What should I avoid while taking Primidone 62.5mg/5ml oral suspension?

Avoid alcohol. Avoid St. John's Wort. (Source: DrugBank, licensed under CC BY-NC 4.0)

Do I need a prescription for Primidone 62.5mg/5ml oral suspension?

Primidone 62.5mg/5ml oral suspension is classified as a Valid as a prescribable product in the UK. However, always consult a pharmacist or doctor before use. (Source: NHS dm+d)

What are the brand names for Primidone 62.5mg/5ml oral suspension?

Primidone 62.5mg/5ml oral suspension is the generic name. It is available under brand names including: Primidone 62.5mg/5ml oral suspension. (Source: NHS dm+d — Actual Medicinal Products)

Primidone 62.5mg/5ml oral suspension

Prescription only

Requires a prescription from a doctor or prescriber

Oral suspension

62.5mg/5ml

Oral

Antiepileptic

Antiepileptic drugs

Active ingredients:

Primidone

BNF classificationBrowse formulary

Where this medicine sits in the British National Formulary — the UK's standard prescribing reference

BNF 04.08.01

ATC classificationBrowse ATC index

International classification by the WHO, grouping medicines by the organ system they act on

ATC N03AA03

Chemical classBrowse classes

Classification based on the molecule's chemical structure and properties

Primary care groupBrowse groups

NHS medication clusters used to compare prescribing patterns across GP practices

Antiepileptic

Check interactions for Primidone

No active safety alerts

Official documents, adverse reaction reporting, and safety monitoring

Report a side effect

Submit a Yellow Card report to the MHRA

Official medicine documents

Yellow Card

Report side effects (MHRA)

Drug safety updates

MHRA alerts for Primidone

Source: MHRA Products DatabaseOGL 3.0

Updated 3 months ago(16 Jan 2026)

Safety monitoring data

Yellow Card reports

MHRA

The MHRA Yellow Card scheme collects reports of suspected side effects from healthcare professionals and patients. View the Drug Analysis Profile (iDAP) for real-world adverse reaction data.

View Drug Analysis Profile

Suspected adverse reactions reported for Primidone

Browse all iDAP reports

Interactive Drug Analysis Profiles for all medicines

Report a side effect

Submit a Yellow Card report to the MHRA

Data from the MHRA Yellow Card scheme. A reported reaction does not necessarily mean the medicine caused it. Contains public sector information licensed under the Open Government Licence v3.0.

EudraVigilance

EMA

The European Medicines Agency (EMA) collects suspected adverse reaction reports from across the EU/EEA through the EudraVigilance system. Search for safety data on this medicine.

View EudraVigilance report

Suspected adverse reactions reported for Primidone

About EudraVigilance

Learn about EU pharmacovigilance and safety monitoring

EudraVigilance data is published by the European Medicines Agency (EMA). A suspected adverse reaction is not necessarily caused by the medicine.

1 branded products available

1 productsShow details

1 products

Possibly available on the UK marketRestricted supplyDiscontinuedAvailability per NHS dm+d

MHRA licensed products

View all licensed products for Primidone on the MHRA register

Primidone 62.5mg/5ml oral suspension

Drug Tariff Special Order

None

Special

Source: NHS dm+dOGL 3.0

Updated about 1 month ago(1 Mar 2026)

Price & daily doseShow details

£0.08indicative price

This is the NHS Drug Tariff indicative price used for reimbursement purposes. It may not reflect the price paid by patients or pharmacies.

View full Drug Tariff

Source: NHS Drug Tariff via NHSBSA. Derived from dm+d VMPP (Virtual Medicinal Product Pack) pricing data. Contains public sector information licensed under the Open Government Licence v3.0.

WHO defined daily dose (DDD)

1.25 gram

Not a recommended dose. The DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults. It is a statistical measure used for research and comparison purposes only.

Source: WHO Collaborating Centre for Drug Statistics Methodology, distributed via NHS dm+d BNF mapping files. Contains public sector information licensed under the Open Government Licence v3.0.

Therapeutically similar medicines

10 similarShow details

Primidone 125mg tablets

Tablet

125mg

Same therapeutic group

Primidone 50mg tablets

Tablet

50mg

Same therapeutic group

Primidone 30mg/5ml oral suspension

Oral suspension

30mg/5ml

Same therapeutic group

Primidone 100mg/5ml oral suspension

Oral suspension

100mg/5ml

Same therapeutic group

Phenobarbital 180mg/5ml oral solution

Oral solution

180mg/5ml

Same therapeutic group

Similarity based on WHO Anatomical Therapeutic Chemical (ATC) classification and NHS BNF section grouping. Source data: NHS dm+d via TRUD (OGL v3.0), WHO ATC/DDD Index.

NHS prescribing volume and spending trends

Show details

Loading prescribing data...

Clinical guidelines and formulary information

British National Formulary

Primidone

BNF

Drug monograph — bnf.nice.org.uk

Source: British National Formulary, NICE. Joint Formulary Committee. Contains public sector information licensed under the Open Government Licence v3.0.

NICE clinical guidance(3)

Unilateral MRI-guided focused ultrasound thalamotomy for treatment-resistant essential tremor (HTG474)

HTG474

Guidance

Updated Jun 2018

Epilepsies in children, young people and adults (NG217)

NG217

NICE guideline

Updated Jan 2025

Vitamin B12 deficiency in over 16s: diagnosis and management (NG239)

NG239

NICE guideline

Updated Mar 2024

Source: National Institute for Health and Care Excellence (NICE). Contains public sector information licensed under the Open Government Licence v3.0.

