Alternatives to Pentasa XR If You Can't Fill Your Prescription

When your pharmacy tells you Pentasa XR is out of stock, it's natural to feel anxious — especially if you've found a regimen that keeps your ulcerative colitis under control. But here's the reassuring truth: Pentasa XR is not unique. It's one of several mesalamine-based medications that treat ulcerative colitis, and several good alternatives can keep your inflammation under control while you navigate the shortage.

In this guide, we'll walk through what makes Pentasa XR unique, which alternatives are most similar, and what you need to know before switching — so you can have an informed conversation with your gastroenterologist or prescriber.

What Makes Pentasa XR Different from Other Mesalamine Products?

All mesalamine products contain the same active ingredient (5-aminosalicylic acid), but they differ in one critical way: where the drug is released in your digestive tract. Pentasa XR uses a controlled-release mechanism (ethylcellulose-coated microspheres) that releases mesalamine continuously throughout the entire gastrointestinal tract — from the duodenum through the colon. This makes it especially useful for patients whose UC involves the small bowel, not just the colon.

Other mesalamine formulations use pH-dependent coatings or matrix systems that delay release until the medication reaches the colon. For patients with colon-only UC, these work just as well. For patients with small bowel involvement, the distinction matters more.

Alternative #1: Lialda (Mesalamine Delayed-Release Tablets)

Lialda is a once-daily mesalamine tablet using a multi-matrix (MMX) system that releases mesalamine throughout the colon. It's FDA-approved for both induction and maintenance of remission in mild-to-moderate UC in adults. The standard dose is 2.4–4.8 g once daily with food.

Key advantages over Pentasa XR:

• Once-daily dosing vs. four times daily for Pentasa XR — much more convenient
• Generic available and widely stocked at most pharmacies
• Also approved for children weighing at least 24 kg

Best for: Patients with colon-only UC looking for once-daily convenience.

Alternative #2: Apriso (Mesalamine ER 0.375 g Capsules)

Apriso is another once-daily mesalamine capsule, taken as four capsules (1.5 g total) once each morning. It uses a delayed-release formulation with a pH-dependent coating to target the colon. It's approved specifically for maintenance of remission in adults.

Note: Apriso itself has experienced shortage issues — its own generic (mesalamine ER 0.375 g) has also had supply disruptions. Check current availability before assuming it's accessible.

Best for: Patients who prefer once-daily morning dosing and have colon-dominant UC.

Alternative #3: Delzicol (Mesalamine Delayed-Release 400 mg Capsules)

Delzicol contains delayed-release mesalamine 400 mg capsules, each containing four 100 mg mesalamine tablets inside. It's FDA-approved to treat active mild-to-moderate UC in adults and children 5 years and older, and to maintain remission in adults. A typical dose is 800 mg three times daily for active disease, or 1.6 g daily in divided doses for maintenance.

Best for: Patients who need a lower per-capsule dose or who prefer a formulation approved for both adults and children.

Alternative #4: Sulfasalazine (Azulfidine)

Sulfasalazine is the original 5-ASA medication, first used for UC in the 1940s. It's broken down in the colon into mesalamine (5-ASA) and sulfapyridine. It's widely available, generic, and very inexpensive. However, the sulfapyridine component causes side effects in roughly 30% of patients, including nausea, headache, and rash. Patients who are sulfa-sensitive or have G6PD deficiency should avoid it.

Best for: Patients looking for a low-cost option and who are not sulfa-sensitive.

Key Differences at a Glance

Pentasa XR: 1 g four times daily | Entire GI tract | 250 mg and 500 mg capsules

Lialda: 2.4–4.8 g once daily | Colon | 1.2 g delayed-release tablet

Apriso: 1.5 g once daily (maintenance) | Colon | 0.375 g ER capsule

Delzicol: 800 mg three times daily (active) | Terminal ileum and colon | 400 mg DR capsule

Sulfasalazine: 3–4 g daily in divided doses | Colon | 500 mg tablet (generic, low cost)

Important: Never Switch Without Talking to Your Doctor

Even though these medications share the same active ingredient, they are NOT interchangeable without medical guidance. Dose equivalencies differ between formulations, and not every formulation covers every part of the GI tract the same way. Your gastroenterologist knows your disease pattern — always get their sign-off before switching.

For more on the current shortage, read: Pentasa XR shortage update 2026. And if you want to know which pharmacies near you can fill any of these alternatives, medfinder.com can help.