Isoflurane: what the FDA reviewed for dog products

Isoflurane NADA 200-821, Original approval, August 28, 2025; sponsor Parnell Technologies Pty. Ltd.; species: Horses and Dogs; foi_id 17356; FDA PDF

Indication

Induction and maintenance of general anesthesia in horses and dogs.

Dose regimen

dogs: induction 2.0 to 2.5% inspired isoflurane in oxygen (after barbiturate induction); maintenance 1.5 to 1.8% in oxygen, Inhalation, continuous inspired concentration during induction, then maintenance, following a barbiturate anesthetic induction; surgical anesthesia expected in 5 to 10 minutes; delivered concentration must be known (calibrated vaporizer)

Dogs: Induction: Inspired concentrations of 2.0 to 2.5% isoflurane alone with oxygen following a barbiturate anesthetic induction are usually employed to induce surgical anesthesia in the dog. These concentrations can be expected to produce surgical anesthesia in 5 to 10 minutes. Maintenance: The concentration of vapor necessary to maintain anesthesia is much less than that required to induce it. Surgical levels of anesthesia in the dog may be sustained with a 1.5 to 1.8% concentration of isoflurane in oxygen.

Effectiveness

No study: generic ANADA granted a waiver of in vivo bioequivalence testing on formulation/chemical equivalence to the pioneer AErrane (isoflurane, USP; NADA 135-773); result: Waiver granted; safety and effectiveness rest on the pioneer product

Based on the formulation characteristics of the generic product, Parnell Technologies Pty. Ltd., was granted a biowaiver for the generic product Isoflurane inhalation anesthetic.

Extraction notes: Generic ANADA (2025, Parnell) with biowaiver; RLNAD AErrane (Baxter, NADA 135-773). Horse regimen (induction 3.0 to 5.0%, maintenance 1.5 to 1.8%) not captured. The only kinetic-type statement is the label onset ('surgical anesthesia in 5 to 10 minutes'), recorded in dose conditions rather than as PK. No PK, target animal safety, effectiveness or adverse reaction data; effectiveness field records the biowaiver only.

Isoflurane, USP NADA 200-237, Original approval, December 19, 1997; sponsor Piramal Pharma Ltd.; species: Horses and dogs; foi_id 1914; FDA PDF

Indication

Induction and maintenance of general anesthesia in horses and dogs.

Dose regimen

dogs: induction 2.0 to 2.5% inspired isoflurane with oxygen (after barbiturate induction); maintenance 1.5 to 1.8% in oxygen, Inhalation, continuous inspired concentration during induction, then maintenance, following a barbiturate anesthetic induction

For induction of surgical anesthesia: Inspired concentrations of 2.0 to 2.5% isoflurane with oxygen, following a barbiturate anesthetic induction, are used to induce surgical anesthesia in the dog. • For maintenance of surgical anesthesia: Surgical levels of anesthesia may be sustained using a 1.5 to 1.8% concentration of isoflurane in oxygen.

Effectiveness

No study: generic ANADA granted a waiver of in vivo bioequivalence testing on formulation/chemical equivalence to the pioneer AErrane (isoflurane, USP; NADA 135-773); result: Waiver granted; safety and effectiveness rest on the pioneer product

Based on the formulation characteristics of the generic product, Rhone-Poulenc Chemicals Ltd. was granted a waiver from the requirement of an in vivo bioequivalence study for the generic product Isoflurane, USP.

Extraction notes: Generic ANADA (1997, Rhone-Poulenc Chemicals Ltd.; catalogue sponsor Piramal) with in vivo bioequivalence waiver on chemical equivalence to AErrane (NADA 135-773). Horse regimen (induction 3.0 to 5.0%, maintenance 1.5 to 1.8%) not captured. No PK, target animal safety, effectiveness or adverse reaction data; effectiveness field records the waiver only.

ANIRANE NADA 200-822, Original approval, February 23, 2026; sponsor Baxter Healthcare Corp.; species: Horses and Dogs; foi_id 18151; FDA PDF

Indication

Induction and maintenance of general anesthesia in horses and dogs.

Dose regimen

dogs: induction 2.0 to 2.5% inspired isoflurane in oxygen (after barbiturate induction); maintenance 1.5 to 1.8% in oxygen, Inhalation, continuous inspired concentration during induction, then maintenance, following a barbiturate anesthetic induction; surgical anesthesia expected in 5 to 10 minutes; delivered concentration must be known (calibrated vaporizer)

Dogs: Induction: Inspired concentration of 2.0 to 2.5% isoflurane alone with oxygen following a barbiturate anesthetic induction are usually employed to induce surgical anesthesia in the dog. These concentrations can be expected to produce surgical anesthesia in 5 to 10 minutes. Maintenance: The concentration of vapor necessary to maintain anesthesia is much less than that required to induce it. Surgical levels of anesthesia in the dog may be sustained with 1.5 to 1.8% concentration of isoflurane in oxygen.

Effectiveness

No study: generic ANADA granted a waiver of in vivo bioequivalence testing on formulation/chemical equivalence to the pioneer AErrane (isoflurane, USP; NADA 135-773); result: Waiver granted; safety and effectiveness rest on the pioneer product

Based on the formulation characteristics of the generic product, Baxter Healthcare Corporation was granted a biowaiver for the generic product ANIRANE (isoflurane) inhalation anesthetic.

