Methylphenidate



Methylphenidate 994
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Definition

Methylphenidate is a mild, central nervous system stimulant. In the United States, the drug is sold under the brand name Ritalin.

Purpose

Methylphenidate is used primarily in the treatment of attention-deficit/hyperactivity disorder (ADHD) in children and adults. It also may be used to treat the sleep disorder, narcolepsy . In rare cases, it is used to decrease sedation and lethargy from opioid pain medications and to help improve the mood of a terminally ill person suffering from depression.

Description

The mode of action for methylphenidate is not fully understood. It presumably activates the brain stem arousal system and cortex to produce a stimulant effect. The brain stem arousal system increases levels of electrical activity in the brain. The effect of methylphenidate is to produce increased alertness and, although children with ADHD are overactive and have decreased attention spans, in these children, methylphenidate actually decreases motor restlessness and increases attention span. Tablets are available in 5-, 10-, and 20-mg strengths, as well as in an extended release, 20-mg tablet.

Recommended dosage

The recommended dosage of methylphenidate is determined by trial and error based on individual responses. Methylphenidate is usually administered in two or three separate doses each day, preferably 45 minutes before a meal. For children suffering from ADHD, the initial recommended dosage is 5 mg twice daily before breakfast and lunch, increased by 5–10 mg per week to a maximum of 60 mg per day. The average total dosage is 20–30 mg per day, although 10–60 mg is not uncommon. For narcolepsy in adults, the recommended dose is 5–20 mg two to three times a day, 30–45 minutes before meals.

The drug should be taken exactly as directed. Methylphenidate can become habit forming if taken in greater amounts or for longer periods than necessary. Individuals should take the last dose of the day before 6 P.M. to decrease sleep difficulties. The tablet should not be broken or crushed, as this changes the time for absorption. If the normal time of administration is missed, people should take the drug as soon as possible. However, two tablets should not be taken at the same time.

Precautions

Methylphenidate has a great potential to produce physical and mental dependence. Administration should not be stopped abruptly. Such action can cause withdrawal symptoms including depression, paranoid feelings, thoughts of suicide , anxiety, agitation, and sleep disturbances. Methylphenidate should not be given to people with extreme anxiety, tension, agitation, severe depression, mental or emotional instability, or a history of alcohol or drug abuse. It is not indicated for use by those with Tourette's syndrome, people with tic disorders , glaucoma, or certain mental health conditions. The drug should be used cautiously by those with high blood pressure, those with a history of seizures , and women who are breast-feeding. Methylphenidate is not typically ordered for women during their childbearing years, unless the physician determines that the benefits outweigh the risks.

Methylphenidate should not be ordered for children younger than six years of age as its safety has not been determined in this age group. People should not drive or operate machinery or appliances until they understand how this drug affects them. They should not drive if they become lightheaded or dizzy. Methylphenidate may cause irregularities in the composition of the blood and produce changes in liver function. People taking methylphenidate should receive regular blood tests.

Side effects

The most common side effects are nervousness, difficulties with sleep, tachycardia, and increased blood pressure. Reducing the dose or changing the time the drug is taken may reduce some side effects. Affected persons should discuss any adverse reactions with their health care professional. Individuals taking methylphenidate should receive regular blood pressure and pulse checks. Methylphenidate also may cause dizziness, irritability, vision changes, drowsiness, and a poor appetite. Less common side effects include chest pain, palpitations, joint pain, skin rash, and uncontrolled movements or speech. Side effects may also include a rapid or irregular heartbeat, stomach upset, nausea, headache, blood in the urine or stools, muscle cramps, red dots on the skin, or bruises. At higher dosages or with long-term use, people may experience weight loss or mental changes such as confusion, false beliefs, mood changes, hallucinations , or feelings that they or their environment are not real.

Interactions

Several drugs may interact adversely with methylphenidate, including anticoagulants and drugs to prevent seizures, combat depression, and treat high blood pressure. The dosages of these drugs may be reduced when taken simultaneously with methylphenidate.

Resources

BOOKS

Adams, Michael and Norman Holland. Core Concepts in Pharmacology. Philadelphia: Lippincott-Raven, 1998.

Breggin, Peter R. and Dick Scruggs. Talking Back to Ritalin: What Doctors Aren't Telling You About Stimulants and ADHD. Boulder, CO: Perseus Book Group, 2001.

Foreman, John C. and Torben Johansen. Textbook of Receptor Pharmacology. 2nd Ed. Boca Raton, FL: CRC Press,2002.

Markowitz, John S., and C. Lindsay DeVane. The Ritalin Handbook. Kearney, NJ: Morris Publishing, 2000.

Page, Clive P. and Michael Murphy. Integrated Pharmacology. St. Louis: Mosby-Year Book, 2002.

Von Boxtel, Chris, Budiono Santoso, and I. Ralph Edwards. Drug Benefits and Risks: International Textbook of Clinical Pharmacology. New York: John Wiley and Sons,2001.

PERIODICALS

Miller, A. R., C. E. Lalonde, K. M. McGrail, and R. W. Armstrong. "Prescription of methylphenidate to children and youth, 1990-1996." Canadian Medical Journal (2001) 165, no. 11: 1489-1494.

Perring C. "Medicating children: the case of Ritalin." Bioethics (1997) 11, no. 3-4: 228-240.

Sund, A. M., and P. Zeiner. "Does extended medication with amphetamine or methylphenidate reduce growth in hyperactive children?" Norwegian Journal of Psychiatry (2002) 56, no. 1: 53-57.

ORGANIZATIONS

American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. Telephone:(913) 906-6000. Web site: <http://www.aafp.org> .

American College of Physicians. 190 N Independence Mall West, Philadelphia, PA 19106-1572. Telephone: (800) 523-1546, x2600 or (215) 351-2600. Web site: <http://www.acponline.org> .

American Medical Association. 515 N. State Street, Chicago, IL 60610. Telephone: (312) 464-5000. Web site: <http://www.ama-assn.org> .

American Psychiatric Association. 1400 K Street NW, Washington, DC 20005. Telephone: (888) 357-7924. Fax(202) 682-6850.

American Society for Clinical Pharmacology and Therapeutics; 528 North Washington Street, Alexandria, VA 22314; Phone: (703) 836-6981. Fax: (703) 836-5223.

American Society for Pharmacology and Experimental Therapeutics. 9650 Rockville Pike, Bethesda, MD 20814-3995. Telephone: (301) 530-7060.

National Institute on Drug Abuse: <http://www.nida.nih.gov/Infofax/ritalin.html> .

Nurse's PDR Resource Center. <http://www.nursespdr.com/members/database/> .

L. Fleming Fallon, Jr., M.D., Dr.P.H.



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