Pentasa XR Shortage: What Providers and Prescribers Need to Know in 2026

As of early 2026, mesalamine extended-release (ER) capsules — sold under the brand name Pentasa XR — are experiencing an active, officially-tracked shortage. The ASHP shortage bulletin for mesalamine ER capsules was created on January 30, 2026, and last updated March 24, 2026, citing Sun Pharmaceutical Industries' 500 mg capsules as on back order with no estimated resupply date. This bulletin has significant implications for how providers prescribe and manage patients with ulcerative colitis.

This guide is for gastroenterologists, primary care physicians, internists, nurse practitioners, and physician assistants who prescribe mesalamine and may need to adjust their approach for affected patients.

Understanding What's in Shortage

The product affected is generic mesalamine ER 500 mg extended-release capsules from Sun Pharma. The brand-name Pentasa (Takeda Pharmaceuticals, 500 mg, 120-count) remains listed in the market but patients face insurance barriers to accessing it when a generic is supposed to be available. The 250 mg capsule may have better availability; prescribers can consider the 250 mg strength as a bridging strategy.

Clinical Considerations: What Makes Pentasa XR Clinically Unique?

Pentasa XR uses ethylcellulose-coated mesalamine microspheres that begin releasing drug as early as the duodenum, continuing throughout the jejunum, ileum, and colon. This is distinct from other mesalamine formulations:

• Lialda (MMX mesalamine): pH-dependent and lipophilic matrix; releases in the colon only. Not appropriate for small bowel disease.
• Apriso (mesalamine ER 0.375 g): pH-dependent coating; targets colon. Also facing shortage issues in 2026.
• Delzicol (mesalamine DR 400 mg): pH-dependent; releases at terminal ileum and colon. A reasonable alternative for most UC patients.

For patients with ulcerative colitis affecting only the colon — the vast majority of UC patients — the clinical difference between these formulations is minimal. A 2020 systematic review found no significant differences in safety and effectiveness between mesalamine formulations for UC induction or maintenance. For patients with small bowel involvement or Crohn's disease with ileal involvement, the loss of Pentasa XR's pan-GI coverage is more clinically significant.

Therapeutic Substitution Guidance

For patients unable to obtain Pentasa XR, consider the following substitution options (always document your clinical reasoning):

• Colon-only UC (mild-moderate): Lialda 2.4–4.8 g once daily or Delzicol 800 mg TID (active) / 1.6 g daily divided (maintenance)
• Maintenance-only patients: Apriso 1.5 g once daily (if available). Check current availability before prescribing.
• Bridging with 250 mg capsules: If 250 mg Pentasa XR capsules are available, patients can take four 250 mg capsules per dose to equal 1 g (same as two 500 mg capsules). Update the prescription accordingly.
• Cost-sensitive patients: Sulfasalazine remains an option for patients without sulfa sensitivity. It is inexpensive and widely available.

Prior Authorization Strategy During the Shortage

When prescribing brand-name Pentasa during the generic shortage, prior authorization is likely required. To maximize approval rates:

1. Reference the current ASHP shortage bulletin for mesalamine ER capsules in the PA documentation
2. Document that the patient's pharmacy has confirmed the generic is unavailable
3. Note any clinical reasons the patient cannot switch formulations (e.g., small bowel involvement, prior failure on alternative formulations)
4. Request expedited PA review citing active drug shortage

Communicating with Patients About the Shortage

Many patients do not understand that a shortage means their medication is not available everywhere — they may think their pharmacy is uniquely unhelpful. Clear communication helps prevent unnecessary anxiety and empowers patients to take action. Consider advising patients to:

• Use medfinder.com to find which pharmacies near them have Pentasa XR in stock
• Start searching for alternatives at least 2–3 weeks before running out of their current supply
• Contact your office proactively rather than waiting for their next appointment

Monitoring Considerations During Formulary Changes

When transitioning patients from Pentasa XR to another mesalamine formulation, consider scheduling a follow-up visit or telemedicine check-in 4–6 weeks after the switch to assess for loss of remission or new symptom onset. Monitor renal function at the start of any new mesalamine formulation per standard of care. Also check CBC and platelet counts in elderly patients (≥65 years) who may be at higher risk of blood dyscrasias with mesalamine-containing products.

How medfinder Can Support Your Patients

medfinder is a service that calls pharmacies on behalf of patients to find which locations have their specific medication in stock. If a patient reports difficulty filling their Pentasa XR prescription, recommending medfinder.com/providers can save them significant time and reduce the risk of dangerous gaps in treatment. For a detailed guide, see: How to help your patients find Pentasa XR in stock