The interest on future teacher loans shall be simple interest and the interest rate to be charged shall be a fixed rate set from time to time by the commissioner and ratified by the board. Interest shall accrue from the date of disbursement until the loans are either totally repaid or canceled. Loans made pursuant to these rules may be eligible for interest subsidy to be paid in accordance with Public Law 89-239, the Higher Education Act of 1965, and 45 Code of Federal Regulations Part 177.