Carbamazepine 

Overview

The most well-known use of carbamazepine is as an anticonvulsant, a drug used to treat epilepsy. When patients get a prescription for carbamazepine without a rationale, it may cause confusion for them and their family. Despite the fact that the U.S. Food and Drug Administration has authorized carbamazepine, an extended-release carbamazepine capsule form, has received formal clearance for the treatment of acute mania associated with bipolar illness, as well as epilepsy and nerve pain (trigeminal neuralgia). Beyond its stated indications, carbamazepine has a wide range of applications.
The term “labeled use” refers to the administration of a drug for its authorized uses. However, in clinical practice, doctors often write prescriptions for unapproved (or “off-label”) uses of drugs when published case reports, clinical research and the safety and effectiveness of such medicines are corroborated by their own clinical experiences. For example, carbamazepine may be used off-label to treat bipolar depression, alcohol withdrawal, and certain symptoms related to other ailments, such as personality disorder. For the treatment of bipolar disorder, doctors often prescribe generic carbamazepine, Tegretol, and Tegretol-XR interchangeably.
Clinical research has shown that carbamazepine is a useful treatment for manic episodes. Carbamazepine may also work well in maintenance treatment to stop manic relapses. Patients with treatment-resistant bipolar disorder often respond better to a combination of carbamazepine and another mood stabilizer like lithium. Carbamazepine, either by itself or in conjunction with another mood stabilizer, may be more successful in stabilizing from frequent cycling in some individuals with rapid-cycling bipolar disease (defined as those who have four or more manic or severe depressive episodes annually).

Information about Dosing

When treating bipolar disorder, the first dose of carbamazepine is 200 mg twice a day. Every three to five days, the dose is often raised by 200 mg. Reaching a therapeutic blood level determines the therapeutic dose.
The usual range for dose is 400–1,200 mg daily. Throughout the first four weeks, blood levels of carbamazepine should be checked every week to make sure that sufficient levels are reached to elicit the desired therapeutic effect.
Despite the fact that therapeutic levels may be reached with a certain dose, the levels may significantly decline in two to four weeks. This is because carbamazepine has the capacity to increase metabolism. The dose for the patient may have to be raised once more in order to reach the intended therapeutic level.

Additionally, carbamazepine comes in tablet and extended-release capsule forms that only need to be taken once daily. Additionally, carbamazepine is available in a liquid formulation with a dosage of 100 mg per milliliter.

Typical Side Effects 

The most typical side effects of carbamazepine are nausea, dizziness, fatigue, and drowsiness. Patients may develop double vision (diplopia) or jerky eye movements (nystagmus) at larger doses, along with clumsiness or coordination. These adverse effects usually pass quickly when a person becomes used to the medication.

Adverse Events and Safety Measures

Particularly at the beginning of treatment, carbamazepine may make you drowsy and less alert. Patients who drive or undertake other duties requiring awareness should drive cautiously.
Carbamazepine side effects that are very uncommon but possibly lethal include aplastic anemia and agranulocytosis. Leukopenia, or a sharp decline in the concentration of white blood cells, is the hallmark of agranulocytosis. A person is vulnerable to potentially fatal infections when their white blood cell type, known as granulocytes, which are crucial for battling infections, are drastically reduced (agranulocytosis, or lacking granulocytes). There is extremely little chance of agranulocytosis brought on by carbamazepine.
When treatment is started early and carbamazepine is stopped, people fully recover. Early warning indicators of infection, such as fever, malaise, and sore throat, should be brought to the doctor’s notice.
When carbamazepine is used with other medications that enhance the risk of agranulocytosis, the risk may rise. For instance, it is not recommended to use carbamazepine with (clozapine) because agranulocytosis risk may rise as a result of the combo.
Aplastic anemia, an uncommon and possibly deadly adverse response, is characterized by the bone marrow’s failure to produce red blood cells, white blood cells, and platelets all of which are necessary for blood clotting.

However, there is extremely little chance that carbamazepine may cause aplastic anemia. If that happens, the person could become anemic from low red blood cells, infections from low white blood cells, and irregular bleeding from low platelets. Before starting therapy, some doctors would request a full blood count.
Because aplastic anemia caused by carbamazepine is so uncommon, many people do not test on a regular basis. Rather, the doctor will advise the patient to report uncontrollable infections, bruising that occurs often, and bleeding tendencies that occur frequently (such as bleeding when cleaning teeth), as well as extended bleeding periods.
Liver damage is infrequent while using carbamazepine; instead, liver enzyme levels are sometimes slightly elevated.

