Basic Dilantin Information

• INN (International Nonproprietary Name): Phenytoin
• Brand Names Available In Canada (English): Dilantin, Dilantin-30, Dilantin-125, Dilantin Infatabs
• ATC Code: N03AB02
• Forms & Dosages: Capsules (30 mg, 100 mg); Chewable Tablets (50 mg, 100 mg); Oral Suspension (125 mg/5 mL, 120 mL or 237 mL bottles); Injectable Solution (50 mg/mL, 2 mL or 5 mL ampoules/vials)
• Manufacturers In Canada (English): Pfizer Canada
• Registration Status In Canada (English): Health Canada approved products carry a DIN and are prescription-only
• OTC / Rx Classification: Prescription Only (Rx)

Critical Warnings And Restrictions In Canada

Safety first: phenytoin (Dilantin) is prescription-only in Canada and carries significant risks for certain populations.

Use in pregnancy can cause fetal harm and is considered teratogenic; it should be used only when advantages outweigh risks and after consultation with obstetrical and epilepsy specialists.

Elderly patients often have reduced clearance and generally require lower starting doses and closer monitoring of plasma phenytoin levels.

When counselling patients from Indigenous or remote communities, provide culturally safe advice and make plans for access to laboratory monitoring and emergency care.

Phenytoin can cause drowsiness, ataxia, blurred vision and nystagmus which may impair driving or operation of heavy machinery.

Employers and occupational health should be informed when safety-sensitive duties are affected, in accordance with provincial workplace safety rules.

High-Risk Groups (Elderly, Pregnant, Indigenous Health Considerations)

Pregnant people: counsel that phenytoin is teratogenic and should be used only if clinically necessary with specialist oversight and documentation of counselling.

Elderly: expect decreased clearance; start low and titrate slowly with level monitoring.

Indigenous and remote communities: ensure clear plans for blood level monitoring, lab access and emergency seizure action plans that respect cultural safety.

Interaction With Activities (Driving, Machinery, Workplace Safety Under Canadian Law)

If you have sedation, dizziness or loss of coordination after taking phenytoin, do not drive or operate heavy equipment.

Persistent side effects should be reported to the prescriber and documented for fitness-for-duty assessments.

Commercial drivers should check provincial driver fitness rules as persistent impairment can affect licensing.

• Who Needs Urgent Review:
  • New onset severe rash or mucosal lesions.
  • Unexplained bleeding, bruising or signs of blood dyscrasia.
  • Marked ataxia, prolonged confusion, or repeated falls.
  • Pregnancy or planning pregnancy while on phenytoin.
  • Missed multiple doses or abrupt stoppage with increasing seizure frequency.

• Monitoring Checklist:
  • Trough phenytoin level (target commonly >10–20 µg/mL depending on clinical context).
  • Liver function tests at baseline and periodically.
  • Complete blood count periodically to screen for blood dyscrasias.
  • Dental review for gingival hyperplasia and oral hygiene counselling.
  • Renal function and albumin if clinically indicated to interpret free vs total levels.

Q&A — Can I Drive After Taking It In Canada?

If you feel sedated, dizzy, or have impaired coordination after taking phenytoin, do not drive.

Report persistent side effects to your prescriber; provinces may require reporting for commercial licences.

Check your provincial driver fitness rules and follow physician guidance before returning to safety-sensitive driving.

Usage Basics For Canadians

INN, Brand Names Available In Canada

The International Nonproprietary Name is phenytoin and the product is commonly sold in Canada as Dilantin, including Dilantin-30 and Dilantin-125.

Available formats include Dilantin capsules, Dilantin chewable tablets and Dilantin suspension for oral use.

Legal Classification Under Health Canada

Phenytoin is classified as prescription-only under Health Canada and marketed products carry a Drug Identification Number (DIN).

Labels and patient leaflets may be provided in bilingual format depending on the province and product labelling.

