According to PwC, generic drugs account for about 80% of all prescriptions in the United States. "Generic equivalents don't immediately hit the market," Thompson said. "So there is a lag time before prices adjust for a drug that goes off patent."
Health plan administration: Insurers make annual changes to the prices of their plans to factor in their own cost of doing business.
For example, insurers may set higher premiums and deductibles if the volume of insurance reimbursements they paid out in the prior year was more than they had expected.