Unfortunately the benefits of levodopa do not persist indefinitely. Within 5-10years of starting treatment with levodopa, many patients develop treatment-related complications e.g. end-of-dose deterioration, drug-induced involuntarymovements, unpredictable “on-off” motor fluctuations and psychiatric effects. 1 These problems have led to the development of strategies which aim to limit ordelay the onset of levodopa-related complications. These strategies arediscussed in Textbox 1 (page 4).

In early Parkinson's disease, the optimum treatment remains to bedetermined. A key object of ongoing research is to determine whether earlytreatment with directly-acting dopamine agonists can retard diseaseprogression as well as influence symptoms. At present this issue remainsunresolved and this uncertainty must be borne in mind when considering newtreatments and their place in therapy. In advanced disease, once levodopa-related complications have set in, a highly individualised approach is requiredto achieve an optimum balance of symptom control and adverse effects.Multiple-drug regimens are usually necessary.