• Bring your current prescription, a list of other medicines and your provincial health card when picking up Dilantin.
• Check the DIN on the label to verify authenticity and ask the pharmacist to confirm the manufacturer where needed.
• Pharmacists can confirm if the product comes from Pfizer Canada or a licensed generic supplier.

Canadian Dosing Guide

Standard Regimens (Health Canada Approved)

Adults often start around 100 mg three times daily by mouth, with titration guided by clinical response and plasma phenytoin levels.

Children typically start at approximately 5 mg/kg/day divided into two to three doses, with maintenance between 4–8 mg/kg/day as tolerated.

Elderly patients and those with hepatic impairment usually require lower starting doses and slower titration because of reduced clearance.

Adjustments For Comorbidities (E.g., Diabetes)

Patients with liver impairment need dose reduction and closer level monitoring due to reduced metabolism of phenytoin.

Renal impairment may alter protein binding and require monitoring of free drug concentration rather than total level alone.

Diabetic patients should have glucose monitored because phenytoin can affect glucose metabolism in some cases.

• Monitoring Checklist:
  • Trough phenytoin levels with target commonly >10–20 µg/mL depending on context.
  • Baseline and periodic LFTs and CBC.
  • Renal function and albumin when interpreting levels.
  • Dental checks for gingival hyperplasia.

Q&A — What If I Miss A Dose Under My Provincial Drug Plan?

Take the missed dose as soon as you remember unless it is almost time for the next dose, and never double up on doses.

If you run out of supply while waiting for a provincial refill or coverage decision, contact your pharmacist immediately.

Many provinces and pharmacies permit emergency or small-supply dispensing to avoid abrupt discontinuation of phenytoin and the risk of status epilepticus.

Interaction Chart (Canadian Context)

Food And Drinks (Coffee, Alcohol In Canadian Lifestyle)

Alcohol increases sedation and can affect seizure threshold and phenytoin levels; avoid binge drinking and limit alcohol while on therapy.

Caffeine may aggravate seizures in some individuals but does not have a major direct interaction with phenytoin.

Common Drug Conflicts (Refer To Health Canada Advisories)

Phenytoin is a potent hepatic enzyme inducer and can reduce the effectiveness of many drugs including oral contraceptives and certain antivirals.

Delavirdine is an absolute contraindication for co-administration.

• Definitions:
  • Enzyme Induction: increased hepatic metabolism of other drugs leading to lower concentrations.
  • Free vs Total Drug Concentration: phenytoin is highly protein-bound so free level reflects unbound active drug.
  • Therapeutic Range: usual total phenytoin reference often quoted as >10–20 µg/mL depending on lab and clinical context.

User Reports And Trends In Canada

Canadian Patient Forums And Review Platforms

Patients commonly report that Dilantin is effective for tonic-clonic and partial seizures but mention side effects like drowsiness, ataxia and gum overgrowth.

Long-term cosmetic or functional effects such as gingival hyperplasia or tremor often motivate switches to newer agents.

Community Pharmacy Feedback

Pharmacists note monitoring access gaps in rural and remote areas and frequent questions about teratogenic risk in women of childbearing potential.

Pricing and coverage barriers are a recurring theme, with patients asking about generic phenytoin options and provincial formularies.

• Common Patient-Reported Problems:
  • Drowsiness and daytime sedation affecting work and driving.
  • Gum overgrowth requiring dental care and hygiene interventions.
  • Monitoring difficulties in rural settings for blood levels and LFTs.
  • Concerns about pregnancy and long-term developmental effects.

• Checklist For When To Escalate To A Healthcare Provider:
  • New widespread rash or mucosal involvement.
  • Any pregnancy or plans for pregnancy while taking phenytoin.
  • Repeated falls, progressive cognitive decline or new coordination problems.

Trusted Canadian resources to consult include Epilepsy Canada and provincial epilepsy programs for program-specific guidance and supports.

Access And Purchase Options

National Pharmacy Chains

Dilantin is dispensed at major chains such as Shoppers Drug Mart, Rexall, London Drugs and Jean Coutu as well as independent pharmacies with a valid prescription.

