Oxcarbazepine By LCMS

What is Oxcarbazepine?

It is a drug patented in 1969 and came into medical use in 1990. It is used to treat Epilepsy and sold by the brand name Trileptal. Now it is a generic drug and available in the market with different brands. Later with further research oxcarbazepine is also used to treat Bipolar disorder and Trigeminal neuralgia.

What is the difference between Oxcarbazepine and Carbamazepine?

Oxcarbazepine is a structural analog of carbamazepine with differences in the metabolic pathway they follow. Carbamazepine is converted to an epoxide metabolite whereas oxcarbazepine is rapidly converted to Monohydroxy derivative ( MHD) which helps in reducing side effects and other drug interactions.

What is its Mechanism of action?

It is a Sodium channel blocker that leads to the decreased generation of action potential and subsequent firing from the cell leading to reduced chances of convulsions.

What is Convulsion?

Convulsions are uncontrolled multiple cycles of spasm and relaxations of muscles.

What is a Seizure?

Seizures are the result of electrical disturbances in the brain. The most common types of seizures are Grand mal (unconsciousness, convulsion, rigidity); Absence (Brief loss of consciousness); Myoclonic ( sporadic jerking movement ); Clonic ( repetitive jerking movement); Tonic ( muscle stiffness ); Atonic ( loss of muscle tone ).

Is convulsion and seizure the same?

Although these terms are interchangeably used, a seizure may or may not lead to convulsion.

What is Bipolar disorder?

It is a mental health condition in which a person experiences mood swings ranging from mania to depression. Each episode may last for days or even months.

What is Trigeminal Neuralgia?

It is a neuropathic condition arising from the 5th cranial nerve i.e. Trigeminal nerve which is widely distributed in the facial area, due to its lesion or inflammation leading to chronic pain over the face.

Why does one need to get tested for Oxcarbazepine level?

Oxcarbazepine is used in multiple medical conditions such as convulsions, bipolar disorder, trigeminal neuralgia, ADHD, to alleviate alcohol withdrawal symptoms. While starting the treating physician will prescribe this test to know whether the appropriate therapeutic blood level of the drug is achieved or not and adjust the dosage accordingly. The later test will be done at regular intervals for dose monitoring.

It is very important to monitor the blood level of this drug as it has a very narrow therapeutic range. If the concentration is low symptoms might recur and if it is above the upper limit then toxicity might precipitate. As this drug is used for chronic conditions this test needs to be done multiple times over the course of treatment.

What can interfere with blood Oxcarbazepine level?

It is primarily an orally administered drug that is absorbed from the intestinal tract, then gets metabolized in the liver. In blood, it is mostly bound to albumin which is an inactive form, and only unbound form is active. Its metabolites also possess similar properties. Any disorder of the intestine or liver might affect its level. Kidney conditions that alter blood protein levels may lead to altered effectiveness of the drug. Apart from this many drugs that are used to treat similar conditions or different illnesses interfere with its metabolism.

What is its Toxicity?

Side effects are dose-dependent. General adverse effects are Hyponatremia, dizziness, sleepiness, headache, blurred vision, difficulty in motor coordination. Measurement of serum sodium levels should be closely monitored while on treatment. It causes bone marrow suppression leading to a decrease in RBC, WBC, and Platelets. If alcohol is consumed when on treatment it may lead to excessive suppression of CNS. People of Asian origin who might carry a special Human Leucocyte Antigen allele HLA-B1502 have a higher risk of developing serious and life-threatening side effects Stevens-Johnson syndrome, Toxic epidermal necrolysis.

Is it safe in pregnancy and lactation?

It is considered teratogenic to a human fetus. Oxcarbazepine and its metabolite licarbazepine are both present in human breast milk hence should only be used in pregnancy and lactation only if the benefit justifies the risk.

Which test should be done along with it?

People of Asian origin should be tested for HLA B 1502 allele which significantly increases the risk of severe side effects. This drug acts by blocking sodium channels which may lead to hyponatremia, hence patients must be monitored for serum electrolytes and seek medical help if symptoms of hyponatremia appear such as dizziness, lethargy, fatigue.

What precautions should be taken while on treatment?

People must not modify the dose of medication without consulting the treating doctor. This might result in an increased risk of seizure and may interfere with another medication metabolism. People should tell their physician about any other prescription drug or Herbal or Ayurvedic supplement they are taking. One should also remember that this drug interferes with the metabolism of hormonal contraceptives and may lead to their failure. Hence, non-hormonal contraceptives should also be used.