Check stock at pharmacies and supply information

Show details

Pharmacy stock checkers

Search for this medicine at major UK pharmacy chains. These links open the retailer's own website — results depend on their current online catalogue.

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DeliveryNHS

Supply & product information

Official product databases and supply status monitoring

Shortages info

NHS Specialist Pharmacy Service (SPS)

emc product search

Discontinuations & alternatives for Primidone

Pharmacy links redirect to the retailer's own search and do not represent real-time stock levels. emc (electronic medicines compendium) is operated by Datapharm Ltd. Shortage information sourced from NHS Specialist Pharmacy Service (SPS), sps.nhs.uk.

Codes for healthcare professionals and prescribing systems

Show details

These codes are used by healthcare IT systems and prescribers to identify this medicine.

NHS UK identifiers

SNOMED CT

8818311000001105

dm+d ID

8818311000001105

VTM (Virtual Therapeutic Moiety)

777315005

VMP (Virtual Medicinal Product)

8818311000001105

BNF code

04080100

International identifiers

ATC code — Anatomical Therapeutic Chemical (WHO)

N03AA03

Browse tools

dm+d Browser

NHSBSA medicines dictionary lookup

SNOMED CT and dm+d codes from NHS TRUD (Technology Reference data Update Distribution), licensed under the Open Government Licence v3.0. BNF codes from NHS Business Services Authority (NHSBSA). ATC codes from the WHO Collaborating Centre for Drug Statistics Methodology (whocc.no).

Active and completed clinical studies from ClinicalTrials.gov

Show details

Searching UK clinical trials...

Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine (NLM), National Institutes of Health (NIH). Data accessed via ClinicalTrials.gov API v2. Trial information is provided for research purposes and does not constitute medical advice.

Pharmacology and chemical data from DrugBank

go.drugbank.com

Key facts

Drug status

Approved

Major interactions

15 found

Half-life

7-22h

Mechanism

Primidone and its metabolites, phenobarbital and phenylethylmalonamide (PEMA), are active anticonvulsants.

Food interactions

2 warnings

Human targets

11 targets

Data: DrugBank · CC BY-NC 4.0

Pharmacokinetics at a glance

Absorption

80%

Oral primidone is up to 80% bioavailable with a T_max if 2-4h.
[A35660][A189486]…

Half-life

7-22h

The half life of primidone is 7-22h in adults, 5-11h in children, and 8-80h in newborns.
[A189486]

Protein binding

10.78-13.70%

Primidone is 10.78-13.70% protein bound in serum.
[A189447]

Volume of distribution

0.5-0.8L/kg

The volume of distribution of primidone is 0.5-0.8L/kg.
[A189477][A189486]

Metabolism

Primidone is metabolized to phenobarbitol and phenylethylmalonamide (PEMA).
[A35126]…

Elimination

72.9-80.6%

Primidone is 72.9-80.6% recovered in urine.
[A189507]

Clearance

30mL/min

Primidone is cleared at a rate of 30mL/min.
[A189492]

Pharmacokinetic data: DrugBank · CC BY-NC 4.0

Status:

Approved

Vet approved

Small molecule

About this compound

Primidone is an anticonvulsant used to treat essential tremor as well as grand mal, psychomotor, and focal epileptic seizures.[L11112] Primidone was developed by J Yule Bogue and H C Carrington in 1949.[A189522]

Primidone was granted FDA Approval on 8 March 1954.[L11112]

Properties:

solid

Avg. mass: 218.25 Da

View FDA drug label

DrugBank indication

Primidone is commonly indicated for the management of grand mal, psychomotor, and focal epileptic seizures.
[L4645][L11112]
In addition, it has also been studied and utilized as an effective management of essential tremor.
[A39414][A39415][L4645]

Also known as(246)

2-deoxyphenobarbital

5-Phenyl-5-ethyl-Hexahydropyrimidine-4,6-dione

Primidon

Primidona

Primidone

Primidonum

GABA(A) receptor subunit alpha-2

GABAAR subunit alpha-2

Dosage forms(11)

Suspension (Oral) — 125 mg

Tablet (Oral) — 0.25 G

Tablet (Oral) — 250 mg

Tablet (Oral) — 250.000 mg

Tablet (Oral) — 125 mg

Tablet (Oral) — 125 mg/1

Tablet (Oral) — 250 mg/1

Tablet (Oral) — 50 mg/1

Molecular properties(19)

Drug interactions(1894)

Known interactions with other medications. Always consult a healthcare professional.

Aripiprazole

Moderate

DB01238

The metabolism of Aripiprazole can be increased when combined with Primidone.

Check this interaction

Buprenorphine

Moderate

DB00921

Primidone may increase the central nervous system depressant (CNS depressant) activities of Buprenorphine.

Check this interaction

Doxylamine

Moderate

DB00366

Doxylamine may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Dronabinol

Moderate

DB00470

Dronabinol may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Droperidol

Moderate

DB00450

Droperidol may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Hydroxyzine

Moderate

DB00557

Hydroxyzine may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Magnesium sulfate

Moderate

DB00653

The therapeutic efficacy of Primidone can be increased when used in combination with Magnesium sulfate.

Check this interaction

Methotrimeprazine

Moderate

DB01403

Primidone may increase the central nervous system depressant (CNS depressant) activities of Methotrimeprazine.

