Assertion: viagra | /r/PartOf | a class of drugs
Facets:
Source sentences:
text: It belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors.
text: Both Viagra and Cialis belong to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors.
text: Both Viagra and Levitra belong to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors.
text: Instead, it belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors.