Identify the peak concentrations for Gentamicin and Tobramycin based on diagnosis.
- 2-4 mcg/ml: uncomplicated lower UTI
- 4-5 mcg/ml: gram+ endocarditis (synergistic w/ penicillin)
- 6-8 mcg/ml: gram- infections (ex: sepsis)
- 8-10 mcg/ml: gram- pneumonia
- 10-12 mcg/ml: gram- pneumonia in pt w/ cystic fibrosis
What is the trough concentration of gentamicin and tobramycin?
< 1-2 mcg/ml
Identify the peak concentrations of Amikacin based on diagnosis.
- 20-30 mcg/ml: gram- infections (ex: sepsis)
- 25-35 mcg/ml: gram- pneumonia
What is the trough concentration Amicakin?
< 5-10 mcg/ml
When should aminoglycoside peaks and troughs be drawn?
Peak: 30-60 min after a 30 minute infusion; 15 min after the end of a 60 min infusion
Trough: 30 min or less prior to next dose
What are the adverse effects and toxicities associated with aminoglycosides?
Describe the effects of nephrotoxicity associated with aminoglycoside toxicity.
- may occur w/in 4-5 days (usually takes 5-10 days)
- highest risk w/ duration > 10 days
- usually nonoliguric
- reversible in most cases
- similar risk w/ gent/tobra/amikacin
- average incidence ~20% (range 0-56%)
- risk factors: age, other dz states, other nephrotoxic drugs
Describe the effects of neurotoxicity associated with aminoglycosides.
- muscle twitching
Describe the effects of ototoxicity associated with aminoglycosides.
- clinical incidence 0.5-3%
- damage to 8th cranial nerve
- may be unilateral or bilateral
- onset is variable
- cochlear (auditory): loss of hearing, tinnitus, feeling of ear fullness; often irreversible
- vestibular: vertigo, ataxia, nystagmus, dizziness, n/v, unsteadiness; often irreversible
When should a loading dose of aminoglycosides be used?
When CrCl is < 30 ml/min
What patient weight should be used for CrCl, Vd and dose when dosing aminoglycoside?
CrCl = TBW
Vd = IBW
Dose = IBW
**Use Adjusted BW if patient is obese**
What are the extended interval aminoglycoside dosing values for gentamicin/tobramycin and amikacin?
Amikacin: 15 mg/kg
How should initial interval dosing of aminoglycosides be determined?
- 1. Calculate weight based dose
- 2. Creatinine clearance determines the dosing interval
ex: > 60ml/min = q 24h dosing