Check this interaction

Metyrosine

Moderate

DB00765

Primidone may increase the sedative activities of Metyrosine.

Check this interaction

Minocycline

Moderate

DB01017

Minocycline may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Mirtazapine

Moderate

DB00370

Primidone may increase the central nervous system depressant (CNS depressant) activities of Mirtazapine.

Check this interaction

Nabilone

Moderate

DB00486

Nabilone may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Orphenadrine

Moderate

DB01173

Primidone may increase the central nervous system depressant (CNS depressant) activities of Orphenadrine.

Check this interaction

Paraldehyde

Moderate

DB09117

Primidone may increase the central nervous system depressant (CNS depressant) activities of Paraldehyde.

Check this interaction

Pramipexole

Moderate

DB00413

Primidone may increase the sedative activities of Pramipexole.

Check this interaction

Rotigotine

Moderate

DB05271

Primidone may increase the sedative activities of Rotigotine.

Check this interaction

Suvorexant

Moderate

DB09034

Primidone may increase the central nervous system depressant (CNS depressant) activities of Suvorexant.

Check this interaction

Tapentadol

Moderate

DB06204

Tapentadol may increase the central nervous system depressant (CNS depressant) activities of Primidone.

Check this interaction

Thalidomide

Moderate

DB01041

Primidone may increase the central nervous system depressant (CNS depressant) activities of Thalidomide.

Check this interaction

Zolpidem

Moderate

DB00425

Primidone may increase the central nervous system depressant (CNS depressant) activities of Zolpidem.

Check this interaction

Amphetamine

Unknown severity

DB00182

The serum concentration of Primidone can be decreased when it is combined with Amphetamine.

Check this interaction

Phentermine

Unknown severity

DB00191

The serum concentration of Primidone can be decreased when it is combined with Phentermine.

Check this interaction

Pseudoephedrine

Unknown severity

DB00852

The serum concentration of Primidone can be decreased when it is combined with Pseudoephedrine.

Check this interaction

Benzphetamine

Unknown severity

DB00865

The serum concentration of Primidone can be decreased when it is combined with Benzphetamine.

Check this interaction

Diethylpropion

Unknown severity

DB00937

The serum concentration of Primidone can be decreased when it is combined with Diethylpropion.

Check this interaction

Lisdexamfetamine

Unknown severity

DB01255

The serum concentration of Primidone can be decreased when it is combined with Lisdexamfetamine.

Check this interaction

Mephentermine

Unknown severity

DB01365

The serum concentration of Primidone can be decreased when it is combined with Mephentermine.

Check this interaction

MMDA

Unknown severity

DB01442

The serum concentration of Primidone can be decreased when it is combined with MMDA.

Check this interaction

Midomafetamine

Unknown severity

DB01454

The serum concentration of Primidone can be decreased when it is combined with Midomafetamine.

Check this interaction

2,5-Dimethoxy-4-ethylamphetamine

Unknown severity

DB01467

The serum concentration of Primidone can be decreased when it is combined with 2,5-Dimethoxy-4-ethylamphetamine.

Check this interaction

Brolamfetamine

Unknown severity

DB01484

The serum concentration of Primidone can be decreased when it is combined with 4-Bromo-2,5-dimethoxyamphetamine.

Check this interaction

Tenamfetamine

Unknown severity

DB01509

The serum concentration of Primidone can be decreased when it is combined with Tenamfetamine.

Check this interaction

Chlorphentermine

Unknown severity

DB01556

The serum concentration of Primidone can be decreased when it is combined with Chlorphentermine.

Check this interaction

Methylenedioxyethamphetamine

Unknown severity

DB01566

The serum concentration of Primidone can be decreased when it is combined with Methylenedioxyethamphetamine.

Check this interaction

Dextroamphetamine

Unknown severity

DB01576

The serum concentration of Primidone can be decreased when it is combined with Dextroamphetamine.

Check this interaction

Metamfetamine

Unknown severity

DB01577

The serum concentration of Primidone can be decreased when it is combined with Metamfetamine.

Check this interaction

Iofetamine I-123

Unknown severity

DB09480

The serum concentration of Primidone can be decreased when it is combined with Iofetamine I-123.

Check this interaction

Ritobegron

Unknown severity

DB12080

The serum concentration of Primidone can be decreased when it is combined with Ritobegron.

Check this interaction

Mephedrone

Unknown severity

DB13108

The serum concentration of Primidone can be decreased when it is combined with Mephedrone.

Check this interaction

Methoxyphenamine

Unknown severity

DB13624

The serum concentration of Primidone can be decreased when it is combined with Methoxyphenamine.

Check this interaction

Gepefrine

Unknown severity

DB13703

The serum concentration of Primidone can be decreased when it is combined with Gepefrine.

Check this interaction

2,5-Dimethoxy-4-ethylthioamphetamine

Unknown severity

DB13940

The serum concentration of Primidone can be decreased when it is combined with 2,5-Dimethoxy-4-ethylthioamphetamine.

Check this interaction

Phendimetrazine

Unknown severity

DB01579

The serum concentration of Primidone can be decreased when it is combined with Phendimetrazine.

Check this interaction

Dabrafenib

Unknown severity

DB08912

The serum concentration of Primidone can be decreased when it is combined with Dabrafenib.

