Determination of dicentrine in rat plasma by high-performance liquid chromatography and its application to pharmacokinetics

A critical review: traditional uses, phytochemistry, pharmacology and toxicology of Stephania tetrandra S. Moore (Fen Fang Ji)

ABSTRACT

Stephania tetrandra S. Moore (S. tetrandra) is distributed widely in tropical and subtropical regions of Asia and Africa. The root of this plant is known in Chinese as "Fen Fang Ji". It is commonly used in traditional Chinese medicine to treat arthralgia caused by rheumatism, wet beriberi, dysuria, eczema and inflamed sores. Although promising reports have been published on the various chemical constituents and activities of S. tetrandra, no review comprehensively summarizes its traditional uses, phytochemistry, pharmacology and toxicology. Therefore, the review aims to provide a critical and comprehensive evaluation of the traditional use, phytochemistry, pharmacological properties, pharmacokinetics and toxicology of S. tetrandra in China, and meaningful guidelines for future investigations.

Plasma pharmacokinetics and tissue distribution study of roemerine in rats by liquid chromatography with tandem mass spectrometry (LC-MS/MS)

In the present study, a new LC-MS/MS method for the determination of roemerine in rat plasma and tissue samples was developed and successfully used to study the pharmacokinetics and tissue distribution of roemerine after oral and intravenous (i.v.) administration in rats. The plasma and tissue samples were processed by liquid-liquid extraction with n-hexane. Isocorydine was used as the internal standard (IS) for sample processing and analysis. The MS/MS detection was carried out by monitoring the transitions of m/z 280→249 and m/z 342→279 for roemerine and the IS, respectively. The calibration curve displayed excellent linearity over the concentration range of 10-2000ng/mL (n=8, r(2)≥0.995), and the lower limit of quantification (LLOQ) was determined to be 10ng/mL. This method was rapid, accurate, highly sensitive, and fully validated. The pharmacokinetic study showed that roemerine was rapidly absorbed and eliminated with a tmax of 0.22±0.08h, t1/2 of 1.59±0.46h, CL of 4.44±0.42L/h/kg, and Vd of 10.16±2.95μg/L following oral administration. Additionally, roemerine showed an excellent oral bioavailability of 84% and a wide tissue distribution with brain penetration. Highest concentrations of roemerine were found in the liver and lung, followed by kidney, spleen, heart, and brain, in that order.

Rapid determination of isocorydine in rat plasma and tissues using liquid chromatography--tandem mass spectrometry and its applications to pharmacokinetics and tissue distribution

A rapid and sensitive method for the determination of isocorydine in rat plasma and tissues was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The biological samples were processed by extracting with diethyl ether-dichloromethane (3:2, v/v) and tetrahydropulmatine was used as the internal standard (IS). Detection of the analytes was achieved using positive ion mode electrospray ionization in the multiple reaction monitoring mode. The MS/MS ion transitions monitored were m/z 342.0→279.0 and 356.0→191.9 for isocorydine and IS, respectively. The maximum plasma concentration (C(max) 2496.8 ± 374.4 µg/L) was achieved at 0.278 ± 0.113 h (T(max)) and the half-life (t(1/2)) of isocorydine was 0.906 ± 0.222 h after a 20 mg/kg oral administration. As for a 2 mg/kg intravenous (i.v.) administration, the C(max) and clearance (CL) were 1843.3 ± 338.3 µg/L and 2.381 ± 0.356 L/h/kg, respectively. Based on the AUC(0-∞) obtained from oral and i.v. administration, the absolute bioavailability (F) was estimated as 33.4%. Tissue distribution results indicated that isocorydine underwent a rapid and wide distribution into tissues and it could effectively cross the blood-brain barrier.

Measurement and pharmacokinetic study of tetramethylpyrazine in rat blood and its regional brain tissue by high-performance liquid chromatography

We used a rapid, sensitive and reliable high-performance liquid chromatographic method for the determination of tetramethylpyrazine in rat brain tissue and plasma. The lower limit of quantification in plasma and brain tissue was 0.1 microgram/ml and 0.1 microgram/g, respectively, and only a small amount of plasma (100 microliters) or brain tissue (100 micrograms) was required for analysis. The decline in the concentration of tetramethylpyrazine in plasma was generally two-exponential at a dose of 2, 5, or 10 mg/kg administered intravenously. Concentrations of tetramethylpyrazine in various regions of the brain (cerebral cortex, brainstem, striatum, hippocampus, cerebellum and midbrain) were not significantly different at 15 min following drug administration (10 mg/kg, i.v.). In additional analysis, mean concentration of the tetramethylpyrazine in rat plasma was approximately five-times greater than the drug in brain tissue.