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Methoxyphenamine inhibits basal and histamine‐induced nasal congestion in anaesthetized rats
Author(s) -
Lau W.A.K.,
King R.G.,
Boura A.L.A.
Publication year - 1990
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1990.tb12720.x
Subject(s) - histamine , methoxamine , nasal congestion , chemistry , pseudoephedrine , yohimbine , endocrinology , medicine , anesthesia , pharmacology , antagonist , nose , agonist , anatomy , receptor , ephedrine
1 Nasal resistance in anaesthetized rats was assessed by measuring air overflow during ventilation of the nasal passages at constant pressure. Nasal basal resistance was reduced in a dose‐dependent manner by methoxyphenamine hydrochloride (0.01–30 mg kg −1 , i.v.), pseudoephedrine hydrochloride (0.03–3 mg kg −1 , i.v.) and adrenaline bitartrate (0.01–3 μg kg −1 , i.v.). Both methoxyphenamine and pseudoephedrine were less potent and less efficacious than adrenaline but caused longer‐lasting responses. 2 Nasal congestion induced by histamine (0.2% nebulised solution passed into the nasal passages for 15 s) was inhibited by i.v. administration of methoxyphenamine, pseudoephedrine, adrenaline, methoxamine or tyramine: the ID 50 s against 0.2% histamine‐induced nasal congestion were 1.16 (95% confidence limits; 0.5, 1.8) mg kg −1 , 0.25 (0.19, 0.33)mg kg − 1, 0.037 (0.018, 0.06) μg kg −1 , 8.12 (6.74, 9.65) μg kg −1 and 30.6(26.1, 35.8) μg kg −1 respectively. 3 The inhibitory effects of both methoxyphenamine and tyramine on histamine‐induced nasal congestion were reduced after administration of desmethylimipramine (0.1 and 1 mg kg −1 , i.v.) or prazosin (0.1 and 0.3 mg kg −1 , i.v.). Similarly, the inhibitory effects of methoxamine were reduced after prazosin (0.1 and 0.3 mg kg −1 ). 4 These results indicate that methoxyphenamine (1 mg kg −1 , i.v.) inhibits histamine‐induced nasal congestion in the rat. This action, at least in part, is probably indirect being mediated by release of neuronal noradrenaline which then acts on α 1 ‐adrenoceptors.