What medicine is best for sinus drainae and runny nose?

Depends on the cause: If your drainage and runny nose is from allergies it will respond best to nasal steroids like flonase, nasonex, (mometasone) etc. Some of these products are approved down to age 2 so they are safe to use. Over the counter options such as zyrtec and Claritin may help with the runny nose for a short time but the effect won't last as long as the nose spray. Nasal steroids also help with nonallergic rhinitis.