1,721,198 research outputs found
Exposure of Nursed Infants to Maternal Treatment with Ethambutol and Rifampicin
No full textMycobacterial diseases remain a significant cause of morbidity and mortality worldwide. Rifampicin and ethambutol are among the drugs recommended by WHO as first-line treatment. In this work, we addressed the question whether doses of the two anti-tuberculosis agents ethambutol and rifampicin transferred to a nursed infant could be of health concerns when the mother is under treatment. We used the approach of pharmacokinetic modelling using a structural model with two interconnected organisms: the first one being the organism of the nursing mother and the second one being the organism of the nursed child. Physiological data were taken from the literature. The models were parameterised by data from the literature concerning clearance, absorption and plasma/milk ratio. Distribution into the tissues was calculated by an algorithm. The predictive power of the model was tested by comparing the predicted plasma concentrations in the mothers with measured data from the literature. Comparison with measured data after direct infant treatment was performed for the rifampicin plasma concentrations predicted in the nursed infant. Both comparisons confirmed the appropriateness of the modelling results. The transfer of 0.08 mg/kg bw/day ethambutol via breast milk to the nursed infant, the dose we have estimated, when the mother received a therapeutic dose of 24.5 mg/kg bw, can be judged as being without health concern. Likewise, for rifampicin, the transferred dose of 0.4 mg/kg bw to the nursed infant resulting from a therapeutic dose of 10.9 mg/kg bw to the mother does not raise health concerns
Metamizol. Überlegungen zum Monitoring zur frühzeitigen Diagnose einer Agranulozytose
Full text linkBACKGROUND
Dipyrone (metamizole) is a non-opioid analgesic commonly used in Germany, which can, in very rare cases, cause life-threatening agranulocytosis. The prescribing information calls for regular monitoring of the differential blood count in cases of long-term treatment. However, there is uncertainty about how this testing should be handled in practice.
OBJECTIVES
Which recommendations can be derived from the published literature for evaluating blood cell counts during treatment with metamizole and which other options for monitoring exist?
METHODS
Data from recent epidemiological studies, reviews, and spontaneously reported cases were evaluated.
RESULTS
Agranulocytosis can emerge at highly variable intervals ranging from the first day of metamizole treatment to months after treatment has begun. As a result, there is no conclusive, evidence-based recommendation for the time intervals at which blood cell counts should be tested. Therefore, the onset of clinical symptoms should be used as trigger for monitoring blood cell counts to enable early diagnosis and avoid agranulocytosis-related complications. In addition to general symptoms like fever, sore throat, fatigue, and muscle pain, mucosal ulcerations, severe angina, and systemic infections leading to sepsis are typical of agranulocytosis.
CONCLUSIONS
Providing patients and medical staff with better information about early symptoms of agranulocytosis could be a sensible way to prevent complications. Any suspicion of agranulocytosis should immediately lead to a differential blood count and to the withdrawal of all drugs possibly associated with agranulocytosis. Patients should be monitored and treated according to the severity of their symptoms
The role of active metabolites in dihydrocodeine effects
No full textObjective: The metabolism of dihydrocodeine to dihydromorphine, a high affinity p-opioid receptor ligand in membrane homogenates, is catalyzed by CYP2D6. However, it is not clear whether an active CYP2D6 enzyme is required for opioid receptor-mediated effects in man after standard dihydrocodeine doses. Methods: Whole cell opioid-receptor affinity and effects on cAMP accumulation of dihydrocodeine and its metabolites were determined in differentiated SH-SY5Y neuroblastoma cells. In a double-blind, 2-period, placebo-controlled randomized crossover pilot study the pharmacokinetics of dihydrocodeine (60 mg single dose) and its metabolites were examined in 5 phenotyped extensive (EMs) and 4 poor metabolizers (PMs) for CYP2D6, and pharmacodynamics were evaluated using a pain threshold model and dynamic pupillometry. Results: Displacement binding and cAMP accumulation experiments showed clearly higher affinities (100- and 50-fold) and activities (180- and 250-fold) of dihydromorphine and dihydromorphine-6-glucuronide, respectively, whereas the other metabolites had similar or lower affinities and activities as compared to dihydrocodeine. The clinical study revealed no significant difference in plasma or urine pharmacokinetics between EMs and PMs for dihydrocodeine and its glucuronide. Dihydromorphine and its glucuronides were detectable in EMs only. A clear reduction of initial pupil diameters was observed up to 6 hours post-dose in both PMs and EMs, with no obvious differences between CYP2D6 phenotypes. In the pain threshold model no effects were observed in either group. Conclusion: CYP2D6 phenotype has no major impact on opioid receptor-mediated effects of a single 60 mg dihydrocodeine dose, despite the essential role of CYP2D6 in formation of highly active metabolites
