Rational prescription of drugs within similar therapeutic or structural class for gastrointestinal disease treatment: Drug metabolism and its related interactions

Extracts of Poria cocos improve functional dyspepsia via regulating brain-gut peptides, immunity and repairing of gastrointestinal mucosa

BACKGROUND

Poria cocos (Schw.) Wolf (PC), a fungus, has been used for more than 2000 years as a food and medicine in China. It has a very good therapeutic effect for functional dyspepsia (FD). However, the material basis and mechanism of PC on FD were not reported.

PURPOSE

To investigate the function and potential mechanisms of PC including its three extracts (triterpenoid, PCT; water-soluble polysaccharide, PCWP; acidic polysaccharide, PCAP) on FD.

STUDY DESIGN

The study explored the therapeutic effect of PC and its three extracts on FD in rats for the first time and discussed its mechanisms based on brain-gut peptides, immunity and repair of the gastrointestinal mucosa.

METHODS

The chemical components of PC extracts were analyzed and quantified using ultra high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) and gel permeation chromatography coupled with size exclusion chromatography (GPC/SEC). The FD rat models were established using weight-loaded forced swimming and alternate-day fasting for 42 days. After 14 days of treatment, the effect and mechanisms were investigated using ELISA, histopathology, immunohistochemistry as well as Western blot.

RESULTS

Seventy-seven triterpenoids in PCT were identified. PCWP was primarily composed of component A (Mw: 3.831 × 10⁷ Da), component B (Mw: 5.650 × 10⁶ Da) and component C (Mw: 113,117 Da). PCAP was a homogeneous composition with an average Mw of 74,320 Da. PCT, PCWP and PCAP alleviated the symptoms of FD. These extracts promoted the repair of gastrointestinal mucosa and regulated the balance between the T helper cell (Th)1/Th2 axis and the Th17/Treg axis. PCT and PCWP regulated brain-gut peptides more effectively, PCWP and PCAP enhanced immunity more effectively. Further study demonstrated that these extracts may have enhanced immunity via the Toll-like receptor (TLR) and c-Jun N-terminal kinase (JNK) signaling pathways.

CONCLUSIONS

PC extracts showed therapeutic effects on FD rats, and the mechanism of action involved multiple pathways. PCAP, which is often discarded in traditional applications, was effective. Our study provides new ideas for the application and development of PC extracts.

Interspecies Variation in NCMN-O-Demethylation in Liver Microsomes from Various Species

NCMN (N-(3-carboxy propyl)-4-methoxy-1,8-naphthalimide), a newly developed ratiometric two-photon fluorescent probe for human Cytochrome P450 1A (CYP1A), shows the best combination of specificity and reactivity for real-time detection of the enzymatic activities of CYP1A in complex biological systems. This study aimed to investigate the interspecies variation in NCMN-O-demethylation in commercially available liver microsomes from human, mouse, rat, beagle dog, minipig and cynomolgus monkey. Metabolite profiling demonstrated that NCMN could be O-demethylated in liver microsomes from all species but the reaction rate varied considerably. CYP1A was the major isoform involved in NCMN-O-demethylation in all examined liver microsomes based on the chemical inhibition assays. Furafylline, a specific inhibitor of mammalian CYP1A, displayed differential inhibitory effects on NCMN-O-demethylation in all tested species. Kinetic analyses demonstrated that NCMN-O-demethylation in liver microsomes form rat, minipig and cynomolgus monkey followed biphasic kinetics, while in liver microsomes form human, mouse and beagle dog obeyed Michaelis-Menten kinetics, the kinetic parameters from various species are much varied, while NCMN-O-demethylation in MLM exhibited the highest similarity of specificity, kinetic behavior and intrinsic clearance as that in HLM. These findings will be very helpful for the rational use of NCMN as a practical tool to decipher the functions of mammalian CYP1A or to study CYP1A associated drug-drug interactions in vivo.

Xenobiotic Metabolising Enzymes: Impact on Pathologic Conditions, Drug Interactions and Drug Design

Background:

The biotransformation of xenobiotics is a homeostatic defensive response of the body against bioactive invaders. Xenobiotic metabolizing enzymes, important for the metabolism, elimination and detoxification of exogenous agents, are found in most tissues and organs and are distinguished into phase I and phase II enzymes, as well as phase III transporters. The cytochrome P450 superfamily of enzymes plays a major role in the biotransformation of most xenobiotics as well as in the metabolism of important endogenous substrates such as steroids and fatty acids. The activity and the potential toxicity of numerous drugs are strongly influenced by their biotransformation, mainly accomplished by the cytochrome P450 enzymes, one of the most versatile enzyme systems.

Objective:

In this review, considering the importance of drug metabolising enzymes in health and disease, some of our previous research results are presented, which, combined with newer findings, may assist in the elucidation of xenobiotic metabolism and in the development of more efficient drugs.

