Pharmacokinetics of paeonol after intravenous administration in rats

Pharmacokinetics, Tissue Distribution and Excretion of Paeonol and Its Major Metabolites in Rats Provide a Further Insight Into Paeonol Effectiveness

Paeonol is a major bioactive ingredient in Moutan Cortex (the root barks of Paeonia suffruticosa Andrews) and exhibited a wide range of bioactivities such as anti-inflammation, anti-oxidation, hypoglycemic effect, analgesic, and others. Even though paeonol has been proven to possess significant pharmacological and therapeutic effects, its pharmacokinetic properties are not satisfactory since it has been found to have a rapid clearance in vivo. In the present study, the pharmacokinetics, tissue distribution and excretion of paeonol and its major metabolites were investigated in rats by an efficient and specific UPLC-MS/MS method. The results indicated that paeonol was rapidly absorbed, extensively metabolized, and widely distributed in various tissues without long-term accumulation after oral administration to rats. The major distribution tissues of paeonol and its metabolites were kidney, liver, and heart. Paeonol was able to cross the blood-brain barrier but rapidly decreased after 10 min. The total excretion of four metabolites in urine, bile, and feces was approximately 35.0% within 24 h, and the metabolites were mainly excreted through the urine. In addition, the hypoglycemic activities of paeonol and its metabolites were investigated by a glucose uptake assay on TNF-α mediated insulin resistance in 3T3-L1 adipocytes. The results showed that paeonol and its major metabolites displayed hypoglycemic activities. This is the first comprehensive and systematic report on the pharmacokinetics of paeonol and its metabolites. This research provides an important basis for the clinical development and application of active metabolites.

Pharmacokinetics and Brain Distribution of the Active Components of DA-9805, Saikosaponin A, Paeonol, and Imperatorin in Rats

DA-9805 is a botanical anti-Parkinson’s drug candidate formulated from ethanol extracts of the root of Bupleurum falcatum, the root cortex of Paeonia suffruticosa, and the root of Angelica dahurica. The pharmacokinetics (PKs) and brain distribution of active/representative ingredients of DA-9805, Saikosaponin a (SSa; 1.1–4.6 mg/kg), Paeonol (PA; 14.8–59.2 mg/kg), and Imperatorin (IMP; 1.4–11.5 mg/kg) were evaluated following the intravenous or oral administration of each pure component and the equivalent dose of DA-9805 in rats. All three components had greater dose-normalized areas under the plasma concentration-time curve (AUC) and slower clearance with higher doses, following intravenous administration. By contrast, dose-proportional AUC values of SSa, PA, and IMP were observed following the oral administration of each pure component (with the exception of IMP at the highest dose) or DA-9805. Compared to oral administration of each pure compound, DA-9805 administration showed an increase in the AUC of SSa (by 96.1–163%) and PA (by 155–164%), possibly due to inhibition of their metabolism by IMP or other component(s) in DA-9805. A delay in the absorption of PA and IMP was observed when they were administered as DA-9805. All three components of DA-9805 showed greater binding values in brain homogenates than in plasma, possibly explaining why the brain-to-plasma ratios were greater than unity following multiple oral administrations of DA-9805. By contrast, their levels in cerebrospinal fluid were negligible. Our results further our understanding of the comprehensive PK characteristics of SSa, PA, and IMP in rats and the comparative PKs between each pure component and DA-9805.

Determination and pharmacokinetic study of tussilagone in rat plasma by RP-HPLC method

A simple and rapid high-performance liquid chromatographic method was used to study the pharmacokinetics of tussilagone, one of the main bioactive constituents in the flower buds of Tussilago farfara L. of traditional Chinese medicines, in rat plasma. Plasma was deproteinized by ethyl acetate for sample clean-up. The drugs were separated on a Dikma Diamonsil C18 column (4.6 x 250 mm, 5.0 microm), and detected by UV absorption at 220 nm. Methanol-water (75:25, v/v) was used as the mobile phase. It was applied to the pharmacokinetic study of tussilagone in rats after a dose of 5 mg/kg by intravenous administration and a dose of 200 mg/kg by intragastrical administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve by intravenous administration, while the plasma concentration-time curve of tussilagone conformed to a one-compartment model by intragastrical administration. The absolute bioavailability of tussilagone is about 1.31%.

