Tegretol 100 mg Tablets

Brand Name

Tegretol is the well-known brand name under which this medication is marketed, recognized globally for its utility in managing neurological and psychiatric conditions. It stands as a cornerstone therapy for healthcare professionals addressing specific chronic disorders.

International Nonproprietary Name (INN)

The active substance within this drug is identified by its International Nonproprietary Name (INN) as carbamazepine. This chemical entity, a dibenzazepine derivative, is engineered to provide targeted therapeutic effects in the nervous system.

Forms of Release

Tegretol is offered in multiple formulations to suit a variety of patient needs and administration preferences. These include immediate-release tablets available in 100 mg, 200 mg, and 400 mg strengths, as well as extended-release tablets in 200 mg and 400 mg doses for sustained delivery. Additionally, a chewable tablet form exists at 100 mg, ideal for those who prefer or require an alternative to swallowing whole tablets. An oral suspension is also provided at a concentration of 100 mg/5 mL, offering precise dosing flexibility, particularly for pediatric or elderly patients. Each variant is crafted to optimize the delivery of carbamazepine according to therapeutic demands.

Composition

The principal active ingredient in Tegretol is carbamazepine, responsible for its clinical efficacy. Accompanying this core component are several inactive substances that ensure stability, bioavailability, and ease of use. Immediate-release tablets contain microcrystalline cellulose, sodium starch glycolate, and magnesium stearate, with a coating that may include hypromellose and titanium dioxide. Extended-release tablets incorporate a matrix of ethylcellulose and hydroxypropyl cellulose for controlled release, alongside excipients like colloidal silicon dioxide. Chewable tablets include mannitol and croscarmellose sodium for texture and disintegration, while the oral suspension features sorbitol, propylene glycol, and a citrus-vanilla flavor, with methylparaben as a preservative. These auxiliary elements collectively enhance the drug’s performance and patient tolerability.

Pharmacologic Properties

Pharmacodynamics

This medication exerts its effects by modulating electrical activity within the nervous system. Carbamazepine primarily acts by stabilizing neuronal membranes through its interaction with sodium channels. It limits the influx of sodium ions into nerve cells during depolarization, thereby reducing the frequency of action potentials and preventing the rapid, repetitive firing characteristic of seizures. This stabilizing influence extends beyond epilepsy, calming hyperexcitable neural circuits in conditions like trigeminal neuralgia by dampening pain signal transmission. In mood disorders, such as bipolar disorder, its ability to regulate neurotransmitter imbalances—potentially involving serotonin and dopamine—contributes to mood stabilization, offering a multifaceted approach to managing neurological excitability.

Pharmacokinetics

The pharmacokinetic behavior of Tegretol describes how carbamazepine is handled by the body. After oral administration, absorption occurs gradually from the gastrointestinal tract, with peak plasma levels reached in 4 to 12 hours for immediate-release forms and up to 24 hours for extended-release versions. Bioavailability ranges from 70% to 85%, influenced by food, which enhances absorption. The drug is approximately 76% bound to plasma proteins, mainly albumin, and distributes widely, including into the brain, with a volume of distribution of 0.8 to 1.9 L/kg. It undergoes extensive hepatic metabolism via the cytochrome P450 system, particularly CYP3A4, producing an active metabolite, carbamazepine-10,11-epoxide, which contributes to its effects. Excretion occurs predominantly through urine (about 70%), with a half-life of 25 to 65 hours initially, decreasing to 12 to 17 hours with chronic use due to autoinduction of metabolism.

Indications for Use

This medication is employed to address disorders characterized by abnormal neural activity or chronic pain, capitalizing on its capacity to regulate nerve function across various clinical scenarios.

Diseases and Conditions

Tegretol is indicated for the treatment of epilepsy, specifically partial seizures with complex symptomatology and generalized tonic-clonic seizures, serving as a primary or adjunctive therapy in adults and children over 6 years. It is also approved for relieving pain associated with trigeminal neuralgia, targeting the sharp, electric-shock-like sensations caused by nerve irritation. Additionally, it is utilized in the management of acute manic and mixed episodes in bipolar I disorder, helping to stabilize mood swings and reduce agitation. Its broad therapeutic scope makes it a versatile option for these neurological and psychiatric challenges.

Contraindications

Despite its efficacy, certain conditions preclude the use of this medication due to heightened risks, necessitating thorough evaluation prior to treatment initiation.

Conditions Prohibiting Use

Tegretol is contraindicated in patients with a known hypersensitivity to carbamazepine or related tricyclic compounds, as reactions could range from mild rashes to life-threatening anaphylaxis. It is also prohibited in individuals with a history of bone marrow suppression, such as aplastic anemia or agranulocytosis, due to its potential hematologic toxicity. Patients with atrioventricular block or other severe cardiac conduction abnormalities should avoid it, given its sodium channel-blocking properties. Additionally, concurrent use with monoamine oxidase inhibitors (MAOIs) is forbidden, requiring a 14-day washout period, and it’s contraindicated in those with acute intermittent porphyria, which could be exacerbated by hepatic enzyme induction. These restrictions safeguard against serious adverse outcomes.

Method of Administration and Dosage

How to Take

This medication is taken orally, with administration details varying by formulation. Immediate-release tablets and chewable tablets should be swallowed or chewed with a glass of water, preferably with food to enhance absorption and reduce stomach irritation. Extended-release tablets must be swallowed whole—never crushed or chewed—to maintain their controlled-release profile, and can also be taken with meals. The oral suspension requires shaking well before use, measured with a dosing spoon or syringe, and followed by water to ensure complete intake. Consistent timing, such as dividing doses evenly across the day, supports stable blood levels and optimal efficacy.

