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:

Fenfluramine may increase slightly the effect of antihypertensive drugs, e.g., guanethidine, methyldopa, reserpine. Other CNS depressant drugs should be used with caution in patients taking fenfluramine, since the effects may be additive.
{"Brand": [], "Drug": ["guanethidine", "methyldopa", "fenfluramine", "reserpine", "Fenfluramine"], "DrugGroup": ["CNS depressant drugs", "antihypertensive drugs"], "UnapprovedDrug": []}