Affinities of dihydrocodeine and its metabolites to opioid receptors
No full textDihydrocodeine is metabolized to dihydromorphine, dihydrocodeine-6-O-, dihydromorphine-3-O- and dihydromorphine-6-O-glucuronide, and nordihydrocodeine. The current study was conducted to evaluate the affinities of dihydrocodeine and its metabolites to mu-, delta- and kappa-opioid receptors. Codeine, morphine, d,l-methadone and levomethadone were used as controls. Displacement binding experiments were carried out at the respective opioid receptor types using preparations of guinea pig cerebral cortex and the specific opioid agonists [H-3]DAMGO (g-opioid receptor), [H-3]DPDPE (8-opioid receptor) and [H-3]U69,593 (K-opioid receptor) as radioactive ligands at concentrations of 0.5, 1.0 and 1.0 nmol/l, respectively All substances had their greatest affinity to the mu-opioid receptor. The affinities of dihydromorphine and dihydromorphine-6-O-glucuronide were at least 70 times greater compared with dihydrocodeine (K-i 0.3 mumol/1), whereas the other metabolites yielded lower affinities. For the 6-opioid receptor, the order of affinities was similar with the exception that dihydrocodeine-6-O-glucuronide revealed a doubled affinity in relation to dihydrocodeine (K-i 5.9 mumol/1). In contrast, for the K-opioid receptor, dihydrocodeine-6-O- and dihydromorphine-6-O-glucuronide had clearly lower affinities compared to the respective parent compounds. The affinity of nordihydrocodeine was almost identical to that of dihydrocodeine (K-i 14 mumol/1), whereas dihydromorphine had a 60 times higher affinity. These results suggest that dihydromorphine and its 6-O-glucuronide may provide a relevant contribution to the pharmacological effects of dihydrocodeine. The O-demethylation of dihydrocodeine to dihydromorphine is mediated by the polymorphic cytochrome P450 enzyme CYP2D6, resulting in different metabolic profiles in extensive and poor metabolizers. About 7% of the caucasian population which are CYP2D6 poor metabolizers thus may experience therapeutic failure after standard doses
The role of active metabolites in dihydrocodeine effects
No full textObjective: The metabolism of dihydrocodeine to dihydromorphine, a high affinity p-opioid receptor ligand in membrane homogenates, is catalyzed by CYP2D6. However, it is not clear whether an active CYP2D6 enzyme is required for opioid receptor-mediated effects in man after standard dihydrocodeine doses. Methods: Whole cell opioid-receptor affinity and effects on cAMP accumulation of dihydrocodeine and its metabolites were determined in differentiated SH-SY5Y neuroblastoma cells. In a double-blind, 2-period, placebo-controlled randomized crossover pilot study the pharmacokinetics of dihydrocodeine (60 mg single dose) and its metabolites were examined in 5 phenotyped extensive (EMs) and 4 poor metabolizers (PMs) for CYP2D6, and pharmacodynamics were evaluated using a pain threshold model and dynamic pupillometry. Results: Displacement binding and cAMP accumulation experiments showed clearly higher affinities (100- and 50-fold) and activities (180- and 250-fold) of dihydromorphine and dihydromorphine-6-glucuronide, respectively, whereas the other metabolites had similar or lower affinities and activities as compared to dihydrocodeine. The clinical study revealed no significant difference in plasma or urine pharmacokinetics between EMs and PMs for dihydrocodeine and its glucuronide. Dihydromorphine and its glucuronides were detectable in EMs only. A clear reduction of initial pupil diameters was observed up to 6 hours post-dose in both PMs and EMs, with no obvious differences between CYP2D6 phenotypes. In the pain threshold model no effects were observed in either group. Conclusion: CYP2D6 phenotype has no major impact on opioid receptor-mediated effects of a single 60 mg dihydrocodeine dose, despite the essential role of CYP2D6 in formation of highly active metabolites
Innovative Strategies to Develop Chemical Categories Using a Combination of Structural and Toxicological Properties
