Can haldol (haloperidol) decanate still work and function in your system after a month has passed from initial injection. does it have permanent effects on brain?

Haldol (haloperidol) decanoate: Haldol (haloperidol) decanoate is much longer acting than oral or IV forms of haldol (haloperidol). It is usually given about every 3-4 weeks, and is active for that time period. Long-term movement disorders (tardive dyskinesia) can result with haldol (haloperidol), and can be irreversible. Risk of this must be weighed against risk of psychotic symptoms without the medication.