Influence of Verapamil on Pharmacokinetics of Triptolide in Rats

The molecular pathogenesis of triptolide-induced hepatotoxicity

Triptolide (TP) is the major pharmacologically active ingredient and toxic component of Tripterygium wilfordii Hook. f. However, its clinical potential is limited by a narrow therapeutic window and multiple organ toxicity, especially hepatotoxicity. Furthermore, TP-induced hepatotoxicity shows significant inter-individual variability. Over the past few decades, research has been devoted to the study of TP-induced hepatotoxicity and its mechanism. In this review, we summarized the mechanism of TP-induced hepatotoxicity. Studies have demonstrated that TP-induced hepatotoxicity is associated with CYP450s, P-glycoprotein (P-gp), oxidative stress, excessive autophagy, apoptosis, metabolic disorders, immunity, and the gut microbiota. These new findings provide a comprehensive understanding of TP-induced hepatotoxicity and detoxification.

Effect of naringenin on the pharmacokinetics of metoprolol succinate in rats

The aim of the present study was to investigate the effect of naringenin (4,5,7-trihydroxy flavonone) on the pharmacokinetics of metoprolol, a substrate of Cytochrome P-450 3A4 (CYP3A4), CYP2C9, and CYP2D6 in rats.Male Wistar rats were treated orally with metoprolol (30 mg/kg) alone and in combination with naringenin (25, 50, and 100 mg/kg) once daily for 15 consecutive days.The plasma concentrations of metoprolol were determined using Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) on the 1st day in single-dose pharmacokinetic (PK) study (SDS) and on the 15th day in multiple dosing PK studies (MDS).Compared to the metoprolol control group, the C_max, AUC, and half-life (T_1/2) of metoprolol increased in rats pre-treated with naringenin, while there was no significant change in T_max. There is a significant decrease in clearance and volume of distribution.The present study results revealed that naringenin significantly enhanced the C_max, AUC, MRT, t_1/2, and decreased the clearance of metoprolol possibly through the inhibition of CYP enzymes involved in the metabolism of metoprolol.

Effects of naringenin on the pharmacokinetics of tofacitinib in rats

Context: Naringenin and tofacitinib are often used together for treatment of rheumatoid arthritis in Chinese clinics.Objective: This experiment investigates the effect of naringenin on the pharmacokinetics of tofacitinib in rats.Materials and methods: Twelve Sprague-Dawley rats were randomly divided into two groups (experimental group and control group). The experimental group was pre-treated with naringenin (150 mg/kg/day) for two weeks before dosing tofacitinib, and equal amounts of CMC-Na solution in the control group. After a single oral administration of 5 mg/kg of tofacitinib, 50 μL blood samples were directly collected into 1.5 mL heparinized tubes via the caudal vein at 0.083, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 and 24 h. The plasma concentration of tofacitinib was quantified by UPLC/MS-MS.Results: Results indicated that naringenin could significantly affect the pharmacokinetics of tofacitinib. The AUC_0-24 of tofacitinib was increased from 1222.81 ± 222.07 to 2016.27 ± 481.62 ng/mL/h, and the difference was significant (p < 0.05). Compared with the control group, the T_max was increased from 0.75 ± 0.29 to 3.00 ± 0.00 h (p < 0.05), and the MRT_(0-24) was increased from 4.90 ± 0.51 to 6.57 ± 0.66 h (p < 0.05), but the clearance was obviously decreased from 4.10 ± 0.72 to 2.42 ± 0.70 L/h/kg (p < 0.05) in experimental group. Although the C_max and t_1/2 of tofacitinib were increased, there were no significant differences (p > 0.05).Conclusions: This research demonstrated a drug-drug interaction between naringenin and tofacitinib possibly when preadministered with naringenin; thus, we should pay attention to this possibility in the clinic.

Circadian clock regulates hepatotoxicity of Tripterygium wilfordii through modulation of metabolism

OBJECTIVES

We aimed to determine the diurnal rhythm of Tripterygium wilfordii (TW) hepatotoxicity and to investigate a potential role of metabolism and pharmacokinetics in generating chronotoxicity.

METHODS

Hepatotoxicity was determined based on assessment of liver injury after dosing mice with TW at different circadian time points. Circadian clock control of metabolism, pharmacokinetics and hepatotoxicity was investigated using Clock-deficient (Clock^-/- ) mice.

