Prescription Drug Coverage; Requires individual & group health insurers & HMOs to provide notice of prescription drug formulary changes within certain timeframe to current & prospective insureds & subscribers & treating physicians; specifies requirements for notice of medical necessity submitted by treating physician; specifies coverage requirement & restrictions on coverage modification by insurers & HMOs receiving notice of medical necessity; requires insurers & HMOs to maintain record of formulary changes; requires insurers & HMOs to annually submit specified report to OIR by specified date; requires office to annually compile certain data & prepare report, make report publicly accessible on its website, & submit report to Governor & Legislature by specified date; requires small employer carriers to comply with certain requirements for prescription drug formulary changes.