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      Simultaneous Estimation of Esomeprazole and Domperidone by UV Spectrophotometric Method

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          Abstract

          A novel, simple, sensitive and rapid spectrophotometric method has been developed for simultaneous estimation of esomeprazole and domperidone. The method involved solving simultaneous equations based on measurement of absorbance at two wavelengths, 301 nm and 284 nm, λ max of esomeprazole and domperidone respectively. Beer's law was obeyed in the concentration range of 5-20 μg/ml and 8-30 μg/ml for esomeprazole and domperidone respectively. The method was found to be precise, accurate, and specific. The proposed method was successfully applied to estimation of esomeprazole and domperidone in combined solid dosage form.

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          Most cited references38

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          Comparison of inhibitory effects of the proton pump-inhibiting drugs omeprazole, esomeprazole, lansoprazole, pantoprazole, and rabeprazole on human cytochrome P450 activities.

          The human clearance of proton pump inhibitors (PPIs) of the substituted benzimidazole class is conducted primarily by the hepatic cytochrome P450 (P450) system. To compare the potency and specificity of the currently used PPIs (i.e., omeprazole, esomeprazole, lansoprazole, pantoprazole, and rabeprazole) as inhibitors of four cytochrome P450 enzymes (CYP2C9, 2C19, 2D6, and 3A4), we performed in vitro studies using human liver microsomal preparations and recombinant CYP2C19. Sample analysis was done using selected reaction monitoring liquid chromatography/tandem mass spectometry. With several systems for CYP2C19 activity (two marker reactions, S-mephenytoin 4'-hydroxylation and R-omeprazole 5-hydroxylation, tested in either human liver microsomes or recombinant CYP2C19), the five PPIs showed competitive inhibition of CYP2C19 activity with K(i) of 0.4 to 1.5 microM for lansoprazole, 2 to 6 microM for omeprazole, approximately 8 microM for esomeprazole, 14 to 69 microM for pantoprazole, and 17 to 21 microM for rabeprazole. Pantoprazole was a competitive inhibitor of both CYP2C9-catalyzed diclofenac 4'-hydroxylation and CYP3A4-catalyzed midazolam 1'-hydroxylation (K(i) of 6 and 22 microM, respectively), which were at least 2 times more potent than the other PPIs. All PPIs were poor inhibitors of CYP2D6-mediated bufuralol 1'-hydroxylation with IC(50) > 200 microM. The inhibitory potency of a nonenzymatically formed product of rabeprazole, rabeprazole thioether, was also investigated and showed potent, competitive inhibition with K(i) values of 6 microM for CYP2C9, 2 to 8 microM for CYP2C19, 12 microM for CYP2D6, and 15 microM for CYP3A4. The inhibitory potency of R-omeprazole on the four studied P450 enzymes was also studied and showed higher inhibitory potency than its S-isomer on CYP2C9 and 2C19 activities. Our data suggest that, although the inhibitory profiles of the five studied PPIs were similar, lansoprazole and pantoprazole are the most potent in vitro inhibitors of CYP2C19 and CYP2C9, respectively. Esomeprazole showed less inhibitory potency compared with omeprazole and its R-enantiomer. The inhibitory potency of rabeprazole was relatively lower than the other PPIs, but its thioether analog showed potent inhibition on the P450 enzymes investigated, which may be clinically significant.
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            Pharmacokinetic studies with esomeprazole, the (S)-isomer of omeprazole.

