medicaments

Yes, this word exists.  No we hardly ever use it.  Medicines is perfectly fine

jedinstven

= unique in the sense that there is only one like it
= unified in the sense that it is integrated i.e. part of one whole

relations(hips)

countries have relations, you can study international relations.  But to my ear when you say that people have relations it sounds a bit like THAT kind of relations.  Relationships is safer and better to my ear.