View source for Dosing of antimicrobials in obesity

== Calculating Body Weight ==
{| class="wikitable"
! Statistic !! Equation (Male) !! Equation (Female) !! Notes
|-
| '''[https://www.mdcalc.com/body-mass-index-bmi-body-surface-area-bsa Body mass index]''' (BMI) (kg/m<sup>2</sup>)
| colspan=2 | weight, kg / (height, m)<sup>2</sup>
| 
|-
| '''[https://www.mdcalc.com/body-mass-index-bmi-body-surface-area-bsa Body surface area]''' (BSA) (m<sup>2</sup>)
| colspan=2 | (height, cm × weight, kg  / 3600)<sup>1/2</sup>
|
|-
| '''[https://www.mdcalc.com/ideal-body-weight-adjusted-body-weight Ideal body weight]''' (IBW) (kg)
| 50 + 2.3 × (inches over 5 ft)
| 45.5 + 2.3 × (inches over 5 ft)
|
|-
| '''[https://www.mdcalc.com/ideal-body-weight-adjusted-body-weight Adjusted body weight]''' (ABW) (kg)
| colspan=2 | IBW + C × (TBW - IBW)
| C = 0.3 to 0.4
|-
| '''Lean body weight''' (LBW) (kg)
| 9270 × TBW / 6680 + 216 x BMI
| 9270 × TBW / 8780 + 244 x BMI
| 
|-
| '''Fat-free weight''' (FFW) (kg)
| 0.00139 × (height, cm)<sup>2</sup> - 0.0801 × R + 0.187 × TBW + 39.83
| 0.00151 × (height, cm)<sup>2</sup> - 0.0344 × R + 0.14 × TBW - (0.158 × age) + 20.387
| R = resistance
|}

== Antibiotics ==
=== β-lactams ===
==== Penicillins ====

{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|-
| [[Amoxicillin]]
| 
| 1 g PO q8h
| No data
|-
| [[Ampicillin]]
|
| 2 g IV q4h
|
|-
| [[Nafcillin]]
|
| 2 g IV q4h
| No data
|-
| [[Piperacillin-tazobactam]]
| 4.5 g IV q6-8h
| Prolonged infusion
| 18 g daily
|}

==== Cephalosporins ====
{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|-
| [[Cefazolin]]
| 1-2 g IV q8h
| 2-3 g IV q6-8h
| No data; 12 g daily
|-
| [[Cephalexin]]
| 500-1000 g PO qid
| 1000 g PO qid
| No data
|-
| [[Cefipime]]
| 2 g IV q8h
| 2 g IV q8h prolonged infusion
| 2 g IV q8h prolonged infusion
|-
| [[Ceftazidime]]
| 2 g IV q8h
| 2 g IV q8h prolonged infusion
| 2 g IV q8h prolonged infusion
|-
| [[Ceftazidime-avibactam]]
|
| Usual dose
| 
|-
| [[Ceftolozane-tazobactam]]
|
| Usual dose
|
|}

==== Carbapenems ====
{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|-
| [[Doripenem]]
| 
| Consider extended infusion
|
|-
| [[Ertapenem]]
| 1 g IV q24h
| Usual dose
| 
|-
| [[Imipenem]]
| 
| 
| 
|-
| [[Meropenem]]
| 
| Consider prolonged infusion
| 
|}

=== Quinolones ===
{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|-
| [[Ciprofloxacin]]
| 500-750 mg PO q12h or 400 mg IV q6-8h
| 400 mg IV q8h or 750 mg PO q12h
|
|-
| [[Levofloxacin]]
| 750 mg PO q24h
| Consider up to 1000 mg PO q24h
|
|-
| [[Moxifloxacin]]
| 
| Usual dose
| 
|}

=== Macrolides ===
{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|}

=== Tetracyclines ===
{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|}

=== Others ===
{| class="wikitable"
! Drug !! Usual Dose !! Obesity !! Max dose
|-
| [[Aztreonam]]
| 
| 2 g IV q6-8h
| 
|-
| [[Colistin]]
| 
| Use IBW
| 360 mg daily (nephrotoxicity)
|-
| [[Polymyxin B]]
| 
| Use ABW<sub>0/4</sub>
| 200 mg or 2 MU daily (toxicity)
|}

== Further Reading ==
* Comprehensive Guidance for Antibiotic Dosing in Obese Adults. ''Pharmacotherapy''. 2017;37(11):1415-1431. doi: [https://doi.org/10.1002/phar.2023 10.1002/phar.2023]

[[Category:Antibiotics]]