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ABSTRACT: This is a summary report of the workshop on the EMA Draft Guideline on Validation of Bioanalytical Methods held April 15-16th 2010 in Brussels (Belgium) and jointly organised by the European Bioanalysis Forum (EBF) and the European Federation for Pharmaceutical Sciences (EUFEPS). Aim of the workshop was to discuss the current scientific knowledge in the area of bioanalysis, the regulatory requirements with special focus on the new Draft Guideline and their subsequent implementation to the work in bioanalytical laboratories. Comments on the Draft Guideline were presented and discussed with representatives from regulatory authorities in Europe. The workshop started with discussions on the scope of the Guideline and the need for implementation of GLP. A special focus was set on method validation of chromatographic procedures and subsequent study sample analysis. In addition, requirements for ligand-binding assays were briefly addressed. Intention of this Conference Report is to summarise important aspects of the discussions in order to draw certain conclusions, and to identify points which remain open and may require clarification at a later stage.
European journal of pharmaceutical sciences: official journal of the European Federation for Pharmaceutical Sciences 02/2011; 42(3):300-5. · 2.61 Impact Factor
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ABSTRACT: Bereits vor mehr als 40 Jahren wurden spezifische Kommunikationsstrukturen zwischen dem Magen-Darm-Trakt und den für die Stoffwechselreaktion des Körpers auf die Aufnahme von Nahrungsbestandteilen verantwortlichen Organe entdeckt. In diesem Zusammenhang kommt dem Inselapparat des endokrinen Pankreas eine entscheidende Bedeutung zu. Neben der direkten Substratstimulation und einer Reizübertragung mittels neuronaler Strukturen wurden auch gastrointestinale Hormone, die so genannten Inkretine, nachgewiesen, die vom Darm ausgesendet die Organe des intermediären Stoffwechsels auf die bevorstehende Resorption wichtiger Nahrungsbestandteile, vor allem Kohlenhydrate, vorbereiten sollen. Dennoch vergingen beinahe vier Jahrzehnte, bis aus diesen Erkenntnissen der Grundlagenforschung innovative Ansätze für therapeutische Interventionen bei Diabetes mellitus entwickelt werden konnten.
Pharmazie in unserer Zeit 03/2010; 39(2):100-6.
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ABSTRACT: Low-molecular-weight heparins (LMWHs) differ considerably in their influence on clotting tests and release of tissue factor pathway inhibitor (TFPI). Biosimilarity therefore becomes an issue when generic forms of LMWHs are developed. So far, no bioequivalence study with a generic LMWH has been reported. A generic enoxaparin (test) was compared with the originator (reference) in 20 volunteers after single-dose subcutaneous administration (40 mg enoxaparin sodium, 4000 IU/mL anti-factor Xa (anti-FXa; activity). Target variables were anti-FXa and anti-FIIa activity, activated partial thromboplastin time (aPTT), prothrombinase-induced clotting time (PiCT), and TFPI over 24 hours. The statistical evaluation of the anti-FXa activity profile demonstrated bioequivalence of test and reference with confidence intervals of area under the plasma concentration-time curve (AUC0-tlast) (93%-99%) and Amax (88%-95%). Confidence intervals of AUC(0-tlast) (89%-102%) and Amax (90%-103%) of anti-FIIa activity also fulfill bioequivalence criteria. The 90% confidence interval for the maximum concentration of TFPI ranged from 90% to 113%. The claim of similarity was also supported by aPTT and PiCT profiles. Bioequivalence with the originator enoxaparin could be demonstrated by ex vivo inhibition of FXa and FIIa activity, by coagulation tests (aPTT and PiCT), and by in vivo release of TFPI. Whether such data also prove biosimilarity of the generic enoxaparin needs to be determined.
The Journal of Clinical Pharmacology 09/2008; 48(10):1189-96. · 2.91 Impact Factor
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ABSTRACT: The objective of this study was to compare the in vitro and in vivo characteristics of 2 nifedipine modified-release tablet formulations for once-daily dosing marketed in the European community, which were expected to be bioequivalent.
In vitro dissolution was tested at different pH values prior to the clinical part of the study. Either 1 tablet of a test formulation or of the reference formulation, both containing 30 mg nifedipine, were administered to healthy white male volunteers immediately after a high-fat breakfast in a randomized, open-label, 2-period crossover design. Plasma samples obtained over the subsequent period of 48 hours were analyzed using a validated LC-MS/MS method. Safety profile and tolerability of the study medications were assessed by analysis of adverse events obtained by vital sign measurements, electrocardiography, and clinical laboratory analysis.