Check this interaction

Secretin porcine

Moderate

DB09527

The therapeutic efficacy of Secretin porcine can be decreased when used in combination with Primidone.

Check this interaction

Luliconazole

Unknown severity

DB08933

The serum concentration of Primidone can be increased when it is combined with Luliconazole.

Check this interaction

Mefloquine

Moderate

DB00358

The therapeutic efficacy of Primidone can be decreased when used in combination with Mefloquine.

Check this interaction

Orlistat

Moderate

DB01083

Orlistat can cause a decrease in the absorption of Primidone resulting in a reduced serum concentration and potentially a decrease in efficacy.

Check this interaction

Chloramphenicol

Moderate

DB00446

The metabolism of Primidone can be decreased when combined with Chloramphenicol.

Check this interaction

Doxycycline

Unknown severity

DB00254

The serum concentration of Doxycycline can be decreased when it is combined with Primidone.

Check this interaction

Showing 50 of 1894 interactions

Food & lifestyle interactions

Avoid Alcohol

Avoid alcohol.

Advice

Avoid St. John's Wort.

Toxicity & overdose

The oral LD₅₀ in rats is 1500mg/kg and in mice is 280mg/kg.
[L11199]
The intraperitoneal LD₅₀ in rats was 240mg/kg and in mice was 332mg/kg.
[L11199]

Patients experiencing a primidone overdose may present with CNS depression, coma, respiratory depression, suppressed reflexes, suppressed response to pain, hypotension, and decreased urine output.
[A189510]
Overdose should be treated with symptomatic and supportive treatment, including the removal of unabsorbed drug.
[A189510]

How it works

Mechanism of action

Primidone and its metabolites, phenobarbital and phenylethylmalonamide (PEMA), are active anticonvulsants.[A35660] Primidone does not directly interact with GABA-A receptors or chloride channels but phenobarbital does.[A35660] 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.[A35660]

Pharmacodynamics

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.[A35660] Primidone has a wide therapeutic window as doses of 50-1000mg/day were effective.[A35660] Patients should be counselled regarding the risk of status epilepticus with abrupt cessation of primidone.[L11112]

Pharmacokinetics

How the body processes this drug — absorption, distribution, metabolism, and elimination

Absorption

Oral primidone is up to 80% bioavailable with a T_max if 2-4h.
[A35660][A189486]
A 500mg oral dose of primidone Reaches a C_max of 2.7±0.4µg/mL with a T_max of 0.5-7h.
[A189492]
Data regarding the AUC of primidone is not readily available.
[L11112]

Half-life

The half life of primidone is 7-22h in adults, 5-11h in children, and 8-80h in newborns.
[A189486]

Protein binding

Primidone is 10.78-13.70% protein bound in serum.
[A189447]

Volume of distribution

The volume of distribution of primidone is 0.5-0.8L/kg.
[A189477][A189486]

Metabolism

Primidone is metabolized to phenobarbitol and phenylethylmalonamide (PEMA).
[A35126]
This metabolism is largely mediated by CYP2C9,[A185927][A35660][A189477] CYP2C19,[A38649][A185927][A189477] and CYP2E1.
[A185927][A189477]

Route of elimination

Primidone is 72.9-80.6% recovered in urine.
[A189507]

Clearance

Primidone is cleared at a rate of 30mL/min.
[A189492]

Drug targets(11)

Proteins and enzymes this drug interacts with in the body

Gamma-aminobutyric acid receptor subunit alpha-2

BE0000381

GABRA2

potentiator

Specific functionbenzodiazepine receptor activity

Cellular location

Postsynaptic cell membrane

General function & pharmacology

Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain .
PMID:10449790 PMID:29961870 PMID:31032849

GABA-gated chloride channels, also named GABA(A) receptors (GABAAR), consist of five subunits arranged around a central pore and contain GABA active binding site(s) located at the alpha and beta subunit interfaces (By similarity). When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient .
PMID:10449790
Chloride influx into the postsynaptic neuron following GABAAR opening decreases the neuron ability to generate a new action potential, thereby reducing nerve transmission (By similarity). The alpha-2 subunit exhibits synaptogenic activity together with beta-2 and very little to no activity together with beta-3, the gamma-2 subunit being necessary but not sufficient to induce rapid synaptic contacts formation (By similarity)

Gamma-aminobutyric acid receptor subunit alpha-3

BE0000523

GABRA3

potentiator

Specific functionbenzodiazepine receptor activity

Cellular location

Postsynaptic cell membrane

General function & pharmacology

Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain .
PMID:16412217 PMID:29053855
GABA-gated chloride channels, also named GABA(A) receptors (GABAAR), consist of five subunits arranged around a central pore and contain GABA active binding site(s) located at the alpha and beta subunit interface(s) (By similarity). When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient .
PMID:16412217 PMID:29053855
Chloride influx into the postsynaptic neuron following GABAAR opening decreases the neuron ability to generate a new action potential, thereby reducing nerve transmission PMID:16412217 PMID:29053855

Gamma-aminobutyric acid receptor subunit alpha-4

BE0000478

GABRA4

potentiator

Specific functionbenzodiazepine receptor activity

Cellular location

Cell membrane

General function & pharmacology

Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain .
PMID:35355020
GABA-gated chloride channels, also named GABA(A) receptors (GABAAR), consist of five subunits arranged around a central pore and contain GABA active binding site(s) located at the alpha and beta subunit interface(s) .
PMID:35355020
When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient .
PMID:35355020
GABAARs containing alpha-4 are predominantly extrasynaptic, contributing to tonic inhibition in dentate granule cells and thalamic relay neurons (By similarity). Extrasynaptic alpha-4-containing GABAARs control levels of excitability and network activity (By similarity). GABAAR containing alpha-4-beta-3-delta subunits can simultaneously bind GABA and histamine where histamine binds at the interface of two neighboring beta subunits, which may be involved in the regulation of sleep and wakefulness PMID:35355020

