Methylphenidate

Methylphenidate, prescription drug classified as a stimulant and used chiefly in the treatment of narcolepsy in adults and attention-deficit hyperactivity disorders (ADHD) in children. It is also used to treat mild to moderate depression and manage social withdrawal in the elderly. Methylphenidate tends to improve alertness and concentration and increases learning ability and attention span, presumably by activating the brain stem.

Methylphenidates are sold under the brand names Concerta, Methylin, Metadate, and Ritalin. About 2.5 million children and 1.5 million adults in the United States take these drugs each year.

In February 2006 a special advisory panel to the Food and Drug Administration recommended in an 8-to-7 vote that “black box” warnings be placed on the labels of these drugs to alert physicians and patients to possible serious effects on the heart and increased risk of heart attack, stroke, or sudden death. Fewer than 10 percent of prescription drugs carry black-box warnings. The warnings mean that the drug could pose significant risks, but doubts about the drug’s safety are not serious enough to withdraw it from the market. Although the panel divided over whether to issue black-box warnings, it agreed unanimously that brochures should be distributed with the drugs to inform patients and their families about the benefits and risks of taking the drugs. The FDA delayed taking any action on the recommendation until it heard from a second advisory panel made up of pediatricians and psychiatrists who are most likely to prescribe the medications. Recommendations are not binding, but the FDA usually follows the advice of its advisory panels.

The first advisory panel was made up of drug safety experts. Their recommendation came after receiving reports of 25 sudden deaths among patients taking methylphenidates or amphetamines. A preliminary analysis of millions of health records also indicated that these stimulants increased the risk of stroke and serious arrhythmias in children and adults (see Palpitation). The panel noted that the stimulants are known to increase blood pressure and heart rate and that increased blood pressure is directly linked to heart problems.

Although the drugs are prescribed most often to treat ADHD among children, increasingly adults are taking the drugs for ADHD. From 2002 to 2005 the number of prescriptions written for adults reportedly increased by 90 percent. A member of the FDA advisory panel noted that adults are more likely to have a higher risk of heart problems. Most of the 25 sudden deaths, however, were among children. Numerous studies have demonstrated the safety of Ritalin, which first went on the market in 1955, but no studies have been done to evaluate the long-term effects of taking these stimulants. Novartis Pharmaceuticals, the maker of Ritalin, and Shire Pharmaceuticals, which manufactures the amphetamine Adderall, defended the safety of their products.

Methylphenidate is available by prescription only and is taken orally. It comes in 5-mg, 10-mg, and 20-mg regular tablets, and in 20-mg sustained release tablets. The typical adult dosage in regular tablet form is 5 to 20 mg taken two or three times a day, preferably 30 to 45 minutes before a meal. For sustained release tablets, the dosage is one 20-mg tablet one to three times a day (every 8 hours), preferably on an empty stomach. Adults over the age of 60 usually begin with small doses. For ADHD in children 6 years old and older, the initial dosage in regular tablets is 5 mg twice a day, taken before breakfast and lunch. This dosage may be increased by 5 to 10 mg per week to a maximum dosage of 60 mg per day. For sustained release tablets, the dosage is one 20-mg tablet one to three times a day. The effectiveness of this drug can usually be determined in three to four weeks.

Methylphenidate can be taken with food or milk to prevent stomach upset. The regular tablet can be crushed, but the sustained release tablet should be taken whole. This drug should not be used by persons who have had a previous allergic reaction to it; pregnant or breast-feeding women; persons with glaucoma, anxiety, nervous tension, severe depression, or Tourette’s syndrome; or children with major psychiatric disorders or acute stress. It should be used with caution by persons with reduced liver function. The safety and effectiveness of the drug in children under the age of six have not been determined. Driving and other risk-related activities may need to be restricted if alertness is impaired. This drug should not be discontinued abruptly if used for an extended period but should be tapered off to avoid severe depression and erratic behavior.

The most common side effects of methylphenidate are nervousness and insomnia. It may also cause dizziness and drowsiness, headache, nausea, a dry mouth, loss of appetite, stomach pain, and weight loss with long-term use. Long-term use has the potential for serious psychological dependence and may interfere with normal growth in children.

Methylphenidate may interact adversely with foods and beverages containing large amounts of tyramine, a chemical that raises blood pressure. Foods and beverages high in tyramine include aged cheeses, avocado, bean curd, bologna, chocolate, canned fish, dried and salted fish, pickled herring, liver, meat extracts, meat tenderizers, pepperoni, raisins, raspberries, salami, sour cream, soy sauce, yeast extracts, unpasteurized beer, chianti, sherry, and vermouth. Caffeine should not be taken in any form. Methylphenidate may also interact adversely with certain drugs including tricyclic antidepressants such as amitriptyline, desipramine, imipramine, and nortriptyline; other antidepressant drugs known as monoamine oxidase (MAO) inhibitors such as isocarboxazid, pargyline, phenelzine, and tranylcypromine; high blood pressure medications (especially guanethidine); oral anticoagulants (blood thinners) such as warfarin; anticonvulsants such as phenytoin, phenobarbital, and primidone; and the nonsteroidal anti-inflammatory drug phenylbutazone.

Brand Names: Concerta, Methylin, Metadate, Ritalin, Ritalin-SR