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: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. 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:

Clinical Pharmacology and the Catalysis of Regulatory Science: Opportunities for the Advancement of Drug Development and Evaluation. The "regulatory paradox" is a tension between aversion to uncertainty and willingness to accept unknowns about a drug before its approval. Finding the right balance may mean the difference between fostering and stifling innovation. Clinical pharmacology applied in the drug development and regulatory contexts can bridge mechanistic reasoning and empiricism to help reconcile the regulatory paradox. Here, we propose that the discipline of clinical pharmacology, in the regulatory setting, is well positioned to build on its past successes in the advancement and acceleration of drug development.Clinical Pharmacology & Therapeutics (2013); advance online publication 10 April 2013. doi:10.1038/clpt.2013.32.
{"Chemical": []}