Comparison of the Effects of Omeprazole and Rabeprazole on Ticlopidine Metabolism In Vitro

Monoester-Diterpene Aconitum Alkaloid Metabolism in Human Liver Microsomes: Predominant Role of CYP3A4 and CYP3A5

Aconitum, widely used to treat rheumatoid arthritis for thousands of years, is a toxic herb that can frequently cause fatal cardiac poisoning. Aconitum toxicity could be decreased by properly hydrolyzing diester-diterpene alkaloids into monoester-diterpene alkaloids. Monoester-diterpene alkaloids, including benzoylaconine (BAC), benzoylmesaconine (BMA), and benzoylhypaconine (BHA), are the primary active and toxic constituents of processed Aconitum. Cytochrome P450 (CYP) enzymes protect the human body by functioning as the defense line that limits the invasion of toxicants. Our purposes were to identify the CYP metabolites of BAC, BMA, and BHA in human liver microsomes and to distinguish which isozymes are responsible for their metabolism through the use of chemical inhibitors, monoclonal antibodies, and cDNA-expressed CYP enzyme. High-resolution mass spectrometry was used to characterize the metabolites. A total of 7, 8, and 9 metabolites were detected for BAC, BMA, and BHA, respectively. The main metabolic pathways were demethylation, dehydrogenation, demethylation-dehydrogenation, hydroxylation and didemethylation, which produced less toxic metabolites by decomposing the group responsible for the toxicity of the parent compound. Taken together, the results of the chemical inhibitors, monoclonal antibodies, and cDNA-expressed CYP enzymes experiments demonstrated that CYP3A4 and CYP3A5 have essential functions in the metabolism of BAC, BMA, and BHA.

Rabeprazole for the treatment of acid-related disorders

Proton pump inhibitors are widely used for the treatment of acid-related disorders. Rabeprazole is a potent and irreversible inhibitor of H(+)/K(+)-ATPase gastric pump, and it is indicated for the treatment of gastroesophageal reflux disease, Zollinger Ellison syndrome, duodenal and gastric ulcers and for the eradication of Helicobacter pylori in combination with antibiotics. Pharmacokinetic and pharmacodynamic data show that rabeprazole achieves a pronounced acid suppression from the first administration that is maintained with repeated use; this may translate into faster onset of symptom relief for patients, particularly suitable when the indication is for the on-demand long-term maintenance of gastroesophageal reflux disease. Due to its predominantly nonenzymatic metabolism, rabeprazole has a lower potential for drug-drug interactions. The objective of this article is to update efficacy and safety data of rabeprazole in the treatment of acid-related disorders, following a previous review dated 2008.

Chrysophanol-8-O-glucoside, an anthraquinone derivative in rhubarb, has antiplatelet and anticoagulant activities

Rhubarb is a widely used traditional medicine and has been reported to elicit a number of biological effects including anti-inflammatory and antiplatelet effects. In the present study, we investigated the effects of anthraquinone derivatives isolated from rhubarb on platelet activity. Of four anthraquinone derivatives isolated from rhubarb examined, chrysophanol-8-O-glucoside (CP-8-O-glc) was found to have the most potent inhibitory effect on collagen- and thrombin-induced platelet aggregation. CP-8-O-glc-treated mice showed significantly prolonged bleeding times. Furthermore, CP-8-O-glc was found to have a significant inhibitory effect on rat platelet aggregation ex vivo and on thromboxane A(2) formation in vitro. In coagulation tests, CP-8-O-glc did not alter prothrombin time, and it prolonged the activated partial thromboplastin time. However, CP-8-O-glc only inhibited platelet phosphatidylserine exposure, but not exert direct inhibition on intrinsic factors. This study demonstrates the antiplatelet and anticoagulant effects of CP-8-O-glc and suggests that this compound might be of therapeutic benefit for the prevention of platelet-related cardiovascular diseases.