Medication Interactions: Prescribed Agents

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Potential interactions between two or more medications prescribed simultaneously need to be taken into account when the decision is made to use targeted combined pharmacotherapy. These interactions include those between the prescribed medications and those that may occur when non-prescribed (“over the counter”) medications are used. All medications are metabolized or broken down by a system of enzymes in the liver and distributed to the brain where they have their active effects. This process if also necessary to prepare the drug for elimination from the body. There is a considerable amount of information about these enzymes, known as the cytochrome oxidase P450 system. Medications such as the selective serotonin reuptake inhibitors (SSRIs) can alter activity in this liver enzyme system, resulting in reduced metabolism and reduced clearance of medication. This may result in increased blood levels of medication and/or increased side effects.

There is a large variation between individuals in their response to drugs. The response may depend on genetic and environmental factors. There may be considerable variation in the response of a single person to different members of the same drug class.

Medication Interactions: Non-Prescribed Agents (“Over the Counter”)

Many children with Tourette’s Syndrome and other tic disorders may receive over the counter medications to reduce symptoms of upper respiratory illness such as nasal decongestants and cough suppressants. Others may take acetaminophen (Tylenol) for muscle paints or for fever, or nonsteroidal anti-inflammatory agents (NSAIDS) such as Ibuprofen (Motrin, Advil) for headaches or muscle pain. Antibiotics are frequently prescribed for children for ear infections or strep throats. While these medications are generally safe for pediatric usage, some may have significant interactions with medications prescribed for children with TS.

Specific Medications for Tourettes Syndrome

The medications commonly used to treat symptoms of Tourette Syndrome are reviewed in the tables at the end. They are listed by their general purpose, typical starting doses, common maximum dosages and common side effects. Children generally require lower dosages of the same medications used for adults. The neuroleptic medications (e.g. Haldol [haloperidol] and Orap (Pimozide) may have uncommon side effects such as restlessness, muscle stiffness or slowness or a rare side effect known as tardive dyskinesia (TD). Symptoms of TD may begin with twitching movements of the face and mouth, which may not disappear when the medication is discontinued.

Some medications prescribed for TS have primary indications other than the treatment of Tourette Syndrome. Catapres (clonidine), and a close relative guafacine (Tenex), have been used to control high blood pressure. Clonazepam (Klonopin) is used in the treatment of seizures as well as for the control of tics.

Whether generic medications are as effective as brand name medication needs to be studied. Some reports have suggested that bioavailability (availability of the medication and its breakdown products after oral dosing is reduced slightly for generic neuroleptics such as haloperidol when compared to the brand Haldol. Some individuals switching to generic from brand name products have reported experiencing no problems, but some have noted that the generics proved less beneficial than the brand name products. It is important that individuals review this issue with their physicians when a medication program is being started.

The more commonly used medications for ADHD are the stimulants such as Ritalin (methylphenidate), and Dexedrine (dextroamphetamine) and Adderall (mixed amphetamines). These medications may cause an increase in tics in some TS patients. Other reports have been unable to find an effect on tic frequency. Experience has shown, however, that these medications can be safely taken by some individuals with TS. For those individuals with significant ADHD symptoms, a cautious trial of stimulant medication may be helpful. A new medication for ADHD is Strattera (atomoxetine), which is reported not to increase tics.

There is no single TS “drug of choice”. A careful matching of the medication to the specific needs of the individual is critical. There are no medical tests, which can predict which medication will work best. More than one medication, even within the same family of drugs may need to be tried before the best treatment program is found. Unfortunately, there are some individuals who may not respond to any of the available medications, or may experience intolerable side effects. These individuals may be candidates for other types of treatment.

Additional medications for TS are also available although they are used less commonly. Research programs are working actively to discover new and better treatment programs. Until that time, the currently available medications can be of help to many individuals with Tourette disorder and other tic disorders.

Medications Used in the Treatment of Tics

continue: Medications To Treat Tourettes Plus Co-Morbid Conditions

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Reviewed: 03/2006