Description

Phenytoin is a hydantoin anticonvulsant used to prevent and control tonic–clonic (grand mal) and focal (temporal lobe) seizures, as well as seizures during or after neurosurgery.(turn0search0)

2. Prescription

This medication is prescription-only (Rx-only) in virtually all jurisdictions.(turn0search1)

3. Therapeutic Category

• Anticonvulsant (antiepileptic drug)

• ATC classification: N03AB02 (hydantoin derivatives).(turn0search1, turn0search12)

4. Active Ingredients / Composition

• Active Ingredient: Phenytoin sodium, commonly in strengths like 25 mg, 50 mg, 100 mg, or 300 mg per capsule.(turn0search1)

• Excipients vary by manufacturer but can include lactose monohydrate, magnesium stearate, talc, gelatin, colorants, and coatings.(turn0search1, turn0search5, turn0search6)

5. Vitamins

None.

6. Minerals

None.

7. Variant

Available in multiple forms:

• Hard gelatin capsules, typically 25–300 mg strengths.(turn0search1)

• Extended-release formulations available (e.g., Dilantin Kapseals, Phenytek) for once-daily dosing.(turn0search0, turn0search6)

8. Consume Type

• Oral administration. Swallowed whole with water.

• Do not crush or chew, as this affects absorption.(turn0search4, turn0search0)

9. Directions / Usage

• Adults (standard): Start with 100 mg extended-release capsule three times daily, adjusting based on clinical response and serum levels. Maintenance often at 300–400 mg/day divided doses.(turn0search0)

• Once-daily dosing: For patients stabilized on 300 mg daily, a single 300 mg extended-release dose may be used.(turn0search0)

• Pediatric dosing: 5 mg/kg/day divided 2–3 times per day; maintenance around 4–8 mg/kg/day up to 300 mg/day.(turn0search0)

• Serum phenytoin monitoring is essential due to narrow therapeutic range (10–20 µg/mL).(turn0search0)

10. Common Side Effects

• Neurological: Nystagmus, ataxia, slurred speech, decreased coordination, somnolence, confusion.(turn0search0, turn0search6)

• Other: Gingival hyperplasia—maintain good dental hygiene.(turn0search6)

• Others: Dizziness, drowsiness.(turn0search4)

11. Package Type

• Hard gelatin capsules, often in blister packs or bottles.

• Extended-release options (e.g., Dilantin): 30 mg or 100 mg capsules with distinctive color caps.(turn0search3, turn0search7)

12. Storage Advice

• Store at room temperature—approximately 20–25 °C, protected from light and moisture, and in tight containers.(turn0search6, turn0search3, turn0search2)

13. Safety Advice

• Contraindications: Known hypersensitivity to phenytoin or other hydantoins.(turn0search0)

• Warnings:

  • Sudden discontinuation may precipitate status epilepticus—taper gradually.(turn0search0)

  • Monitor for suicidal ideation.

  • Discontinue immediately if signs of severe skin reaction (e.g., Stevens–Johnson syndrome), or DRESS.(turn0search0)

  • Hepatotoxicity, blood dyscrasias, osteomalacia, teratogenicity (fetal hydantoin syndrome), and effects on vitamin D and bone.(turn0search0)

• Special populations:

  • Pregnancy: teratogenic risk; use only if benefits justified; supplement prenatal vitamin K.(turn0search1, turn0search0)

  • Elderly, those with hepatic or renal impairment: monitor unbound phenytoin levels.(turn0search0)

  • Avoid abrupt cessation; counsel on interaction (e.g., hormonal contraception).(turn0search0, turn0search12)

• Other precautions: Avoid alcohol; may impair driving or machinery operation.(turn0search4, turn0search2)

14. Product Substitute

Common equivalents include:

• Prescription brands: Dilantin, Phenytek, or generics (capsules or extended-release).(turn0search12, turn0search0)

15. Manufacturer / Marketer

Without brand-specific info (“Cap Exeter”), here are representative manufacturers:

• Flynn Pharma Ltd (UK) markets Phenytoin Sodium capsules.(turn0search1)

• AvKARE (USA) markets extended-release capsules.(turn0search0)

• Various multinational and regional pharmaceutical firms produce generics globally.

16. Country of Origin

Phenytoin is a long-established generic available worldwide. Manufacturing and origin vary by brand—commonly India, EU, or U.S.—but “Cap Exeter” origin is currently unspecified.