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Combination of
PhenytoinSodium channel blocker
Clinical data
Trade namesBeuthanasia-D Special
Routes of
Intravenous injection
ATCvet code

Phenytoin/pentobarbital (trade name Beuthanasia-D Special) is an animal drug product used for euthanasia of non-food animals, which contains a mixture of phenytoin and pentobarbital.[1] It is administered as an intravenous injection to give animals a quick and humane death.[1]

Generics of this product are also available under the names Euthasol, Euthanasia-III Solution and Somnasol.[1]


The two active ingredients, phenytoin and pentobarbital are present as salts of sodium. In addition, Rhodamine B dye is added to clearly distinguish the solution. Benzyl alcohol is added to slow bacterial growth, though this does not make the solution sterile.[2]

Euthasol has the following composition: 390 mg/mL pentobarbital sodium, 50 mg/mL phenytoin sodium, 10% ethyl alcohol, 18% propylene glycol, 0.003688 mg/mL Rhodamine B, 2% Benzyl alcohol, water and sodium hydroxide and hydrochloric acid as needed to achieve desired pH.

Mechanism of action[edit]

This drug combination causes painless and rapid euthanasia through multiple pathways, including brain death, cessation of breathing and circulatory collapse. Brain death is observed first. Breathing generally stops within seconds. However, euthanasia may be delayed in dogs that have deficient cardiac and circulatory function.[2]

The pentobarbital component produces anesthesia and rapid unconsciousness. A lethal dose causes loss of medullary respiration and vasomotor function.

The phenytoin component produces reduced central nervous system funciton and cardiovascular collapse, causing hypotension.

Veterenary Practice[edit]

When used to euthanise dogs in a veteranary context, 1 mL of the drug is administered per 10 pounds of the animal's body weight. The dose is given as a single bolus. Intravenous injection is preferred, though intracardiac injection may be used in some circumstances (e.g. a very small animal, or a comatose animal with impaired circulatory function).[2]


This product is hazardous both to humans and wildlife, whether due to accidental consumption (e.g. by scavangers eating a body of an animal euthanised with Phenytoin/pentobarbital) or exposure to wounds, or accidental self-injection.[2]

Law and Society[edit]

In the US, it is classified by the Drug Enforcement Administration (DEA) as a Class III substance.[3] US federal law restricts the drug to usage by, or on the order of, a licensed veterinarian.[2]


  1. ^ a b c Plumb, DC (2015). "Euthanasia Agents with Pentobarbital". Plumb's Veterinary Drug Handbook (8th ed.). John Wiley & Sons. ISBN 9781118911921.
  2. ^ a b c d e "EUTHASOL® (EUTHANASIA SOLUTION)". Retrieved 20 December 2018.
  3. ^ Tighe, MM; Brown, M, eds. (2014). Mosby's Comprehensive Review for Veterinary Technicians (4th ed.). Elsevier Health Sciences. p. 414. ISBN 9780323171397.