokinetics; Aporphines - analysis; Area Under Curve; Calibration; Chromatography, High Pressure Liquid - methods; Dopamine Agonists - blood; Dopamine Agonists - chemistry; Dopamine Agonists - pharmacokinetics; Drug Stability; Half-Life; Humans; Linear Models; Mercaptoethanol - chemistry; Reference Standards; Reproducibility of Results; Sensitivity and Specificity; Spectrometry, Fluorescence; Temperature; Time Factors
• ISSN: 0378-4347; 1572-6495
• DOI: 10.1016/0378-4347(95)00534-X

A novel HPLC assay which is rapid, reproducible and sensitive has been developed for the analysis of apomorphine in plasma. The assay incorporates boldine as an internal standard, and uses solid-phase extraction on C 18 mini-columns for sample clean-up and concentration, so enabling quantitation of apomorphine at 500 pg/ml using fluorescence detection ( λ ex 270 nm, λ em). The HPLC assay comprised a 25 cm-long Techopakk C 18 column and a mobile phase of (0.25 M sodium dihydrogen phosphate plus 0.25% heptane sulphonic acid, to pH 3.3 with orthophosphoric acid) containing 30% (v/v) methanol and 0.003% (w/v) EDTA, run at a flow-rate of 1.5 ml/min. Calibration plots prepared in plasma were linear over the range 1–30 ng/ml, (limit of quantitation (LOQ)=490 PG/ML) with R.S.D. of 0.05% and R.E. of 5.0% at the level of 1 ng/ml. Preliminary pharmacokinetic data from two patients given apomorphine by 12 h subcutaneous infusion (patient A dose=35 mg and patient B dose=141 mg) showed apomorphine elimination from plasma to fit a two-compartment model, with initial half-lives of 8.2 and 46.6 min, elimination half-lives of 76.4 and 166.5 min and area under the plasma concentration-time curve (AUC) values of 236 and 405 ng h/ml, respectively.