Table 4.

Definition of the 5R criteria used for assessing appropriateness.

Parameter	Definition	Example
Right indication	When the prescribed polymyxin B is the most appropriate selection in terms of site of infection and pathogen	1.Prescribing polymyxin B instead of colistin for a mul-tidrug-resistant Klebsiella pneumoniae urinary tract infection is considered inappropriate because polymyxin B does not achieve optimal concentration in the urine. 2.Appropriate escalation to colistin or polymyxin B when the patient clinically does not respond to carbapenems.
Right drug	When colistin or polymyxin B is the narrowest and most effective antibiotic	3.Appropriate tailoring to colistin or polymyxin B based on a culture and sensitivity report. 4.Prescribing colistin alone for bacteremia is considered to be inappropriate (polymyxins should be prescribed with an appropriate syner-gistic agent). 5.Prescribing inhalational colistin alone for pneumonia is considered to be inappropriate.
Right dose	When the loading dose and maintenance dose of the prescribed antimicrobial are appropriate and accurate for the patient’s diagnosis as per standard recommendations	6.Prescribing the appropriate loading dose of colistin irrespective of creatinine clearance is mandatory to achieve an adequate steady state concentration. 7.Prompt dose adjustment based on creatinine clearance and according to body weight for pediatric patients
Right frequency	When the frequency of the prescribed antimicrobial dose is appropriate for the patient’s diagnosis as per standard recommendations	8.Maintenance dose to be administered 12 h after the loading dose and to pursue further frequency based on creatinine clearance.
Right duration	When the prescribed antimicrobial has been administered for the correct duration based on the patient’s diagnosis as per standard recommendations	9.Prescribing colistin for 7–10 days for hospital-acquired pneumonia.