IRCT201710109014N194 IRCT 2017-10-12 Vice-chancellor for Research and Technology, Hamadan University of Medical Sciences Comparison of the different doses of vancomycin on plasma concentration of the drug in patients hospitalized in ICU Comparison of the different doses of vancomycin on plasma concentration of the drug in patients hospitalized in ICU: a double blind randomized clinical trial 2017-10-23 anticipated 70 Complete https://irct.ir/trial/9632 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Other design features: Randomization: / Random assignment of the patients to the intervention and control groups through drawing of lot. Blinding: Patients will be unaware of the type of intervention. The physician who will examine the patients will not be aware of the intervention. Therefore, the trial will be run as double blind. 2 Condition 1: Meningitis. Condition 2: Endocarditis. Condition 3: Sepsis. Condition 4: Osteomyelitis. Intervention 1: Intervention group 1: First injection of 1 g vancomycin as single dose and then 2 g per day for 2 weeks. Intervention 2: Intervention group 2: First injection of 1 gr vancomycin as single dose and then 15 mg/kg per day for 2 weeks.