Invega Sustenna 100mg Injection contains paliperidone, an atypical antipsychotic agent used primarily for the treatment of schizophrenia and schizoaffective disorder. Administered via intramuscular injection, Invega Sustenna provides a long-acting, extended-release formulation designed to maintain therapeutic plasma concentrations over a one-month period, thereby improving patient adherence and reducing relapse risk. Paliperidone acts as a dopamine D2 and serotonin 5-HT2A receptor antagonist, modulating neurotransmitter activity implicated in psychotic symptoms. The 100mg dose is typically initiated following a recommended dosing schedule, often preceded by oral paliperidone or risperidone to assess tolerability. Common adverse effects include extrapyramidal symptoms, weight gain, sedation, and increased prolactin levels, necessitating regular monitoring. Caution is advised in patients with cardiovascular disease, seizure disorders, or a history of neuroleptic malignant syndrome. Invega Sustenna should be used under strict medical supervision, with dose adjustments based on clinical response and tolerability. This formulation offers a convenient monthly dosing regimen, facilitating long-term management of chronic psychiatric conditions and enhancing overall treatment outcomes.