Atipamezole
Atipamezole hydrochloride
Also known as: Antisedan · Revertidine · Alzane · Revertor · Sedastop · Tipafar · Atipamezole HCl · MPV-1248 · Atipamezole hydrochloride · Atipamezolum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidenceReversal of dexmedetomidine constant rate infusion (extralabel)
Verified clinician required
- once · discontinuation of dexmedetomidine CRI
NA
Governing clinical context (1)
- Atipamezole HCl injection should be stored at room temperature of 15°C to 30°C (59°F-86°F) and protected from light. Use within 90 days of first vial puncture.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Atipamezole is a highly specific and potent alpha-2 adrenergic antagonist primarily used in veterinary medicine as a reversal agent for alpha-2 agonists such as medetomidine and dexmedetomidine. It may also be used off-label to reverse other alpha-2 agonists like xylazine, amitraz, and clonidine.
Clinical Pearls:
- Atipamezole has an $\alpha_2:\alpha_1$ selectivity ratio of 8526:1, making it significantly more specific than older reversal agents like yohimbine or tolazoline. This high specificity results in a rapid, clean reversal with fewer cardiovascular side effects.
- Because it rapidly reverses both sedation and analgesia, patients must be evaluated for pain prior to administration, and alternative analgesics (e.g., opioids, NSAIDs) should be provided if the patient has undergone a painful procedure.
- The half-life of atipamezole is relatively short (2-3 hours in dogs). When treating toxicities from long-acting alpha-2 agonists (like amitraz), the offending agent may outlast the reversal agent, leading to re-sedation and requiring repeated dosing.
Mechanism of action
Atipamezole competitively binds to central and peripheral $\alpha_2$-adrenergic receptors, displacing alpha-2 agonists.
By blocking these receptors, it inhibits the negative feedback loop on presynaptic neurons $\rightarrow$ increases the release of norepinephrine into the synaptic cleft $\rightarrow$ leads to rapid arousal, reversal of sedation, increased heart rate, increased blood pressure, and loss of analgesia. It also antagonizes the diuretic action of alpha-2 agonists like xylazine.
Safety & warnings
Contraindications
- Reptiles (Intravenous administration is contraindicated due to profound hypotension)
Adverse effects
- Vomiting
- Diarrhea
- Hypersalivation
- Tremors
- Brief excitation or apprehensiveness
- Aggression upon rapid waking
- Profound hypotension (if given IV in reptiles)
- Loss of analgesia
Precautions
Pregnancy/Lactation: Not recommended in pregnant or lactating animals, or animals intended for breeding due to lack of safety data.
- Rapid Emergence: Because reversal can occur rapidly, care should be exercised as animals emerging from sedation and analgesia may exhibit apprehensive or aggressive behaviors. Protect animals from falling or self-harm.
- Loss of Analgesia: Additional analgesia (e.g., butorphanol, buprenorphine) should be considered, particularly after painful procedures.
- Relapse of Sedation: When used as an antidote for alpha-2 agonist toxicity (e.g., amitraz), atipamezole's effects may subside before non-toxic levels of the offending agent are reached; repeat dosing may be necessary.
- Geriatric/Debilitated Patients: Caution should be used in administration of anesthetic agents to elderly or debilitated animals.
- Reptiles: Do NOT give IV to reptiles as profound hypotension can occur.
Drug interactions
Atipamezole can partially block alpha-1 receptors and reduce the effects of prazosin.
Atipamezole can reduce the effects (toxic or therapeutic) of these agents.
Reverses sedative, analgesic, and cardiovascular effects (intended therapeutic interaction)
Reverses sedative, analgesic, and cardiovascular effects (intended therapeutic interaction)
If atipamezole is given less than 30 minutes after a medetomidine/ketamine combination in cats, it can cause severe CNS excitation during recovery.
Additive antagonistic effects
May exacerbate transient hypotension
Monitoring
- Level of sedation and analgesia
- Heart rate
- Body temperature
Pharmacokinetics
Half-life
Absorption
After IM administration in the dog, peak plasma levels occur in about 10 minutes.
Metabolism
Atipamezole is apparently metabolized in the liver.
Elimination
Eliminated in the urine.
Overdose
Dogs receiving up to 10X the listed dosage apparently tolerated the drug without major effects.
Clinical signs of overdose:
- Panting
- Excitement
- Trembling
- Vomiting
- Soft or liquid feces
- Vasodilatation of sclera
- Muscle injury at the IM injection site
Specific overdose therapy should generally not be necessary as effects are typically transient.
Available products
Formulations
- Injection: 5 mg/mL
Veterinary
- Atipamezole HCl for Injection: 5 mg/mL in 10 mL multidose vials; Antisedan® (Pfizer); (Rx)
Regulatory status
Approved for reversal of medetomidine and dexmedetomidine in dogs and cats.
POM-V classification.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Atipamezole HCl injection should be stored at room temperature (15°-30°C) and protected from light.
Client information
Atipamezole is a reversal agent used to wake your pet up after sedation or anesthesia. It should be administered by veterinary professionals only.
What to watch for at home:
- Occasionally, pets may experience vomiting, diarrhea, drooling (hypersalivation), excitation, or tremors after receiving this medication.
- Because the medication rapidly removes pain relief along with sedation, your pet may seem anxious or uncomfortable if they had a painful procedure. Ensure you give any prescribed pain medications as directed.
- If any side effects are severe, or if your pet seems excessively agitated or re-sedated after leaving the clinic, contact your veterinarian immediately.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.