Indications
Rimidon Tablet is used for:
Seizures (Psychomotor, Focal, & Grand Mal)
Adult Dose
Adult
Oral
Dose is individualised based on patient’s clinical response and tolerability. As monotherapy or in combination with other anticonvulsants:
Initial: 100-125 mg PO once daily at bedtime, for 3 days, THEN
100-125 mg BID for 3 days, THEN
100-125 mg TID for 3 days, THEN
250 mg TID-QID; not to exceed 2 g/day
In patients on other anticonvulsants, initiating primidone and withdrawal of previous treatment should be gradually done over a period of 2 weeks.
Hepatic Impairment
Dosage reduction may be required.
Child Dose
Seizures (Psychomotor, Focal, & Grand Mal)
Initial: 50 mg PO once daily at bedtime for 3 days, THEN
50 mg BID for 3 days, THEN
100 mg BID for 3 days, THEN
After 9th day: 125-250 mg PO TID, OR 10-25 mg/kg/day divided q8hr PO
Renal Dose
Renal Impairment
Dosage reduction may be required.
Administration
May be taken with or without food. May be taken w/ food or milk to avoid stomach upset.
Contra Indications
Porphyria
Hypersensitivity to phenobarbital
Precautions
Do not interchange brands, due to bioequivalence issues
When replacing another antiseizure drug, gradually increase dosage of primidone while gradually decreasing dosage of other drug over at least 2 weeks
Withdraw gradually, due to risk of precipitation of status epilepticus
Limited number of reports indicate maintaining serum concentration of 5-12 mcg/mL is necessary
Inhibits transplacental vitamin K transport, leading to increased risk of fetal hemorrhage
May render OCPs ineffective
May cause CNS depression; caution performing tasks that require mental alertness, including heavy machinery
Use cautioin in patients with clinical depression; Increased risk of suicidal thoughts or behavior reported; monitor patients for notable changes in behavior indicating suicidal thoughts or depression; inform healthcare provider immediately if symmptoms occur
Use caution in patients with hypoadrenalism, hepatic impairment, renal impairment, respiratory disease, and patients with a history of substance abuse
May cause paradoxical responses in the elderly and debilitated patients
Associated with cognitive deficits in children receiving chronic therapy for febrile seizures
Not for administration to patients with acute pain
Caution in neonates; some formulations may contain sodium benzoate/benzoic acid (associated with gasping syndrome in neonates)
Pregnancy-Lactation
Pregnancy category: D; continue use if pregnant; consider vitamin K supplementation for 1 month before birth
Lactation: Distributed in breast milk; discontinue if drug effects occur in nursing infant
Interactions
May have increased serum concentration with CYP3A4 inhibitors (e.g. chloramphenicol, felbamate, nelfinavir, metronidazole, Na valproate).
May increase metabolism resulting in lower serum concentration and shorter half-life of androgens, β-antagonists, carbamazepine, chloramphenicol, clozapine, corticosteroids, cyclophosphamide, cyclosporin, dicoumarins, digitoxin, doxycycline, ethosuximide, etoposide, felbamate, granisetron, lamotrigine, losartan, methadone, metronidazole, mianserin, montelukast, nelfinavir, nimodipine, oral contraceptives, oxcarbazepine, phenytoin, quinidine, rocuronium, Na valproate, tiagabine, theophylline, topiramate, TCAs, vecuronium, warfarin, zonisamide.
May increase the hepatotoxicity of paracetamol. Additive CNS depressant effect with other CNS depressant (e.g. barbiturates, opiates).
Side Effects
Side effects of Primidone :
1-10%
Dysarthria
Paresthesia
Ataxia
Vertigo
Pediatric patients
Paradoxical excitement
Hyperactivity
Geriatric patients
Excitement
Confusion
Depression
Adverse effects that decrease with continued treatment
Drowsiness
Ataxia
Irritability
Headache
Restlessness
Nystagmus
Dizziness
Vertigo
Frequency Not Defined
Acute psychosis (rare)
Nausea
Vomiting
Constipation
Diarrhea
Megaloblastic (folate-deficiency) anemia
Hepatotoxicity
Hypocalcemia
Rickets (rare)
Osteomalacia (rare)
Rash
Stevens-Johnson syndrome (rare)
Mode of Action
Primidone raises the seizure threshold and decreases the excitability of neurons. It is metabolised into 2 active metabolites namely, phenobarbital and phenylethylmalonamide (PEMA) where PEMA potentiates the activity of phenobarbital.
Note
Rimidon 50mg Tablet generic name is Primidone. Rimidon 50mg Tablet is manufactured by Beacon Pharmaceuticals Ltd.Rimidon is availble in all over Bangladesh.
Mes BD drug index information on Rimidon Tablet is not intended for diagnosis, medical advice or treatment; neither intended to be a substitute for the exercise of professional judgment.