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Trihexyphenidyl is a generic drug. What agents check before quoting it: how many 2026 Part D plans cover it, on which tier, with what restrictions and copays, by plan type, carrier and state.
In 2026, 5,256 of 5,496 Medicare Part D and Medicare Advantage drug plans (95.6%) list Trihexyphenidyl on their formulary, across 305 of 328 formularies. The most common placement is tier 2 (3,219 plans, 61.2% of those covering it). 1,098 of the covering plans require prior authorization (20.9%), 0 step therapy and 0 a quantity limit.
3,886 covering plans charge a flat copay for a 30-day supply at a preferred retail pharmacy after the deductible — median $4, 1,638 of them $0; 1,370 charge coinsurance instead — median 25% of the drug's cost. Once a member's out-of-pocket drug spending reaches $2,100 in 2026, covered drugs cost $0 for the rest of the year.
2025: 5,344 of 5,631 plans covered it (94.9%); 2026: 5,256 of 5,496 (95.6%).
Of 4,368 plans offered in both years, 19 added it to the formulary and 24 dropped it.
Among plans covering it both years, 158 moved it to a higher tier and 78 to a lower one; 798 added prior authorization and 1,398 removed it.
Medicare Part D paid for 276,739 30-day fills of Trihexyphenidyl in 2024 for about 31,122 enrollees, at an average total cost of $9.22 per 30-day fill (CMS Part D Prescribers by Geography and Drug, national).
Price Trihexyphenidyl and the rest of a client's list on every plan in their county.
Estimate Trihexyphenidyl costs by plan
Free tools for licensed insurance agents. Data from CMS public files; verify with plan documents before advising a client.
Counts are over every Medicare Advantage drug plan and stand-alone Part D plan in the CMS monthly formulary files, excluding employer plans. A plan counts as covering a drug when any strength or form of it is on the plan’s formulary; the tier, prior authorization, step therapy and quantity limit shown are the most favorable version on that formulary. Copays are for a 30-day supply at a preferred retail pharmacy after the deductible. This is a reference for licensed agents, not a plan recommendation; verify with the plan’s formulary before advising a client. Source: CMS Part D formulary files (release 09/16/2026). CMS formulary data.