You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Brand", "UnapprovedDrug", "Drug", "DrugGroup"].

Please return the output as a JSON object of the format: {"Brand" : ["Aspirin", ...], "DrugGroup": ["Salicyclate", ...], "Drug": ["Phenobarbital", ...], "UnapprovedDrug": ["Heroin", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

[The effect of cimetidine on the renal excretion of verografin and iodamide in dogs] The intravenous injection of cimetidine in a dose of 20 mg/kg enhanced verografine and iodamide excretion in chronic canine experiments. The higher verografine and iodamide excretion was due to their increased renal tubular secretion. In dogs, cimetidine unchanged the secretion of cardiotrast, a test agent for anionic transport. Possible extrarenal mechanisms of action of cimetidine on verografine and iodamide transport were also examined.
{"Brand": [], "Drug": ["cardiotrast", "iodamide", "verografin", "cimetidine", "verografine"], "DrugGroup": [], "UnapprovedDrug": []}