Midification of tardive dyskinesia and spasmodic torticollis by apomorphine. Possible role of dopamine autoreceptors.

A group of 16 patients afflicted with involuntary movement disorders received subcutaneous injections of the direct dopamine agonist, apomorphine hydrochloride. Paradoxically, these injections were generally followed by a reduction of dyskinesia; this was most noticeable in patients with tardive dyskinesia and was only mild in some patients with spasmodic torticollis. Preferential stimulation by apomorphine of inhibitory dopamine presynaptic receptors (so-called dopamine autoreceptors) is proposed as the most likely explanation for the observed antidyskinetic effect of this drug. The results of this study also suggest that direct dopamine agonists may be used clinically to attenuate CNS dopaminergic transmission, especially when use of antidopminergic drugs such as the nuroleptics is contraindicated, as in the case of tardive dyskinesia.