            This article reviews the pharmacokinetics of esomeprazole, the (S)-isomer of the proton pump inhibitor (PPI) omeprazole. Esomeprazole is the first single isomer PPI developed for the treatment of patients with acid-related diseases. In vitro experiments in human liver microsomes demonstrated that the formation of the hydroxy and 5-O-desmethyl metabolites of esomeprazole is via cytochrome P450 (CYP) 2C19, whereas that of the sulphone metabolite is via CYP3A4. The formation rate of the hydroxy metabolite from esomeprazole is lower than for (R)-omeprazole, but that of the 2 other metabolites is higher, demonstrating stereoselective metabolism. The sum of the intrinsic clearances of all 3 metabo- lites for esomeprazole was one-third of that for (R)-omeprazole, suggesting lower clearance of esomeprazole in vivo. In vivo investigations demonstrated that esomeprazole is chirally stable after administration. Esomeprazole is 97% bound to plasma proteins. In normal (extensive) metabolisers with regard to CYP2C19, esomeprazole is metabolised more slowly than omeprazole, resulting in a higher area under the concentration-time curve (AUC) after administration of the same dose. This is more pronounced after repeated administration rather than after a single dose. In poor metabolisers, the AUC is lower for esomeprazole than for omeprazole, contributing to less overall interindividual variability for esomeprazole than for omeprazole. In general, esomeprazole and omeprazole are subject to the same metabolic transformations. Almost complete recoveries were reported and the ratio between urinary and faecal excretion is about 4:1 for both compounds. The dose-dependent increase in AUC of esomeprazole with repeated administration results from a combination of decreased first-pass elimination and decreased systemic clearance. Patients with gastro-oesophageal reflux disease exhibit a pharmacokinetic pattern similar to that in healthy individuals, whereas elderly individuals exhibited a slightly lower metabolism rate. Patients with a severe deficit in their liver function had a lower rate of metabolism, as would be expected, whereas those with mild to moderate liver disease did not exhibit any alteration in the pharmacokinetics. The pharmacokinetics of esomeprazole in individuals with impaired renal function is unlikely to differ from that in healthy individuals. A slight sex difference in the pharmacokinetics of esomeprazole was demonstrated in that the AUC and peak plasma drug concentration were slightly, but not statistically significantly, higher in females than in males.
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              Pharmacokinetics of esomeprazole after oral and intravenous administration of single and repeated doses to healthy subjects.

              To study the pharmacokinetics of esomeprazole, one of the optical isomers of omeprazole, after 20 mg or 40 mg single and repeated oral and intravenous administration to healthy subjects. The main metabolites of esomeprazole were also assessed after the 40-mg oral dose. In two separate studies, 16 healthy male subjects and 16 healthy male and female subjects received intravenous doses of 20 mg and 40 mg esomeprazole, respectively, on the first investigation day. After a washout period of 5-14 days, the same doses (20 mg as a solution and 40 mg as a capsule) were given orally for 5 days and then again intravenously on day 6. Blood samples for determination of esomeprazole and its metabolites were collected 12 h or 24 h post-dose and were analysed using normal-phase liquid chromatography with ultraviolet (UV) detection. Pharmacokinetic parameters of esomeprazole and its metabolites were estimated using non-compartmental analysis. Geometric means and ratios of the geometric means together with 95% confidence intervals (CI) of the pharmacokinetic parameters were calculated using analysis of variance (ANOVA). Plasma clearance (CL) of esomeprazole decreased from 22 l/h to 16 l/h and from 17 l/h to 9 l/h following repeated dosing of 20 mg and 40 mg, respectively. Total area under the plasma concentration-time curve (AUC) increased (from 1.34 micromol x h/l to 2.55 micromol x h/l) with absolute bioavailability (F) being 50% on day 1 and 68% on day 5 after the 20-mg oral dose. AUC increased (from 4.32 micromol x h/l to 11.21 micromol x h/l) with F being 64% on day 1 and 89% on day 5 after the 40-mg oral dose. The plasma levels for esomeprazole sulphone were substantially higher on day 5 than on day 1, while those for 5-hydroxy esomeprazole were marginally higher on day 5 than on day 1 following repeated oral dosing of 40 mg esomeprazole. No side effects attributable to esomeprazole were noticed. The increased AUC of esomeprazole with repeated dosing is probably due to a combination of a decreased first-pass elimination and a decreased systemic clearance.
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                Author and article information

                Journal
                Indian J Pharm Sci
                IJPhS
                Indian Journal of Pharmaceutical Sciences
                Medknow Publications (India )
                0250-474X
                1998-3743
                Jan-Feb 2008
                : 70
                : 1
                : 128-131
                Affiliations
                Department of Pharmaceutical Quality Assurance, Manipal College of Pharmaceutical Sciences, Manipal - 576 104, India
                [1 ]Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal - 576 104, India
                [2 ]Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal - 576 104, India
                [3 ]Department of Pharmaceutical Chemistry, Manipal College of Pharmaceutical Sciences, Manipal - 576 104, India
                Author notes
                [* ] For correspondence: E-mail: arunshirwaikar@ 123456yahoo.co.in
                Article
                IJPhS-70-128
                10.4103/0250-474X.40351
                2852053
                20390100
                98e41cb9-d0f9-4ee2-ab6d-06af71d56796
                © Indian Journal of Pharmaceutical Sciences

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 15 March 2007
                : 10 September 2007
                : 14 February 2008
                Categories
                Short Communication

                Pharmacology & Pharmaceutical medicine
                spectrophotometric method,λ max,domeperidone,esomeprazole

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