The invention provides novel oral modified release dosage forms of neramexane which are useful for the continuous therapy of patients suffering from diseases and conditions such as Alzheimer's dementia and neuropathic pain. The compositions have drug release profiles that are suitable for achieving steady state plasma concentrations of neramexane which have relatively small fluctuation when administered on a twice-daily or even once-daily regimen. The dosage forms may be designed as modified release matrix tablets, which are optionally coated for taste masking. The invention further provides therapeutic methods of treating conditions such as Alzheimer's dementia and neuropathic pain which involve the administration of such dosage forms.