Primidone belongs to the class of medications known as anticonvulsants. It is indicated for the control of seizures in the treatment of epilepsy and other seizure disorders. Primidome may be prescribed alone or as part of a combination of medications for preventing seizures.
Primidone is thought to decrease abnormal activity within the brain that may trigger seizures. While primidone controls some types of seizures associated with epilepsy (grand mal, psychomotor, and focal seizures) there is no known cure for the disorder. Additionally, primidone has shown promise in alleviating some forms of essential tremors, but is not approved in the United States for this use.
In the United States, primidone is also sold under the names Myidone and Mysoline. Although the precise mechanism by which primidone exerts its therapeutic effects is unknown, it is thought to help slow and control nerve impulses in the brain. The active metabolites of primidone are phenobarbital and phenylmethylmalonamide (PEMA), both barbiturate-type compounds with anticonvulsant and sedative properties. Primidone is supplied in chewable tablets (in Canada), tablets to be swallowed whole, and in suspension (syrup) forms for oral administration.
Primidone is available in 50 milligram (mg) and 250 mg tablets, and is prescribed by physicians in varying dosages. The usual initial dose for adults, teenagers, and children over eight years of age is 100 mg or 125 mg per day. Dosages are gradually increased until arriving at the lowest possible dosage that results in control of seizures. Children under eight years of age typically take an initial daily dose of 50 mg. The maximum daily dose for anyone taking primidone usually is not greater than 2000 mg.
The prescribing physician will schedule a patient's daily dosages, gradually increasing them over the course of several weeks. Primidone may not exert its full therapeutic effect during the initial dose-increasing period.
Primidone should be taken at approximately the same time every night. If a daily dose is missed, it should be taken as soon as possible. However, if it is almost time for the next dose, the missed dose should be skipped. Double doses of primidone should not be taken.
A patient should consult their physician before they stop taking primidone. Suddenly discontinuing this medicine may cause seizures to return or occur more frequently. When ending treatment including primidone, physicians typically direct patients to taper their daily dosages gradually.
Adrienne Wilmoth Lerner, The Gale Group Inc., Gale, Detroit,