KEY FINDINGS

Hepatotoxicity of TW displayed a significant circadian rhythm (the highest level of toxicity was observed at ZT2 and the lowest level at ZT14). Pharmacokinetic experiments showed that oral gavage of TW at ZT2 generated higher plasma concentrations (and systemic exposure) of triptolide (a toxic constituent) compared with ZT14 dosing. This was accompanied by reduced formation of triptolide metabolites at ZT2. Loss of Clock gene sensitized mice to TW-induced hepatotoxicity and abolished the time-dependency of toxicity that was well correlated with altered metabolism and pharmacokinetics of triptolide. Loss of Clock gene also decreased Cyp3a11 expression in mouse liver and blunted its diurnal rhythm.

CONCLUSIONS

Tripterygium wilfordii chronotoxicity was associated with diurnal variations in triptolide pharmacokinetics and circadian expression of hepatic Cyp3a11 regulated by circadian clock. Our findings may have implications for improving TW treatment outcome with a chronotherapeutic approach.

Effects of puerarin on the pharmacokinetics of triptolide in rats

Context: Puerarin and triptolide are sometimes used together for the treatment of disease in Chinese clinics; however, the drug-drug interaction between puerarin and triptolide is still unknown. Objective: This study investigates the effects of puerarin on the pharmacokinetics of triptolide in rats and clarifies its main mechanism. Materials and methods: The pharmacokinetic profiles of oral administration of triptolide (1 mg/kg) in Sprague-Dawley rats with (test group, n = 6) or without pretreatment (control group, n = 6) with puerarin (100 mg/kg/day for seven days) were investigated. The effects of puerarin on the transport and metabolic stability of triptolide were also investigated using Caco-2 cell transwell model and rat liver microsomes. Results: The results showed that puerarin could significantly increase the peak plasma concentration (from 187.25 ± 15.36 to 219.67 ± 21.52 ng/mL), and decrease its oral clearance (from 4.92 ± 0.35 to 62.46 ± 3.75 ± 0.19 L/h/kg). The Caco-2 cell transwell experiments indicated that puerarin could decrease the efflux ratio of triptolide from 2.70 to 1.33, and the intrinsic clearance rate of triptolide was decreased by the pretreatment with puerarin (38.8 ± 4.7 vs. 32.9 ± 6.5 μL/min/mg protein). Discussion and conclusions: Puerarin could significantly change the pharmacokinetic profiles of triptolide in rats, and it might exert these effects through increasing the absorption of triptolide by inhibiting the activity of P-gp, or through inhibiting the metabolism of triptolide in rat liver. The results also showed that the dose of triptolide should be decreased when these drugs were co-administered.

Effects of glycyrrhizin on the pharmacokinetics of paeoniflorin in rats and its potential mechanism

Context: Paeoniflorin is reported to possess numerous pharmacological activities. Paeoniflorin and glycyrrhizin are always used together for the treatment of disease in China clinics; however, the drug-drug interaction between glycyrrhizin and paeoniflorin is still unknown. Objective: This study investigates the effects of glycyrrhizin on the pharmacokinetics of paeoniflorin in rats. Materials and methods: The pharmacokinetics of orally administered paeoniflorin (20 mg/kg) with or without glycyrrhizin pre-treatment (at a dose of 100 mg/kg/day for 7 days) were investigated in male Sprague-Dawley rats using LC-MS/MS. Additionally, Caco-2 cell transwell model and rat liver microsome incubation experiments were also conducted to investigate its potential mechanism. Results: The results showed that when the rats were pre-treated with glycyrrhizin, the C_max of paeoniflorin decreased from 59.57 ± 10.24 to 45.36 ± 8.61 ng/mL, and AUC_0-inf also decreased from 282.02 ± 35.06 to 202.29 ± 28.28 μg·h/L. The t_1/2 value of paeoniflorin decreased from 8.48 ± 2.01 to 5.88 ± 1.15 h (p < 0.05). The Caco-2 cell transwell experiments indicated that glycyrrhizin could increase the efflux ratio of paeoniflorin from 2.71 to 3.52, and the rat liver microsome incubation experiments showed that glycyrrhizin could significantly increase its intrinsic clearance rate from 53.7 ± 4.6 to 85.6 ± 7.1 μL/min/mg protein. Conclusions: These results indicated that glycyrrhizin could affect the pharmacokinetics of paeoniflorin, and it might work through decreasing the absorption of paeoniflorin by inducing the activity of P-gp or through increasing the clearance rate in rat liver by inducing the activity of CYP450 enzyme.

