Yes you can get them in most of the pharmacies, but also in Carrefour or other super markets.
It depends the type and quality... where the super markets have more "unreliable" ones... but cheaper.

Most of the european brands you will get at Doha Clinic Pharmacy, as mentioned above.
But don't try to get them to help you... they have no clue what it is and what for...
You point and they will give...