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The carboxylic acid functional group can be an important constituent of a pharmacophore , however , the presence of this moiety can also be responsible for significant drawbacks , including metabolic instability , toxicity , as well as limited passive diffusion across biological membranes .
 Chemical: carboxylic acid
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: carboxylic acid