How many generic, brand and OTC medications are there

Is there a rough estimate as to how many medications are only available as brand names, how many are available as generics and how many are OTC?

The Physicians desk reference supposedly covers over 4000 drugs, but I have no idea how many are brand, generic, OTC, etc.

You might be able to gather the info from the FDA’s pages, at least for US-specific drugs (patent law/generic approval/etc is different in each country, and some countries may have generics available that aren’t available in the US). I haven’t sorted through their pages, but if anyone knows the answer, it would be them! The Canadian equivalent is the http://www.hc-sc.gc.ca/ahc-asc/branch-dirgen/hpfb-dgpsa/index-eng.php.

You might be able to narrow it down by sorting according to manufacturer. Most companies don’t produce both brand and generic products under the same name, so if you find product X from Novartis and product X from Sandoz, you’ve got one brand name and one generic right there (respectively). Finding a list of all pharmaceutical companies might be tough, though, since there are a ton of them. A contract lab I used to work for did work on products from well over 200 companies (as of 2006), but not all products were on the market. As a rule of thumb, generic manufacturers will put a prefix on the drug name, so a generic drug might be "Apo-drugname’ or “Ratio-drugname” while a brand name will have a funky made up BrandName XTC.

From my experience, I’d have to say that just about any medication that gets approved as a brand name eventually has a generic once its patent expires - if it’s cost effective for an R&D company, it’s definitely cost effective for a generic, assuming they have the capabilities to manufacture it (special treatments, sterilization, lyophilization, etc).