Micronucleus induction in the bone marrow of rats by pharmacological mechanisms. II: long-acting beta-2 agonism
| Autor: | Ingrid Pontén, Michael R. O’Donovan, David J. Nicholls, Alan Young, Alaa Saad, Cecilia Diaz Pohl, Peter Mutch, Charlotta Fred, Per M. Åberg |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Blood Glucose
Male Erythrocytes Health Toxicology and Mutagenesis Tachyphylaxis Biology Pharmacology Toxicology medicine.disease_cause Pharmacokinetics In vivo Bone Marrow Genetics medicine Animals Benzothiazoles Rats Wistar Adrenergic beta-2 Receptor Agonists Genetics (clinical) Micronucleus Tests Dose-Response Relationship Drug Rats Receptors Adrenergic Comet assay Tolerance induction medicine.anatomical_structure Liver Potassium beta-Alanine Bone marrow Comet Assay Micronucleus Genotoxicity DNA Damage Mutagens |
| Zdroj: | Mutagenesis. 28(2) |
| ISSN: | 1464-3804 |
| Popis: | AZD9708 is a new chemical entity with selective and longacting β2-agonistic properties currently being evaluated by AstraZeneca for potential use in treatment of respiratory diseases by the inhaled route. As part of the toxicological characterisation of this compound, an increased incidence of micronucleated immature erythrocytes (MIEs) was seen in the bone marrow of rats following single intravenous doses near the maximum tolerated. This effect was seen in the absence of in vitro genotoxicity in bacterial and mammalian cells and no consistent evidence of in vivo DNA damage in the the bone marrow or liver using the comet assay was observed. Because of the lack of signals for mutagenic potential, combined with the observation that MIE frequencies appeared to be increased in only some of the rats and the clearest response was seen at the intermediate dose, it was hypothesised that the effect was secondary to β2-adrenergic receptor overstimulation. Because it appears that this has not been previously described for β2-agonists and because pharmacodynamic/pharmacokinetic factors may influence the response, studies using repeated dosing were performed to investigate whether this would lead to compound-induced tachyphylaxis with tolerance induction and decreased responses indicated by β2-effect biomarkers. A series of experiments confirmed that a sequence of five escalating daily doses leading to systemic exposure cor responding to that after a single dose led to symptomatic tolerance, declining or diminished effects on plasma biomarkers of β2-effects (plasma glucose and potassium) and elimination of the micronucleus response. This suggests that the increased MIE frequencies after single doses of AZD9708 are secondary to physiological overstimulation of β2-adrenergic receptors, not a consequence of genotoxicity. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|