i bought some Nitrix with such high hopes & was very disappointed although i've since read that you need to take it for 6-8 weeks before starting to get results.
this is only what i read in another thread.
i liked Tribex but you have to take too many to get anything out of it.
the only trib i've used and WILL use regularly now is an Australian brand called "Wild Bull" Tribulus.
-12.5 g of trib (fruit & root) per tab & also has zinc & avena sativa.
Jag