Chapter 91: Aminoglycosides: Bactericidal Inhibitors of Protein Synthesis Flashcards
What are the 3 most commonly used aminoglycosides?
Gentamicin
Tobramycin
Amikacin
Aminoclycosides end in …….
-mycin
-micin
-cin
NOT -thromycin (Macrolides)
Are aminoglycosides bacteriostatic or bacteriocidal?
bacteriocidal
disrupts protein synthesis likely causing cell membrane leakage
Use for aminoglycosides
aerobic gram-negative bacilli
Can cause serious injury to inner ear and kidney:
Nephrotoxicity
Ototoxicity
Are aminoglycosides polar or non-polar?
highly polar molecules - not absorbed from GI tract (IV or IM)
Oral dosing only used for GI infections
Use of Gentamicin
“serious infection” with aerobic gram-negative bacilli
Adverse Effects of Gentamicin
Nephrotoxicity (monitor BUN and creatinine)
Ototoxicity (assess for tinnitus - r/t elevated trough level)
Hypersensitivity Reactions
Neuromuscular blockade
Gentamicin Drug Interactions
Penecillins, cephalosporins, and vancomycin: enhance bactericidal effect
Ototoxic Drugs: ethacrynic acid
Nephrotoxic Drugs
Skeletal Muscle Relaxants (increase neuromuscular blockade)
Gentamicin who monitors levels, half life, and patient variation
pharmacist dose and monitor levels
Half life: 2-3 hours
wide patient variation: age, body fat, pathophysiology
Gentamicin serum levels
Dosing: single large dose each day or 2 or3 smaller doses
Monitoring of serum levels is common; the same aminoglycoside dose can produce very different plasma levels in different patients
Gentamicin peak and trough levels
peak levels must be high enough to kill bacteria (4-8mcg/ml)
trough levels must be low enough to minimize toxicity (< or = 2 mcg/ml)
Gentamicin: samples for peak levels should be taken
30 minutes after giving an IM injection or after completing a 30 minute IV infusion
Gentamicin: sample for trough levels depends on
dosing schedule
Divided doses: take sample just before the next dose
Once-daily doses: Draw a single sample 1 hour before the next dose; value should be very low - preferably close to 0