469
Although it is acknowledged that the main impediment of orally administered therapeutic agents is their extensive and changeable pre - systemic metabolism , low absorption and instability in harsh environment of the gastrointestinal ( GI ) tract are also main influential factors , resulting into inadequate and erratic drug bioavailability .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None