Flumazenil: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Anexate, Romazicon, Flumaz(enil)

Species with doses

Dogs, Cats, Cattle, Horses, Sheep and Pigs

General dose range

0.01–0.02 mg/kg IV single dose (repeat as needed) — check the species tables for the indication

Routes

IV

Last reviewed

1 October 2026

Indications

• Reversal of benzodiazepine (diazepam/midazolam) over-sedation or paradoxical excitation
• Reversal of the zolazepam component of tiletamine-zolazepam (Zoletil/Telazol) for rough/prolonged recoveries
• Benzodiazepine-induced respiratory depression (adjunct to ventilation)
• Hepatic encephalopathy — transient improvement of obtundation (adjunct)

Flumazenil dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Benzodiazepine reversal: Papich 5e: 0.02 mg/kg (20 µg/kg) IV, or 0.2 mg total IV as needed. Plumb’s p.535: 0.01 mg/kg IV (Bunch; Wismer) — may need repeating as the half-life is about 1 h; can be given intratracheally in an emergency. Watch for re-sedation.
• Hepatic encephalopathy (adjunct): Plumb’s p.535: 0.02 mg/kg IV once (Bunch 2003); if the dog responds it is safe to repeat (Michel 2003).

Cats

• Benzodiazepine reversal: Papich 5e: 0.02 mg/kg IV (or 0.2 mg total). Plumb’s p.535 (Wismer 2004): 0.01 mg/kg IV, repeated as needed (half-life about 1 h).

Cattle

• Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

Horses

• Benzodiazepine reversal: Papich 5e (horses, cattle, swine, sheep): 20 µg/kg (0.02 mg/kg) IV.

Sheep

• Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

Pigs

• Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Benzodiazepine reversal: Papich 5e: 20 µg/kg IV. No withdrawal established — obtain FARAD advice.

Contraindications

Patients on long-term benzodiazepines for seizure control (reversal can precipitate seizures). Mixed overdoses where a benzodiazepine is protecting against another drug's seizures (e.g. TCA overdose). Known hypersensitivity. Use judiciously — it removes the benzodiazepine's anticonvulsant protection.

Adverse effects

• Re-sedation when it wears off before the benzodiazepine (short duration)
• Seizures (if reversing in a benzodiazepine-dependent or mixed-overdose patient)
• Agitation/anxiety on abrupt reversal
• Rare arrhythmia

Drug interactions

• Benzodiazepines (diazepam, midazolam, zolazepam): the drugs it antagonises (intended)
• Pro-convulsant drugs / TCA overdose: reversing benzodiazepine protection can unmask seizures
• Does NOT reverse opioids, alpha-2 agonists, barbiturates, propofol or the dissociative component of tiletamine

Pregnancy and lactation

Limited data; use when reversal is clinically needed.

Monitoring

• Level of consciousness / sedation and respiration after reversal
• Re-sedation (it is shorter-acting than most benzodiazepines — watch and re-dose)
• Seizure activity (especially in benzodiazepine-dependent or mixed-overdose patients)

Toxicity and overdose

Generally well tolerated; the principal risks are SEIZURES (in benzodiazepine-dependent patients or mixed overdoses where the benzodiazepine was suppressing seizures) and RE-SEDATION as it wears off before a longer-acting benzodiazepine. Abrupt reversal can cause agitation. True overdose toxicity is uncommon.

Management: No specific antidote. Supportive — manage seizures with... (re-administering a benzodiazepine is logical if seizures result from reversal) and provide standard seizure/supportive care; monitor for re-sedation and re-dose flumazenil as needed for recurrent benzodiazepine sedation.

Clinical pearls

• The specific antidote for benzodiazepines — reverses diazepam/midazolam over-sedation and the zolazepam part of Zoletil (smoothing rough recoveries)
• It is SHORT-acting: a single dose may wear off before the benzodiazepine, so watch for re-sedation and re-dose
• Avoid abrupt reversal in benzodiazepine-dependent (chronic seizure) patients or mixed overdoses (e.g. TCA) — you may precipitate seizures
• It does NOT touch opioids, alpha-2 agonists, propofol/barbiturates, or the dissociative (tiletamine/ketamine) component — use the right reversal for the right drug

Mechanism of action

A competitive antagonist at the benzodiazepine binding site of the GABA-A receptor. It displaces benzodiazepines (and benzodiazepine-like ligands) without activating the receptor itself, abolishing their potentiation of GABA-mediated inhibition — thereby reversing benzodiazepine sedation, respiratory depression and paradoxical excitation. It has little effect in the absence of a benzodiazepine (and does not reverse other sedatives/opioids).

Formulations and products

• Injection 0.1 mg/mL
• Anexate — 0.1 mg/mL (0.5 mg/5 mL) injection, Injection (human-label)
• Flumazenil — 0.1 mg/mL injection, Injection (human-label)

Storage

Injection: 15–30 °C, protect from light; do not freeze.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other hormones, emergency drugs, supplements and other drugs

• Estriol
• Ferrous Sulfate
• Finasteride
• Fludrocortisone
• Fluoxetine
• Fluticasone (Inhaled)
• Fomepizole (4-MP)
• Glipizide

Frequently asked questions