Gamma-aminobutyric acid receptor subunit alpha-5

BE0000471

GABRA5

potentiator

Specific functionGABA receptor binding

Cellular location

Postsynaptic cell membrane

General function & pharmacology

Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain .
PMID:14993607 PMID:29961870 PMID:30140029 PMID:31056671

GABA-gated chloride channels, also named GABA(A) receptors (GABAAR), consist of five subunits arranged around a central pore and contain GABA active binding site(s) located at the alpha and beta subunit interface(s) .
PMID:30140029
When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient .
PMID:14993607 PMID:30140029
GABAARs containing alpha-5/GABRA5 subunits are mainly extrasynaptic and contribute to the tonic GABAergic inhibition in the hippocampus (By similarity). Extrasynaptic alpha-5-containing GABAARs in CA1 pyramidal neurons play a role in learning and memory processes (By similarity)

Gamma-aminobutyric acid receptor subunit alpha-6

BE0000764

GABRA6

potentiator

Specific functionbenzodiazepine receptor activity

Cellular location

Postsynaptic cell membrane

General function & pharmacology

Alpha subunit of the heteropentameric ligand-gated chloride channel gated by gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the brain .
PMID:8632757
GABA-gated chloride channels, also named GABA(A) receptors (GABAAR), consist of five subunits arranged around a central pore and contain GABA active binding site(s) located at the alpha and beta subunit interface(s) (By similarity). When activated by GABA, GABAARs selectively allow the flow of chloride anions across the cell membrane down their electrochemical gradient (By similarity). Alpha-6/GABRA6 subunits are found at both synaptic and extrasynaptic sites .
PMID:8632757
Chloride influx into the postsynaptic neuron following GABAAR opening decreases the neuron ability to generate a new action potential, thereby reducing nerve transmission (By similarity).

Extrasynaptic alpha-6-containing receptors contribute to the tonic GABAergic inhibition. Alpha-6 subunits are also present on glutamatergic synapses (By similarity)

Metabolizing enzymes(6)

Enzymes involved in drug metabolism — important for understanding drug interactions

Enzyme activity key

substrate

inhibitor

inducer

CYP2C9Cytochrome P450 2C9

substrate

inducer

CYP2C19Cytochrome P450 2C19

substrate

inducer

CYP2E1Cytochrome P450 2E1

substrate

inducer

CYP3A4Cytochrome P450 3A4

inducer

CYP1A2Cytochrome P450 1A2

inducer

UGT2B7UDP-glucuronosyltransferase 2B7 · UDP-glucuronosyltransferases (UGTs)

inducer

Transporters(1)

Proteins that transport this drug across cell membranes

Transient receptor potential cation channel subfamily M member 3

BE0009808

TRPM3

inhibitor

Specific functioncalcium channel activity

Cellular location

Cell membrane

General function & pharmacology

Constitutively active, non-selective divalent cation-conducting channel that is permeable to Ca(2+), Mn(2+), and Mg(2+), with a high permeability for Ca(2+). However, can be enhanced by increasing temperature and by ligands, including the endogenous neurosteroid pregnenolone sulfate and sphingosine-1 and suppressed by intracellular Mg(2+) .
PMID:12672799 PMID:12672827 PMID:32343227

Implicated in a variety of cellular processes, including insulin/peptide secretion, vascular constriction and dilation, noxious heat sensing, inflammatory and spontaneous pain sensitivity. In neurons of the dorsal root ganglia, functions as thermosensitive channel for the detection of noxious heat and spontaneous pain.

Suggested to function as an ionotropic steroid receptor in beta-cell, indeed pregnenolone sulfate leads to Ca(2+) influx and enhanced insulin secretion. Mediates Zn(2+) uptake into the lumen of pancreatic beta cell secretory granules, thereby regulating insulin secretion (By similarity). Forms heteromultimeric ion channels with TRPM1 which are permeable for Ca(2+) and Zn(2+) ions .
PMID:21278253
Exists as multiple splice variants which differ significantly in their biophysical properties (By similarity)

Scientific references(13)

Rajput A.H., Rajput A.

Medical treatment of essential tremor.

Journal Cent Nerv Systems Diseases

2014 Apr 216:29-39. doi: 10.4137/JCNSD.S13570. eCollection 2014

PMID: 24812533 DOI: 10.4137/JCNSD.S13570

Schneider S.A., Deuschl G.

The treatment of tremor.

Neurotherapeutics

2014 Jan11(1):128-38. doi: 10.1007/s13311-013-0230-5

PMID: 24142589 DOI: 10.1007/s13311-013-0230-5

Haidukewych D., Rodin E.A.

Serial free and plasma valproic acid and phenytoin monitoring and drug interactions.

Therapeutics Drug Monit

19813(3):303-7. doi: 10.1097/00007691-198103000-00013

PMID: 6798720 DOI: 10.1097/00007691-198103000-00013

Hedera P., Cibulcik F., Davis T.L.

