Cinnarizine & Tardive Dyskinesia

Unlike the overwhelming majority of drugs implicated in the development of tardive dyskinesia, cinnarizine was not originally used as an antipsychotic. However cinnarizine is linked to the development of movement disorders — including tardive dyskinesia and Parkinsonism (also known as Parkinson's syndrome). Cinnarizine was developed by the same European drug company (Janssen Pharmaceutica, now a division of drug conglomerate Johnson & Johnson) that later came out with haloperidol, a medication initially rejected in the U.S. because of its side effects.

Indications

Originally cinnarizine was an antihistamine, used primarily for treating nausea and vomiting related to motion sickness. Cinnarizine fits the definition of a "smart drug" as well (like the herb gingko biloba) and is a vaso-dilator, reputedly able to increase brain function by opening up blood vessels and increasing oxygen supply. It has also been used as an adjunctive therapy in the treatment of peripheral arterial disease.

Marketed under the brand names Stugeron and Stunarone, it is no longer available in North America. It is however still sold in Vietnam, where it is known as Emecin.

Mechanism

Cinnarizine functions in a manner similar to antipsychotics, or neuroleptic medications, but operates on dopamine receptors (the neurochemical transmitter between the brain and the body's cells). Whereas most typical and atypical neuroleptics inhibit dopamine receptors involved in emotion and basic cognitive functions, cinnarizine blocks signals between the inner ear and the hypothalamus, where the regurgitation impulse is controlled. It is reportedly safe for use by scuba divers who run the risk of hypoxia (oxygen poisoning).

Side Effects and Hazards

The company that continues to market and sell cinnarizine is fairly straight-forward about the side effects, including:

Drowsiness or narcolepsy
Dizziness
Lack of co-ordination
Gastro-intestinal disturbances (including nausea, diarrhea and constipation)
Lack of or excessive appetite
Blurred vision
Urinary difficulties
Dry mouth
Respiratory difficulty

In addition, patients may experience muscle weakness, headaches or even feelings of euphoria. Weight gain, excessive sweating, and even symptoms similar to lupus have been noted.

Janssen Pharmaceutica states that symptoms of tardive dyskinesia are seen primarily in older adults.

Other Movement Disorders

Cinnarizine is also associated with Parkinsonism, a syndrome with symptoms normally associated with Parkinson's disease. Symptoms are usually drug-induced (particularly by anti-psychotic medications) or due to exposure to certain environmental toxins. In a Spanish study (originally completed in the mid-1990s, but published in 2004), 43 percent of patients treated with cinnarizine were found to have symptoms of parkinsonism and most patients were women. Of those with drug-induced parkinsonism, the majority recovered within a year and a half once they were taken off the drug. Four patients later developed Parkinson's disease, and five developed symptoms of tardive dyskinesia.

A later study done in Argentina and published in 2004 reported a high rate of tardive dyskinesia among patients treated with cinnarizine and flunarizine. The average age of patients with tardive dyskinesia was 70-years-old. It was later found that most patients reported feeling normal within two years once the medication was discontinued.

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