Evaluation of Pharmacokinetic Interaction of Cilostazol with Metoclopramide after Oral Administration in Human

Conjoint hepatobiliary-enterohepatic cycles for amyloid excretion and enhancing its drug-induced clearance: a systems biology approach to Alzheimer's disease

The liver is the major organ responsible for metabolism of amyloid-beta, the primary toxic misfolded protein responsible for Alzheimer's disease (AD). The present study focuses on the crucial role of liver in AD. We have developed a framework that formulates and integrates two reciprocal transport processes of amyloid, via hepato-biliary and enterohepatic circulations (EHC). Our system analysis approach shows that activating the liver X-receptor (LXR) can reduce amyloid-beta formation by increasing expression of the genes: ATP-binding-cassette-transporter (ABCA1) and Stearoyl-CoA-desaturase (SCD). Besides, activating the pregnane-X-receptor (PXR) can enhance the clearance of amyloid-beta by increasing the expression of the genes: ATP-Binding-Cassette-Superfamily-G-member-2 (ABCG2) and multidrug-resistance protein-1 (MDR1). We also identified receptor-like apical sodium-dependent bile-acid transporter (ASBT) of intestinal enterocyte, showing affinity towards amyloid-beta, suggesting amyloid-beta's possible reuptake from intestinal contents to the systemic circulation through this receptor. Further, we have performed protein-protein interaction to evaluate the binding affinity of amyloid-beta to these receptors. Moreover, we undertook molecular docking and molecular dynamic simulation of some repurposed drugs (rifampicin, 24-hydroxycholesterols, resveratrol, cilostazol) which can target the aforesaid receptors to enhance amyloid-beta's fecal clearance, reduce amyloid-beta formation, and prevent the reuptake of amyloid-beta from intestinal feces. Additionally, network pharmacology and synergism analysis were utilized to validate our hypothesis and identify the drug combinations, respectively. Gene-ontology investigation, network pharmacology, and consolidated pathway analysis validate the alteration of the above-mentioned gene expression profiles. Furthermore, our neuropharmacological synergism study identifies the optimal combination of the repurposed drugs. Finally, our findings on candidate drugs are substantiated by clinical-trial outcomes.Communicated by Ramaswamy H. Sarma.

Effect of clarithromycin pre-treatment on the pharmacokinetics of metoclopramide after their simultaneous oral intake

OBJECTIVE

The objective of this study was to assess the influence of enzyme suppression on the values of various pharmacokinetic factors of orally administered metoclopramide.

METHOD

This study was conducted in two phases and a 4-week duration was adopted for drug washout. This randomized study involved 12 healthy human volunteers who received a single oral dose of metoclopramide 20 mg. After the washout period, volunteers received clarithromycin 500 mg two times per day for consecutive 5 days. On test day (fifth day), a single oral dose of metoclopramide 20 mg was also given to the volunteers, and collection of blood samples was conducted at pre-decided time points. Various pharmacokinetic parameters such as C_max, T_max, and AUC_0-∞ of metoclopramide were determined by analyzing the blood samples using a validated HPLC-UV method.

RESULTS

Clarithromycin increased the mean values of C_max, AUC_0-∞, and T_1/2 of metoclopramide by 46%, 78.6%, and 9.8%, respectively.

CONCLUSION

Clarithromycin noticeably increased the concentration of plasma metoclopramide. This study's results provide in vivo confirmation of the CYP3A4 involvement in metoclopramide metabolism, in addition to CYP2D6. Therefore, metoclopramide pharmacokinetics may be clinically affected by clarithromycin and other potent enzyme inhibitors.

Influence of Rifampicin Pre-treatment on the In vivo Pharmacokinetics of Metoclopramide in Pakistani Healthy Volunteers Following Concurrent Oral Administration

BACKGROUND

Metoclopramide is metabolized by various cytochrome P450 (CYP) enzymes such as CYP3A4, CYP1A2, CYP2D6, CYP2C9, and CYP2C19. Rifampicin is a non-selective inducer of P-glycoprotein (P-gp) and CYP enzymes such as CYP3A4 and others.

OBJECTIVE

This study was aimed at the evaluation of rifampicin's enzyme induction effect on the pharmacokinetic parameters of orally administered metoclopramide.

METHOD

This randomized, single-blind, two-phase cross-over pharmacokinetic study separated by a 4-week washout period was conducted at a single center in Pakistan. It involved twelve Pakistani healthy male volunteers (nonsmokers) divided into two groups. In the reference phase, each volunteer received a single oral dose of 20 mg metoclopramide (Maxolon 10 mg, GlaxoSmithKline, Pakistan), while in the rifampicin-treated phase, each volunteer received 600 mg rifampicin once daily for 6 days through oral route. On day 6, metoclopramide (20 mg) was administered 2 hours after the last pretreatment dose of rifampicin. The serial blood samples were collected on predetermined time points (0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 14, and 18 h) and analyzed using a validated HPLC method for the determination of pharmacokinetic parameters, i.e. Cmax, Tmax, and AUC0-∞ of metoclopramide. The whole study was monitored by an unblinded clinician for the purpose of volunteer's health safety.

RESULTS

All the volunteers participated in the study until the end. Twelve healthy Pakistani males having mean age 26.0 (range 20.6-34.1) years and body mass index 25.1 (range 16.2-31.5) kg/m2 were included in this study after taking written informed consent. Rifampicin significantly (P<0.05) decreased the mean Cmax, AUC0-∞ and T1/2 of metoclopramide by 35%, 68%, and 44%, respectively. The laboratory tests did not reveal any significant change in the biochemical, physical, hematological, or urinalytical values before and after metoclopramide treatment. None of the volunteers complained of any discomfort during the study.

CONCLUSION

Rifampicin noticeably decreased the concentration of plasma metoclopramide. These results give in vivo confirmation of the CYP3A4 involvement in the metoclopramide metabolism, in addition to CYP2D6. Therefore, metoclopramide pharmacokinetics may be clinically affected by rifampicin and other potent enzyme inducers.