Primidone

Primidone Uses, Dosage, Side Effects, Food Interaction and all others data.

Primidone is an anticonvulsant used to treat essential tremor as well as grand mal, psychomotor, and focal epileptic seizures. Primidone was developed by J Yule Bogue and H C Carrington in 1949.

Primidone was granted FDA Approval on 8 March 1954.

Primidone alters sodium and calcium channel transport, reducing the frequency of nerve firing, which may be responsible for its effect on convulsions and essential tremor. Primidone has a wide therapeutic window as doses of 50-1000mg/day were effective. Patients should be counselled regarding the risk of status epilepticus with abrupt cessation of primidone.

Primidone
Uses
Dosage
Side Effect
Precautions
Interactions
Uses during Pregnancy
Uses during Breastfeeding
Accute Overdose
Food Interaction
Half Life
Volume of Distribution
Clearance
Interaction With other Medicine
Contradiction
Storage

Trade Name	Primidone
Availability	Prescription only
Generic	Primidone
Primidone Other Names	2-deoxyphenobarbital, Primidon, Primidona, Primidone, Primidonum
Related Drugs	gabapentin, clonazepam, lamotrigine, diazepam, pregabalin, Lyrica, topiramate, levetiracetam, Keppra, Topamax
Weight	250mg, 50mg
Type	Oral tablet
Formula	C₁₂H₁₄N₂O₂
Weight	Average: 218.2518 Monoisotopic: 218.105527702
Protein binding	Primidone is 10.78-13.70% protein bound in serum.
Groups	Approved, Vet approved
Therapeutic Class
Manufacturer
Available Country	United States
Last Updated:	September 19, 2023 at 7:00 am

Uses

Primidone is an antiepileptic used to treat grand mal, psychomotor, and focal epileptic seizures.

Primidone is commonly indicated for the management of grand mal, psychomotor, and focal epileptic seizures. In addition, it has also been studied and utilized as an effective management of essential tremor.

Primidone is also used to associated treatment for these conditions: Grand mal Generalized tonic-clonic seizure, Partial-Onset Seizures, Temporal Lobe Epilepsy (TLE), Tremor, Essential

How Primidone works

Primidone and its metabolites, phenobarbital and phenylethylmalonamide (PEMA), are active anticonvulsants. Primidone does not directly interact with GABA-A receptors or chloride channels but phenobarbital does. Primidone alters transmembrane sodium and calcium channel transport, reducing the frequency of nerve firing, which may be responsible for the primidone’s effect on convulsions and essential tremor.

Toxicity

The oral LD₅₀ in rats is 1500mg/kg and in mice is 280mg/kg. The intraperitoneal LD₅₀ in rats was 240mg/kg and in mice was 332mg/kg.

Patients experiencing a primidone overdose may present with CNS depression, coma, respiratory depression, suppressed reflexes, suppressed response to pain, hypotension, and decreased urine output. Overdose should be treated with symptomatic and supportive treatment, including the removal of unabsorbed drug.

Food Interaction

Avoid alcohol.
Avoid St. John's Wort.

Primidone Alcohol interaction

[Major] GENERALLY AVOID:

Concurrent acute use of barbiturates and ethanol may result in additive CNS effects,

including impaired coordination, sedation, and death.

Tolerance of these agents may occur with chronic use.

The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

The combination of ethanol and barbiturates should be avoided.

Primidone Drug Interaction

Moderate: duloxetine, escitalopram, atorvastatin, pregabalin, metoprolol, metoprolol, montelukast, levothyroxine, acetaminophen, cholecalciferolUnknown: aspirin, aspirin, rosuvastatin, omega-3 polyunsaturated fatty acids, fluticasone nasal, furosemide, tiotropium, budesonide / formoterol, cyanocobalamin, ascorbic acid

Primidone Disease Interaction

Major: acute alcohol intoxication, drug dependence, porphyria, rash, respiratory depression, phenobarbital metabolite 1, renal/liver diseaseModerate: suicidal tendency, adrenal insufficiency, depression, hematologic toxicity, osteomalacia, paradoxical reactions, phenobarbital metabolite 2

Volume of Distribution

The volume of distribution of primidone is 0.5-0.8L/kg.

Elimination Route

Oral primidone is up to 80% bioavailable with a T_max if 2-4h. A 500mg oral dose of primidone Reaches a C_max of 2.7±0.4µg/mL with a T_max of 0.5-7h. Data regarding the AUC of primidone is not readily available.