Pharmacotherapy of essential tremor.

Journal Cent Nerv Systems Diseases

2013 Dec 225:43-55. doi: 10.4137/JCNSD.S6561

PMID: 24385718 DOI: 10.4137/JCNSD.S6561

Marvanova M.

Pharmacokinetic characteristics of antiepileptic drugs (AEDs).

Ment Health Clinical

2016 Mar 86(1):8-20. doi: 10.9740/mhc.2015.01.008. eCollection 2016 Jan

PMID: 29955442 DOI: 10.9740/mhc.2015.01.008

Patsalos P.N., Spencer E.P., Berry D.J.

Therapeutic Drug Monitoring of Antiepileptic Drugs in Epilepsy: A 2018 Update.

Therapeutics Drug Monit

2018 Oct40(5):526-548. doi: 10.1097/FTD.0000000000000546

PMID: 29957667 DOI: 10.1097/FTD.0000000000000546

Lee C.S., Marbury T.C., Perchalski R.T., Wilder B.J.

Pharmacokinetics of primidone elimination by uremic patients.

Journal of Clinical Pharmacology

1982 Jul22(7):301-8. doi: 10.1002/j.1552-4604.1982.tb02679.x

PMID: 7107978 DOI: 10.1002/j.1552-4604.1982.tb02679.x

Treston A.M., Hooper W.D.

Urinary metabolites of phenobarbitone, primidone, and their N-methyl and N-ethyl derivatives in humans.

Xenobiotica

1992 Apr22(4):385-94. doi: 10.3109/00498259209046650

PMID: 1523859 DOI: 10.3109/00498259209046650

van Heijst A.N., de Jong W., Seldenrijk R., van Dijk A.

Coma and crystalluria: a massive primidone intoxication treated with haemoperfusion.

Journal Toxicology Clinical Toxicology

1983 Jun20(4):307-18. doi: 10.3109/15563658308990598

PMID: 6655772 DOI: 10.3109/15563658308990598

HANDLEY R., STEWART A.S.

Mysoline; a new drug in the treatment of epilepsy.

The Lancet

1952 Apr 121(6711):742-4. doi: 10.1016/s0140-6736(52)90500-x

PMID: 14918421 DOI: 10.1016/s0140-6736(52)90500-x

El-Masri H.A., Portier C.J.

Blood and cerebrospinal fluid pharmacokinetics of primidone and its primary pharmacologically active metabolites, phenobarbital and phenylethylmalonamide in the rat.

European Journal of Drug Metabolism and Pharmacokinetics

199924(3):255-264. doi: 10.1007/bf03190029

PMID: 9616196 DOI: 10.1007/bf03190029

Zaccara G., Perucca E.

Interactions between antiepileptic drugs, and between antiepileptic drugs and other drugs.

Epileptic Disord

2014 Dec16(4):409-31. doi: 10.1684/epd.2014.0714

PMID: 25515681 DOI: 10.1684/epd.2014.0714

Tanaka E.

Clinically significant pharmacokinetic drug interactions between antiepileptic drugs.

Journal Clinical Pharmacy Therapeutics

1999 Apr24(2):87-92. doi: 10.1046/j.1365-2710.1999.00201.x

PMID: 10380060 DOI: 10.1046/j.1365-2710.1999.00201.x

ATC classification(2 codes)

ATC N05CB01

ATC N03AA03

Affected organisms(1)

Humans and other mammals

International brands(7)

Experimental properties(4)

External resources(2)

RxList Drugs.com

Commercial products(88)

Chemical identifiers

CAS, UNII, InChI Key and database cross-references

Show

Linked compound data from DrugBank Open Data (CC BY-NC 4.0)

Primidone

DB00794

CAS number

125-33-7

UNII (FDA)

13AFD7670Q

InChI Key (molecular fingerprint)

DQMZLTXERSFNPB-UHFFFAOYSA-N

Additional database identifiers

Drugs Product Database (DPD)

