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Pharmacokinetic Dosing

Aminoglycoside-Vancomycin Dosing

Welcome to the updated version. We added some of the functionality from the advanced
version and improved the reporting section.

Patient-Specific Data

Patient Name: Location:
Age:     Sexselect Gender    Serum Creatinine

:      Weight:

Clearance method

Drug Selection, Levels, and Drug-specific PK Parameters:

Select Drug: Desired Peak:   mcg/ml

Desired Trough:   mcg/ml
Volume of distribution:led
Usual range: aminoglycosides: 0.25 - 0.35. 
Vanco: 0.65 - 0.9  
Infusion time (ti): Select infusion time
 Additional Info
New option based on input from clinicians - general assumption, adjusted body weight may be used in the morbidly obese patients receiving vancomycin:   Historically actual or total is used in all cases.
Use Adjusted body weight     or   Use Actual (total) weight for vanco dosing (default value)

Amputations (Optional Field)

Loading Dose - Aminoglycosides


Program Hints

Selecting the infusion time
Infusion time (ti)
Sample recommendations
Aminoglycosides:   (All doses) 0.5
(0 - 500mg/  0.5 )
501 - 1250 mg 1
1251 -1750 mg 1.5 - 2.5
1751 - 2250 mg 2.5 - 3
Sample recommendations for peak / trough concentrations

(Review levels) Gentamicin /Tobramycin Amikacin
Infection Site Peak Trough Peak Trough
Abdominal 6-7 <1 25-30 4-6
Cystitis 4-5 <1 20-25 4-6
Endocarditis 4-12 <1.5 25-30 <8
Osteomyelitis 6-7 <1 25-30 4-6
Pneumonia 8-10 <1.5 25-30 <8
Pyelonephritis 6-7 <1 25-30 4-6
Sepsis 7-8 <1 25-30 4-6
Soft tissue 6-7 <1 20-25 <6
Synergy 5-6 <1 20-25 4-6
Wound Infections 6-7 <1 25-30 <6
Vancomycin - Target trough levels??
Rybak M, Lomaestro B, Rotschafer JC, et al. (2009). "Therapeutic monitoring of vancomycin in adult patients: A consensus review of the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists". American Journal of Health-System Pharmacy 66 (1): 82–98.

Direct quotes from this reference (Rybak et al.):

"Further, data derived from more recent studies appear to suggest that vancomycin has little potential for nephrotoxicity or ototoxicity when used at conventional dosages (e.g., 1 g every 12 hours [15 mg/kg every 12 hours]), unless it is used concomitantly with known nephrotoxic drugs or at very high dosages."

Recommended TDM Parameters- Optimal monitoring parameter: "Trough serum vancomycin concentrations are the most accurate and practical method"

Timing of monitoring: "Troughs should be obtained just prior to the next dose at steady-state conditions (approximately after the fourth dose)."

Optimal trough concentration (see also Optimal trough concentration—complicated infections) : "Minimum serum vancomycin trough concentrations should always be maintained above 10 mg/L to avoid development of resistance. For a pathogen with an MIC of 1 mg/L, the minimum trough concentration would have to be at least 15 mg/L to generate the target AUC:MIC of 400."

Criteria for monitoring: "Data do not support using peak serum vancomycin concentrations to monitor for nephrotoxicity."

"Trough monitoring is recommended for patients receiving aggressive dosing (i.e., to achieve sustained trough levels of 15–20 mg/L) and all patients at high risk of nephrotoxicity (e.g., patients receiving concurrent nephrotoxins). Monitoring is also recommended for patients with unstable (i.e., deteriorating or significantly improving) renal function and those receiving prolonged courses of therapy (more than three to five days)."

Summary and recommendations
"Vancomycin dosages should be calculated on ABW. For obese patients, initial dosing can be based on ABW and then adjusted based on serum vancomycin concentrations to achieve therapeutic levels. Continuous infusion regimens are unlikely to substantially improve patient outcome when compared with intermittent dosing. (Level of evidence = II, grade of recommendation = A.)"

"Trough serum vancomycin concentrations are the most accurate and practical method for monitoring vancomycin effectiveness. Trough concentrations should be obtained just before the next dose at steadystate conditions. (Level of evidence = II, grade of recommendation = B.) (Note: Steady-state achievement is variable but occurs approximately after the fourth dose.)"

