Clonidine

Definition

Clonidine belongs to a class of drugs called central alpha-adrenergic agonists. In the United States, clonidine tablets are sold under the brand name Catapres and clonidine skin patches are sold under the brand name Catapres-TTS. The tablets are also available generically. There is also an injectable form that is administered directly into the spinal cord for the treatment of postoperative pain.

Purpose

Clonidine tablets and patches are approved by the United States Food and Drug Administration (FDA) for the treatment of high blood pressure. However, clonidine has been found to be useful in the treatment of alcohol, opiate, and nicotine withdrawal syndromes, attention-deficit/hyperactivity disorder (ADHD), and Tourette's syndrome, one of the tic disorders .

Description

Clonidine was synthesized in 1960s and was initially tested as a nasal decongestant. In the United States, clonidine was first used to treat hypertension although it has also been investigated for treatment of different neuropsychiatric disorders. Clonidine works on specific nerve cells in the brain that are responsible for lowering blood pressure, slowing heart rate, and decreasing the body's reaction to the withdrawal of chemicals like alcohol, opiates, cocaine, and nicotine. Because of this, clonidine is often used to treat the symptoms of drug, alcohol, and nicotine withdrawal.

Clonidine is beneficial in opiate withdrawal because it treats symptoms that are commonly associated with that condition (watery eyes and nose, diarrhea, irritability). For this condition, clonidine is often used alone. For the treatment of alcohol withdrawal, clonidine is usually combined with benzodiazepine tranquilizers such as Librium, Valium, Xanax, or Ativan.

Several studies of treatment for smoking cessation showed patients treated with clonidine had decreased nicotine craving. Clonidine skin patches appear to be more effective than tablets in this condition. Both dermal patches and tablets are effective in the treatment of Tourette's syndrome and ADHD.

Clonidine tablets are available in 0.1-mg, 0.2-mg, and 0.3-mg strengths. Clonidine skin patches are available in 0.1-mg, 0.2-mg, and 0.3-mg per day patches. Each patch lasts seven days.

Recommended dosage

Dosages of 0.4–0.6 mg have been used for the treatment of alcohol withdrawal. Total daily dosage for the treatment of opiate withdrawal range between 0.5 and 1.4 mg, depending on the stage as well as the severity of withdrawal symptoms. If the clonidine patch is used to treat nicotine withdrawal symptoms, dosages that deliver 0.1–.2 mg daily are used. For oral therapy (tablets), a total dosage of 0.2–0.4 mg daily is taken in divided doses.

Pediatric doses of clonidine are calculated based on the child's body weight. Clonidine dosage for ADHD in children is 5 micrograms per kilogram of body weight per day orally in four divided doses. Children who require a daily dosage of 0.2 mg usually can use the 0.3 mg dermal patch. If ADHD is associated with sleep disturbances, low to moderate doses of clonidine can be taken at bedtime. Oral doses in children with Tourette's syndrome range from 3 to 6 micrograms per kilogram of body weight per day divided into two to four even doses.

Precautions

Clonidine should not be used by people who have a known allergy to this drug. If a person has underlying depression, clonidine should be used with caution and under close physician supervision.

Clonidine should not be abruptly withdrawn but rather, slowly decreased over several days to avoid withdrawal symptoms. Withdrawal symptoms include increases in blood pressure, irritability, nervousness, insomnia , and headache. Because of the possibility of withdrawal, clonidine should not be used in patients who are unwilling or unable to follow the prescribing information.

Clonidine should be used only with caution and close physician supervision in patients with chronic renal failure, coronary artery disease, and in patients with preexisting eye problems. Often people with kidney disease should take a reduced dosage. Clonidine should not be used by pregnant women, except in the rare case where the benefits of taking clonidine outweigh the risks to the developing fetus.

Side effects

The most common side effect associated with clonidine is dizziness associated with sudden changes in position such as standing up rapidly. In order to avoid this, atients should stand up slowly. People using the dermal patch may develop rash, hair loss, a burning sensation on the skin, or other skin irritations where the patch is applied. Switching to tablets may not completely eliminate these skin problems, however.

Clonidine can cause dry mouth, constipation, nausea, daytime sleepiness, weakness, and lethargy. These side effects may take several weeks to disappear. In some cases, these side effects can be eliminated with dosage readjustment. In addition, clonidine may cause eye dryness, loss of sex drive, and decreased sexual activity.

If patients experience weight gain in the beginning of therapy, they can expect this side effect to decline over a period of several days to weeks.

Interactions

Clonidine's blood pressure-lowering effects may be enhanced by other drugs that lower blood pressure. Conversely, the blood pressure-lowering effects of clonidine may be negated by many antidepressants.

Resources

BOOKS

Kaplan, Harold. Comprehensive Textbook of Psychiatry. Williams and Wilkins, 1995.

Lacy, Charles F. Drug Information Handbook. Lexi-Comp, Inc. 2002.

PERIODICALS

Kellner, Michael. "Influence of Clonidine on Psychopathological, Endocrine and Respiratory Effects of Cholecystokinin Tetrapeptide In Patients With Panic Disorder." Psychopharmacology. 133 (1997): 55-61.

Ajna Hamidovic, Pharm.D.