Baclofen
Medication Facts
- Performance enhancing
- No
- Total hours to clear
- Not recorded
- Frequently used
- N/A
- ESC ID
- BACLOF-0096
- Trade names
- Lioresal
- Drug type
- Muscle relaxant
- Plasma half-life · hours
- Not Published
- Equine dosing
- 0.05-0.1 mg/kg IV/PO
- Cmax · peak plasma concentration
- 1.5 µg/mL
- Tmax · time to peak plasma concentration
- 12
- ESC concentration guidance
- May not exceed 6% efficacy in plasma
- Primary withdrawal · hours
- 12
- Washout withdrawal · hours
- 0
- ESC control type
- A1 - Generally Controlled - Therapeutic
- Medication report required
- Generally not required, however understand exceptions.
Uses & side effects
Product-specific side effects await source review.
Drug interactions
Skeletal muscle relaxants in horses interact most critically with sedatives, general anesthetics, and calcium channel blockers, primarily risking dangerous levels of central nervous system (CNS) depression, profound weakness, or acute cardiovascular collapse. Muscle relaxants like methocarbamol (Robaxin), guaifenesin (GGE), and dantrolene are commonly used in equine veterinary medicine to manage exertional rhabdomyolysis ("tying up"), treat acute muscle spasms from injury, or assist with anesthetic induction.Because these drugs alter neuromuscular signals or depress brain and spinal cord pathways, combining them with other veterinary treatments requires close tracking. The key drug interactions are broken down below by drug class:1. Central Nervous System (CNS) Depressants & SedativesMedications: Alpha-2 agonists (Xylazine, Detomidine, Romifidine), Acepromazine, and Benzodiazepines (Diazepam, Midazolam).The Interaction: Centrally acting muscle relaxants like methocarbamol and guaifenesin naturally cause mild tranquilization as a side effect. Giving them alongside standard equine sedatives produces a heavy, additive sedative effect.Clinical Impact: High. The horse may experience severe ataxia (unsteadiness), profound muscle weakness, or can become recumbent (unable to stand). This combination compromises the horse's ability to safely maintain its balance.2. General Anesthetics (The "Triple Drip" Effect)Medications: Ketamine, Propofol, and inhalant gases (Isoflurane).The Interaction: Intravenous guaifenesin is routinely combined with ketamine and xylazine (a mixture known as "triple drip") to smoothly induce or maintain short-term anesthesia in horses.Clinical Impact: Intended but narrow safety margin. While this is a common therapeutic technique, precise dosing is vital. If the horse receives excessive guaifenesin, the muscle relaxation overrides the respiratory muscles, resulting in severe respiratory depression, hypoxemia, or an inability to stand during the recovery phase.3. Calcium Channel Blockers (with Dantrolene)Medications: Diltiazem, Amlodipine.The Interaction: Dantrolene is a peripherally acting muscle relaxant that works by directly blocking calcium release inside muscle cells to prevent cramping. Calcium channel blockers similarly restrict calcium movement in cardiac and blood vessel tissues.Clinical Impact: Critical risk / Contraindicated. Combining dantrolene with a calcium channel blocker can cause severe cardiovascular collapse, profound myocardial depression (heart failure), and dangerously high potassium levels in the blood (hyperkalemia).4. Overlapping Muscle Relaxants (Methocarbamol + Guaifenesin)Medications: Concurrent use of oral/IV methocarbamol and IV guaifenesin.The Interaction: Methocarbamol is chemically related to guaifenesin; in fact, guaifenesin is a direct metabolic byproduct of methocarbamol breakdown in the horse's body.Clinical Impact: High regulatory and toxicity risk. Using both simultaneously exponentially increases the risk of overdosage, leading to severe weakness, recumbency, and muscle tremors. For competitive horses, this combination significantly extends drug clearing times, risking positive drug tests under USEF or racing regulations.