Usually, the rise of liver enzymes is temporary, and levels gradually revert to normal. However, when liver enzyme levels are increased, careful monitoring of liver function is necessary. Stopping the carbamazepine if liver enzyme levels rise to three times normal, could be required.

Use of carbamazepine during pregnancy and lactation: Pregnancy Category D

Carbamazepine may damage the fetus once it crosses the placenta. Carbamazepine during pregnancy has been linked to cases of babies with developmental delays, deformities of the head and face, and spinal cord problems (spina bifida). When carbamazepine is used during the first trimester, the risk seems to be greatest. Therefore, if at all feasible, avoid using carbamazepine during pregnancy, particularly the first trimester. However, if the doctor stops taking carbamazepine and mania returns, they may talk about the need to resume the medicine after the first trimester or look for another one.
Carbamazepine should not be given to nursing women since it is secreted in breast milk and might damage the unborn child if consumed. Breastfeeding should not begin or should be stopped if quitting the medication is not an option. 

Potential Interactions with Drugs

The liver enzymes that metabolize a wide range of drugs, including carbamazepine, may be impacted by carbamazepine, which can reduce the concentration and lessen the efficacy of the treatments. In contrast, Carbamazepine’s metabolism may be hampered and its levels raised by other drugs. The following table provides an overview of the clinically significant medication interactions associated with carbamazepine.

Alcohol consumption should be avoided by patients on carbamazepine since this combination may worsen sleepiness and sedation. Furthermore, alcohol’s sedative properties may have a depressive impact, masking the therapeutic benefits of carbamazepine and making therapy more difficult.
(fluoxetine), (fluconazole), (verapamil), (diltiazem), Erythromycin, (clarithromycin), (fluvoxamine), (divalproex), and (cimetidine), Isoniazid (e.g., INH), (propoxyphene), (itraconazole), and grapefruit extract; When used with carbamazepine, these drugs may raise the blood levels of carbamazepine up to lethal doses. When these drugs are used in addition to carbamazepine, their dosages may need to be reduced. 

Oral contraceptives, Theophylline, (felodipine), benzodiazepines, (haloperidol), Phenothiazines (e.g., thioridazine), (bupropion), (warfarin), (phenytoin), and theophylline; Combining these medications with carbamazepine may cause their blood levels to drop and their efficacy to decrease. 
If an oral contraceptive is successful, it may result in an unwanted pregnancy. 
Neuromuscular abnormalities, such as rapid eye movements (nystagmus), jerky muscle jerks (myoclonus), heightened reflex responses (hyperreflexia), and extreme nausea and vomiting, are examples of toxicity.

Overdosing 

The level of carbamazepine that is consumed determines how poisonous the symptoms are, and overdosing on it is quite dangerous. The deadly dosage in tiny children is far smaller than in adults. Overdose may be fatal, particularly in young infants, causing respiratory depression, convulsions, cardiac arrhythmia, shock, and coma. 
Treating any suspected overdose as an emergency is imperative. The individual has to be brought to the emergency space for care and observation. It is advisable to include both the prescription bottle of medicine and any other medication suspected in the overdose, since the information on the label may be useful in helping the treating physician figure out how many tablets the patient has taken. 

Precaution Points to Remember

• If you forget to take a dosage, catch up by taking it two to three hours later than planned. If it’s near, Skip the missed dosage and resume your usual dosing regimen for the next scheduled dose. Never take two doses at once.
• To lessen unpleasant stomach, use carbamazepine right after meals or with food.
• If you have recurrent infection symptoms, such as fever, sore throat, malaise, or unexpected bleeding or bruising, get in touch with your doctor.
• Carbamazepine may affect your attention and produce sleepiness and drowsiness, particularly during the start of treatment. When driving or doing other duties that call for attentiveness, proceed with care.
• Keep the medicine out of direct sunlight and dampness, in the light-resistant container that came with it. Your drug may break down more quickly in hot and humid environments, losing its therapeutic benefits.
• Keep your medicine out of children’s reach since it may be very harmful for young children to overdose.