As of January 1, 2014, group health coverage, including any form of self-insurance, offered, issued or renewed under the Health Care Purchasing Act that provides coverage for prescription drugs categorized or tiered for purposes of cost-sharing through deductibles or coinsurance obligations shall not make any of the following changes to coverage for a prescription drug within one hundred twenty days of any previous change to coverage for that prescription drug, unless a generic version of the prescription drug is available: