Acetaminophen (Tylenol, APAP, Paracetamol)

Oral Analgesic, Antipyretic

Highlights Of Prescribing Information

Contraindicated in cats at any dosage; ferrets may be as sensitive to acetaminophen as cats

At recommended dosages, not overly toxic to dogs, rodents, or rabbits

Often used in combined dosage forms with codeine; see codeine monograph for more information

What Is Acetaminophen Used For?

Acetaminophen is occasionally used as an oral analgesic in dogs. In conditions of more severe pain, it may be used in combination with oral codeine phosphate. See the codeine monograph for more information on the use of acetaminophen-codeine combination preparations.

Before you take Acetaminophen

Contraindications / Precautions / Warnings

Acetaminophen is contraindicated in cats at any dosage. Severe methemoglobinemia, hematuria, and icterus can be seen. Cats are unable to significantly glucuronidate acetaminophen leading to toxic metabolites being formed and resultant toxicity. Acetaminophen should not be used in ferrets as they may be as sensitive to it as are cats. At this time, acetaminophen should not be used in Sugar Gliders or Hedgehogs as its safety has not been determined.

Dogs do not metabolize acetaminophen as well as humans and its use must be judicious. In dogs, it is generally not recommended to use acetaminophen during the immediate post-operative phase (first 24 hours) due to an increased risk of hepatotoxicity

Adverse Effects

Because acetaminophen is not routinely used in veterinary medicine, experience on its adverse effect profile is limited. At suggested dosages in dogs, there is some potential for renal, hepatic, GI, and hematologic effects occurring.

Overdosage / Acute Toxicity

Because of the potentially severe toxicity associated with acetaminophen, consultation with an animal poison control center is recommended (see appendix). For overdosage in dogs or cats, standard gut emptying techniques and supportive care should be administered when applicable. Further treatment with acetylcysteine maybe warranted (see acetylcysteine monograph for more information).

How to use Acetaminophen

Note: For dosages of acetaminophen/codeine combination products refer to the codeine monograph.

Acetaminophen dosage for dogs:

As an analgesic:

a) 15 mg/kg PO q8h (); ()

b) 10 mg/kg PO ql2h ()

c) In the treatment of degenerative myelopathy (in German Shepherds): 5 mg/kg PO (not to exceed 20 mg/kg per day) ()

Acetaminophen dosage for rabbits, rodents, and small mammals:

As an analgesic:

a) Using Children’s Tylenol: 1-2 mg/mL in drinking water. Effective for controlling low-grade nociception. ()

b) Mice, Rats, Gerbils, Hamsters, Guinea pigs, Chinchillas: 1-2 mg/mL in drinking water ()

Monitoring

■ When used at recommended doses for pain control in otherwise healthy patients, little monitoring should be necessary. However, with chronic therapy, occasional liver, renal and hematologic monitoring may be warranted, particularly when clinical signs occur.

Client Information

■ Follow directions carefully; do not exceed dosage or increase dosing frequency. Do not administer to cats or ferrets for any reason. Keep out of reach of children.

Chemistry / Synonyms

A synthetic non-opiate analgesic, acetaminophen (also known as paracetamol) occurs as a crystalline, white powder with a slightly bitter taste. It is soluble in boiling water and freely soluble in alcohol. Acetaminophen is known in the U.K. as paracetamol.

Acetaminophen may also be known as: paracetamol, MAPAP or APAP; many trade names are available.

Storage / Stability

Acetaminophen products should be stored at temperatures less than 40°C. Do not freeze oral solution or suspension.

Dosage Forms / Regulatory Status

Veterinary-Labeled Products: None

The ARCI (Racing Commissioners International) has designated this drug as a class 4 substance. See the appendix for more information.

Human-Labeled Products:

There are many different trade names and products of acetaminophen available. The most commonly known trade name is Tylenol9. Acetaminophen is commonly available in, 325 mg, 500 mg, 650 mg tablets; 80 mg chewable tablets; 650 mg extended release tablets; 160mg, 500 mg, & 650 mg caplets; 500 mg gelcaps; 325 mg, & 500 mg capsules, 80 mg and 160 mg sprinkle capsules; 80 mg/0.8 mL drops; 80 mg/2.5 mL, 80 mg/5 mL, 120 mg/5 mL, & 160 mg/5 mL elixirs; 160 mg/5 mL, 500 mg/15 mL, and 100 mg/mL liquids and solutions; 80 mg, 120 mg, 125 mg 300 mg, 325 mg and 650 mg suppositories. Combinations with other analgesics (aspirin, codeine phosphate, oxycodone or propoxyphene) are also available.