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:

Enhanced oral bioavailability of isradipine via proniosomal systems. The objective of the present research was to develop a proniosomal formulation of isradipine and to evaluate the influence of proniosomal systems on the oral bioavailability of the drug in albino Wistar rats. Proniosomes were prepared by film deposition on carrier's method using various molar ratios of nonionic surfactants such as span20, span40, span60, and span80 with cholesterol as membrane stabilizing agent and dicetylphosphate as a charge inducer. The formation of niosomes and surface morphology of proniosome formulations were studied by optical and scanning electron microscopy (SEM), respectively. The prepared proniosomes have shown higher dissolution of isradipine compared with pure drug powder. Fourier transform infrared spectroscopy, differential scanning calorimetry, and powder X-ray diffractometry studies were performed to understand the solid state properties of the drug. Ex vivo permeation enhancement assessed from flux, permeability coefficient, and enhancement ratio were significantly higher for proniosomes compared with control. The pharmacokinetic parameters were evaluated in male albino Wistar rats and a significant enhancement in the bioavailability (2.3-fold) was observed from optimized proniosome formulation compared with control (oral suspension). The stability study reveals that the proniosome formulations are stable when stored at 4°C.
{"Chemical": ["span80", "span40", "isradipine", "span20", "span60", "cholesterol", "dicetylphosphate"]}