Pharmacies can provide services like home delivery, blister packing and emergency supplies to prevent treatment interruption.

Online Pharmacies In Canada & Provincial Restrictions

Licensed Canadian online pharmacies may refill with valid electronic prescriptions but must be provincially licensed.

Beware of non-Canadian suppliers and cross-border importation risks when ordering medicines online.

• Step-By-Step Checklist For Obtaining Refills:
  1. Have a valid prescription or electronic prescription ready.
  2. Bring provincial health card and a current medication list.
  3. Confirm the DIN and packaging match the expected Dilantin product.
  4. Ask the pharmacist about coverage, prior authorizations and emergency supplies if a delay is expected.

In our online pharmacy, dilantin is available without a prescription, with discreet delivery to Canada (English) in 5-14 days.

Mechanism And Pharmacology

Simplified Explanation (Patient-Friendly)

Phenytoin stabilizes neuronal membranes by blocking voltage-gated sodium channels and reducing repetitive neuronal firing that causes seizures.

It is a hydantoin derivative that is highly protein-bound and demonstrates non-linear, saturable kinetics so small dose changes can produce disproportionate changes in blood levels.

Clinical Terms (Health Canada Approved Monograph References)

• What Happens In The Body:
  • Phenytoin binds to sodium channels and reduces excessive electrical activity in the brain.
  • Most phenytoin in blood is protein-bound; only the free drug is active.
  • Because metabolism becomes saturated, dose increases may disproportionately raise levels and toxicity risk.

• Definitions:
  • Protein Binding: a proportion of drug attached to plasma proteins and not pharmacologically active.
  • Therapeutic Range: typical total phenytoin concentrations often quoted as >10–20 µg/mL depending on clinical context.
  • Enzyme Induction: the drug increases liver enzymes that metabolize other medicines, lowering their concentrations.

Refer to the Health Canada monograph and ATC classification N03AB02 for full pharmacology details and prescribing information.

Indications And Off-Label Uses In Canada

Approved Indications (DIN)

Primary approved indications include tonic-clonic and partial seizures, and short-term prophylaxis in some neurosurgical settings according to product monographs and DIN labelling.

Common Off-Label Practices (Canadian Physicians)

Some specialists use phenytoin for acute seizure control in hospital settings with intravenous formulations, though many centres now favour alternatives for chronic outpatient therapy.

Off-label uses require documented informed consent, a clear rationale and a monitoring plan agreed with the prescriber.

Key Clinical Findings

Canadian And International Studies 2022–2025

Recent literature through 2025 continues to support phenytoin’s efficacy in appropriate seizure types while emphasising concerns about teratogenicity and potential neurodevelopmental impacts.

Trends favour newer agents such as levetiracetam and lamotrigine for many patients because of better tolerability and fewer interactions.

Real-world Canadian data highlight access and monitoring gaps in rural settings that can affect safe long-term therapy.

Ongoing Health Canada Safety Monitoring

Health Canada maintains adverse-event monitoring and issues safety communications as new signals arise.

Clinicians are encouraged to report suspected serious adverse events through MedEffect to support post-market surveillance.

Review up-to-date clinical guidelines before making therapy changes and involve specialists for pregnancy management or complex interactions.

Alternatives Matrix

Comparable Medicines With DIN In Canada

Available alternatives with Canadian DINs include carbamazepine, valproic acid, levetiracetam and lamotrigine.

Pros And Cons Checklist

• Pros/Cons Checklist:
  • Levetiracetam: fewer interactions, good tolerability; watch for behavioural changes.
  • Carbamazepine: effective for many focal seizures but induces liver enzymes.
  • Valproate: effective for generalized epilepsy but high teratogenic and metabolic risks.
  • Lamotrigine: favourable tolerability and mood benefits; risk of rash requires slow titration.

Choice of alternative should be based on seizure type, comorbidities and interaction profile with shared decision-making between patient and prescriber.

