The Pharmacokinetic Interaction Study between Carvedilol and Bupropion in Rats

Formulation and Bioavailability of Novel Mucoadhesive Buccal Films for Candesartan Cilexetil in Rats

Candesartan cilexetil (CC) is an antihypertensive drug. It has low solubility and faces hepatic first-pass metabolism after oral ingestion. We formulated bioadhesive buccal films and studied the respective drug pharmacokinetics. Different bioadhesive films were prepared (40, 80, 120, 160, 200, and 240 mg CC per film) by using the solvent casting method. The drug concentrations used affect the drug entrapment mechanism, which was reflected in the film physicochemical properties like thickness, weight, drug content, bioadhesion, and drug release. Low drug concentration (F2, 40 mg per film) led to minute drug crystal dispersion while increasing the drug concentration (F7, 240 mg per film) showed drug crystal encapsulation, which affects the drug release. The drug pharmacokinetic from the prepared films was studied compared to the oral form by serial blood sampling via an inserted catheter in the carotid of rats. High-Performance Liquid Chromatography assay was used to measure the plasma concentration of CC in different forms. Compared to other films, the F2 showed the highest maximal concentration (Cmax) and the lowest elimination half-life (t_1/2). Bioadhesion buccal film of CC has better bioavailability, especially at low concentrations. The ease, robustness, and ruggedness of the preparation suggests the same procedure for drugs like CC.

Comparative Pharmacokinetic Study of Taxifolin after Oral Administration of Fructus Polygoni Orientalis Extract in Normal and Fibrotic Rats by UPLC-MS/MS

Fructus polygoni orientalis (FPO) is widely used in clinical practice in China, especially in treatment of liver diseases including viral hepatitis, liver fibrosis, and liver cirrhosis. However, its pharmacokinetic (PK) alterations in liver fibrotic rats have rarely been reported. To study whether taxifolin, one of the main flavonoids in FPO can be absorbed into blood after oral administration of FPO extract and to compare the differences in pharmacokinetic parameters of taxifolin to normal and liver fibrotic rats induced by porcine serum (PS), a UPLC-MS/MS method was developed and validated for determination of taxifolin in rat plasma using puerarin as the internal standard (IS). All validation parameters met the acceptance criteria according to regulatory guidelines. The results indicated that after treatment of rats with PS alone for 12 weeks, the liver fibrotic model group was built successfully. The taxifolin can be absorbed into the blood after oral administration of the FPO extract. The C _max of taxifolin was 1940 ± 502.2 ng/mL and 2648 ± 208.5 ng/mL (p < 0.05), the AUC_0∼t of taxifolin was 4949.7 ± 764.89 h·ng/mL and 6679.9 ± 734.26 h·ng/mL (p < 0.05), the AUC_0∼∞ of taxifolin was 5049.4 ± 760.7 and 7095.2 ± 962.3 h·ng/mL (p < 0.05), and the mean residence time (MRT) of taxifolin was 2.46 ± 0.412 h and 3.17 ± 0.039 h (p < 0.05) in the normal and fibrotic model groups, respectively. These results confirmed that the pharmacokinetic parameters of taxifolin are altered in liver fibrosis, manifested as C _max, AUC_0∼t , AUC_0∼∞, and the mean residence time (MRT). It suggested that it is essential to consider the characteristics of pharmacokinetics after oral administration of FPO in liver disease patients.

Pharmacokinetic interactions study between carvedilol and some antidepressants in rat liver microsomes - a comparative study

Background and aims

Cardiovascular diseases and depressive disorders are some of the most frequent diseases. The probability of concomitant prescription of antihypertensive and antidepressive medication is increasing. The aim of this study was to investigate the enzyme inhibition by bupropion, sertraline and fluvoxamine on the metabolism of carvedilol using rat pooled liver microsomes and to assess the importance of these interactions from the pharmacokinetic mechanism point of view.

Methods

Two substrate concentrations (0.5 and 1 μM) and four inhibitor concentrations (0, 0.1, 0.75 and 1.5 μM) were used for each tested inhibitor.

Results

The results of the in vitro experiments showed a significant decrease of the metabolic rate of carvedilol to 4′-hydroxyphenyl carvedilol, for all tested inhibitors, when the inhibitor was added to the incubation mixture containing the substrate. Moreover, an increase of the area under the concentration-time curve for carvedilol was observed after incubation with each tested inhibitor compared with the control state (no inhibitor). The most potent inhibitor was sertraline, followed by fluvoxamine and bupropion.

Conclusion

The co-administration of tested antidepressants led to a significant alteration of carvedilol’s metabolism in vitro. CYP2D6 inhibition is the main pharmacokinetic mechanism that can explain these drug-drug interactions, with possible clinical implications.

Inhibitory Effect of Citalopram on the Pharmacokinetics of Carvedilol in Rats and in vitro Models

BACKGROUND/AIMS

The aim of this study was to investigate the drug-drug interaction between carvedilol and citalopram based on carvedilol metabolism in vitro and his pharmacokinetics (PKs) in vivo after the oral administration of the single drug and both drugs, and reveal citalopram effects on the PKs of carvedilol.

METHODS

Each rat was cannulated on the femoral vein, prior to being connected to BASi Culex ABC®. Carvedilol was orally administrated in rats (3.57 mg/kg body weight [b.w.]) in the absence of citalopram or after a pre-treatment with multiple oral doses of citalopram (1.42 mg/kg b.w.). Plasma concentrations of carvedilol were determined using high-performance liquid chromatography-MS at the designated time points after drug administration, and the main PK parameters were calculated by noncompartmental analysis. In addition, effects of citalopram on the metabolic rate of carvedilol were investigated using rat-pooled liver microsome incubation systems.

RESULTS

During co-administration, significant increases of the area under the plasma concentration-time curve as well as of the peak plasma concentration were observed. The rat-pooled liver microsome incubation experiment indicated that citalopram could decrease the metabolic rate of carvedilol.

CONCLUSION

Citalopram co-administration led to a significant alteration of carvedilol's PK profile in rats; it also demonstrated, in vitro, these effects could be explained by the existence of a drug-drug interaction mediated by CYP2D6 inhibition.