Why Is Terrell (Isoflurane) So Hard to Find? [Explained for 2026]

If you're a patient scheduled for surgery, an anesthesiologist managing a busy OR, or a facility administrator trying to keep your supply closet stocked, you may have encountered a frustrating problem: Terrell (isoflurane) isn't always easy to find. Supply disruptions, distribution bottlenecks, and consolidating manufacturer bases have all contributed to challenges sourcing this essential inhaled anesthetic over the years.

This article explains what Terrell is, why its supply can be unpredictable, what factors drive shortage situations, and what you can do when your surgical center can't get it.

What Is Terrell (Isoflurane)?

Terrell is the brand name for isoflurane USP, a general inhalational anesthetic manufactured by Piramal Critical Care, Inc. It was first approved in the United States in 1979 and remains one of the most widely used inhaled anesthetics in the world. Terrell is a clear, colorless, nonflammable liquid that is vaporized and inhaled to induce and maintain general anesthesia during surgery.

It is not a controlled substance under DEA scheduling. However, it requires a prescription and can only be administered by trained anesthesia professionals — anesthesiologists, certified registered nurse anesthetists (CRNAs), and anesthesiologist assistants (AAs) — using a calibrated isoflurane-specific vaporizer.

Terrell comes in 100 mL and 250 mL amber glass bottles and is procured through hospital and surgical-center formularies or medical supply distributors — not through retail pharmacies.

Why Does Terrell (Isoflurane) Face Supply Challenges?

Several factors contribute to availability challenges for isoflurane:

• Specialized equipment required: Terrell must be delivered using an isoflurane-specific vaporizer. You can't simply swap to a different brand of anesthetic without confirming vaporizer compatibility, which complicates substitution in a shortage.
• Competition from newer agents: Sevoflurane and desflurane have taken significant market share, particularly in high-income countries. This has led to reduced production investment in isoflurane infrastructure in some regions.
• Dual-use demand (veterinary and human): Isoflurane is widely used in veterinary medicine. When veterinary demand surges or human supply dips, competition for available stock increases. A notable veterinary shortage of isoflurane occurred in 2018–2019.
• Stringent storage and transport requirements: Isoflurane must be stored in specialized amber bottles, kept away from direct sunlight, and transported carefully. Logistics complexity can add delays.

Is There a Current Terrell Shortage in 2026?

As of 2026, the FDA and ASHP do not list an active nationwide shortage of isoflurane (Terrell). However, localized supply constraints and distribution gaps remain a real concern for individual hospitals, ambulatory surgical centers (ASCs), and veterinary clinics. A facility that relies on a single distributor or a just-in-time inventory model may find itself unable to secure product even when there is no broad national shortage.

Surgical volumes globally continue to rise, driven by aging populations requiring orthopedic, cardiac, and other elective procedures. This sustained demand, combined with a lean manufacturing supply chain, keeps Terrell's availability tight.

Who Does a Terrell Supply Problem Affect Most?

While patients don't typically procure anesthetics themselves, they absolutely feel the downstream effects of a supply disruption:

• Elective surgeries may be postponed or rescheduled if a facility's anesthetic stock is critically low.
• Facilities may switch to alternative anesthetics (e.g., sevoflurane or TIVA with propofol), which can have different side-effect profiles.
• Smaller or rural surgical centers with less purchasing power may face availability challenges before large hospital systems.

What Can Facilities Do When Terrell Is Hard to Source?

Anesthesia departments and facility administrators can take several steps:

1. Contact multiple medical distributors simultaneously to compare availability and pricing.
2. Check the FDA Drug Shortages database and ASHP shortage list regularly for updates.
3. Implement low-flow anesthetic techniques to conserve existing isoflurane supply.
4. Evaluate alternative agents such as sevoflurane (if compatible vaporizers are available) or total intravenous anesthesia (TIVA) with propofol.
5. Contact Piramal Critical Care directly at 1-800-414-1901 to inquire about availability and direct purchasing options.

What About Patients Who Need Terrell for Their Surgery?

If you're a patient and your surgery has been delayed due to an anesthetic supply issue, speak with your surgical team about alternative agents or rescheduling options at a different facility. For other prescription medications you might need around your surgery, medfinder can help locate pharmacies near you that have your medications in stock.

For a full analysis of the current supply landscape, read our Terrell shortage update for 2026.

The Bottom Line

Terrell (isoflurane) has a long track record as a safe and effective inhaled general anesthetic. While no broad national shortage exists in 2026, the concentrated manufacturing base, dual human-veterinary demand, and specialized supply chain mean that localized availability problems can and do occur. Facilities should maintain vigilant supply chain monitoring, have contingency plans for alternative anesthetics, and know where to turn when their usual distributor runs short.