Abstract
In the search for a conveniently small animal in which morphine addiction might be developed preparatory to a study of its effect on tissue metabolism, the hamster was found to be so resistant to the drug that the extremely high lethal dose was thought to be worthy of note. Coincidentally, the toxic symptoms observed differed from those reported in the literature for other species. 1
The present communication describes the toxic effects of morphine in the hamster. The lethal dose 50 and the lethal dose 100 are presented.
Morphine sulfate was injected subcutaneously, intramuscularly, and intraperitoneally; the route of administration did not alter the response. In all cases where large quantities had to be given at a single time, a combination of the 3 routes was used. Dosage levels ranged from 1 mg to 2000 mg per kilogram body weight. Normal hamsters of both sexes were included. Body weights were from 26 to 130 g with age corresponding from 1 to 8 months (life span of the hamster usually 12 months). Neither sex, age, nor weight of the animal made any apparent difference in the response to morphine. The seasonal or temperature variations during the course of the investigation also caused no difference in response.
In doses up to and including 150 mg per kg of body weight of the hamster, morphine had no noticeable effect. An increase to 300 mg per kg resulted in stimulation of salivary secretion, some incoordination in the extremities, increased activity, and hyperirritability to handling or to any direct contact stimulus. At dosage levels of 500 to 600 mg, the animal also showed some discomfort as indicated by circling movements and by the rubbing of its ventral surface on the floor of the cage.
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