PHENYTOIN
#pathology #pharmacotherapy #pharmacology #pathology #diagnosis #pathologies #pathologylab #pharmacy #medical #symptoms #therapy #treatment @educationonly #quran #qurantranslation #quranfehmi #understandingquraninurdu #treatments #interactions #diagnosis #symptoms #adverseeffects #summary #languagelearning
Here’s a **comprehensive overview and monograph of Phenytoin**, perfect for educational content, YouTube videos, or pharmacology presentations.
Phenytoin is a *widely used antiepileptic drug (AED)**. It's primarily prescribed to control **generalized tonic-clonic seizures* and **partial seizures**. It works by stabilizing neuronal membranes and decreasing repetitive firing of action potentials.
*Phenytoin Monograph*
| *Field* | *Details* |
|----------------------------------|------------------------------------------------------------------------------|
| *Generic Name* | Phenytoin |
| *Brand Names* | Dilantin, Eptoin, Phenytek |
| *Chemical Name* | 5,5-Diphenylimidazolidine-2,4-dione |
| *Molecular Formula* | C₁₅H₁₂N₂O₂ |
| *Molecular Weight* | 252.27 g/mol |
| *CAS Number* | 57-41-0 |
| *Drug Class* | Antiepileptic (Hydantoin derivative) |
| *Pharmacological Class* | Voltage-gated sodium channel blocker |
| *Mechanism of Action* | Blocks voltage-sensitive Na⁺ channels in neurons, reducing repetitive firing|
| *Indications* | Tonic-clonic seizures, complex partial seizures, seizure prevention post-trauma |
| *Other Uses* | Trigeminal neuralgia (off-label), status epilepticus (IV form) |
| *Available Forms* | Oral capsules, chewable tablets, suspension, IV solution |
| *Dose (Adult)* | Initial: 100 mg TID; maintenance: 300–400 mg/day in divided doses |
| *Therapeutic Range* | 10–20 µg/mL (serum level) |
| *Absorption* | Variable (especially with suspension); decreased by tube feeding |
| *Distribution* | Highly protein-bound (~90%) |
| *Metabolism* | Hepatic (CYP2C9, CYP2C19) → non-linear (zero-order) at higher doses |
| *Excretion* | Renal (metabolites) |
| *Half-life* | 22 hours (varies with dose and saturation) |
| *Side Effects* | Ataxia, diplopia, gingival hyperplasia, hirsutism, rash, lethargy, nystagmus |
| *Serious Adverse Effects* | SJS/TEN, hepatotoxicity, blood dyscrasias, lupus-like syndrome |
| *Contraindications* | Hypersensitivity to phenytoin or other hydantoins |
| *Pregnancy Category* | D (teratogenic – fetal hydantoin syndrome) |
| *Monitoring Parameters* | Serum drug levels, LFTs, CBC, signs of toxicity |
| *Drug Interactions* | Strong enzyme inducer (reduces effects of OCPs, warfarin, steroids, etc.) |
| *Toxicity Symptoms* | Nystagmus, ataxia, slurred speech, confusion, coma in overdose |
| *Antidote in Overdose* | Supportive care; no specific antidote |
| *Black Box Warning* | IV form: Risk of severe hypotension and arrhythmias with rapid infusion |
*Pharmacological Insights*
**Nonlinear kinetics**: Small changes in dose → large changes in serum level
**Zero-order metabolism**: Saturates liver enzymes at therapeutic dose
Storage & Handling
Store below 25°C
Protect from moisture and light
Do not refrigerate suspension
#phenytoin #pharmacology #pharmacystudents #medicaleducation #pharmacokinetics #toxicology #TherapeuticRange