Is Tiazac (diltiazem hydrochloride) covered by Medicare Part D?
2 of 5,052 Medicare Part D plan offerings (under 0.1%) list Tiazac on their 2026 formulary, most often on tier 1; 0% of the formularies that cover it require prior authorization. Part D spending on it was $77 thousand in 2024 for 108 people: what plans and patients paid at the pharmacy, before manufacturer rebates (CMS Part D Spending by Drug).
- Plans that cover it
- under 0.1%
- 2 of 5,052 offerings; the median drug: 76%
- Usual tier
- Tier 1
- the same tier on every formulary
- Prior authorization
- 0%
- of formularies that cover it; the median drug: 1%
- Quantity limits
- 0%
- of formularies that cover it; the median drug: 30%
Source: CMS Part D formulary file, 2026 second quarter: the formularies in use in 2026. A plan's 2027 formulary can differ; check your own plan's coverage in Medicare Plan Finder.
What does it cost under Part D in 2027?
- Your yearly cap in 2027
- Out-of-pocket spending on covered Part D drugs stops at $2,400 in 2027 ($2,100 in 2026); after that, you pay nothing for covered drugs for the rest of the year.
- The deductible
- A plan's drug deductible is at most $700 in 2027 ($615 in 2026); many plans charge less or none.
Source: CMS, Announcement of calendar year 2027 Part D parameters; Medicare.gov, “How much does Medicare drug coverage cost?” (read Oct. 7, 2026).
How much does Medicare spend on it?
Part D spending by year
108 people filled it under Part D in 2024, in 424 claims. The amounts are what plans and patients paid at the pharmacy, before manufacturer rebates.
Source: CMS Medicare Part D Spending by Drug, 2020 to 2024 (published June 2026). Row used: Tiazac (Diltiazem HCl).
Which forms and strengths are counted?
- 24 hour diltiazem hydrochloride 120 mg extended-release oral capsule
- 24 hour diltiazem hydrochloride 180 mg extended-release oral capsule
- 24 hour diltiazem hydrochloride 240 mg extended-release oral capsule
- 24 hour diltiazem hydrochloride 300 mg extended-release oral capsule
- 24 hour diltiazem hydrochloride 360 mg extended-release oral capsule
- 24 hour diltiazem hydrochloride 420 mg extended-release oral capsule
Which other versions are listed?
The same ingredients under other names, each with its own coverage and spending.
- Diltiazem hydrochloride100% of plan offerings
- Cartia (diltiazem hydrochloride)99.7% of plan offerings
- Dilt (diltiazem hydrochloride)99.7% of plan offerings
- Tiadylt (diltiazem hydrochloride)96.4% of plan offerings
- Matzim (diltiazem hydrochloride)58.4% of plan offerings
- Cardizem (diltiazem hydrochloride)under 0.1% of plan offerings
What else should you check?
- Stand-alone drug plans for 2027Premiums and deductibles
- Drugs Medicare spends the most onThe 2024 spending list
- 2027 costs and limitsDeductibles and out-of-pocket limits
Data, not medical advice. Coverage is the share of plan formularies listing the drug; your plan's formulary, tier and pharmacy decide what you pay.