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1. In clinical practice, diammonium glycyrrhizinate is usually used with omeprazole in patients with viral hepatitis and cirrhosis accompanied by peptic ulcers. However, the drug interaction between diammonium glycyrrhizinate and omeprazole remains unclear. 2. In this study, the effects of diammonium glycyrrhizinate on the pharmacokinetics of omeprazole was investigated by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method. Male Sprague–Dawley rats were randomly assigned to two groups: omeprazole and omeprazole + diammonium glycyrrhizinate, and the main pharmacokinetic parameters were estimated after oral administration. It was found that using the omeprazole along with the diammonium glycyrrhizinate increased the AUC, AUMC, Cmax for omeprazole. 3. For this reason, we used the LC-MS/MS to detect the binding rate of plasma protein (BRPP) of omeprazole in rats, it was found that diammonium glycyrrhizinate could decrease the BRPP in rats. In addition, we found that diammonium glycyrrhizinate specifically inhibited the enzyme activity of the CYP2C19 and CYP3A4, which are involved in the metabolism of the omeprazole. 4. These results mean that diammonium glycyrrhizinate could inhibit the metabolism and increase the plasma concentration of the omeprazole in rats. Overall, diammonium glycyrrhizinate can influence the pharmacokinetics of omeprazole by inhibiting CYP2C19 and CYP3A4 activities and decreasing BRPP of omeprazole. [ABSTRACT FROM AUTHOR]

Context: Danshen tablets (DST), an effective traditional Chinese multi-herbal formula, are often combined with atorvastatin calcium (AC) for treating coronary heart disease in the clinic. Objective: This study investigated the effects of DST on the pharmacokinetics of AC and the potential mechanism. Materials and methods: The pharmacokinetics of AC (1 mg/kg) with or without pretreatment of DST (100 mg/kg) were investigated using LC-MS/MS. The effects of DST (50 μg/mL) on the metabolic stability of AC were also investigated using rat liver microsome incubation systems. Results: The results indicated that Cmax (23.87 ± 4.27 vs. 38.94 ± 5.32 ng/mL), AUC(0-t) (41.01 ± 11.32 vs. 77.28 ± 12.92 ng h/mL), and t1/2 (1.91 ± 0.18 vs. 2.74 ± 0.23 h) decreased significantly (p < 0.05) when DST and AC were co-administered, which suggested that DST might influence the pharmacokinetic behavior of AC when they are co-administered. The metabolic stability (t1/2) of AC was also decreased (25.7 ± 5.2 vs. 42.5 ± 6.1) with the pretreatment of DST. Discussion and conclusions: This study indicated that the main components in DST could accelerate the metabolism of AC in rat liver microsomes and change the pharmacokinetic behaviors of AC. So these results showed that the herb-drug interaction between DST and AC might occur when they were co-administered. Therefore, the clinical dose of AC should be adjusted when DST and AC are co-administered. [ABSTRACT FROM AUTHOR]

Nifedipine is completely absorbed by the gastrointestinal tract and its pharmacokinetics and metabolism may be influenced by microorganisms. If gut microbes are involved in the metabolism of nifedipine, plateau hypoxia may regulate the bioavailability and the therapeutic effect of nifedipine by altering the metabolic activity of the gut microbiota. We herein demonstrated for the first time that gut flora is involved in the metabolism of nifedipine by in vitro experiments. In addition, based on the results of 16S rRNA analysis of feces in rats after acute plateau, we first confirmed that the plateau environment could cause changes in the number and composition of intestinal microbes. More importantly, these changes in flora could lead to a slower metabolic activity of nifedipine in the body after an acute plateau, resulting in increased bioavailability and therapeutic efficacy of nifedipine. Our research will provide basis and new ideas for changes in the fecal flora of human acutely entering the plateau, and contribute to rational drug use of nifedipine. [ABSTRACT FROM AUTHOR]

Gut microbiota, one of the determinants of pharmacokinetics, has long been underestimated. It is now generally accepted that the gut microbiota plays an important role in drug metabolism during enterohepatic circulation either before drug absorption or through various microbial enzymatic reactions in the gut. In addition, some drugs are metabolized by the intestinal microbiota to specific metabolites that cannot be formed in the liver. More importantly, metabolizing drugs through the gut microbiota prior to absorption can alter the systemic bioavailability of certain drugs. Therefore, understanding intestinal flora-mediated drug metabolism is critical to interpreting changes in drug pharmacokinetics. Here, we summarize the effects of gut microbiota on drug pharmacokinetics, and propose that the influence of intestinal flora on pharmacokinetics should be organically related to the therapeutic effects and side effects of drugs. More importantly, we could rationally perform the strategy of intestinal microflora-mediated metabolism to design drugs. [ABSTRACT FROM AUTHOR]

Some newest studies indicated that drug transports may play the key role in pharmacokinetics changes under hypoxia at high altitude; MDR1 is now known to affect the disposition of many administered drugs and make a major contribution to absorption, distribution, metabolism, excretion. Different expression of MDR1 is frequently found in different normal tissues and tumor cells; it is important to better understand how MDR1 is regulated under hypoxia, which seems to be a complex and highly controlled process. Several signaling pathways and transcription factors have been described as being involved in the regulation of MDR1 expression, such as MAPK/ERK, nuclear factor-kappaB, hypoxia-inducible factor-1a, pregnane × receptor, constitutive androstane receptor and microRNA. Recently, researches have been increasingly appreciating long non-coding RNAs (lncRNAs) as an integral component of gene regulatory networks. lncRNAs play crucial roles in various biological processes ranging from epigenetic gene regulation, transcriptional control, post-transcriptional regulation, pre-mRNA processing and nuclear organization. A last recent research showed that H19 gene non-coding RNA is believed to induce P-glycoprotein expression under hypoxia. [ABSTRACT FROM AUTHOR]