Tip toe into the Chinese Drug companies with caution. The ownership of these companies aren't as cut and dry as the American companies.
I believe Guangzhou Pharma is hooked with Alliance Boots out of Switzerland somehow.
The best area that I know of when looking at Chinese Pharma's are to look at the larger API manufacturers who sell to European or American Companies. If you follow that logic you'll find that they have outside certifications and have to produce to the trusted companies specifications.
I believe that anywhere from 20% to 30% of drug sales in China are still counterfeit.