Twelve volunteers were enrolled (median age, 28.0 years [range, 21-42 years]; mean body mass index, 24.2 kg/m(2) [range, 19.3-27.0 kg/m(2)]). In vitro dissolution experiments revealed a significant pH dependency in drug release from the investigational tablets, while the reference tablets were found to have pH-independent dissolution. After oral administration of both tablet formulations in the fed state, marked differences in rate and extent of bioavailability were observed. Geometric mean of AUC(0-last)(test, 504.21 h x ng/mL; reference, 361.28 h x ng/mL) was significantly higher for the test product, with a point estimate of 140% and a corresponding 90% CI of 121% to 161%. For the comparison of Cmax values, geometric means were: test, 76.46 ng/mL; reference, 19.20 ng/mL, with a point estimate of 398% and a CI of 316% to 503%. Thus, a significant difference in rate and extent of bioavailability was observed between the 2 products.
Although both treatments were well tolerated by all volunteers, the test and reference tablets were found to have different pharmacokinetic properties when administered after a high-fat meal.
Clinical Therapeutics 02/2008; 30(1):48-58. · 2.32 Impact Factor
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ABSTRACT: The aim of this study was to investigate the effects of roflumilast, an investigational PDE4 inhibitor for the treatment of COPD and asthma, on the pharmacokinetics of the CYP3A probe drug midazolam and its major metabolites.
In an open, randomized (for midazolam treatment sequence) study, 18 healthy male subjects received single doses of midazolam (2 mg oral and 1 mg i.v., 1 day apart) alone, repeated doses of roflumilast (500 microg once daily for 14 days) alone, and repeated doses of roflumilast together with single doses of midazolam (2 mg oral and 1 mg i.v., 1 day apart).
A comparison of clearance and peak and systemic exposure to midazolam following administration of roflumilast indicated no effect of roflumilast dosed to steady state on the pharmacokinetics of midazolam. Point estimates (90% CI) were 0.97 (0.84, 1.13) for the AUC of i.v. midazolam and 0.98 (0.82, 1.17) for that of oral midazolam with and without roflumilast.
Therapeutic steady state concentrations of roflumilast and its N-oxide do not alter the disposition of the CYP3A substrate midazolam in healthy subjects. This finding suggests that roflumilast is unlikely to alter the clearance of drugs that are metabolized by CYP3A4.
British Journal of Clinical Pharmacology 04/2007; 63(3):365-70. · 2.96 Impact Factor
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ABSTRACT: Proton pump inhibitors are used extensively for the treatment of gastric acid-related disorders because they produce a greater degree and longer duration of gastric acid suppression and, thus, better healing rates, than histamine H(2) receptor antagonists. The need for long-term treatment of these disorders raises the potential for clinically significant drug interactions in patients receiving proton pump inhibitors and other medications. Therefore, it is important to understand the mechanisms for drug interactions in this setting. Proton pump inhibitors can modify the intragastric release of other drugs from their dosage forms by elevating pH (e.g. reducing the antifungal activity of ketoconazole). Proton pump inhibitors also influence drug absorption and metabolism by interacting with adenosine triphosphate-dependent P-glycoprotein (e.g. inhibiting digoxin efflux) or with the cytochrome P450 (CYP) enzyme system (e.g. decreasing simvastatin metabolism), thereby affecting both intestinal first-pass metabolism and hepatic clearance. Although interactions based on the change of gastric pH are a group-specific effect and thus may occur with all proton pump inhibitors, individual proton pump inhibitors differ in their propensities to interact with other drugs and the extent to which their interaction profiles have been defined. The interaction profiles of omeprazole and pantoprazole have been studied most extensively. A number of studies have shown that omeprazole carries a considerable potential for drug interactions, since it has a high affinity for CYP2C19 and a somewhat lower affinity for CYP3A4. In contrast, pantoprazole appears to have lower potential for interactions with other medications. Although the interaction profiles of esomeprazole, lansoprazole and rabeprazole have been less extensively investigated, evidence suggests that lansoprazole and rabeprazole seem to have a weaker potential for interactions than omeprazole. Although only a few drug interactions involving proton pump inhibitors have been shown to be of clinical significance, the potential for drug interactions should be taken into account when choosing a therapy for gastric acid-related disorders, especially for elderly patients in whom polypharmacy is common, or in those receiving a concomitant medication with a narrow therapeutic index.
