Zeptol CR

Carbamazepine.

ZEPTOL CR contains carbamazepine controlled release formulation and is available as 200 mg and 400 mg tablets. Carbamazepine is an iminostilbene used widely for treatment of epilepsy.

Pharmacology: Pharmacodynamics: Mechanism of Action: The exact mechanism of action of carbamazepine is unknown. Present evidence strongly suggests that carbamazepine mediates its therapeutic effects by slowing recovery of voltage-sensitive sodium channels of neurons from inactivation. The slowed down recovery leads to prolonged inactivation and results in inhibition of neuronal repetitive firing potential. Clinically, Carbamazepine is effective as a primary drug for tonic clonic seizures, partial seizures and for non-epileptic disorders like mania and trigeminal neuralgia.
Pharmacokinetics: Upon oral administration, 72 to 96% of the dose of carbamazepine is absorbed. Maximum plasma concentrations are obtained between 6 to 24 hours following drug administration. Plasma protein binding is 75%. Volume of distribution is 2 L/kg body weight. It is extensively metabolised in the liver. Carbamazepine 10, 11 epoxide is an active metabolite. 1% is excreted unchanged in urine. Elimination half-life is 30 to 40 h. Carbamazepine is an enzyme inducer in the liver and hence several drug interactions may occur. Steady state levels are 4-12 mcg/ml while toxicity appears at 15 mcg/ml and above. Carbamazepine crosses placenta and is secreted into breastmilk.

Tonic clonic seizures.
Partial epilepsy.
Resistant maniac depressive psychoses.
Treatment of hypomania and mania.
Also used in trigeminal neuralgia and chronic pain.

ZEPTOL CR is a controlled release formulation for oral administration. The distinct advantages are reduced peak plasma concentrations and reduced fluctuations in plasma concentration throughout the day. Therefore, ZEPTOL CR can be given twice daily. The tablet should not be chewed but swallowed wholly with little liquid during meal or after meal. 100-200 mg once or twice daily is the initiation dose. Carefully observe the response and give small increments of 200 mg/week until the best response is obtained which is usually at the range of 800-1200 mg per day (400 mg bid or 600 mg bid). In elderly, there is no specific reason for dosage adjustments in the absence of liver, kidney or heart disease. However, a smaller initiation dose is recommended. In children (age more than 5 years), the dose is 10-20 mg/kg body weight in 2 divided doses. The preparation is not recommended for children below 5 years. 400-600 mg per day and 600-1000 mg per day is the maximum recommended dose for children aged 5-10 years and 10-15 years, respectively.
For trigeminal neuralgia, the dose is variable and should be individualised on the basis of weight, age and reduction in pain. For majority of the patients, ZEPTOL CR doses of 600-800 mg are adequate for complete pain relief. ZEPTOL CR should be recommended ideally during acute stage and not for prophylaxis.

Tremor, excitation, convulsions, unstable blood pressure, coma and cardiac arrhythmias are known to occur. There is no specific antidote. Activated charcoal, gastric lavage and symptomatic supportive therapy are the mainstay.

Hypersensitivity to carbamazepine.
Previous history of acute intermittent porphyria.
Atrioventricular conduction blockade.
Absence attack (Petit mal).

In patients with serious heart disease, liver or kidney disorders and in elderly patients, the initiation dose of carbamazepine controlled release should be low. Before starting therapy liver function tests and complete hemogram should be performed. Periodic blood counts and liver function observations should be made. An alteration in liver condition or occurrence of neutropenia, leucopenia and thrombocytopenia should lead to cessation of therapy. However, non-progressive asymptomatic neutropenia does not warrant cessation of therapy. Treatment should not be stopped abruptly, if abrupt cessation is necessary then it should be under the cover of benzodiazepines. In early stages of therapy, sedation and marked motor impairment occur, therefore, patient should be advised against driving and operating machinery.

Conclusive evidence that carbamazepine when given alone leads to congenital abnormalities or increases the risk of abnormalities is not available. In view of lack of adequate and rigorously controlled clinical trial data, carbamazepine should be prescribed if and only if the potential benefits outweigh the potential risks. Folic acid supplementation should always be given before and during pregnancy because carbamazepine aggravates its deficiency.

Sedation, ataxia, visual problems, headache and confusion; dry mouth, nausea, constipation, loss of appetite; skin allergy, serious exfoliative dermatitis, acne, blood dyscrasias, pedal edema. Rarely, hepatitis and anaphylaxis.

Oral contraceptives, anticoagulants, other antiepileptics, hormones, MAO inhibitor therapy, erythromycin, isoniazid, calcium channel blockers and cimetidine are known to cause significant interactions. Alcohol and psychoactive drugs exacerbate CNS side effects of carbamazepine. Carbamazepine increases lithium neurotoxicity.

Anticonvulsants / Drugs for Neuropathic Pain

N03AF01 - carbamazepine ; Belongs to the class of carboxamide derivatives antiepileptic.

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