Dihydromyricetin affect the pharmacokinetics of triptolide in rats

1. Dihydromyricetin (DMY) has anti-tumor and hepatoprotective activities and inhibits the activity of CYP enzymes and P-gp. In this research, we explored the effect of DMY on the pharmacokinetics of triptolide (TP), an anti-tumor Chinese medicine that is mainly metabolized by CYP enzymes and is the substrate of P-gp.2. Rats were administrated TP (1.2 mg/kg) with and without DMY in different dosage regimens, then a sensitive and reliable LC-MS/MS method was developed and applied to assess the pharmacokinetics of TP. The blood samples for TP were collected from each rat up to 120 min after administration of TP.3. When co-administrated with single dose of DMY (100 mg/kg), the AUC, Cmax and T1/2 of TP were significantly enhanced by 98, 83 and 66%, respectively. The T1/2 of TP was significantly prolonged from 23.6 ± 6.4 to 70.5 ± 12.5 min with 14-doses pretreatment of DMY (500 mg/kg), conversely, the Cmax was decreased by 30% and the AUC was enhanced by 24%.4. These results hinted that administration of DMY with TP did alter the pharmacokinetics of TP, and provided the theoretical pharmacokinetic basis to study on the protective effects of DMY against acute liver injury caused by TP.

Preclinical Pharmacokinetics of Triptolide: A Potential Antitumor Drug

Background:

Triptolide, a bioactive component in Tripterygium wilfordii extracts, possess strong antiproliferative activity on all 60-National Cancer Institute (NCI) cancer cell lines. However, the widespread use of triptolide in the clinical practice is greatly limited for its multi-organ toxicity and narrow therapeutic window. All the toxic characteristics of triptolide are associated with the pharmacokinetics especially its distribution and accumulation in the target organ.

Methods:

The literature review was done using PubMed search, SciFinder and Google Scholar databases with specific keywords such as triptolide, pharmacokinetics, drug-drug interaction, transporters, metabolism, modification to collect the related full-length articles and abstracts from 2000 to 2018.

Results:

Oral triptolide is rapidly and highly absorbed. Grapefruit juice affects oral absorption, increasing the area under the concentration-time curve (AUC) by 153 % and the maximum concentration (Cmax) by 141 %. The AUC and the Cmax are not dose proportional. Triptolide distributes into the liver, heart, spleen, lung and kidney. Biotransformation of triptolide in rats includes hydroxylation, sulfate, glucuronide, N-acetylcysteine (NAC) and Glutathione (GSH) conjugation and combinations of these pathways. Less than 4 % of triptolide was recovered from the feces, bile and urine within 24 h. After repeating dosage, triptolide was eliminated quickly without accumulation in vivo. As a substrate of P-glycoprotein (P-gp) and CYP3A4, triptolide could have clinically significant pharmacokinetic interactions with those proteins substrates/inhibitors.

Conclusion:

The findings of this review confirm the importance of pharmacokinetic character for understanding the pharmacology and toxicology of triptolide.

PTEN-induced partial epithelial-mesenchymal transition drives diabetic kidney disease

