Effects of serotonin-3 receptor antagonists on cytochrome P450 activities in human liver microsomes

A phase I study of the effect of repeated oral doses of pantoprazole on the pharmacokinetics of a single dose of fedratinib in healthy male subjects

PURPOSE

Fedratinib, an oral, selective Janus kinase 2 inhibitor with activity against both wild-type and mutant Janus kinase 2, has pH-dependent solubility, with free solubility at pH 1. Concomitant administration of drugs that reduce gastric acid secretion, such as pantoprazole, may decrease the absorption of fedratinib and affect patient outcomes. The aim of this study was to evaluate the impact of 7-day repeated 40-mg doses of pantoprazole on the pharmacokinetic (PK) properties of a single 500-mg dose of fedratinib in healthy male subjects.

METHODS

In this phase I, single-center, open-label, two-period, two-treatment, fixed-sequence crossover study, healthy male subjects were administered a single dose of fedratinib 500 mg on day 1 in Period 1, followed by pantoprazole 40 mg daily for 7 days (day 1 to day 7) and a single dose of fedratinib 500 mg on day 7 in Period 2. After the discontinuation of nine subjects due to vomiting, the protocol was amended to provide ondansetron as antiemetic prophylaxis to an additional ten enrolled subjects.

RESULTS

Twenty-six subjects were included. Repeated doses of pantoprazole 40 mg resulted in clinically insignificant increases in fedratinib exposure. Maximum plasma concentration increased by 1.09-fold and area under the plasma concentration-time curve from time 0 to infinity increased by 1.15-fold. All treatment-emergent adverse events were mild or moderate, except for one instance of neutropenia, which was considered unrelated to study intervention.

CONCLUSION

Coadministration with pantoprazole did not have clinically meaningful effects on fedratinib PK. No new or unexpected safety signals were observed with fedratinib.

Ramosetron Does Not Reduce the Analgesic Efficacy of Tramadol after Gynecological Laparoscopic Surgery

Background

The effect of ramosetron on the analgesic action of tramadol is not well known when ramosetron is added to intravenous-tramadol patient-controlled analgesia (PCA) and infused continuously. The aim of this randomized noninferiority study was to evaluate the effects of ramosetron on the analgesic action of tramadol when it is administered simultaneously in women undergoing laparoscopic gynecology who are receiving tramadol via IV PCA.

Method

This study used a prospective, randomized, controlled, noninferiority clinical trial design and compared the analgesic effect of tramadol plus ramosetron with that of tramadol only. A total of 110 postoperative patients, who were using IV PCA tramadol, were randomly assigned either to a group receiving ramosetron (group R, n=49) or to a group that received the same volume of normal saline continuously (group N, n=51). Observation time points for cumulative tramadol consumption were the first hour, and every 4 h up to 12 h and then 24 h after surgery. Pain intensity at rest and during movement, coughing, and nausea scores, the analgesic and antiemetic doses used, side effects, and patient satisfaction were evaluated 1 and 24 h after surgery.

Results

Groups R and N received, respectively, 88 ± 55 vs. 79 ± 42 mg tramadol (P=0.511) after 1 h, 211 ± 122 vs. 198 ± 109 mg cumulative tramadol (P=0.610) after 4 h, 244 ± 150 vs. 231 ± 134 mg cumulative tramadol (P= 0.793) after 8 h, 250 ± 156 vs. 247 ± 153 mg cumulative tramadol (P=0.972) after 12 h, and 294 ± 190 vs. 284 ± 178 mg cumulative tramadol (P=0.791) after 24 h, postsurgery. Tramadol plus ramosetron was shown to be not significantly inferior to tramadol alone in alleviating the postoperative pain.

Conclusions

The analgesic effect of tramadol combined with ramosetron was found to be noninferior to tramadol alone for postoperative PCA after laparoscopic gynecologic surgery.

Drug-drug interactions in pharmacologic management of gastroparesis

BACKGROUND

Gastroparesis is a disorder characterized by delayed gastric emptying due to chronic abnormal gastric motility. The treatment of the disease often entails the co-administration of several classes of pharmacological agents. These agents may be metabolized via the same pathway. Inhibition or induction of a shared metabolic pathway leads to change in the systemic levels of prescribed drugs, possibly leading to undesired clinical outcomes.

