What Factors Affect a Sufficient Carbamazepine Dose?

The anticonvulsant drug carbamazepine is most commonly used in the treatment of neuropathic pain, trigeminal neuralgia, and seizure disorders like epilepsy. Carbamazepine is also used as a therapeutic adjunct in the management of schizophrenia and has shown some promise as a substitute for lithium in the treatment of bipolar disorder. Like many drugs in its class, the medication has been prescribed experimentally for a wide variety of unapproved uses, including attention-deficit hyperactivity disorder, intermittent explosive disorder, phantom limb syndrome, complex regional pain syndrome, paroxysmal extreme pain syndrome, neuromyotonia, and post-traumatic stress. Due to the risk of life-threatening side-effects, however, this medication should only be used when necessary and at the lowest adequate dosage level. Factors like the patient's condition, age and drug regimen may affect the initial carbamazepine dose a patient should receive, necessitating a dosage adjustment.

When giving this medication for any condition, a low initial daily carbamazepine dose should be used and only gradually increased to the point of therapeutic efficacy. Once a given carbamazepine dose is able to manage a condition, the level may be slowly reduced to the lowest effective dosage. If switching a patient to carbamazepine from another anticonvulsant drug, it is essential that the patient be closely monitored while the carbamazepine dose is gradually increased and the other medications are reduced. The drug phenytoin is an exception, as it may need to be increased when combined with carbamazepine rather than reduced.

If the patient has never before taken any anticonvulsant medications, then an initial immediate or extended release carbamazepine dose of 100 mg should be given orally twice per day to treat epilepsy. A maintenance dose of 800 to 1,200 mg may be given, although in most cases the daily dosage should not exceed 1,200 mg. Increases of 200 mg to the initial daily dose should be evaluated on a weekly basis.

Children under the age of 13 should receive a lower initial and maximum carbamazepine dose. Those between the ages of six and 12 can be given 100 mg of the immediate or extended release forms two times daily, plus a maintenance dose of up to a maximum of 800 mg. The initial dose for children under six years of age should be a total daily carbemezepine dose of 10 to 20 mg per kg of body weight in two to three divided doses. Dosage increases should be evaluated on a weekly basis, with children under six taking no more than 35 mg/kg daily and children between six and 12 taking no more than 1,000 mg daily.

The carbamazepine dose for the treatment of diabetic neuropathy is initially 100 mg given orally twice daily, with 100 mg increases to the daily dose evaluated every one to two weeks. A maintenance dose between 600 and 1,200 mg in three to four divided doses may be administered in three or four divided doses. When treating trigeminal neuralgia, the same initial dose can be used, but the recommended maintenance dose is only 400 to 800 mg given daily. Dosage increases can be as high as 200 mg per day in two divided doses. Every three months, an attempt should be made to reduce or discontinue the use of this drug for the treatment of neuralgia.