Vanmathi Arulselvam1 , Devadharshini Kamalakannan1,* , Agnishwaran Ramajothi1 , Abiramy Prabavathy Arumugam2 and Vijayalakshmi Padmanadan2 1 Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry, India 2 Department of Veterinary Medicine, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry, India * Corresponding author: Devadharshini Kamalakannan, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry, India. Email: devadharshini77@gmail.com
Abstract:
Introduction: Baclofen is a centrally-acting skeletal muscle relaxant used to control spasticity and pain in humans. In an overdose situation, the onset of clinical signs, such as vocalization, vomiting, ataxia, disorientation, salivation, coma, weakness, recumbency, and seizures, is usually noticed. Case report: Case 1- A two-month-old female Spitz pup weighing 5 kg was brought to the Small Animal Medicine unit of Veterinary Clinical. Complex (VCC), Rajiv Gandhi Institute of Veterinary Education and Research (RIVER), Puducherry, India, with a history of vomiting, vocalization, and restlessness for the past hour. After recording the history, it was revealed that the dog had accidentally consumed four Baclofen tablets (10 mg each). The animal was immediately treated with fluids, activated charcoal, and Kaolin mixed with water (orally). The gradual reduction in clinical signs was noticed by the lower of 12 hours, and a dramatic improvement was noticed the day after, and the pup recovered completely. Case 2- A six-month-old male Labrador dog weighing 20 kg was brought to the Small Animal Medicine unit of VCC, RIVER, Puducherry, India, with a history of vocalization, restlessness, and salivation for the past two hours. After considering the history, it was revealed that the dog had accidentally ingested eight Baclofen tablets of 10 mg. The animal was immediately treated with fluids (Injection) Atropine sulfate and activated charcoal mixed with water (orally). The gradual reduction of clinical signs was noticed in less than 12 hours, dramatic improvement was noticed the next day, and the dog recovered completely. Conclusion: Timely diagnosis and proper management of the toxicity with drugs can eliminate the clinical signs, and fluid therapy can help the animal’s recovery.
1. Introduction:
Baclofen is a centrally-acting skeletal muscle relaxant that stimulates gamma amino butyric acid (GABA) within the spinal cord. Baclofen is used to control spasticity and pain in people with multiple sclerosis and spinal disorders1. Baclofen has also been used extra-label in dogs (1 to 2 mg/kg orally) to treat urinary retention by reducing urethral resistance2. Baclofen is first renally excreted, with only a small portion (15%) being metabolized by the liver. Small amounts of baclofen can cross the blood–brain barrier at therapeutic doses; however, at higher doses, significant drug concentrations can accumulate within the cerebrospinal fluid, leading to coma and respiratory depression3. Baclofen is available in 10 and 20 mg tablets and as a parenteral injection. Baclofen undergoes first‐order elimination kinetics at therapeutic doses with a half‐life of 2-6 hours. In first‐order elimination kinetics, a constant fraction of the drug is eliminated per unit of time. The time required for the drug concentration to fall by one half‐life (t½) is regular, and over 95% of the drug should be eliminated within five t½. A transition to zero‐order kinetics may occur when first-order elimination mechanisms become saturated. In zero‐order kinetics, a constant amount, rather than a constant fraction of the drug, is eliminated per unit
of time. Therefore, the serum half‐life of the medication is constantly changing. In drug overdoses, this can result in prolonged drug elimination. Baclofen may transition to zero‐order elimination kinetics in high-dose ingestion, which might explain a prolonged duration of clinical signs following ingestion3. The onset of clinical signs after acute oral exposure may be rapid (within 30 to 60 minutes) or delayed for several hours 4. Common clinical signs are vocalization, vomiting, ataxia, disorientation, salivation, depression, coma, weakness, generalized flaccid paralysis, recumbency, seizures, and hypothermia. Life-threatening signs involve dyspnoea, respiratory depression, and respiratory arrest secondary to paralysis of the diaphragm and intercostal muscle1. The current treatment recommendations include gastrointestinal decontamination, intravenous fluid therapy, intravenous lipid emulsion (ILE, Baxter Healthcare, Deerfield, IL), hemodialysis, haemoperfusion, and mechanical ventilation. Dogs with persistent neurologic abnormalities may still have an excellent prognosis despite the lack of initial response3.
