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: ["Disease", "Chemical"].

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

Acute low back pain during intravenous administration of amiodarone: a report of two cases. Amiodarone represents an effective antiarrhythmic drug for cardioversion of recent-onset atrial fibrillation (AF) and maintenance of sinus rhythm. We briefly describe two patients suffering from recent-onset atrial fibrillation, who experienced an acute devastating low back pain a few minutes after initiation of intravenous amiodarone loading. Notably, this side effect has not been ever reported in the medical literature. Clinicians should be aware of this reaction since prompt termination of parenteral administration leads to complete resolution.
{"Chemical": ["amiodarone", "Amiodarone"], "Disease": ["low back pain", "atrial fibrillation", "AF"]}