PURPOSE

This review discusses different pharmacological treatment for gastroparesis patients and describes the potential for drug-drug interactions (DDIs) in some of the combinations that are currently used. Prokinetic agents such as metoclopramide and domperidone are the cornerstone in treatment of gastroparesis. Antiemetic agents such as promethazine and ondansetron are frequently administered to gastroparesis patients to reduce nausea and vomiting. Gastroparesis is prevalent in diabetic patients and therefore antidiabetic agents are also prescribed. Many of these co-administered drugs are metabolized via common drug metabolizing enzymes and this can trigger potential DDIs. The scientific literature was reviewed from the years 1975-2014 for original research articles and reviews that evaluated DDIs in gastroparesis. Many commonly prescribed combinations were predicted to cause potential DDIs in gastroparesis patients. This review will help inform about potential hazardous combinations. This information will hopefully lead to less adverse effects and more successful gastroparesis management.

Metabolic and toxicological considerations for the latest drugs used to treat irritable bowel syndrome

INTRODUCTION

The high prevalence of irritable bowel syndrome (IBS), a chronic gastrointestinal (GI) disorder, its lack of satisfactory effective drugs and its complicated pathophysiology lead to the demand of new therapeutic agents. During a new drug development process, the pharmacokinetic profiling is of a great considerable importance comparable to drug's efficacy. This involves the drug's absorption, distribution, metabolism and excretion, all of which are crucial to its usefulness. In addition, the toxicological profile and possible adverse reactions of the drug should be identified. Also its interactions should be identified at different phases of trials. Several pharmacokinetic studies are carried out to achieve drugs with the best absorption and bioavailability and the least adverse effects and lowest toxicity.

AREAS COVERED

To make an update on new clinically introduced drugs for IBS and their dynamics and kinetics data, the present systematic review was accomplished. All relevant bibliographic databases were searched from the year 2003 up to May 2012 to identify all clinical trials that evaluated the potential efficacy of a novel agent in IBS.

EXPERT OPINION

Some evaluated drugs, such as ramosetron (5-HT3 antagonist) and pexacerfont (CRF1 receptor antagonist), have shown some benefits in diarrhea-predominant IBS (D-IBS), while, prucalopride and mosapride (5-HT4 agonist) with prokinetic effect were found useful in constipation-predominant IBS (C-IBS). Besides, dexloxiglumide, lubiprostone and linaclotide have shown beneficial effects in C-IBS patients. Melatonin regulates GI tract motility and, asimadoline, gabapentin and pregabalin show reduction of pain threshold and visceral hypersensitivity. Glucagon-like peptide analog, calcium-channel blockers and neurokinin receptor antagonists have shown benefits in pain attacks. More time is required to indicate both efficacy and safety in long-term treatment due to multifactorial pathophysiology, variations in individual responses and insufficient assessment methods, which limit the right decision-making process about the efficacy and tolerability of these new drugs.

Potential for drug-drug interactions in treating cancer-related nausea and distress

PURPOSE

To determine the extent and severity of drug-drug interactions between anti-emetics and antipsychotics or antidepressants.

SUMMARY

Oncology patients are often required to deal with chemotherapy-induced nausea and vomiting at the same time as psychosocial distress. A review of primary literature, as well as several drug interaction databases, was performed with anti-emetics used in The NCCN® 1.2010 Anti-emesis Guidelines (n = 11) and all currently US-marketed antidepressants or antipsychotics (n = 40).(1) The results from these databases were compiled into a single easy-to-use chart that portrays the severity of the interaction and brief recommendation.(2,3,4) In total, 197 drug-drug interactions out of a total of 440 possible combinations (44.8%) were discovered during the analysis.

CONCLUSIONS

Although most anti-emetics had several serious interactions with antidepressants or antipsychotics, palonosetron, and granisetron were found to have no significant interactions. The results can be used to avoid or limit drug interactions in the prescribing of new medications for the oncology patient.(1,2,3,4).

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

AIM: To review and summarize drug metabolism and its related interactions in prescribing drugs within the similar therapeutic or structural class for gastrointestinal disease treatment so as to promote rational use of medicines in clinical practice.

METHODS: Relevant literature was identified by performing MEDLINE/Pubmed searches covering the period from 1988 to 2006.

RESULTS: Seven classes of drugs were chosen, including gastric proton pump inhibitors, histamine H₂-receptor antagonists, benzamide-type gastroprokinetic agents, selective 5-HT₃ receptor antagonists, fluoroquinolones, macrolide antibiotics and azole antifungals. They showed significant differences in metabolic profile (i.e., the fraction of drug metabolized by cytochrome P450 (CYP), CYP reaction phenotype, impact of CYP genotype on interindividual pharmacokinetics variability and CYP-mediated drug-drug interaction potential). Many events of severe adverse drug reactions and treatment failures were closely related to the ignorance of the above issues.

CONCLUSION: Clinicians should acquaint themselves with what kind of drug has less interpatient variability in clearance and whether to perform CYP genotyping prior to initiation of therapy. The relevant CYP knowledge helps clinicians to enhance the management of patients with gastrointestinal disease who may require treatment with polytherapeutic regimens.