Colistin Dosing Calculator (Beta)
Colistin, also known as polymyxin E, is a mixture of the cyclic polypeptides colistin A and B and belongs to the class of polypeptide antibiotics known as polymyxins. Colistin is effective against most Gram-negative bacilli. It remains one of the last-resort antibiotics for multidrug-resistant Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter.
(Scr) currently stable?:
Restrict maximum CrCl:
Colistin Dosing Factors 1,2,3
Colistin targeted average steady
state serum concentration (Css):
The desired Css should be based on the MIC for the target
the site and severity of the infection. Highly resistant organisms in
critical care patients: Usual target: 3.5 mg/L (possibly higher).
Nephrotoxic effects can occur much more frequently at dosages that exceed
5mg/kg - monitor closely.
Restrict the maximum calculated
dose to the following:
Latest guidelines seem to point to a maximum dose of 475mg1
Cockcroft and Gault equation - utilizes actual body weight:
Male: CrCl (ml/min) = (140 - age) x wt (kg) / (serum creatinine x 72)
Female: Multiply above result by 0.85
Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum
creatinine. Nephron 1976;16(1):31-41.
The original Cockcroft and Gault equation utilized total body weight,
however, the most commonly used version of this equation incorporates
the Ideal body weight (IBW).
Male: CrCl (ml/min) = (140 - age) x IBW (kg) / (serum creatinine x 72)
Female: Multiply above result by 0.85
Ideal body weight (IBW):
IBW (males) = 50 kg + 2.3 x (height [inches] - 60)
IBW (females) = 45.5 kg + 2.3 x (height [inches] - 60)
Devine BJ. Gentamicin therapy. DICP. 1974; 8:650–5.
Jelliffe equation - normalized for BSA:
Male: (98 - (0.8 * (age - 20)) / (SCR in mg/dL)) x 1.73 M2/Patient’s
Female: Multiply above result by 0.9
Jelliffe RW. Estimation of creatinine clearance when urine cannot be
collected. Lancet 1971;1:975-6.
Jelliffe RW. Creatinine clearance: Bedside estimate. Ann Inter Med.
Body Surface Area (BSA):
Program uses the following equation:
(Weight) kg0.425 x (Height) cm0.725 x 0.007184
= BSA in M2
DuBois D, DuBois DF. A formula to estimate the approximate surface area
if height and weight be known. Arch Int Med 1916;17:863-71.
Normalized CrCl (ml/min/1.73m2) = CrCl
(ml/min) x 1.73/BSA4
Loading dose (mg) = colistin
Css,avg target x 2.0 x body wt (kg). [Use the lower of
ideal or actual body weight, expressed in kg. ]
Maintenance dose (mg):
Daily dose = colistin
Css,avg target x (1.50 x CrCLn + 30).1,2
- Divide dose and give q12h.
- Maximum daily dose: 475mg
- Colistin Css,avg target expressed in mg/L.
- Creatinine clearance (CrCL)
expressed in ml/min/1.73 m2 (normalized value). Although the Jelliffe equation was used to
estimate CrCL in this study, other means (e.g., Cockcroft and Gault
equation) may be used to estimate CrCL which would then be normalized to
a body surface area of 1.73 m2.2
mL/min: 2.5 - 5 mg/kg/day IV in 2 to 4 divided doses.
CrCl 50-79 mL/min: 2.5-3.8 mg/kg/day IV divided q12hr
CrCl 30-49 mL/min: 2.5 mg/kg/day IV q24h or divided q12hr
CrCl 10-29 mL/min: 1.5 mg/kg IV q36hr
Auwaerter, PG. Colistin: Optimal Dosing and Outcomes? Medscape
Infectious Diseases © 2012 WebMD, LLC (Dec 03, 2012).
https://www.medscape.com/viewarticle/775212. Accessed: July 2014.
Garonzik SM, Li J, Thamlikitkul V, et al. Population
pharmacokinetics of colistin methanesulfonate and formed colistin in
critically ill patients from a multicenter study provide dosing
suggestions for various categories of patients. Antimicrob Agents
Suggested loading dose and daily
maintenance doses of CMSa
Source: Garonzik SM, et al.
Category of critically ill patient
||All patient categories
Loading dose of CBA (mg) = colistin
Css,avg targetb x 2.0 x body wt (kg).c
See caveat in footnote c. First maintenance dose should be
given 24 h later.
||Not on renal replacement
Daily dose of CBA (mg) = colistin
Css,avg targetb x (1.50 x CrCL + 30).d
Recommended dosage intervals based on CrCL:
m2, every 12 h,
10-70 ml/min/1.73 m2 every 12 (or 8) h, and
>70 ml/min/1.73 m2 every 12 (or 8) h.
See important caveat in
||Receiving intermittent hemodialysis
||Daily dose of CBA on a non-HD day to
achieve each 1.0-mg/liter colistin Css,avg targetb
= 30 mge.
Supplemental dose of CBA on a HD dayf: add 50% to
the daily maintenance dose if the supplemental dose is
administered during the last hour of the HD session, or add
30% to the daily maintenance dose if the supplemental dose is
administered after the HD session. Twice-daily dosing is
||Receiving continuous renal replacement
||Daily dose of CBA to achieve each
1.0-mg/liter colistin Css,avg target = 192 mg.g
Doses may be given every 8-12 h.
- Expressed as mg of colistin base activity (CBA) for
various categories of critically ill patients. The
suggested maintenance daily dose would commence 24 h after
administration of a CMS loading dose. Example: To target a
colistin Css,avg of 2.5 mg/liter, a 55-kg patient with a
CrCL of 40 ml/min/1.73 m2 would receive a loading dose of
275 mg CBA followed in 24 h by commencement of a
maintenance regimen of 225 mg CBA/day in 2 to 3 equally
- Colistin Css,avg target is expressed in mg/liter. This
target should be based on MIC, site, and severity of
- Use the lower of ideal or actual body weight,
expressed in kg. At this time, we suggest caution in the
use of a loading dose greater than 300 mg CBA (see the
text for more details).
- Based upon the population PK analysis for 101
critically ill patients not on continuous renal
replacement therapy. Colistin Css,avg target expressed in
mg/L.Creatinine clearance (CrCL) expressed in ml/min/1.73
m2. Although the Jelliffe equation was used to estimate
CrCL in this study, other means (e.g., Cockcroft and Gault
equation) may be used to estimate CrCL which would then be
normalized to a body surface area of 1.73 m2. See text for
caveat regarding use of the algorithm in patients with CrCL
values > 70 ml/min/1.73 m2 or when targeting a “high”
colistin Css,avg, both being circumstances where the
algorithm may predict daily doses of CBA substantially
greater than the current upper limit in the product label.
- Based upon use of equation 10 and setting CrCL to
- Supplemental dose of CMS to achieve a similar colistin
Css,avg on a HD day as occurs on a non-HD day. It is
assumed that the hemodialysis session occurs toward the
end of a CMS dosage interval.
- Based on the population PK analysis for 4 critically
ill patients receiving continuous renal replacement
Gilbert DN, Chambers HF, Eliopoulos GM. The Sanford Guide To
Antimicrobial Therapy 2014. 44th ed. Sperryville: Antimicrobial
Murphy JE. Estimating Creatinine Clearance.
In: Murphy JE, ed. Clinical Pharmacokinetics, 4th ed. Bethesda, MD:
American Society of Health-System Pharmacists, 2008:(4).