Study on the pharmacokinetics and metabolism of paeonol in rats treated with pure paeonol and an herbal preparation containing paeonol by using HPLC-DAD-MS method

Paeonol, a principal bioactive component of the Chinese herb Moutan Cortex with anti-inflammatory and analgesic effects, was comparatively studied to determine its pharmacokinetic behavior and metabolic profile in rat following oral administration of the pure paeonol alone and an herbal preparation "Qingfu Guanjieshu" (QFGJS) containing paeonol. An HPLC-DAD method was developed and validated for determining the concentration of paeonol in rat plasma. The in vivo time curves and AUC of paeonol at three doses were increased in a dose-dependent manner, while the pharmacokinetic parameters of paeonol in QFGJS at a comparable dosage were significantly elevated in comparison with those of pure paeonol. By using LC-Q/TOF-MS technique, four metabolites of paeonol were identified in plasma at 5min after dosing, with T(max) around 20min after treatment with the pure paeonol or QFGJS. Interestingly, relative concentrations of metabolites P2, P3 and P5 were markedly increased in plasma of rats treated with QFGJS compared with those of pure paeonol. These results indicate that other components in QFGJS could effectively influence the pharmacokinetic behavior and metabolic profile of paeonol in rats. The current studies emphasize the significance of the research toward an understanding of pharmacokinetic interactions of the co-existing components in the herbal preparations.

Determination of paeonol in rat plasma by high-performance liquid chromatography and its application to pharmacokinetic studies following oral administration of Moutan cortex decoction

Quantification of paeonol, the principal bioactive component of Moutan cortex, in rat plasma following oral administration of Moutan cortex decoction was achieved by using a simple and sensitive high-performance liquid chromatographic method. The calibration curves for paeonol were linear in both the low (25-200 ng/mL) and the high concentration range (200-4000 ng/mL) with r(2) values of 0.9928 and 0.9993, respectively. The coefficients of variation of intra- and inter-day assays were 14.36, 6.52, 1.76, 1.25, 5.36, 3.30 and 1.42% and 12.70, 1.19, 2.98, 1.91, 1.75, 1.78 and 0.96% at concentrations of 25, 50, 100, 200, 500, 1000 and 2000 ng/mL, respectively. The recoveries of paeonol from rat plasma were found to be 101.9, 104.5, 105.4 and 101.2% for concentrations of 50, 500, 1000 and 2000 ng/mL, respectively. The paeonol plasma concentrations were fitted to two-compartment model with fi rst order absorption. The mean terminal half-lives (t(1/2)) of paeonol was 80.9 min.

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.

Determination of naringenin and its glucuronide conjugate in rat plasma and brain tissue by high-performance liquid chromatography

An isocratic high-performance liquid chromatographic method with ultraviolet detection was utilized for the investigation of the pharmacokinetics of naringenin and its glucuronide conjugate in rat plasma and brain tissue. Plasma and brain tissue were deproteinized by acetonitrile, then centrifuged for sample clean-up. The drugs were separated by a reversed-phase C18 column with a mobile phase consisting of acetonitrile-orthophosphoric acid solution (pH 2.5-2.8) (36:64, v/v). The detection limits of naringenin in rat plasma and brain tissue were 50 ng/ml and 0.4 microg/g, respectively. The glucuronide conjugate of naringenin was evaluated by the deconjugated enzyme beta-glucuronidase. The naringenin conjugation ratios in rat plasma and brain tissue were 0.86 and 0.22, respectively, 10 min after naringenin (20 mg/kg, i.v.) administration. The mean naringenin conjugation ratio in plasma was approximately four fold that in brain tissue.

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

A simple high-performance liquid chromatographic method was developed to study the pharmacokinetics of dicentrine in rat plasma after 10 mg/kg intravenous administration. After addition of an internal standard (coumarin), plasma was deproteinized by acetonitrile for sample clean-up. The drugs were separated on a reversed-phase Nucleosil C18 column (250 x 4 mm I.D., particle size 5 microns) and detected by photodiode-array detection at a wavelength of 308 nm. Acetonitrile-water (35:65, v/v, pH 2.5-2.8, adjusted with orthophosphoric acid) was used as the mobile phase. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve.

Pharmacokinetics of osthole in rat plasma using high-performance liquid chromatography

A simple high-performance liquid chromatographic method was developed to study the pharmacokinetics of osthole in rat plasma. After addition of an internal standard (paeonol), plasma was deproteinized by acetonitrile for sample clean-up. The drugs were separated on a reversed-phase column and detected by UV absorption at 323 nm. Acetonitrile-water-diethylamine (50:50:0.1, v/v/v) (pH 3.0, adjusted with orthophosphoric acid) was used as the mobile phase. It was applied to the pharmacokinetic study of osthole in rats after a dose of 10 mg kg-1 by intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve.

High-performance liquid chromatographic determination of evodiamine in rat plasma: application to pharmacokinetic studies

A previously published simple and sensitive high-performance liquid chromatographic method for determination and identification of rutaecarpine in rat plasma was used for evodiamine determination. However, the ultraviolet detection was not 344 nm, but 227 nm. The method was applied to a pharmacokinetic study of evodiamine in rats after 2 mg/kg intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve. Compartmental analysis yielded a two-compartment model.