Full text link1.AbstractInterest is increasing in the development of non-animal methods for toxicological evaluations. These methods are however, particularly challenging for complex toxicological endpoints such as repeated dose toxicity. European Legislation, e.g. the European Union´s Cosmetic Directive and REACH, demands the use of alternative methods. Frameworks, such as the Read-across Assessment Framework or the Adverse Outcome Pathway Knowledge Base, support the development of these methods. The aim of the project presented in this publication was to develop substance categories for a read-across with complex endpoints of toxicity based on existing databases. The basic conceptual approach was to combine structural similarity with shared mechanisms of action. Substances with similar chemical structure and toxicological profile form candidate categories suitable for read-across. We combined two databases on repeated dose toxicity, RepDose database and ELINCS database to form a common database for the identification of categories. The resulting database contained physicochemical, structural and toxicological data, which were refined and curated for cluster analyses. We applied the Predictive Clustering Tree (PCT) approach for clustering chemicals based on structural and on toxicological information to detect groups of chemicals with similar toxic profiles and pathways/mechanisms of toxicity. As many of the experimental toxicity values were not available, this data was imputed by predicting them with a multi-label classification method, prior to clustering. The clustering results were evaluated by assessing chemical and toxicological similarities with the aim of identifying clusters with a concordance between structural information and toxicity profiles/mechanisms. From these chosen clusters, seven were selected for a quantitative read-across, based on a small ratio of NOAEL of the members with the highest and the lowest NOAEL in the cluster (<5). We discuss the limitations of the approach. Based on this analysis we propose improvements for a follow-up approach, such as incorporation of metabolic information and more detailed mechanistic information. The software enables the user to allocate a substance in a cluster and to use this information for a possible read- across. The clustering tool is provided as a free web service, accessible at http://mlc-reach.informatik.uni-mainz.de
Oral controlled release products therapeutic and biopharmaceutic assessment ; with 9 tables
No full textSCENIHR (Scientific Committee on Emerging and Newly Identified Health Risks) Opinion on The safety of the use of bisphenol A in medical devices
Full text linkSCENIHR (Scientific Committee on Emerging and Newly Identified Health Risks), Safety of the use of bisphenol A in medical devices, 18 February 2015Testai, Emanuela; Hartemann, Philippe; Rodríguez-Farré, Eduard; Rastogi, Suresh Chandra; de Jong, Wim; Bustos, Juana; Castle, Laurence; Gundert-Remy, Ursula; Hensten, Arne; Kopperud, Hilde Molvig; Olea, Nicolás; Piersma, Aldert; SCENIHR (Scientific Committee on Emerging and Newly Identified Health Risks). The Safety of the use of Bisphenol A in medical devices. [S.l.]: European Commission, 2015. 166 p. ISSN 1831-4783 . ISBN 978-92-79-30133-9 . DOI Doi: 10.2772/75546This opinion assesses whether the use of bisphenol A in medical devices such as implants, catheters, and dental devices could give reasons for safety concerns, to provide indications on limit values for BPA release from medical devices and to identify any patient group, e.g. infants, pregnant and breastfeeding women who would be particularly at risk.
Several exposure scenarios have been evaluated taking into account the material used, information related to BPA leaching, the duration of a single treatment and the frequency of treatments, giving rise to toxicologically relevant acute, short and long term exposure.
The SCENIHR concludes that risk for adverse effects of BPA may exist when the BPA is directly available for systemic exposure after non-oral exposure routes, especially for neonates in intensive care units, infants undergoing prolonged medical procedures and for dialysis patients. Although the benefit of medical devices has also to be considered, the SCENIHR recommends that, where practicable, medical devices that do not leach BPA should be used. The possibility of replacing BPA in these products should be considered against their efficiency in the treatment, as well as the toxicological profile of the alternative materials.
However, better data on exposure would be beneficial for the refinement of the present risk assessment, to be carried out when new data on exposure via medical devices will be available.Peer Reviewe
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