Provider Briefing: Diltiazem ER Supply Disruptions in 2026

If your patients are reporting difficulty filling Diltiazem extended-release prescriptions, the problem is real — and it's been simmering for years. This briefing covers the current state of Cardizem XR and generic Diltiazem ER availability, the factors driving supply issues, and actionable strategies to keep your patients on effective therapy.

Timeline: How We Got Here

Diltiazem extended-release products have experienced intermittent supply disruptions since approximately 2019. Key milestones include:

• 2019–2020: Several generic Diltiazem ER manufacturers reported production delays related to raw material sourcing and facility upgrades
• 2021–2022: Spot shortages became more frequent, particularly for 120 mg and 360 mg capsule strengths. The FDA Drug Shortage database listed certain NDCs intermittently.
• 2023–2024: Generic manufacturer consolidation reduced the number of suppliers, making the market more vulnerable to individual production disruptions
• 2025–2026: Intermittent availability continues. Brand-name Cardizem XR has limited production, with generics handling the bulk of prescriptions. Specific formulations and strengths remain sporadically unavailable.

Unlike some high-profile drug shortages (e.g., Adderall, GLP-1 agonists), the Diltiazem ER situation has not received widespread media attention. This means patients may not understand why they're having trouble and may assume the drug is being discontinued.

Prescribing Implications

Formulation Non-Interchangeability

The most clinically significant consideration is that Diltiazem ER formulations are not interchangeable. The following products all contain Diltiazem but use different drug delivery systems:

• Cardizem XR — Extended-release capsule (once daily)
• Cardizem CD — Extended-release capsule (once daily, different release profile)
• Cardizem LA — Extended-release tablet (once daily)
• Tiazac — Extended-release capsule (once daily)
• Cartia XT — Extended-release capsule (once daily)
• Taztia XT — Extended-release capsule (once daily)

Pharmacists generally cannot substitute between these formulations without a new prescription. When switching between formulations, dose adjustments may be necessary, and patients should be monitored for changes in blood pressure and heart rate.

Therapeutic Alternatives

When Diltiazem ER is unavailable in any formulation, consider these alternatives based on indication:

For hypertension:

• Verapamil ER — Closest pharmacological match (non-dihydropyridine CCB). Provides both blood pressure reduction and rate control. Higher constipation risk.
• Amlodipine — Dihydropyridine CCB. Excellent blood pressure reduction but no rate-controlling effect. Widely available and inexpensive.
• Nifedipine ER — Dihydropyridine CCB. Good blood pressure control, no rate effect. Available as extended-release tablets.

For rate control (atrial fibrillation/flutter):

• Verapamil ER — Preferred non-DHP CCB alternative
• Metoprolol Succinate ER or Atenolol — Beta-blockers for rate control. Different side effect profile; avoid in decompensated HF and severe reactive airway disease.

For angina:

• Amlodipine or Nifedipine ER for vasospastic and chronic stable angina
• Long-acting nitrates (Isosorbide Mononitrate ER) as adjunctive therapy
• Ranolazine for refractory angina

Current Availability Picture

Availability is uneven across the market:

• Generic Diltiazem ER capsules (AB-rated to Cardizem CD or Tiazac) are generally more available than products rated to Cardizem XR specifically
• Certain strengths (240 mg) tend to be more consistently in stock than others (120 mg, 360 mg)
• Independent pharmacies may have access to different distribution channels and may be able to source products that chain pharmacies cannot
• Mail-order pharmacies often maintain larger buffer inventories

For real-time availability data, Medfinder for Providers allows you to check pharmacy stock across your area and direct patients accordingly.

Cost and Access Considerations

Cost is generally not the primary barrier for Diltiazem ER — this is an inexpensive generic:

• Generic cash price: $10–$60/month
• With discount cards: $4–$15/month
• Insurance: Tier 1 or Tier 2 on most formularies ($0–$15 copay)
• Brand Cardizem XR: $80–$350+/month (rarely prescribed given generic availability)

For patients facing financial hardship, patient assistance programs are available through NeedyMeds (needymeds.org) and RxAssist (rxassist.org). Generic Diltiazem ER is also available on Walmart's $4 list and through Cost Plus Drugs.

Tools and Resources for Your Practice

• Medfinder for Providers — Real-time pharmacy stock lookup. Direct patients to pharmacies that have their medication in stock.
• FDA Drug Shortage Database — Official shortage listings and expected resolution dates (accessdata.fda.gov/scripts/drugshortages)
• ASHP Drug Shortage Resource Center — Clinical guidance on managing specific drug shortages

Consider adding a workflow note in your EHR to flag patients on Diltiazem ER for proactive formulation discussions at their next visit.

Looking Ahead

The Diltiazem ER supply situation is unlikely to resolve overnight. Structural factors — thin margins, formulation fragmentation, and reduced manufacturer competition — suggest intermittent disruptions will continue. Proactive prescribing strategies can mitigate the impact on your patients:

• Prescribe by generic name with a note indicating acceptable formulations
• Include "dispense as available" or list 2–3 acceptable alternatives on the prescription
• Consider 90-day prescriptions to reduce refill frequency
• Discuss backup plans with patients before a shortage affects them

Final Thoughts

The Diltiazem ER shortage is a logistics problem, not a clinical one. The drug remains effective and indicated for the same conditions it always has been. The challenge is getting it into patients' hands. By understanding the supply landscape and using available tools, you can help your patients maintain uninterrupted therapy.

For a patient-facing version of this information, see Cardizem XR Shortage Update: What Patients Need to Know. For guidance on helping patients locate the drug, see How to Help Your Patients Find Cardizem XR in Stock.