Alternatives to Terrell (Isoflurane) If You Can't Fill Your Prescription

Terrell (isoflurane, USP) is one of the most widely used inhaled general anesthetics in the world. But when supply is disrupted, surgical facilities need to pivot — and they need to do so safely. If your hospital or ambulatory surgical center can't obtain Terrell, there are several well-established clinical alternatives that anesthesia teams can use.

This guide breaks down the most practical substitutes for Terrell (isoflurane), comparing them on clinical properties, advantages, limitations, and the situations where each is most appropriate.

Why Switching Anesthetics Isn't Always Simple

Inhaled anesthetics require specific calibrated vaporizers. You can't just pour a different agent into an existing vaporizer without risking a dangerous overdose or underdose. Each agent has a different vapor pressure and MAC (minimum alveolar concentration), so the vaporizer must be designed specifically for that drug.

Before substituting an inhaled anesthetic, your anesthesia team must confirm:

• Compatible vaporizers are available and properly calibrated for the alternative agent.
• Staff are trained and familiar with the dosing and clinical characteristics of the substitute.
• Patient-specific contraindications for the alternative agent have been reviewed.

Alternative 1: Sevoflurane (Sojourn, Ultane)

Sevoflurane is the most commonly used inhalational anesthetic in the United States and a natural first-line substitute for isoflurane. Key properties:

• Induction: Smoother and more pleasant than isoflurane due to less pungency. Suitable for mask induction in pediatric patients.
• MAC value: ~2.0% in adults (vs. isoflurane ~1.15%), so higher concentrations are needed.
• Emergence: Faster recovery than isoflurane in most cases.
• Limitation: Can produce Compound A (a nephrotoxic degradation product) with soda lime CO2 absorbents; low-flow sevoflurane requires special attention to CO2 absorbent selection.

Best for: Pediatric cases, outpatient/ambulatory surgery, mask induction, and when smooth induction is preferred.

Alternative 2: Desflurane (Suprane)

Desflurane is another halogenated ether anesthetic with very different clinical characteristics from isoflurane:

• Fastest emergence: The fastest recovery of any inhalational anesthetic due to very low blood-gas solubility.
• High MAC: ~6-7% in adults, requiring a specially heated vaporizer (the TEC 6 Desflurane Vaporizer).
• Limitation: Strong airway irritant; not suitable for inhalational induction. Has a very high global warming potential and is being phased out at some institutions for environmental reasons.

Best for: Long surgical cases requiring rapid emergence, obese patients, neurosurgery where rapid neurological assessment is needed.

Alternative 3: Propofol-Based Total Intravenous Anesthesia (TIVA)

When no inhalational alternative is available, total intravenous anesthesia (TIVA) using propofol (brand name: Diprivan) with or without remifentanil is a well-established technique:

• No vaporizer required: Administered intravenously; eliminates the need for compatible anesthetic equipment.
• Reduced PONV: Propofol-based TIVA is associated with lower rates of post-operative nausea and vomiting compared to inhalational agents.
• Limitation: Requires target-controlled infusion (TCI) equipment or careful manual dosing. Risk of awareness if not monitored properly. Propofol is also subject to its own supply constraints.

Best for: Patients at high PONV risk, those with concerns about malignant hyperthermia susceptibility, procedures where isoflurane vaporizers are unavailable.

Alternative 4: Ketamine

Ketamine is a dissociative anesthetic that can be given IV or IM and is particularly useful in resource-limited settings or when other agents are unavailable:

• Maintains airway reflexes: Unlike most anesthetics, ketamine tends to preserve upper airway tone.
• Limitation: Can cause emergence delirium, hallucinations, and dysphoria. Not ideal for procedures requiring a motionless surgical field at standard doses.

How to Choose the Right Alternative

The right alternative depends on your available equipment, patient population, case mix, and clinical preferences. An anesthesiologist or CRNA should lead the decision-making process. No substitution should be made without a formal review of patient-specific risks and available resources.

For other medications your patients may need around a surgical procedure, medfinder helps locate them at pharmacies near your patients.

Also read: How to find Terrell (isoflurane) in stock near you for sourcing tips.