The groups that are most likely to be barriers to the pharmaceutical industry are consumer protection and advocacy groups.
These groups tend to have two main problems with the pharmaceutical industry. First, they believe that its products are sometimes unsafe for lack of regulation. Second, they believe that the industry makes too much profit and should be more closely regulated and/or exposed to more competition. Both of these goals on the part of the consumer groups are contrary to what the pharmaceutical industry sees as its interests. They would both impose more regulations on the industry. This would cut into the industry’s profits. Since businesses are all about making profit, these consumer groups can be seen as barriers to the pharmaceutical industry.