Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
J Sep Sci. 2009 Nov;32(22):3866-70. doi: 10.1002/jssc.200900469.
Sildenafil is a selective inhibitor of phosphodiesterase type 5 enzyme. A simple and sensitive LC-MS assay was developed to determine the concentration of sildenafil in human plasma. Sildenafil and omeprazole (internal standard) were extracted from the plasma with diethyl ether. The extract was evaporated under nitrogen and the residue was constituted with ACN and injected onto Novapak C(18) column (75x3.9 mm, 4 microm). The mobile phase consisted of 90% ACN plus 10% ammonium acetate (20 mM) containing 0.02% formic acid and was delivered isocratically at a flow rate of 0.2 mL/min. Sildenafil and omeprazole were monitored using a positive electrospray mode with single-ion recording set at m/z 475 and 346, respectively, which are consistent with M+H molecular ions, and the run time was less than 5 min. The detection limit of sildenafil was 0.5 ng/mL, and the calibration curve was linear between 0.5 and 2000 ng/mL (R(2)>0.99). Within- and between-day coefficients of variation were less than 7%. This method has been successfully used to measure sildenafil plasma concentrations in a beagle dog model following an oral administration of the drug.
西地那非是一种磷酸二酯酶 5 型酶的选择性抑制剂。建立了一种简单、灵敏的 LC-MS 法测定人血浆中西地那非的浓度。西地那非和奥美拉唑（内标）用人血浆中的乙醚提取。提取物在氮气下蒸发，残渣用 ACN 构成，并注入 Novapak C（18）柱（75x3.9mm，4μm）。流动相由 90％ACN 和 10％含 0.02％甲酸的乙酸铵（20mM）组成，以 0.2mL/min 的流速等度洗脱。西地那非和奥美拉唑分别采用正电喷雾模式，以单离子记录模式，m/z 分别为 475 和 346 进行监测，这与[M+H]+分子离子一致，运行时间小于 5 分钟。西地那非的检测限为 0.5ng/mL，校准曲线在 0.5-2000ng/mL 之间呈线性（R（2）>0.99）。日内和日间变异系数均小于 7％。该方法已成功用于在狗模型中口服西地那非后测定血浆中西地那非的浓度。
