Paracetamol (Acetaminophen)

Paracetamol (Acetaminophen) In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Paracetamol’s antipyretic actions are suggested to result from reduced prostaglandin synthesis within the central nervous system (CNS).
• The potential mechanism involves indirect actions on the cannabinoid system.
• The precise mechanism of action for paracetamol’s antipyretic effects remains unclear.

Uses of Paracetamol (Acetaminophen)

• Control of mild to moderate pain.
• Antipyretic action.
• Injectable paracetamol may be useful to provide adjunctive analgesia in dogs during the perioperative period.

Dose of Paracetamol (Acetaminophen) in Dogs and Cats

Dogs:

• 10–20 mg/kg p.o., i.v. q8h. The authorized dose of Pardale-V preparation is 1 tablet per 12 kg body weight (equivalent to 33 mg/kg) q8h.
• After 7 days the dose should be titrated down to the lowest effective dose.
• For acute pain management, doses at the top of the suggested range (20 mg/kg q8h), for a period not exceeding 5–7 days, have been advocated.

Cats:

• Do not use.

Side Effects of Paracetamol (Acetaminophen) in Dogs and Cats

• Paracetamol overdose results in liver damage by generating N-acetyl-p aminobenzoquinonimine during metabolism. This compound induces hepatocyte cell death and centrilobular hepatic necrosis.
• Overdose treatment involves oral methionine or intravenous acetylcysteine, aiming to replenish hepatic glutathione. However, clinical data supporting this treatment is lacking.
• Cats may experience fatal toxicosis due to methaemoglobinaemia resulting from paracetamol ingestion.

Contraindications of Paracetamol (Acetaminophen) in Dogs and Cats

• Do not use in cats as they lack the glucuronyl transferase enzymes required to metabolize the drug.

Some Notes:

• Metoclopramide boosts the absorption of paracetamol, consequently intensifying its effects.
• Drugs with the ability to induce cytochrome P450 enzymes, such as NSAIDs, have the potential to amplify the toxicity of paracetamol.
• There is limited information on the analgesic effectiveness of paracetamol in dogs.
• Paracetamol exhibits weak anti-inflammatory effects. Its use is associated with minimal gastrointestinal (GI) side effects, making it a common choice for patients with gastric ulceration, especially when traditional NSAIDs are not suitable.
• The practice of combining an NSAID and paracetamol for perioperative analgesia in dogs lacks thorough investigation in terms of safety and analgesic efficacy.
• The licensed oral paracetamol preparation contains codeine; however, due to high first-pass metabolism, the codeine is not bioavailable and does not contribute to analgesia.