Rational use of antibiotics in an intensive care unit: a retrospective study of the impact on clinical outcomes and mortality rate Muhammad Ali,1 Humaira Naureen,1 Muhammad Haseeb Tariq,2,3 Muhammad Junaid Farrukh,4,5 Abubakar Usman,3 Shahana Khattak,1 Hina Ahsan1 1Faculty of Pharmaceutical Sciences, Riphah International University, Islamabad, Pakistan; 2Pharmaceutical Evaluation and Registration Division, Drug Regulatory Authority of Pakistan, Islamabad, Pakistan; 3Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang, Malaysia; 4Department of Clinical Pharmacy, Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia; 5Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia Background: Intensive care units (ICUs) are specialized units where patients with critical conditions are admitted for getting specialized and individualized medical treatment. High mortality rates have been observed in ICUs, but the exact reason and factors affecting the mortality rates have not yet been studied in the local population in Pakistan. Aim: This study was aimed to determine rational use of antibiotic therapy in ICU patients and its impact on clinical outcomes and mortality rate. Methods: This was a retrospective, longitudinal (cohort) study including 100 patients in the ICU of the largest tertiary care hospital of the capital city of Pakistan. Results: It was observed that empiric antibiotic therapy was initiated in 68% of patients, while culture sensitivity test was conducted for only 19% of patients. Thirty-percent of patients developed nosocomial infections and empiric antibiotic therapy was not initiated for those patients (P