[phaedrus]

Four companies. The doctor's office which may be controlled by profit-optimizing administration, the big profit pharma corporation, the for-profit medical insurance company, and the company the insured works for who picks the available insurance plan(s).

[NeutralCrane]

Doctor's office won't make money from prescriptions for a drug, and the pharmaceutical company will sell their drug to whoever will buy it. Both those entities also exist in non-US medication transactions as well, so I'm not sure it's relevant. The point is that the insurer and the employer are two extra middlemen.