8265

ChEBI

8412

PubChem Compound

4909

PubChem Substance

46507775

KEGG Compound

C07371

KEGG Drug

D00474

ChemSpider

4740

BindingDB

50248152

PharmGKB

PA451105

PDB

A1AIA

Therapeutic Targets Database

DAP000678

Wikipedia

Primidone

ChEMBL

CHEMBL856

ZINC

ZINC000000001979

RxCUI

8691

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4076

GenAtlas

GABRA2

GeneCards

GABRA2

GenBank Gene Database

S62907

GenBank Protein Database

386422

IUPHAR

405

Guide to Pharmacology

405

UniProtKB

P47869

UniProt Accession

GBRA2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4077

GenAtlas

GABRA3

GeneCards

GABRA3

GenBank Gene Database

S62908

GenBank Protein Database

386424

IUPHAR

406

Guide to Pharmacology

406

UniProtKB

P34903

UniProt Accession

GBRA3_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4078

GenAtlas

GABRA4

GeneCards

GABRA4

GenBank Gene Database

U30461

GenBank Protein Database

905393

IUPHAR

407

Guide to Pharmacology

407

UniProtKB

P48169

UniProt Accession

GBRA4_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4079

GenAtlas

GABRA5

GeneCards

GABRA5

GenBank Gene Database

L08485

GenBank Protein Database

182916

IUPHAR

408

Guide to Pharmacology

408

UniProtKB

P31644

UniProt Accession

GBRA5_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4080

GenAtlas

GABRA6

GeneCards

GABRA6

GenBank Gene Database

S81944

GenBank Protein Database

1470364

IUPHAR

409

Guide to Pharmacology

409

UniProtKB

Q16445

UniProt Accession

GBRA6_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4075

GenAtlas

GABRA1

GeneCards

GABRA1

GenBank Gene Database

X13584

GenBank Protein Database

31631

IUPHAR

404

Guide to Pharmacology

404

UniProtKB

P14867

UniProt Accession

GBRA1_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4076

GenAtlas

GABRA2

GeneCards

GABRA2

GenBank Gene Database

S62907

GenBank Protein Database

386422

IUPHAR

405

Guide to Pharmacology

405

UniProtKB

P47869

UniProt Accession

GBRA2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4077

GenAtlas

GABRA3

GeneCards

GABRA3

GenBank Gene Database

S62908

GenBank Protein Database

386424

IUPHAR

406

Guide to Pharmacology

406

UniProtKB

P34903

UniProt Accession

GBRA3_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4078

GenAtlas

GABRA4

GeneCards

GABRA4

GenBank Gene Database

U30461

GenBank Protein Database

905393

IUPHAR

407

Guide to Pharmacology

407

UniProtKB

P48169

UniProt Accession

GBRA4_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4079

GenAtlas

GABRA5

GeneCards

GABRA5

GenBank Gene Database

L08485

GenBank Protein Database

182916

IUPHAR

408

Guide to Pharmacology

408

UniProtKB

P31644

UniProt Accession

GBRA5_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4080

GenAtlas

GABRA6

GeneCards

GABRA6

GenBank Gene Database

S81944

GenBank Protein Database

1470364

IUPHAR

409

Guide to Pharmacology

409

UniProtKB

Q16445

UniProt Accession

GBRA6_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4081

GenAtlas

GABRB1

GeneCards

GABRB1

GenBank Gene Database

X14767

GenBank Protein Database

31635

IUPHAR

410

UniProtKB

P18505

UniProt Accession

GBRB1_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4082

GenAtlas

GABRB2

GeneCards

GABRB2

GenBank Gene Database

S67368

GenBank Protein Database

455946

IUPHAR

411

UniProtKB

P47870

UniProt Accession

GBRB2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4083

GenAtlas

GABRB3

GeneCards

GABRB3

GenBank Gene Database

M82919

GenBank Protein Database

182925

IUPHAR

412

Guide to Pharmacology

412

UniProtKB

P28472

UniProt Accession

GBRB3_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4084

GeneCards

GABRD

GenBank Gene Database

AF016917

GenBank Protein Database

2388693

UniProtKB

O14764

UniProt Accession

GBRD_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4085

GeneCards

GABRE

GenBank Gene Database

U66661

GenBank Protein Database

1857126

UniProtKB

P78334

UniProt Accession

GBRE_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4086

GeneCards

GABRG1

GenBank Gene Database

AK122845

GenBank Protein Database

193783776

UniProtKB

Q8N1C3

UniProt Accession

GBRG1_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4087

GeneCards

GABRG2

GenBank Gene Database

X15376

GenBank Protein Database

31637

UniProtKB

P18507

UniProt Accession

GBRG2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4088

GeneCards

GABRG3

GenBank Gene Database

S82769

GenBank Protein Database

1754749

UniProtKB

Q99928

UniProt Accession

GBRG3_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4089

GeneCards

GABRP

GenBank Gene Database

U95367

GenBank Protein Database

2197001

UniProtKB

O00591

UniProt Accession

GBRP_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:14454

GeneCards

GABRQ

GenBank Gene Database

AF189259

GenBank Protein Database

7861736

UniProtKB

Q9UN88

UniProt Accession

GBRT_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4075

GenAtlas

GABRA1

GeneCards

GABRA1

GenBank Gene Database

X13584

GenBank Protein Database

31631

IUPHAR

404

Guide to Pharmacology

404

UniProtKB

P14867

UniProt Accession

GBRA1_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:1958

GenAtlas

CHRNA4

GeneCards

CHRNA4

GenBank Gene Database

L35901

GenBank Protein Database

755648

IUPHAR

465

Guide to Pharmacology

465

UniProtKB

P43681

UniProt Accession

ACHA4_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:1960

GenAtlas

CHRNA7

GeneCards

CHRNA7

GenBank Gene Database

X70297

GenBank Protein Database

496607

IUPHAR

468

Guide to Pharmacology

468

UniProtKB

P36544

UniProt Accession

ACHA7_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4572

GenAtlas

GRIA2

GeneCards

GRIA2

GenBank Gene Database

L20814

GenBank Protein Database

493134

IUPHAR

445

Guide to Pharmacology

445

UniProtKB

P42262

UniProt Accession

