TEGRETOL 200 MG TAB

Indications

Approved Uses

Epilepsy (partial seizures with complex symptomatology, generalized tonic-clonic seizures, mixed seizure patterns), Trigeminal neuralgia, Glossopharyngeal neuralgia, Bipolar disorder (manic episodes)

Off-Label Uses

Off‑label: other neuropathic pain syndromes (beyond trigeminal neuralgia), alcohol withdrawal (adjunct), and certain behavioral/psychiatric uses as adjunct (e.g., aggression/impulsivity). Restless legs syndrome and schizophrenia adjunct have been used but are not well supported compared with alternatives.

Dosage & Administration

Dosing by Condition

Epilepsy (adults): start 200 mg twice daily (ER/CR) or 100-200 mg 1-2 times daily (IR), increase by ~200 mg/day at weekly intervals; usual maintenance 800-1200 mg/day in divided doses (some require up to 1600 mg/day). Trigeminal neuralgia: start 100 mg twice daily (or 200 mg/day), increase by 100-200 mg/day as needed; usual maintenance 400-800 mg/day; max commonly 1200 mg/day. Acute mania/bipolar: start 200 mg twice daily (or 400 mg/day), titrate to clinical response; typical range 400-1600 mg/day.

Initial Dose

100-200mg once or twice daily, titrated gradually

Maintenance Dose

800-1200mg/day in 2-3 divided doses for epilepsy; 400-800mg/day for trigeminal neuralgia

Maximum Dose

Epilepsy: up to 1600 mg/day (some patients may require this); Trigeminal neuralgia: up to 1200 mg/day; Bipolar disorder/acute mania: up to 1600 mg/day.

Children's Dosage

Children 6-12 years: Initial 100mg twice daily, increase by 100mg/day at weekly intervals; Maintenance 400-800mg/day (20-30mg/kg/day). Children under 6 years: 10-20mg/kg/day in 2-3 divided doses. Suspension preferred for young children

Dose Adjustment Notes

Titrate gradually to minimize CNS adverse effects; ER/CR formulations often allow twice‑daily dosing. Dose adjustments are frequently required with CYP3A4 inhibitors/inducers and due to auto‑induction over the first weeks; elderly may need lower starting doses and slower titration.

How to Take

Oral prolonged‑release (CR/XR) tablet: swallow whole with water; do not crush or chew. The scored tablet may be split only to aid swallowing (do not crush/chew). Take consistently with food if GI upset occurs and at evenly spaced intervals.

Side Effects

Common Side Effects

Common: dizziness, drowsiness/somnolence, ataxia, nausea/vomiting, diplopia/blurred vision, headache, fatigue; can also cause rash and hyponatremia.

Side Effect Frequency

Very common (>10%): dizziness, somnolence/drowsiness, ataxia, nausea, vomiting, diplopia/visual disturbance. Common (1-10%): headache, blurred vision, fatigue, rash, hyponatremia, elevated liver enzymes, leukopenia. Rare/very rare: agranulocytosis, aplastic anemia, Stevens-Johnson syndrome/toxic epidermal necrolysis, severe hepatitis/liver failure.

Safety & Warnings

Contraindications

Contraindications: hypersensitivity to carbamazepine or tricyclic antidepressants; bone marrow depression; concomitant MAOIs (or within 14 days); atrioventricular (AV) block; concomitant use with nefazodone; acute hepatic porphyria; concomitant use with voriconazole.

Warnings & Precautions

Key warnings/precautions: screen at-risk patients (especially Asian ancestry) for HLA-B*1502 before starting; baseline and periodic CBC and LFTs; monitor for rash and stop promptly if serious reaction suspected; monitor sodium (hyponatremia/SIADH); avoid abrupt withdrawal; monitor for suicidality; significant CYP induction causing many interactions including reduced hormonal contraceptive efficacy; caution in cardiac disease/conduction disorders; pregnancy counseling/contraception planning.

Age Restriction

No absolute minimum age restriction; pediatric use is permitted (including <6 years) but requires specialist-directed dosing and monitoring.

Driving Warning

May Cause Drowsiness

Drug Interactions

Drug Interactions

Major interactions: strong CYP3A4 inhibitors (e.g., macrolides like erythromycin/clarithromycin, azole antifungals, grapefruit juice) ↑ carbamazepine levels/toxicity; carbamazepine induces CYP3A4/1A2/2C9/2C19/2B6 (per OpenFDA) ↓ levels/efficacy of many drugs (e.g., hormonal contraceptives, warfarin, cyclosporine/tacrolimus, some antipsychotics, methadone, doxycycline); MAOIs contraindicated; notable anticonvulsant interactions (phenytoin/phenobarbital/valproate) alter levels; lithium may ↑ neurotoxicity; clozapine may ↑ hematologic risk.

