19207
The fourth study ( FEM - PrEP ) in heterosexual women did not show a statistically significant difference between FTC / TDF and placebo , although low adherence rates reported in this trial may have been a factor .
 Chemical: FTC; Chemical: TDF
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: FTC, TDF 
Answer:
 Chemical: FTC; Chemical: TDF