Conclusion:

Study of drug metabolism is of major importance for the development of drugs and provides insight into the control of human health. This review is an effort towards this direction and may find useful applications in related medical interventions or help in the development of more efficient drugs.

Proton pump inhibitors: from CYP2C19 pharmacogenetics to precision medicine

Introduction: Proton Pump inhibitors (PPIs) are commonly used for a variety of acid related disorders. Despite the overall effectiveness and safety profile of PPIs, some patients do not respond adequately or develop treatment related adverse events. This variable response among patients is in part due to genotype variability of CYP2C19, the gene encoding the CYP450 (CYP2C19) isoenzyme responsible for PPIs metabolism.

Areas covered: This article provides an overview of the pharmacokinetics and mechanism of action of the currently available PPIs, including the magnitude of CYPC19 contribution to their metabolism. Additionally, the role of CYP2C19 genetic variability in the therapeutic effectiveness or outcomes of PPI therapy is highlighted in details, to provide supporting evidence for the potential value of CYP2C19 genotype-guided approaches to PPI drug therapy.

Expert opinion: There is a large body of evidence describing the impact of CYP2C19 variability on PPIs and its potential role in individualizing PPI therapy, yet, CYP2C19 pharmacogenetics has not been widely implemented into clinical practice. More data are needed but CYP2C19 genotype-guided dosing of PPIs is likely to become increasingly common and is expected to improve clinical outcomes, and minimize side effects related to PPIs.

Partnership in optimizing management of reflux symptoms: a treatment algorithm for over-the-counter proton-pump inhibitors

BACKGROUND

Uncomplicated heartburn and acid regurgitation are increasingly treated and managed using over-the-counter medications. However, with over-the-counter availability of antacids, alginates, histamine 2 receptor antagonists (H2RAs), and proton-pump inhibitors (PPIs), consumers need guidance as to appropriate options and how to use them.

METHODS

Relevant guidelines, studies, and reviews were identified via literature searches of PubMed/Medline and Google Scholar, as well as cross-referencing from the identified papers.

RESULTS

Antacids, alginates, and H2RAs are best suited to management of occasional heartburn, taken either before provocative meals or other triggers or on demand when symptoms arise. Over-the-counter PPIs are appropriate options across the range of symptom severity/frequency typically encountered in the pharmacy, but may be particularly appropriate for treatment of those with frequent and/or very bothersome heartburn. A 2-4 week course of daily PPIs can lead to complete resolution of frequent heartburn. Counseling is important to ensure that patients understand that failure of symptoms to resolve or a rapid return of symptoms while taking a PPI is an indication to consult a doctor, whereas a return of symptoms after a period of months may be an indication for just another course of treatment. The need for effective communication and for ensuring use of the correct medication in the over-the-counter setting puts much of the responsibility for management of heartburn and acid regurgitation on the pharmacist. A proposed algorithm that details when and how to use available over-the-counter medications is presented. This algorithm also highlights alarm features and atypical symptoms indicative of other underlying conditions that should be referred directly to a physician.

CONCLUSION

Implementation of a simple algorithm will empower pharmacists and consumers alike and ensure consistent and appropriate care.

Drug utilization of clarithromycin for gastrointestinal disease treatment

AIM: To evaluate the patterns of use of clarithromycin for gastrointestinal disease treatment and promote its rational use.

METHODS: Using a structured pro forma, we conducted a two-month survey of the electronic prescriptions containing immediate-release (IR) or sustained-release (SR) product of clarithromycin for outpatients with gastrointestinal diseases in a 2200-bed general hospital. Suitability of the prescription was audited retrospectively.

RESULTS: One hundred and sixty-four prescriptions of SR product and 110 prescriptions of IR product were prescribed for gastrointestinal disease treatment. Among prescriptions for anti-Helicobacter pylori (H pylori) therapy, triple therapy take the dominant position (91.8%), followed by quadruple therapy (4.3%) and dual therapy (3.9%). Amoxicillin was the most frequently co-prescribed antibiotic. Furazolidone and levofloxacin are used more widely than metronidazole or tinidazole. Clarithromycin SR was administered at inappropriate time points in all prescriptions. Fifty percent of all prescriptions of clarithromycin SR, and 6.4% of prescriptions of clarithromycin IR, were prescribed at inappropriate dosing intervals. Surprisingly, disconcordance between diagnoses and indications was observed in all prescriptions of clarithromycin SR which has not been approved for treating H pylori infection although off-label use for this purpose was reported in literature. On the contrary, only one prescription (0.9%) of clarithromycin IR was prescribed for unapproved indication (i.e. gastro-oesophageal reflux disease). 1.4% of prescriptions for chronic gastritis or peptic ulcer treatment were irrational in that clarithromycin was not co-prescribed with gastric acid inhibitors. Clinical significant CYP3A based drug interactions with clarithromycin were identified.

CONCLUSION: There is a great scope to improve the quality of clarithromycin prescribing in patients with gastrointestinal disease, especially with regard to administration schedule, concordance between indications and diagnoses and management of drug interactions.