Clinical efficacy of pramipexole in the treatment of conditions other than Parkinson's disease

The non-ergot dopamine receptor agonist, pramipexole, which shows affinity for the D-2 and D-3 subtypes of the D2 dopamine receptor subfamily, with preference for the D-3 receptor, is currently licensed for the treatment of advanced-stage Parkinson's disease in the European Union, and for both early and advanced-stage Parkinson's disease in the USA and Canada. There are, however, intriguing reports that this agent may also have other beneficial clinical effects on symptoms associated with, or occurring independently of, Parkinson's disease. It has been shown that depression, which is a frequent accompaniment of Parkinson's disease, may not necessarily be simply an emotional reaction to the parkinsonian symptoms but could be aetiopathotogically linked to the same underlying dopaminergic mechanisms. There is evidence that pramipexole can alleviate mild-to-moderate depression, whether or not this occurs in association with Parkinson's disease. Such findings may throw interesting new light on the involvement of dopaminergic processes in depressive illness. Pramipexole may also have an antianxiety potential, though currently it is not clear whether this is secondary to, or independent of, its antidepressive actions. Although some studies have been conducted on possible antischizophrenic effects of pramipexole, these have generally been small and have either given negative results or have suggested that the treatment may alleviate negative schizophrenic symptoms, with effects on positive symptoms being less evident. Pramipexole is a potent treatment for restless legs syndrome (RLS), a dose of 0.375-0.75 mg/day producing complete relief of symptoms in the majority of cases. Other conditions in which pramipexole might be expected to produce some clinical improvements include attention-deficit-hyperactivity disorder, sexual impotence in males, cocaine addiction, and supranuclear palsy, though no direct evidence currently exists to support any of these putative applications. Exploration of the profile of clinical effectiveness of pramipexole may be expected to throw interesting new light on the interrelationships between a range of neurological and neuropsychiatric conditions.