Corrupt behavior of government employees is already illegal, so if your concern is that they'd approve R&D funding for a drug and development company they have a financial stake in, that wouldn't be allowed and would be dealt with, unless they can prove that the drug really should be developed and the company getting the contract and funding really is the best choice.
Same goes for the manufacturing side, once the drug is approved.
And for the approval process, what perverse incentives would be created that don't already exist, and are already being dealt with? Today, anyone at the FDA who approves a drug that they've got some way to benefit from is already breaking the law.