Simultaneous Estimation of Quercetin and <i>trans</i>-Resveratrol in <i>Cissus quadrangularis</i> Extract in Rat Serum Using Validated LC-MS/MS Method: Application to Pharmacokinetic and Stability Studies

Cissus quadrangularis is a nutrient-rich plant with a history of use in traditional medicine. It boasts a diverse range of polyphenols, including quercetin, resveratrol, β-sitosterol, myricetin, and other compounds. We developed and validated a sensitive LC-MS/MS method to quantify quercetin and t-res biomarkers in rat serum and applied this method to pharmacokinetic and stability studies. The mass spectrometer was set to negative ionization mode for the quantification of quercetin and t-res. Phenomenex Luna (C18(2), 100 A, 75 × 4.6 mm, 3 µ) column was utilized to separate the analytes using an isocratic mobile phase consisting of methanol and 0.1% formic acid in water (82:18). Validation of the method was performed using various parameters, including linearity, specificity, accuracy, stability, intra-day, inter-day precision, and the matrix effect. There was no observed significant endogenous interference from the blank serum. The analysis was completed within 5.0 min for each run, and the lower limit of quantification was 5 ng/mL. The calibration curves showed a linear range with a high correlation coefficient (r2 > 0.99). The precision for intra- and inter-day assays showed relative standard deviations from 3.32% to 8.86% and 4.35% to 9.61%, respectively. The analytes in rat serum were stable during bench-top, freeze-thaw, and autosampler (−4 °C) stability studies. After oral administration, the analytes showed rapid absorption but underwent metabolism in rat liver microsomes despite being stable in simulated gastric and intestinal fluids. Intragastric administration resulted in higher absorption of quercetin and t-res, with greater Cmax, shorter half-life, and improved elimination. No prior research has been conducted on the oral pharmacokinetics and stability of anti-diabetic compounds in the Ethanolic extract of Cissus quadrangularis EECQ, making this the first report. Our findings can provide the knowledge of EECQ’s bioanalysis and pharmacokinetic properties which is useful for future clinical trials

Preclinical pharmacokinetics and herb-drug interaction studies of atorvastatin co-administered with the herbal slimming products

Herbal slimming products (HSPs) contain multiple herbs used in weight loss. Phytoconstituents of several plant extracts show the inhibitory effects on the drug-metabolizing enzymes causing interaction when taken with other drugs. Atorvastatin (ATS) is used in the treatment of hyperlipidemia. This study aimed to investigate the effect of HSPs on the pharmacokinetics and pharmacodynamics of ATS. ATS (10 mg/Kg) was administered alone or in combination with HSP1 (200 mg/Kg)/ HSP2 (165 mg/Kg) orally in the SD rats for pharmacokinetics study. Hyperlipidemia was induced in Golden Syrian Hamster by feeding HFD (60% kcal). Furthermore, biochemical levels in serum, ROS, gene expression and lipid accumulation levels were examined in hamster liver tissue. HSPs have significantly enhanced the permeability and inhibited the metabolism of ATS by inhibiting the CYP3A4 isoenzyme confirmed by in vitro assay. Co-administration of HSPs with ATS enhanced the relative bioavailability of ATS.Concomitant administration of HSPs with ATS has significantly reduced the fat content, inflammatory cytokines, TG, VLDL, LDL levels, tissue MDA level, HMGCR and SREBP1c mRNA expression levels, lipid accumulation as well as collagen content and has increased the serum HDL level as well as tissue SOD, CAT, GHS and mRNA expression levels of LXRα and CYP7A1. The aforementioned outcomes indicated that co-administration of HSPs with ATS may lead to herb-drug interaction. Therefore, precaution should be taken and dose adjustment is required when administered simultaneously.

Evaluation of the Pharmacokinetics of the Pancreastatin Inhibitor PSTi8 Peptide in Rats: Integration of In Vitro and In Vivo Findings

PSTi8 is a pancreastatin inhibitory peptide that is effective in the treatment of diabetic models. This study investigates the pharmacokinetic (PK) properties of PSTi8 in Sprague Dawley rats, for the first time. In vitro and in vivo PK studies were performed to evaluate the solubility, stability in plasma and liver microsomes, plasma protein binding, blood–plasma partitioning, bioavailability, dose proportionality, and gender difference in PK. Samples were analyzed using the validated LC-MS/MS method. The solubility of PSTi8 was found to be 9.30 and 25.75 mg/mL in simulated gastric and intestinal fluids, respectively. The protein binding of PSTi8 was estimated as >69% in rat plasma. PSTi8 showed high stability in rat plasma and liver microsomes and the blood–plasma partitioning was >2. The bioavailability of PSTi8 after intraperitoneal and subcutaneous administration was found to be 95.00 ± 12.15 and 78.47 ± 17.72%, respectively, in rats. PSTi8 showed non-linear PK in dose proportionality studies, and has no gender difference in the PK behavior in rats. The high bioavailability of PSTi8 can be due to high water solubility and plasma protein binding, low clearance and volume of distribution. Our in vitro and in vivo findings support the development of PSTi8 as an antidiabetic agent

LC–MS/MS method for simultaneousestimation of raloxifene, cladrin in ratplasma: application in pharmacokineticstudies – supplementary materials

Aim: A newer LC–MS/MS method was developed and validated for the simultaneous quantification ofraloxifene (RL) and cladrin (CL). Methodology: Both drugs were resolved in RP-18 (4.6 × 50 mm, 5 μ)Xbridge Shield column using acetonitrile and 0.1% aqueous solution of formic acid (FA) (70:30% v/v)as mobile phase by using biological matrices in female Sprague–Dawley rats using–MS/MS. Results: Thedeveloped method was found to be linear over the concentration ranges of 1–600 ng/ml, and lowerlimit of quantification was 1 ng/ml for RL and CL, respectively. Pharmacokinetic results of RL+CL showedCmax = 4.23 ± 0.61, 26.97 ± 1.14 ng/ml, at Tmax(h) 5.5 ± 1.00 and 3.5 ± 1.00, respectively. Conclusion:Pharmacokinetic study results will be useful in the future for the combined delivery of RL and CL forosteoporosis treatment.</p