Epithelial-mesenchymal transition (EMT) contributes significantly to interstitial matrix deposition in diabetic kidney disease (DKD). However, detection of EMT in kidney tissue is impracticable, and anti-EMT therapies have long been hindered. We reported that phosphatase and tensin homolog (PTEN) promoted transforming growth factor beta 1 (TGF-β), sonic hedgehog (SHH), connective tissue growth factor (CTGF), interleukin 6 (IL-6), and hyperglycemia-induced EMT when PTEN was modified by a MEX3C-catalyzed K27-linked polyubiquitination at lysine 80 (referred to as PTENK27-polyUb). Genetic inhibition of PTENK27-polyUb alleviated Col4a3 knockout-, folic acid-, and streptozotocin-induced (STZ-induced) kidney injury. Serum and urine PTENK27-polyUb concentrations were negatively correlated with glomerular filtration rate (GFR) for diabetic patients. Mechanistically, PTENK27-polyUb facilitated dephosphorylation and protein stabilization of TWIST, SNAI1, and YAP in renal epithelial cells, leading to enhanced EMT. We identified that a small molecule, triptolide, inhibited MEX3C-catalyzed PTENK27-polyUb and EMT of renal epithelial cells. Treatment with triptolide reduced TWIST, SNAI1, and YAP concurrently and improved kidney health in Col4a3 knockout-, folic acid-injured disease models and STZ-induced, BTBR ob/ob diabetic nephropathy models. Hence, we demonstrated the important role of PTENK27-polyUb in DKD and a promising therapeutic strategy that inhibited the progression of DKD.

CYP3A4 inducer and inhibitor strongly affect the pharmacokinetics of triptolide and its derivative in rats

Triptolide is the most active ingredient of Tripterygium wilfordii Hook F, which is used to treat rheumatoid arthritis. (5R)-5-Hydroxytriptolide is a hydroxylation derivative of triptolide with a reduced toxicity. To investigate the metabolic enzymes of the two compounds and the drug-drug interactions with enzyme inducers or inhibitors, a series of in vitro and in vivo experiments were conducted. In vitro studies using recombinant human cytochrome P450 enzyme demonstrated that cytochrome P450 3A4 (CYP3A4) was predominant in the metabolism of triptolide and (5R)-5-hydroxytriptolide, accounting for 94.2% and 64.2% of the metabolism, respectively. Pharmacokinetics studies were conducted in male SD rats following administration of triptolide or (5R)-5-hydroxytriptolide (0.4 mg/kg, po). The plasma exposure to triptolide and (5R)-5-hydroxytriptolide in the rats was significantly increased when co-administered with the CYP3a inhibitor ritonavir (30 mg/kg, po) with the values of AUC_0-∞ (area under the plasma concentration-time curve from time zero extrapolated to infinity) being increased by 6.84 and 1.83 times, respectively. When pretreated with the CYP3a inducer dexamethasone (50 mg·kg^-1·d^-1, for 3 d), the AUC_0-∞ values of triptolide and (5R)-5-hydroxytriptolide were decreased by 85.4% and 91.4%, respectively. These results suggest that both triptolide and (5R)-5-hydroxytriptolide are sensitive substrates of CYP3a. Because of their narrow therapeutic windows, clinical drug-drug interaction studies should be carried out to ensure their clinical medication safety and efficacy.

WITHDRAWN: Toxicity of triptolide and the molecular mechanisms involved

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Effects of verapamil on the pharmacokinetics of dihydromyricetin in rats and its potential mechanism

1. This study investigates the effects of verapamil on the pharmacokinetics of dihydromyricetin in rats and clarifies its main mechanism. 2. The pharmacokinetic profiles of oral or intravenous administration of dihydromyricetin in Sprague-Dawley rats with or without pretreatment with verapamil were investigated. In addition, the effects of verapamil on the transport and metabolic stability of dihydromyricetin were investigated using Caco-2 cell transwell model and rat liver microsomes. 3. In the oral group, verapamil could significantly increase C_max, and decrease oral clearance of dihydromyricetin (p < 0.05). In the intravenous group, the C_max also increased compared with the control group, but the difference was not significant. However, the t_1/2 and clearance rate decreased than that of the control (p < 0.05). The oral bioavailability increased significantly (p < 0.05) from 3.84% to 6.84% with the pretreatment of verapamil. A markedly higher transport of dihydromyricetin across the Caco-2 cells was observed in the basolateral-to-apical direction and was abrogated in the presence of the P-gp inhibitor, verapamil. Additionally, the intrinsic clearance rate of dihydromyricetin was decreased by the pretreatment with verapamil (27.0 versus 32.5 μL/min/mg protein). 4. Those results indicated that verapamil could significantly change the pharmacokinetic profiles of dihydromyricetin in rats, and it might exert these effects through increasing the absorption of dihydromyricetin by inhibiting the activity of P-gp, or through inhibiting the metabolism of dihydromyricetin in rat liver.