Interaction Severity

MAJOR/contraindicated: concomitant MAOIs (avoid; require washout), nefazodone (contraindicated), strong CYP3A4 inhibitors such as certain azoles/macrolides can cause toxicity (often avoid/close monitoring), and voriconazole is generally contraindicated due to bidirectional interaction. Clinically significant (often major/moderate): oral contraceptives (reduced efficacy), warfarin (reduced INR/anticoagulant effect), many antiepileptics (e.g., phenytoin/valproate/lamotrigine-complex bidirectional effects), immunosuppressants (e.g., cyclosporine/tacrolimus-reduced levels), and lithium (neurotoxicity risk).

Food Interaction

May take with food to reduce GI upset (and keep administration consistent). Avoid grapefruit/grapefruit juice because it can increase carbamazepine concentrations via CYP3A4 inhibition.

Alcohol Interaction

Avoid

Special Populations

Pregnancy

Category C (prior to 2015); Risk Summary post-2015

Breastfeeding

Caution

Children

Children 6-12 years: Initial 100mg twice daily, increase by 100mg/day at weekly intervals; Maintenance 400-800mg/day (20-30mg/kg/day). Children under 6 years: 10-20mg/kg/day in 2-3 divided doses. Suspension preferred for young children

Elderly

Start at lower doses (100mg once or twice daily), titrate slowly, monitor for hyponatremia, cardiac conduction effects, and CNS side effects; increased sensitivity to adverse effects

Kidney Impairment

No specific renal dose adjustment is generally required; use caution in severe renal impairment and monitor (including sodium and drug levels if indicated).

Liver Impairment

Use with caution in hepatic impairment; avoid/not recommended in severe hepatic impairment and monitor LFTs.

Storage & Patient Advice

Missed Dose

Take the missed dose as soon as remembered; if it is close to the next scheduled dose, skip the missed dose and resume the regular schedule-do not double doses.

Stopping the Medicine

Do not stop abruptly; taper gradually under medical supervision (typically over weeks, individualized).

Overdose

Overdose can cause CNS depression (drowsiness, ataxia, nystagmus, seizures, coma), respiratory depression, and cardiac conduction abnormalities/arrhythmias; management is urgent supportive care with airway/ventilation, ECG monitoring, and activated charcoal (often multiple-dose) ± gastric decontamination as appropriate; no specific antidote-seek emergency care immediately.

Patient Counseling

Swallow CR/XR tablets whole (may split only along score and swallow halves intact); do not crush/chew. Take consistently (with food if GI upset). Do not stop abruptly. Avoid alcohol and grapefruit. May cause dizziness/drowsiness-use caution driving. Use backup contraception with hormonal contraceptives. Seek urgent care for rash/blistering, fever/sore throat, mouth ulcers, unusual bruising/bleeding, jaundice, or severe confusion; keep scheduled labs/levels.

Monitoring Requirements

Baseline and periodic: CBC (with platelets), liver function tests, electrolytes (especially sodium), and serum carbamazepine concentration (typical therapeutic range ~4-12 mcg/mL). Consider HLA‑B*1502 (and often HLA‑A*3101 where applicable) before initiation in at‑risk ancestry; monitor for rash, infection, hepatic symptoms; consider ECG in patients with cardiac disease and pregnancy/contraception counseling.

Pharmacology

Mechanism of Action

Use‑dependent blockade of voltage‑gated sodium channels (preferentially the inactivated state), stabilizing hyperexcited neuronal membranes and reducing repetitive firing and seizure propagation.

Duration of Effect

Approximately 12 hours per dose for the prolonged-release (CR/XR) tablet (typically dosed twice daily).

Half-Life

Single dose: ~25-65 hours; after repeated dosing (autoinduction): ~12-17 hours.

Bioavailability

Approximately 70-85% (extended-/prolonged-release carbamazepine has high but incomplete oral bioavailability, broadly comparable to immediate-release).

Metabolism

Hepatic, primarily via CYP3A4, to an active metabolite (carbamazepine-10,11-epoxide). It is a potent auto-inducer of its own metabolism.

Protein Binding

76% (range 50-88%)

Product Information

Available Dosage Forms

Carbamazepine is available (globally) as immediate‑release tablets, prolonged/extended‑release tablets (CR/XR), chewable tablets, and oral suspension; some markets also have suppositories.

Composition per Dose

Each prolonged-release tablet: 200mg carbamazepine

Generic Availability

Yes

OTC Alternatives

No OTC alternative

Also Used For

Neuropathic Pain, Mood Stabilization, Trigeminal Neuralgia, Bipolar Disorder, Alcohol Withdrawal, Restless Legs Syndrome, Post-herpetic Neuralgia, Diabetic Peripheral Neuropathy

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