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:

Metformin: In healthy subjects given single 500 mg doses of cephalexin and metformin, plasma metformin mean cmax and AUC increased by an average of 34% and 24%, respectively, and metformin mean renal clearance decreased by 14%. No information is available about the interaction of cephalexin and metformin following multiple doses of either drug. Although not observed in this study, adverse effects could potentially arise from co-administration of cephalexin and metformin by inhibition of tubular secretion via organic cationic transporter systems. Accordingly, careful patient monitoring and dose adjustment of metformin is recommended in patients concomitantly taking cephalexin and metformin. Probenecid: As with other b-lactams, the renal excretion of cephalexin is inhibited by probenecid. Drug / Laboratory Test Interactions As a result of administration of Keflex, a false-positive reaction for glucose in the urine may occur. This has been observed with Benedict s and Fehling s solutions and also with Clinitest  tablets.
{"Brand": ["Keflex"], "Drug": ["Metformin", "cephalexin", "metformin", "probenecid", "Probenecid"], "DrugGroup": ["b-lactams"], "UnapprovedDrug": []}