A study by Queen's University, Belfast found that 20.3% of care home patients were dispensed the drugs, such as tranquilizers, sedatives, or antidepressants, in January 2009 - compared to 1.1% in the community.
Antipsychotic drugs prescribed to older people more than doubled from 8.2% before entry to care homes to 18.6% after entering care.
The study is due to be published in the Journal of the American Geriatrics Society, and was carried out by researchers from Queen's Centre for Public Health in the School of Medicine, Dentistry and Biomedical Sciences.
Prescribing data for over 250,000 people, aged 65 years and over living in Northern Ireland from 2008 to 2010, was analysed.
Researchers looked at drug uptake within the older population during the transition from community to care.
The report found that psychotropic drugs prescribed to patients included in the study were being prescribed for the first time for many.
Six months after admission, 37.1% of all new residents had received at least one prescription for a hypnotic drug - used for example to treat sleep disorders - and 30.2% for an antipsychotic, which can be used to treat psychotic episodes.
Anxiolytic medication, prescribed to treat anxiety, was dispensed to 24.5%.
Aideen Maguire, lead researcher, said: "Although drug dispensing is high in older people in the community, we have found that it increases dramatically on entry to care.
"This study showed that the high uptake of psychotropic drugs observed in care homes in Northern Ireland cannot be explained by a continuation of drug use initiated in the community prior to entering care.
"With an ageing population globally it is important that we look at the reasons behind this type of increase following admission to care."
Ms Maguire said that antipsychotic uptake in Northern Ireland is similar to that in the rest of the UK and Ireland, before adding that the study "highlights the need for routine medicines reviews especially during the transition into care."