Novel pyridopyrimidine derivatives which have a binding affinity for the human 5-HT6 receptor and, therefore, are useful in treating disorders responsive to antagonism of the 5-HT6 receptor such as psychosis, schizophrenia, manic depression, depression, neurological disorder, memory disorder, Parkinson's disease, amyotrophic lateral sclerosis, Alzheimer's disease and Huntington's chorea.
Pyridopyrimidine derivatives as 5-HT6 antagonists