Carbamazepine

Carbamazepine is an anticonvulsant, a type of pharmaceutical that controls seizures by reducing abnormal electrical activity in the brain. It is sold under the brand names Carbatrol, Epitol, Equetro, Tegretol, and Tegretol XR.

Why It's Prescribed
Carbamazepine is prescribed to control seizures and to treat trigeminal neuralgia (a condition that causes facial nerve pain). Additionally, the Equetro brand of Carbamazepine extended-release capsules is used to treat episodes of mania or mixed episodes (simultaneous symptoms of mania and depression) in patients with bipolar disorder.

Carbamazepine's labeled uses include: Complex-Partial Epilepsy, Epilepsy, Mixed Epilepsy, Tonic-Clonic Epilepsy, Trigeminal Neuralgia. Additionally, its unlabeled uses include: Attention-Deficit Hyperactivity Disorder, Bipolar Disorder in Remission, Manic Bipolar Disorder, Mixed Bipolar I Disorder, Neuralgia, Prevention of Seizures following Cranial Trauma or Surgery, and Restless Legs Syndrome.

Form, Route, and Dosage
Carbamazepine is available as a tablet, a chewable tablet, an extended-release (long-acting) tablet, an extended-release capsule, and a suspension (liquid) to be taken orally. It comes in the strengths 100mg/5ml (suspension), 100mg, 200mg, and 400mg. Adults are prescribed up to 400mg every 6 hours, or 1600mg in 24 hours.

Side Effects
Carbamazepine may cause the following side effects:
 * drowsiness
 * dizziness
 * unsteadiness
 * nausea
 * vomiting
 * headache
 * anxiety
 * memory problems
 * diarrhea
 * constipation
 * heartburn
 * dry mouth
 * back pain
 * confusion
 * loss of contact with reality
 * chest pain
 * yellowing of the skin or eyes
 * vision problems

Overdoses
Patients may suffer an overdose if they take too much carbamazepine. If one overdoses, the following symptoms may occur:
 * unconsciousness
 * seizures
 * restlessness
 * muscle twitching
 * abnormal movements
 * shaking of a part of your body that you cannot control
 * unsteadiness
 * drowsiness
 * dizziness
 * blurred vision
 * irregular or slowed breathing
 * rapid or pounding heartbeat
 * nausea
 * vomiting
 * difficulty urinating

Warnings
Carbamazepine can sometimes cause life-threatening allergic reactions called Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN), causing severe damage to both skin and internal organs. The risk of this occurring is highest in people of Asian descent who have a genetic risk factor. Doctors can test for the risk factor before prescribing carbamazepine, and if a patient tests positive, they can prescribe a different drug with lower risk. Patients are instructed to contact their doctors immediately if they develop a rash, blisters, or fever while taking carbamazepine.

Carbamazepine may also decrease the number of blood cells produced by the patient's body. In rare cases, this may result in serious or life-threatening health problems. Patients are instructed to call their doctor if they experience the following symptoms: sore throat, fever, chills, or other signs of infection; unusual bleeding or bruising; tiny purple dots or spots on the skin; mouth sores; or rash.

As a Pollutant
Because humans and animals often do not fully metabolize pharmaceuticals in their body, they can excrete drugs or their breakdown products, which may the enter the environment.

In Sewage Sludge
Carbamazepine has been found in sewage sludge. In the Targeted National Sewage Sludge Survey, a 2009 test of 84 samples of sewage sludge from around the U.S., the EPA found carbamazepine in 80 samples (95%) in concentrations ranging from 8.74 to 6,030 parts per billion. There are no federal regulations governing how much of this drug may be present in sewage sludge applied to land as fertilizer.

Plant Uptake of Sludge Contaminants
Several pharmaceuticals are routinely found in sewage sludge and effluent from wastewater treatment plants, which are then used to fertilize or irrigate farm fields. A study by researchers at the University of Toledo simulated both fertilization with sewage sludge and irrigation with wastewater laced with three three pharmaceuticals, carbamazepine, diphenhydramine (Benadryl), and fluoxetine (Prozac), and two personal care products, triclosan and triclocarban, to then examine their uptake by soybean plants. The study found that, "With the exception of fluoxetine, all of the chemicals accumulated in the plant tissues from exposure to both wastewater and biosolids. The greatest accumulation was observed for carbamazepine, triclosan and tricloarban. Concentrations increased in the plant tissues up to six times the levels present in the biosolid amended soils. Greater accumulation of all chemicals was found in the soybeans exposed to soils treated with biosolids; however, this may be partially due to the naturally higher concentrations of these chemicals in the biosolids versus the wastewater."

In Drinking Water
An Associated Press investigation found that, of 62 metropolitan areas in the U.S., only 28 tested for pharmaceuticals, and 24 found pharmaceuticals in the drinking water when they tested it. The following cities tested positive for carbamazepine: Las Vegas, Louisville, Ky., Northern New Jersey, Philadelphia, Tucson, AZ, and Washington, DC.

Related SourceWatch articles

 * Biosolids
 * Sewage sludge
 * Food Rights Network
 * Pharmaceuticals

External resources

 * Carbamazepine: MedlinePlus Drug Information

External articles
"Survey: Three pharmaceutical drugs are found in Tucson water", Associated Press, March 10, 2008.