Disclosed herein are tricyclic fused dihydropyrazolo[3,4,5-de]isoquinolinone and dihydropyrrolo[4,3,2-de]isoquinolinone compounds of formula I, wherein the substituents are as defined with in the specification processes for their preparation, compositions comprising said compounds and uses thereof. Said compounds are useful as serotonin typ-3 (5-HT3) receptor modulators and as such are useful in the treatment of anxiety disorders, social phobias, vertigo, obsessive-compulsive disorders, panic disorders, post-traumatic stress disorders, bulimia nervosa, drug withdrawal effects, alcohol dependency, pain, sleep related central apneas, chronic fatigue syndrome, Parkinsons Disease Psychosis, schizophrenia, cognitive decline and defects in schizophrenia, Parkinsons Disease, Huntingtons Chorea, pre-senile dementias, Alzheimers Disease, obesity, substance abuse disorders, dementia associated with neurodegenerative disease, cognition deficits, fibromyalgia syndrome, rosacea, cardiovascular disorders mediated by serotonin, chemotherapy induced nausea and vomiting (CINV), post-operative induced nausea and vomiting (PONV), radiation induced nausea and vomiting (RINV), gastrointestinal disorders, gastroesophageal reflux disease (GERD), Burkitts lymphoma, bronchial asthma, pruritus, migraine, and epilepsy.
