Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022104 (irritable bowel syndrome)
 8,033 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lotronex (alosetron hydrochloride) is a 5-HT3 receptor antagonist indicated for the treatment of irritable bowel syndrome (IBS) in females whose predominant bowel habit is diarrhea. Alosetron is extensively metabolized by multiple cytochrome P450 (CYP) enzymes, including CYP2C9 and CYP3A4. Fluoxetine is an antidepressant that is administered as a racemic mixture of equipotent R- and S-enantiomers. Fluoxetine metabolism involves CYP2D6 and CYP2C9 in the formation of its major metabolite, norfluoxetine. This metabolite is also present as two enantiomers, of which only the S-enantiomer exhibits comparable antidepressant activity. This study was conducted to assess the potential for an effect of alosetron on the pharmacokinetics of fluoxetine. This was an open-label, two-period, nonrandomized, crossover study in 12 healthy female and male volunteers. The pharmacokinetics for both enantiomers of fluoxetine and norfluoxetine were examined following single oral doses of 20 mg fluoxetine, given alone and in combination with alosetron 1 mg twice daily for 15 days. The results showed small delays in peak concentration but no clinically significant effect of alosetron on the pharmacokinetics of S- and R-fluoxetine or S- and R-norfluoxetine. Coadministration of alosetron and fluoxetine was well tolerated by all subjects.
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PMID:Effect of alosetron on the pharmacokinetics of fluoxetine. 1130 3

Dexloxiglumide (DEX) is a cholecystokinin type-1 receptor antagonist under development for the treatment of constipation-predominant irritable bowel syndrome. Studies of the potential interaction of DEX with human cytochromes P450 (CYPs) were conducted in vitro. DEX (300 micro M), both with and without a 15-min pre-incubation, was incubated with pooled human liver microsomes and substrates selective for each of eight CYPs. This resulted in >30% inhibition of tolbutamide 4-methyl-hydroxylase (CYP2C9/10) and lauric acid 11-hydroxylase (CYP2E1) activities. Mean K(i) (SD) for CYP2C9/10 and CYP2E1 were 69.0 (24.3) and 426 (60) microM, respectively. Incubations of [(14)C]DEX with pooled human liver microsomes produced one major phase I metabolic fraction, with V(max)=131 pmol/min/mg protein and K(m)=23.7 microM. Further incubations with (i) liver microsomes from 16 individual donors (correlation analysis), (ii) Supersomes trade mark and (iii) selective chemical inhibitors, implicated CYP3A4/5, CYP2B6 and CYP2C9 in the formation of this component. Thus, DEX interacts with CYP2C9 both as inhibitor (K(i)=69.0 microM) and as substrate in vitro. However, based on the maximum concentration (27 microM) after repeated oral doses of 200 mg t.i.d. and the unbound fraction (0.03) of DEX in human plasma, no clinically relevant metabolic interactions with other CYP substrates are predicted.
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PMID:Interaction of dexloxiglumide, a cholecystokinin type-1 receptor antagonist, with human cytochromes P450. 1510 19

Dexloxiglumide is a potent and selective cholecystokinin type 1 (CCK1) receptor antagonist currently under development in a variety of diseases affecting the gastrointestinal tract such as gastro-oesophageal reflux disease, irritable bowel syndrome (IBS), functional dyspepsia, constipation and gastric emptying disorders. In female patients with constipation-predominant IBS, clinical efficacy has been demonstrated following administration of dexloxiglumide 200 mg three times daily. Dexloxiglumide is rapidly and extensively absorbed after single oral administration in humans with an absolute bioavailability of 48%. The incomplete bioavailability is due to both incomplete absorption and hepatic first-pass effect. Following multiple-dose administration of 200 mg three times daily, the accumulation is predictable, indicating time-independent pharmacokinetics. In addition, dexloxiglumide pharmacokinetics are dose-independent after both single and repeated oral three-times-daily doses in the dose range 100-400 mg. Dexloxiglumide absorption window extends from the jejunum to the colon and the drug is a substrate and a weak inhibitor of P-glycoprotein and multidrug resistance protein 1. Plasma protein binding of dexloxiglumide is 94-98% and the drug has a moderate to low volume of distribution in humans. Systemic clearance of dexloxiglumide is moderate and cytochrome P450 (CYP) 3A4/5 and CYP2C9 have been implicated in the metabolism of dexloxiglumide to produce O-demethyl dexloxi-glumide. This metabolite is further oxidised to dexloxiglumide carboxylic acid. These two major metabolites (accounting for up to 50% of dexloxiglumide elimination) have been identified. However, in human plasma the unchanged drug represents the major (up to 91%) component of the metabolic profile. The parent drug is believed to be the major contributor to the efficacy of the compound, since its major metabolites are pharmacologically inactive. In addition, the drug is a single isomer chiral drug (eutomer) that does not undergo chiral inversion into its pharmacologically inactive enantiomer (distomer). After oral administration of (14)C-dexloxiglumide, radioactivity is mainly excreted in bile and in faeces (74% of dose) with much lower excretion in urine (20% of dose). Renal excretion of unchanged dexloxiglumide is low (7% of dose in urine and faeces, 1% of dose in urine) and is dose-independent in the dose range 100-400 mg. As the kidney is a minor contributor to the elimination of dexloxiglumide and/or its metabolites in humans, the pharmacokinetics of the drug should not be affected in patients with renal insufficiency. The pharmacokinetics of dexloxiglumide are also not affected by age, sex and administration with a high-fat breakfast. Mild and moderate liver impairment do not affect the pharmacokinetics of dexloxiglumide but severe liver impairment causes increases in systemic exposure to dexloxiglumide and O-demethyl dexloxiglumide. Thus, the drug should be prescribed with caution in patients with severe hepatic impairment even though no dose adjustment is warranted. The results of different drug interaction studies have indicated that no clinically relevant metabolic and concomitant drug-drug interactions are expected during the clinical use of dexloxiglumide.
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PMID:Pharmacokinetic profile of dexloxiglumide. 1711 94