"Based on evidence suggesting that S. aureus exposure to trough serum vancomycin concentrations of <10 mg/L can produce strains with VISAlike characteristics, it is recommended that trough serum vancomycin concentrations always be maintained above 10 mg/L to avoid development of resistance. (Level of evidence = III, grade of recommendation = B.)"

"Based on the potential to improve penetration, increase the probability of optimal target serum vancomycin concentrations, and improve clinical outcomes for complicated infections such as bacteremia, endocarditis, osteomyelitis, meningitis, and hospitalacquired pneumonia caused by S. aureus, total trough serum vancomycin concentrations of 15–20 mg/L are recommended. Trough serum vancomycin concentrations in that range should achieve an AUC/MIC of geq400 in most patients if the MIC is leq1 mg/L. (Level of evidence = III, grade of recommendation = B.) In order to achieve rapid attainment of this target concentration for seriously ill patients, a loading dose of 25–30 mg/kg (based on ABW) can be considered. (Level of evidence = III, grade of recommendation = B.) A targeted AUC/MIC of geq 400 is not achievable with conventional dosing methods if the vancomycin MIC is geq2 mg/L in a patient with normal renal function (i.e., CLcr of 70–100 mL/min). Therefore, alternative therapies should be considered. Vancomycin dosages of 15–20 mg/kg (based on ABW) given every 8–12 hours are required for most patients with normal renal function to achieve the suggested serum concentrations when the MIC is leq1 mg/L. It should be noted that currently available nomograms were not developed to achieve these targeted endpoints. Individual pharmacokinetic adjustments and verification of serum target achievement are recommended. When individual doses exceed 1 g (i.e., 1.5 and 2 g), the infusion period should be extended to 1.5–2 hours. (Level of evidence = III, grade of recommendation = B.)"

"Available evidence does not support monitoring peak serum vancomycin concentrations to decrease the frequency of nephrotoxicity. (Level of evidence = I, grade of recommendation = A.) Monitoring of trough serum vancomycin concentrations to reduce nephrotoxicity is best suited to patients receiving aggressive dosing targeted to produce sustained trough drug concentrations of 15–20 mg/L or who are at high risk of toxicity, such as patients receiving concurrent nephrotoxins. (Level of evidence = III, grade of recommendation = B.) Monitoring is also recommended for patients with unstable renal function (either deteriorating or significantly improving) and those receiving prolonged courses of therapy (over three to five days). (Level of evidence = II, grade of recommendation = B.) All patients receiving prolonged courses of vancomycin should have at least one steady-state trough concentration obtained (approximately after the fourth dose). Frequent monitoring (more than a single trough concentration before the fourth dose) for short-course therapy (less than five days) or for lower-intensity dosing (targeted to attain trough serum vancomycin concentrations below 15 mg/L) is not recommended. (Level of evidence = II, grade of recommendation = B.)"

Background information

Background information  (Equations listed are calculated by the program)
Obtain baseline data:
Patient age, sex, height, weight, allergies, diagnosis, infection site, current 
drug therapy, I/O's for past 24 hours, Tmax, WBC with diff, albumin, 
Past medical history, Lab work-up: Scr, Bun, cultures etc.
Estimate Ideal body weight in (kg)
 Males: IBW = 50 kg + 2.3 kg for each inch over 5 feet.
 Females: IBW = 45.5 kg + 2.3 kg for each inch over 5 feet.
If the actual body weight is greater than 25% of the calculated IBW, calculate the adjusted body weight (ABW):            
 ABW = IBW + 0.4(Total body weight - IBW) 
Estimate Creatinine Clearance: (ml/min)
       Cockcroft and Gault equation:
       CrCl = [(140 - age) x IBW] / (Scr x 72)       (x 0.85 for females)
       Note: if the ABW (actual body weight) is less than the IBW use the 
       actual body weight for calculating the CRCL. If the patient is >65yo and 
       creatinine<1,  use 1 to calculate the creatinine clearance
Estimate kel (Elimination rate constant):
  Amikacin /Gentamicin/Tobramycin: Kel = (0.00285 x CrCl) + 0.015
      May also use: (0.003 x CrCl) + 0.01
  Vancomycin: kel = (0.00083 x CRCL)  + 0.0044 (used by program)
        Equation used by the Detroit VA Medical Center: CRCL x 0.0012

