Description

Primidone is a medication used in the management of grand mal, psychomotor, and focal seizures in horses and foals. Primidone is also used in horses with seizures induced by toxins or adverse drug effects.

In the body, primidone is converted into other chemicals, including phenobarbital, a type of barbiturate that can help control seizures by acting as an anticonvulsant. Primidone works by decreasing the excitability of the brain cells, thereby helping to prevent abnormal electrical activity from starting and helps keep such activity from spreading to other parts of the brain.

Primidone is less preferred than direct use of phenobarbital because most of its anticonvulsant activity is due to its metabolism of phenobarbital. It requires administration three times a day and it can be toxic to the liver.

One of the main advantages of primidone, unlike phenobarbital, is that it is not a controlled substance with special rules for prescribing and dispensing.

Usage

Primidone is used in the management of grand mal, psychomotor, and focal seizures, and sometimes to treat tremors.

Dosage and Administration

Primidone
Method	Dosage (click row for calculator)	Concentration	Period	Duration
Oral	55 mg/kg 1	250 mg/tablet	Daily	NA
Notes: 1When convulsions are frequent, the dosage should be divided and administered at intervals. When convulsions occur only every few days, or less often, daily dosage should be given at one time. Reduction in dosage should always be made gradually and should never be discontinued abruptly. Federal law restricts this drug to use by or on the order of a licensed veterinarian. Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian). The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your equine appears to feel better, the entire treatment plan should be completed to prevent relapse. This medication may be available in forms and concentrations not noted in the above table. Always check the label and literature provided with the medication about the form and concentration and DO NOT USE the calculator if the information differs. Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

Primidone may cause drowsiness and lethargy in horses

Precautions

Careful monitoring of liver functions to prevent hepatotoxicity may be necessary.

Interactions

No literature detailing interactions is available.

Overdose

In case of overdose, an activated charcoal slurry introduced through a stomach tube will help rid the system of the drug.