Dosages for Adults and Children

Dosing is tailored to the condition, patient age, and response. For epilepsy in adults, treatment typically starts at 200 mg twice daily, increasing by 200 mg/day every week to a usual range of 800–1200 mg/day in divided doses, with a maximum of 1600 mg/day in some cases. Children aged 6–12 begin at 100 mg twice daily, titrating up to 400–800 mg/day, while those over 12 follow adult guidelines. For trigeminal neuralgia, adults initiate at 100 mg twice daily, adjusting to 400–800 mg/day, up to 1200 mg/day if needed. In bipolar disorder, adults start at 200 mg twice daily, targeting 800–1600 mg/day based on efficacy and tolerability. Tegretol’s gradual escalation minimizes initial side effects while achieving therapeutic concentrations.

Dose Adjustment in Specific Conditions

Adjustments are necessary in hepatic or renal impairment. In liver dysfunction, doses should be reduced and monitored closely due to altered metabolism and risk of accumulation, though severe cases may preclude use. Renal impairment requires caution, particularly with glomerular filtration rates below 30 mL/min, where lower doses and extended intervals may be needed, guided by plasma levels. Elderly patients often start at 100 mg twice daily, with slower increases due to heightened sensitivity and potential organ decline, ensuring safety through regular blood monitoring.

Side Effects

This medication can provoke a spectrum of adverse reactions, from mild annoyances to severe complications, and patients should be educated to recognize and address them promptly.

Possible Adverse Reactions

Frequent side effects include dizziness, drowsiness, and unsteadiness, which may affect coordination, especially early in treatment. Nausea, vomiting, and dry mouth are common gastrointestinal complaints, often improving with food or time. Skin rashes occur in up to 10% of users, with rare progression to serious conditions like Stevens-Johnson syndrome or toxic epidermal necrolysis, particularly in those with HLA-B*1502 alleles. Hematologic effects, such as leukopenia or thrombocytopenia, may emerge, while severe cases like aplastic anemia are rare but critical. Neurological symptoms like double vision or headache, and psychiatric effects like confusion or agitation, can also arise, necessitating regular oversight to balance benefits and risks.

Overdose

Symptoms of Overdose

An overdose of Tegretol can produce significant symptoms demanding urgent intervention. These include profound drowsiness, confusion, or coma from nervous system depression, alongside irregular heart rhythms or hypotension reflecting cardiac toxicity. Seizures may paradoxically increase, accompanied by muscle twitching or respiratory suppression in severe instances. Nausea, vomiting, and urinary retention are additional signs, with potential progression to multi-organ dysfunction if untreated. The severity hinges on the dose ingested and individual factors like concurrent medications.

First Aid Measures

In an overdose scenario, immediate action is vital. If the patient is conscious and ingestion was recent, contact emergency services or poison control without inducing vomiting unless instructed. Ensure airway patency and monitor breathing and pulse while awaiting help. In clinical settings, gastric lavage may be performed within an hour of ingestion, followed by activated charcoal to curb absorption. Supportive measures—IV fluids, cardiac monitoring, and oxygen—are essential, with physostigmine considered for anticholinergic effects and hemodialysis for extreme cases, though its efficacy is limited due to high protein binding.

Drug Interactions

Effects on Other Medications

This medication significantly influences other drugs due to its potent induction of hepatic enzymes, particularly CYP3A4. It accelerates the metabolism of agents like warfarin, oral contraceptives, and phenytoin, reducing their efficacy and requiring dose adjustments or alternatives. Conversely, inhibitors like erythromycin or cimetidine can elevate its levels, increasing toxicity risk. It also lowers concentrations of antipsychotics, antidepressants, and immunosuppressants, complicating co-therapy. Careful monitoring and therapeutic drug level checks are crucial to manage these interactions effectively.

Compatibility with Alcohol and Food

Alcohol consumption should be minimized with Tegretol, as it can heighten sedation, dizziness, and liver strain, potentially worsening side effects. Food enhances its absorption, making administration with meals advisable for better tolerability and consistency, though no specific dietary exclusions apply beyond avoiding grapefruit juice, which may inhibit metabolism. Patients should maintain a stable intake pattern to support predictable plasma levels.

Special Precautions

Use During Pregnancy and Breastfeeding

This medication poses risks in pregnancy, with evidence of teratogenicity including spina bifida and craniofacial defects, classifying it as Category D. It should only be used if benefits outweigh risks, with folate supplementation and fetal monitoring advised. Carbamazepine enters breast milk at low levels; while generally compatible, infants should be watched for sedation or poor feeding, with alternatives considered if effects are noted.

Impact on Driving and Operating Machinery

Tegretol may compromise alertness or coordination due to drowsiness, dizziness, or blurred vision, especially during dose initiation or escalation. Patients should avoid driving or machinery operation until they gauge its impact, prioritizing safety in daily tasks.

Considerations for Elderly and Pediatric Patients

In elderly patients, this drug demands cautious use due to increased sensitivity, slower metabolism, and risks like hyponatremia or cardiac effects, starting at 100 mg twice daily with gradual increases and frequent monitoring. In children over 6, it’s effective for epilepsy, with weight-based dosing (10–20 mg/kg/day, up to 35 mg/kg/day) and close supervision for behavioral or hematologic changes, ensuring a tailored approach to safety and efficacy.