GRIA2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:4580

GenAtlas

GRIK2

GeneCards

GRIK2

GenBank Gene Database

U16126

GenBank Protein Database

790532

IUPHAR

451

Guide to Pharmacology

451

UniProtKB

Q13002

UniProt Accession

GRIK2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:2623

GenAtlas

CYP2C9

GeneCards

CYP2C9

GenBank Gene Database

AY341248

Guide to Pharmacology

1326

UniProtKB

P11712

UniProt Accession

CP2C9_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:2621

GeneCards

CYP2C19

GenBank Gene Database

M61854

GenBank Protein Database

181344

Guide to Pharmacology

1328

UniProtKB

P33261

UniProt Accession

CP2CJ_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:2631

GeneCards

CYP2E1

GenBank Gene Database

J02625

GenBank Protein Database

181360

Guide to Pharmacology

1330

UniProtKB

P05181

UniProt Accession

CP2E1_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:2637

GenAtlas

CYP3A4

GeneCards

CYP3A4

GenBank Gene Database

M18907

Guide to Pharmacology

1337

UniProtKB

P08684

UniProt Accession

CP3A4_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:2596

GenAtlas

CYP1A2

GeneCards

CYP1A2

GenBank Gene Database

Z00036

Guide to Pharmacology

1319

UniProtKB

P05177

UniProt Accession

CP1A2_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12530

GeneCards

UGT1A1

GenBank Gene Database

M57899

GenBank Protein Database

184473

Guide to Pharmacology

2990

UniProtKB

P22309

UniProt Accession

UD11_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12531

GeneCards

UGT1A10

GenBank Gene Database

U89508

GenBank Protein Database

2039362

UniProtKB

Q9HAW8

UniProt Accession

UD110_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12535

GeneCards

UGT1A3

GenBank Gene Database

M84127

GenBank Protein Database

340135

UniProtKB

P35503

UniProt Accession

UD13_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12536

GeneCards

UGT1A4

GenBank Gene Database

M57951

GenBank Protein Database

184475

UniProtKB

P22310

UniProt Accession

UD14_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12538

GeneCards

UGT1A6

UniProtKB

P19224

UniProt Accession

UD16_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12539

GeneCards

UGT1A7

UniProtKB

Q9HAW7

UniProt Accession

UD17_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12540

GeneCards

UGT1A8

GenBank Gene Database

AF030310

GenBank Protein Database

2613044

UniProtKB

Q9HAW9

UniProt Accession

UD18_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12541

GeneCards

UGT1A9

GenBank Gene Database

S55985

GenBank Protein Database

7690346

UniProtKB

O60656

UniProt Accession

UD19_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12546

GeneCards

UGT2B15

UniProtKB

P54855

UniProt Accession

UDB15_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12553

GeneCards

UGT2B4

GenBank Gene Database

Y00317

GenBank Protein Database

37589

UniProtKB

P06133

UniProt Accession

UD2B4_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:12554

GeneCards

UGT2B7

GenBank Gene Database

J05428

GenBank Protein Database

340080

UniProtKB

P16662

UniProt Accession

UD2B7_HUMAN

HUGO Gene Nomenclature Committee (HGNC)

HGNC:17992

GeneCards

TRPM3

Guide to Pharmacology

495

UniProtKB

Q9HCF6

UniProt Accession

TRPM3_HUMAN

International reference pricing

7 formulations

Reference pricing from DrugBank. Prices are indicative and may not reflect current UK costs.

From $0.06/tablet

To $10.56/g

Apo-Primidone 125 mg Tablet

$0.06/tablet

Apo-Primidone 250 mg Tablet

$0.09/tablet

Primidone 50 mg tablet

$0.51/tablet

Primidone 250 mg tablet

$1.02/tablet

Mysoline 50 mg tablet

$1.26/tablet

Source: DrugBank. Used under CC BY-NC 4.0 academic licence for non-commercial purposes.

DrugBank citations

If you use DrugBank data in your research, please cite the following publications:

Knox C., Wilson M., Klinger C.M., et al

DrugBank 6.

0: the DrugBank Knowledgebase for 2024

Nucleic Acids Res. 2024 Jan 552(D1):D1265-D1275

PMID: 37953279

Wishart D.S., Feunang Y.D., Guo A.C., et al

DrugBank 5.

0: a major update to the DrugBank database for 2018

Nucleic Acids Res. 2017 Nov 846(D1):D1074-D1082

PMID: 29126136

Show earlier publications

Law V., Knox C., Djoumbou Y., et al

DrugBank 4.

0: shedding new light on drug metabolism

Nucleic Acids Res. 2014 Jan 142(1):D1091-7

PMID: 24203711

Knox C., Law V., Jewison T., et al

DrugBank 3.

0: a comprehensive resource for 'omics' research on drugs

Nucleic Acids Res. 2011 Jan39(Database issue):D1035-41

PMID: 21059682

Wishart D.S., Knox C., Guo A.C., et al

DrugBank: a knowledgebase for drugs, drug actions and drug targets.

Nucleic Acids Research

2008 Jan36(Database issue):D901-6

PMID: 18048412

Wishart D.S., Knox C., Guo A.C., et al

DrugBank: a comprehensive resource for in silico drug discovery and exploration.

Nucleic Acids Research

2006 Jan 134(Database issue):D668-72

PMID: 16381955

Source: go.drugbank.comCC BY-NC 4.0

Updated 26 days ago(8 Mar 2026)

Back to medicines

Primidone 62.5mg/5ml oral suspension

Official medicine documents

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Primidone

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Primidone 62.5mg/5ml oral suspension

Safety & regulatory

Official medicine documents

Safety monitoring data

Yellow Card reports

EudraVigilance

Brand versions and licensed products

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WHO defined daily dose (DDD)

Medicines like this

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Key facts

Pharmacokinetics at a glance

Absorption

Half-life

Protein binding

Volume of distribution

Metabolism

Elimination

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Clinical essentials

Pharmacology

Deep science18

Chemical identifiers

Primidone

Additional database identifiers

International reference pricing

DrugBank citations

Deep science
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