Extraction notes: Generic ANADA (2026, Baxter) with biowaiver; RLNAD AErrane (Baxter, NADA 135-773). Horse regimen (induction 3.0 to 5.0%, maintenance 1.5 to 1.8%) not captured. The only kinetic-type statement is the label onset ('surgical anesthesia in 5 to 10 minutes'), recorded in dose conditions rather than as PK. No PK, target animal safety, effectiveness or adverse reaction data; effectiveness field records the biowaiver only.

ATTANE™ NADA 200-141, Original approval, July 26, 1994; sponsor Piramal Pharma Ltd.; species: Horses and dogs; foi_id 1956; FDA PDF

Indication

Induction and maintenance of general anesthesia in horses and dogs.

Dose regimen

dogs: induction 2.0 to 2.5% inspired isoflurane with oxygen (after barbiturate induction); maintenance 1.5 to 1.8% in oxygen, Inhalation, continuous inspired concentration during induction, then maintenance, following a barbiturate anesthetic induction

Dogs: For induction of anesthesia: Inspired concentrations of 2.0 to 2.5% isoflurane with oxygen, following a barbiturate anesthetic induction, are used to induce surgical anesthesia in the dog. For maintenance of anesthesia: Surgical levels of anesthesia may be sustained using a 1.5 to 1.8% concentration of isoflurane in oxygen.

Effectiveness

No study: generic ANADA granted a waiver of in vivo bioequivalence testing on formulation/chemical equivalence to the pioneer AErrane (isoflurane, USP; NADA 135-773); result: Waiver granted; safety and effectiveness rest on the pioneer product

Based on the formulation characteristics of the generic product, Inhalon Pharmaceuticals, Inc. was granted a waiver on April 4, 1994 from conducting an in vivo bioequivalence study with Isoflurane, USP.

Extraction notes: Generic ANADA (1994) with in vivo bioequivalence waiver granted April 4, 1994 on chemical equivalence to AErrane (NADA 135-773). Proprietary name in the summary is 'Isoflurane, USP' (Inhalon Pharmaceuticals); catalogue lists ATTANE (Piramal). The General Information section retains unfilled template placeholders (pharmacological category 'Anticoccidial, antimicrobial, antiparasitic, etc.', amount 'X mg/ml, g/lb, etc.'), and the horse maintenance entry erroneously repeats the dog induction text. No PK, target animal safety, effectiveness or adverse reaction data; effectiveness field records the waiver only.

Isospire™ NADA 200-129, Original approval, June 29, 1995; sponsor Dechra Veterinary Products LLC; species: Dogs and horses; foi_id 3642; FDA PDF

Indication

Induction and maintenance of general anesthesia in dogs and horses.

Dose regimen

dogs: induction 2.0 to 2.5% inspired isoflurane in oxygen (after barbiturate induction); maintenance 1.5 to 1.8% in oxygen, Inhalation, continuous inspired concentration during induction, then maintenance, following a barbiturate anesthetic induction

Dogs For induction of anesthesia: Inspired concentrations of 2.0 to 2.5% isoflurane alone with oxygen, following a barbiturate anesthetic induction, are usually employed to induce surgical anesthesia in the dog. For maintenance of anesthesia: Surgical levels of anesthesia may be sustained using a 1.5 to 1.8% concentration of isoflurane in oxygen.

Effectiveness

No study: generic ANADA granted a waiver of in vivo bioequivalence testing on formulation/chemical equivalence to the pioneer AErrane (isoflurane, USP; NADA 135-773); result: Waiver granted; safety and effectiveness rest on the pioneer product

Based on the formulation characteristics of the generic product, Halocarbon Laboratories was granted a waiver January 24, 1994 (photocopy attached) from conducting an in vivo bioequivalence study with Isoflurane, USP.

Extraction notes: Generic ANADA (1995) with in vivo bioequivalence waiver granted January 24, 1994 on chemical equivalence to AErrane (NADA 135-773). Proprietary name in the summary is 'Isoflurane, USP' (Halocarbon Laboratories); the catalogue lists Isospire (Dechra). Horse regimen (induction 3.0 to 5.0%, maintenance 1.5 to 1.8%) not captured in dose_regimen. No PK, target animal safety, effectiveness or adverse reaction data; effectiveness field records the waiver only.

IsoFlo™ NADA 200-070, Original approval, March 11, 1993; sponsor Zoetis Inc.; species: Horses and dogs; foi_id 1390; FDA PDF

Indication

Induction and maintenance of general anesthesia in horses and dogs.

Effectiveness

No study: generic ANADA granted a waiver of in vivo bioequivalence testing on formulation/chemical equivalence to the pioneer AErrane (isoflurane, USP; NADA 135-773); result: Waiver granted; safety and effectiveness rest on the pioneer product

generic product, Abbott Laboratories was granted a waiver from conducting an in vivo bioequivalence study for IsoFlo(TM). The generic and pioneer products are liquid anesthetics with the same active and inactive ingredients.

Extraction notes: Generic ANADA (1993) with in vivo bioequivalence waiver granted October 5, 1992. The summary contains no dosage regimen section (route Inhalation only), no Species/Class field (species taken from the indication), and no PK, target animal safety, effectiveness or adverse reaction data; the effectiveness field records the waiver only.