Drug Safety 02/2006; 29(9):769-84. · 3.63 Impact Factor
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Pharmazie in unserer Zeit 02/2005; 34(5):400-10.
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ABSTRACT: The neurotropic-musculotropic spasmolytic agent denaverine hydrochloride is used mainly in the treatment of smooth muscle spasms of the gastrointestinal and urogenital tract. Despite its commercial availability as a solution for intravenous or intramuscular administration (ampoule) and as a suppository formulation, no pharmacokinetic data in man was available to date. Therefore, the objectives of this clinical trial were to determine the basic pharmacokinetic parameters of denaverine after intravenous administration, to assess the feasibility of using the oral route of administration and to characterise the bioavailability of the suppository formulation. To achieve this, healthy subjects received 50 mg denaverine hydrochloride intravenously, orally and rectally in aqueous solutions and rectally as suppository in an open, randomised crossover design. Total body clearance, volume of distribution at steady-state and half-life of denaverine are 5.7 ml/min per kg, 7.1 l/kg and 33.8 h, respectively. The absolute bioavailability after oral administration of an aqueous solution is 37%. First-pass metabolism leading to the formation of N-monodemethyl denaverine was found to be one reason for the incomplete bioavailability after oral administration. Rectal administration of an aqueous solution of denaverine hydrochloride resulted in a decreased rate (median of C(max) ratios: 26%, difference in median t(max) values: 1.9 h) and extent (31%) of bioavailability compared to oral administration. Using the suppository formulation led to a further reduction in rate (median of C(max) ratios: 30%, difference in median t(max) values: 3 h) and extent (42%) of bioavailability compared to the rectal solution.
European Journal of Pharmaceutical Sciences 03/2003; 18(2):121-8. · 3.21 Impact Factor
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ABSTRACT: A sensitive and specific procedure for the simultaneous determination of dihydroergotamine (DHE) and its 8'-hydroxylated metabolite (8'-OH-DHE) in human plasma was developed and validated. The analytes were extracted from plasma samples by liquid-liquid extraction, separated through a Zorbax C18 column (50x2.1 mm I.D.) and detected by tandem mass spectrometry with an electrospray ionization interface. Caroverine was used as the internal standard. The method has a lower limit of quantitation (LOQ) of 10.0 and 11.0 pg/ml for DHE and 8'-OH-DHE, respectively. The intra- and inter-run precision was measured to be below 9.1% for both DHE and 8'-OH-DHE. The inter-run accuracy was within 4% for the analytes. The overall extraction recoveries of DHE and 8'-OH-DHE were determined to be about 58 and 52% on average, respectively. The chromatographic run time was approximately 2.5 min. More than 120 samples could be assayed daily with this method, including sample preparation, data acquisition and processing. The method developed was successfully used to investigate plasma concentrations of DHE and 8'-OH-DHE in a pharmacokinetic study of volunteers who received DHE orally.
Journal of Chromatography B 04/2002; 768(2):267-75. · 2.89 Impact Factor
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ABSTRACT: Bioequivalence of highly variable drugs (i.e. high clearance drugs) is difficult to assess by means of conventional study designs. This paper reports a study on bioequivalence of two immediate release formulations of the antiarrhythmic drug propafenone in which a steady-state crossover design was used. The decision on bioequivalence was made with regard to the data of propafenone. Bioavailability data of the active metabolite, 5-hydroxypropafenone, and circadian pharmacokinetics of both analytes are also discussed. Following 5 days of administration (300 mg twice daily) to 20 volunteers, all parameters measured for estimating bioequivalence (AUC, Cmax and PTF) were determined for both propafenone and 5-hydroxypropafenone during two consecutive dosage intervals. All target parameters obtained after administration of the test formulation were within the defined limits of bioequivalence when compared to reference for both parent compound and active metabolite for both dosage intervals. Basing on the calculated 90% confidence intervals it can be concluded that the two formulations are bioequivalent. Moreover, the steady-state study design may be applicable to other compounds with similar pharmacokinetic behaviour and seems to be generally advantageous for bioequivalence studies of highly variable drugs.
European Journal of Pharmaceutical Sciences.
