Question 1

What is Phenobarbital used for?

Accepted Answer

Phenobarbital is indicated for: Epilepsy, Epilepsy (maintenance), Seizures, Status epilepticus (loading).

Question 2

What routes can Phenobarbital be administered by?

Accepted Answer

Available routes: PO, IV, IM.

Question 3

Which species have cited Phenobarbital dosing data?

Accepted Answer

Phenobarbital dosing in the ExoticRx formulary covers 3 species: Cat (Domestic), Dog (Domestic), Rabbit (Domestic).

Question 4

Is Phenobarbital a controlled substance?

Accepted Answer

Yes — Phenobarbital is a controlled substance under US federal law.

Question 5

What are the warnings or contraindications for Phenobarbital?

Accepted Answer

First-line anticonvulsant for dogs. Hepatotoxicity with chronic use (monitor liver enzymes and serum levels). PU/PD, polyphagia, sedation (often transient). Hepatic enzyme inducer (many drug interactions). DEA controlled.

Question 6

What are the side effects of Phenobarbital?

Accepted Answer

First-line anticonvulsant for dogs. Hepatotoxicity with chronic use (monitor liver enzymes and serum levels). PU/PD, polyphagia, sedation (often transient). Hepatic enzyme inducer (many drug interactions). DEA controlled.

Question 7

How does Phenobarbital work?

Accepted Answer

Enhances GABA-A receptor activity by prolonging chloride channel opening. Also blocks AMPA/glutamate receptors. Raises seizure threshold.

Species	Route	Dose	Frequency	Evidence	Source
Dog (Domestic)	IV	16–20 mg/kg	Loading dose (give in 4 mg/kg increments q20min)	Strong	Plumb's Veterinary Drug Handbook, 9th Ed
Dog (Domestic)	PO	2.5–5 mg/kg	q12h	Strong	Plumb's Veterinary Drug Handbook, 9th Ed

Phenobarbital

Drug Class

Routes

Indications

Mechanism of Action

Side effects & warnings

Species with Phenobarbital dosing data (4 dose rules)

Controlled Substance

Evidence levels across 4 dose rules

Backed by 2 published primary sources

Sample dosing (2 of 4 cited rules)

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