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Frequently Asked Questions About Alpha-2-Adrenoreceptor Agonists and ADHD

This article answers some common questions about the treatment of ADHD with Alpha-2-Adrenoreceptor Agonists.

Frequently Asked Questions About Alpha-2-Adrenoreceptor Agonists and ADHD

What are the effects of Catapres and Tenex on ADHD?
These drugs are most widely used as blood pressure medications, but they're seeing use as an alternative to stimulants for treatment of ADHD. They work best in children with a lot of hyperactivity and aggression, and those who tend to be overfocused rather than simply distractible or inattentive. They're also drugs of choice when ADHD appears with tics or Tourette's syndrome (a disorder that may include both vocal and body tics). In fact, they're used to treat Tourette's syndrome even when it doesn't involve ADHD. They're often used in combination with stimulants.

Catapres is available as a skin patch. Placed on the torso, it provides a slow, sustained release of the drug. This helps avoid sleepiness and provides good behavioral control.

What are the key benefits?
As with the stimulants, they don't seem to create tolerance. Also, they don't appear to suppress appetite the way the stimulants do. Catapres may help a child fall asleep when given in the evening--a benefit for many children with ADHD. Tenex has no effect on sleep.

Although the research is still preliminary, these drugs may emerge as the treatment of choice for a particular subtype of ADHD: overfocused behavior.

What are the drawbacks?
These medications have little effect on the inattentiveness that's seen with classic ADHD. But since attentional problems and impulsivity can occur in the same child, combining them with stimulants may offer the best control. The two types of drugs can be taken together safely.

Another possible drawback: Unlike stimulants, which take effect immediately, your child may have to take these drugs for several weeks before their full effects become apparent. However, most begin to experience some improvement within days.

Also, these drugs can (rarely) make depression worse, so the doctor has to monitor mood carefully in children who have ADHD and depression.

What kinds of side effects can I expect to see?
Side effects are uncommon, and generally mild when they do occur. They include drowsiness, low blood pressure and re- sulting dizziness, headache, nausea, depression, and effects on heart rhythm. Most side effects can be managed by reducing the dosage.

The most common side effect is drowsiness. If your child has trouble getting up and staying awake, it probably means that the medication levels are being increased too quickly. Your doctor will likely reduce the dosage and then increase it again more gradually.

These drugs also tend to lower blood pressure. A mild drop in blood pressure usually produces no symptoms, but bigger drops may cause dizziness, especially when the child stands up quickly after sitting or lying down. This and other side effects--which may include headaches and nausea--usually go away after a few weeks of treatment. More serious, but rare, are reports that these drugs may worsen depression or trigger it in a child with a family history of mood disorders. Catapres has also caused irregular heartbeats in adults, but its heart effects in children and adolescents haven't been studied yet in any detail.

If your child has to be taken off Catapres or Tenex--for example, because it isn't helping or because of side effects--your physician has to do it gradually. Like most blood pressure medications, these can cause "rebound hypertension"--that is, a sudden and potentially dangerous rise in blood pressure-- if it's discontinued too quickly.

What are the odds that treatment will be effective?
These drugs are effective in about 70 percent of cases of impulsivity. They are not particularly effective for focus and attention.

Can these medications be used if my child is on other medications?
Yes. They have few known contraindications or interactions with other drugs or with foods.

What are the typical dosages?
Traditionally, Clonidine tablets are given in the evening, because they act as a sedative. But the medication usually works best when it's administered in several small doses during the day rather than a single larger dose. To reduce the sedative effects, doses should be low at the beginning of treatment--for example, half of a 0.1 mg tablet a day for Catapres--and gradually increased to get the maximum benefit. Typically, dosages for a child will be about 0.15 to 0.3 mg--that is, three half or full tablets--a day. For adolescents the dosages will likely be a little higher. In most cases, the maximum dose won't be more than 0.5 mg a day.

Catapres is available in a skin patch as well as a pill, so it can be used in children who have trouble taking medication. The patch doesn't cause sleepiness either, so it's a useful alternative for those who can't tolerate the pills' sedative effects. Usually, however, the doctor will prescribe pills at the beginning, until tolerance to the sedative effects are established. A single patch usually lasts for four to five days. Some develop a mild skin irritation where the patch is attached; it's easily treated with a low-dose corticosteroid cream.

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