Dosing of antimicrobials in obesity
From IDWiki
Calculating Body Weight
| Statistic | Equation (Male) | Equation (Female) | Notes |
|---|---|---|---|
| Body mass index (BMI) (kg/m2) | weight, kg / (height, m)2 | ||
| Body surface area (BSA) (m2) | (height, cm × weight, kg / 3600)1/2 | ||
| Ideal body weight (IBW) (kg) | 50 + 2.3 × (inches over 5 ft) | 45.5 + 2.3 × (inches over 5 ft) | |
| Adjusted body weight (ABW) (kg) | 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)2 - 0.0801 × R + 0.187 × TBW + 39.83 | 0.00151 × (height, cm)2 - 0.0344 × R + 0.14 × TBW - (0.158 × age) + 20.387 | R = resistance |
Antibiotics
β-lactams
Penicillins
| 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
| 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
| Drug | Usual Dose | Obesity | Max dose |
|---|---|---|---|
| Doripenem | Consider extended infusion | ||
| Ertapenem | 1 g IV q24h | Usual dose | |
| Imipenem | Usual dose | ||
| Meropenem | Consider prolonged infusion |
Quinolones
| 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
| Drug | Usual Dose | Obesity | Max dose |
|---|
Tetracyclines
| Drug | Usual Dose | Obesity | Max dose |
|---|
Aminoglycosides
| Drug | Usual Dose | Obesity | Max dose |
|---|---|---|---|
| Amikacin | Use ABW0.4 | ||
| Gentamicin | Use ABW0.4 | ||
| Tobramycin | Use ABW0.4 |
Others
| Drug | Usual Dose | Obesity | Max dose |
|---|---|---|---|
| Aztreonam | 2 g IV q6-8h | ||
| Colistin | Use IBW | 360 mg daily (nephrotoxicity) | |
| Polymyxin B | Use ABW0/4 | 200 mg or 2 MU daily (toxicity) | |
| Ceftaroline | Consider 18h | ||
| Clindamycin | 600 mg IV q6h 900 mg IV q8h 450-600 mg PO q6h 600-900 mg PO q8h |
2700 mg daily; or 4800 mg daily IV if life-threatening | |
| Dalbavancin | Usual dose | ||
| Daptomycin | Use ABW0.4 | ||
| Linezolid | 600 mg PO/IV q12h | Usual dose | |
| Oritavancin | Usual dose | ||
| Cotrimoxazole | Up to 320 mg(TMP) PO q12h 8-10 mg(TMP)/kgABW in divided doses |
Consider ABW0.4 when doing high dose | |
| Telavancin | Usual dose | ||
| Tigecycline | Usual dose | ||
| Vancomycin | 20-25 mg/kg load (max 2.5 g) 10-15 mg/kg q12h (maintenance) |
Use TBW; or 25-30 mg/kg load and 15 mg/kg q12h with ABW0.4 |
Further Reading
- Comprehensive Guidance for Antibiotic Dosing in Obese Adults. Pharmacotherapy. 2017;37(11):1415-1431. doi: 10.1002/phar.2023