     The above equations provide an estimate of the elimination rate
     constant based on population kinetics. The following may decrease
     the usefulness of these equations:
          *Renal failure, CHF, Burn patients, cystic fibrosis, severe
            hypotension, rapidly changing renal function. (Burn victims 
            and patients with cystic fibrosis usually have increased 
            rates of elimination. Patients with CHF or severe hypotension 
            will have decreased rates of elimination due to decreased 
            renal perfusion).
Estimate half-life (T1/2) in hours:
      T1/2 = 0.693 / Kel
Estimate Volume of Distribution (Vd): (Liters)
    Use IBW unless obese, then use ABW= 0.4 x (TBW-IBW) + IBW
    Vd (Normal) = 0.25 to 0.3 L/kg
    [Use actual body weight in all cases]
    Vd (Normal): 0.6 to 0.7 L/kg 
Select Time of Infusion (ti):
(a) Aminoglycosides: 30 minutes (0.5 hrs)
(b) Vancomycin: 0-500 mg/ 0.5 hrs ; 501 to 1250 mg/ 1 hour ;
        1251 to 1750/ 1.5 hrs ; >1750/ 2 hours
Calculate Dosing Interval (T)    hrs.
    T = Ln (Cmax/Cmin) / kel + ti or estimated T = 3 x T1/2
Calculate Maintenance dose (MD):_____mg.
   MD = [(kel) x (Vd) x (ti) x (Cpeak desired) x (1 - e-kT)] / (1 - e-kti)
     or MD = (Cpeak desired) x Vd (eg: C = D/V, therefore D=C*V)
Calculate Predicted Peak and Trough at Steady State.
          Cmax = [Dose * 1-e-kti] / (kel)(Vd)(ti) 1-e-kT

          Cmin = Cmax * e-k(T-ti)


1) Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976;16(1):31-41

2) Davis GA, Chandler MH. Comparison of creatinine clearance estimation methods in patients with trauma. Am J Health-Syst Pharm 1996;53:1028-32.

3) Dawson-Saunders B, Trapp RG. Basic and Clinical Biostatistics. 2nd ed. Norwalk, CT: Appleton & Lange; 1994.

4) Dettli LC. Drug dosage in patients with renal disease. Clin Pharmacol Ther 1974;16:274-80.

5) Drusano LG, Munice HL, Hoopes JM et al. Commonly used methods of estimating creatinine clearance are inadequate for elderly debilitated nursing home patients. J Am Geriatrics Soc 1998;36:437-41.

6) Hailemeskel B, Namanny M, Kurz A. Estimating aminoglycoside dosage requirements in patients with low serum creatinine concentrations. Am J Health-Syst Pharm 1997;54:986-7.

7) Jelliffe RW. Estimation of creatinine clearance when urine cannot be collected. Lancet 1971;1:975-6.

8) Levey AS, Greene T, Kusek JW, et al. A simplified equation to predict glomerular filtration rate from serum creatinine (Abstr) J Am Soc Nephrol 2000;(11):155A

9) Levey AS, Greene T, Schluchter MD, et al. Glomerular filtration rate measurements in clinical trials. Modification of Diet in Renal Disease Study Group and the Diabetes Control and Complications Trial Research Group. J Am Soc Nephrol 1993;4(5):1159-71

10) Levey AS. Assessing the effectiveness of therapy to prevent the progression of renal disease. Am J Kidney Dis 1993;22(1):207-14

11) Levey AS, Bosch JP, Lewis JB, et al. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med 1999;130(6):461-70

12) Rhodes RS, Sims PJ, Culbertson VL et al. Accuracy of creatinine clearance estimates in geriatric males with elevated serum creatinine clearance. J Geriatric Drug Ther 1991;5:31-45.

13) Smythe M, Hoffman J, Kizy K et al. Estimating creatinine clearance in elderly patients with low serum creatinine concentrations. Am J Hosp Pharm 1994;51:189-204.
Aminoglycosides -Vancomycin AUC dosing