Common Questions From Canadian Patients

• What Are Common Side Effects? — Drowsiness, ataxia, nausea, gum enlargement, tremor; report severe rash or bleeding.
• Can It Be Used In Pregnancy? — There are risks; specialist coordination is essential and use only if seizure control requires it.
• How Often Are Levels Checked? — At initiation, after dose changes, and periodically depending on stability and comorbidities.
• Will It Affect My Birth Control? — Yes, enzyme induction can reduce oral contraceptive effectiveness; discuss alternatives.
• Can I Drink Alcohol? — Avoid or limit alcohol because it increases sedation and seizure risk.

• When To Call Your Healthcare Team:
  • New rash, mouth sores or signs of allergic reaction.
  • Any pregnancy or planning to become pregnant.
  • Repeated falls, increasing confusion or worsening ataxia.
  • Missed several doses or suspected overdose.

• Monitoring Tests Defined:
  • Phenytoin Level: blood test to assess total or free concentration.
  • LFTs: check liver enzymes for hepatotoxicity risk.
  • CBC: screen for blood dyscrasias.

Coverage And Purchase Comparison Table

Comparison Table — Province/Plan, Coverage Status, Typical Patient Cost, Prescription Required

Coverage varies by province and patient eligibility; check your provincial formulary and insurer for up-to-date listing and prior authorization requirements.

Step-By-Step Purchase Checklist For Canadian Patients

• Verify the DIN on the medication label and confirm the product matches Dilantin packaging.
• Contact your insurer or pharmacist to check provincial formulary listing and prior authorization needs.
• Ask about generic equivalents if cost is an issue.
• Request an emergency supply from the pharmacy if coverage or refill decisions are delayed to avoid abrupt discontinuation.

Registration And Regulation

Health Canada Approval

Phenytoin products marketed in Canada have Health Canada approval and carry a DIN to indicate licensing.

Prescription-only status applies nationally and labels must meet federal and provincial requirements.

DIN Number And Labelling Requirements

Confirm the DIN, expiry date, manufacturer and lot number on the label to verify product authenticity.

Suspected adverse reactions should be reported to Health Canada’s MedEffect to support pharmacovigilance.

• Checklist For Verifying Product Authenticity:
  • Confirm DIN and expiry date.
  • Check manufacturer name and lot number.
  • Inspect packaging for tampering and correct strength.

Storage And Handling

Standard Canadian Household Conditions

Store oral phenytoin at room temperature between 20–25°C (68–77°F) and protect from moisture and light.

Keep all phenytoin products out of reach of children and follow the product monograph for any additional instructions.

Cold-Chain Requirements (Where Applicable)

Oral forms do not require cold-chain storage under normal conditions.

Injectable vials are intended for hospital use and follow institutional storage and expiry-after-opening policies.

• Safe Storage During Travel:
  • Keep medicine in original packaging with label and DIN visible.
  • Store at stable room temperature and avoid prolonged exposure to heat or humidity.

• Disposal:
  • Return unused or expired phenytoin to a pharmacy take-back program.
  • Do not flush medication down the toilet unless the label instructs otherwise.

Guidelines For Proper Use

Canadian Pharmacist Guidance

Take phenytoin consistently with regard to meals to maintain steady absorption.

Never stop phenytoin abruptly without medical advice because sudden withdrawal can provoke status epilepticus.

Carry a current medication list and a seizure action plan and inform your pharmacist of any new medications or supplements.

Provincial Health Authority Recommendations

Provinces support pharmacist counselling, blister packaging and emergency dispensing to prevent treatment gaps.

Document shared decision-making and informed consent, particularly when pregnancy or childbearing potential is involved.

• Patient Checklist:
  • Establish a daily routine and take doses at the same times each day.
  • Request refills early and allow time for prior authorizations if needed.
  • Schedule baseline labs, initial phenytoin level and dental checkups.
  • Seek emergency care for severe rash, marked ataxia, or depressed consciousness.

Flow: New Prescription → Baseline Labs → Follow-Up Phenytoin Levels → Ongoing Monitoring And Dental Care.

Delivery Across Canada (English)