Gentamicin

General

• Type: Aminoglycoside
• Dosage Forms: IM; IV
• Common Trade Names: Genticyn, Garamycin, Gentak

Adult Dosing

Indications by Disease

Disease	Dose	Context
Acute cystitis	3mg/kg/day divided q8hr	Inpatient
Cervicitis	240 mg IM x 1	GC/Chlamydia, CTX Contraindicated
Corneal abrasion	0.3% solution 2 drops six times for 5 days	Contact Lens
Endocarditis	3mg/kg/day IV in 2 or 3 doses	Native Valve Endocarditis
Endocarditis	3mg/kg/day IV in 2 or 3 doses	Native Valve Endocarditis, with Amoxicillin/Clavulanate
Endocarditis	3mg/kg/day IV in 2 or 3 doses	MRSA Native Valve Endocarditis
Endocarditis	3mg/kg/day IV in 2 or 3 doses	Prosthetic Valve Endocarditis (Early)
Neisseria gonorrhoeae	240mg IM x 1	Uncomplicated Gonococcal
Pelvic inflammatory disease	2mg/kg loading then 1.5mg/kg q8hr IV	Inpatient; combined with Clindamycin
Peritoneal dialysis-associated peritonitis	0.6mg/kg daily	Empiric IP
Plague	5mg/kg IV/IM once daily x 10 days	Active disease
Postpartum endometritis	5mg/kg IV q24hrs or 1.5mg/kg IV q8hrs	Combined with Clindamycin; <48hrs postpartum
Prostatitis	7mg/kg IV daily	Septic
Pyelonephritis	3mg/kg/day divided q8hr	Adult Inpatient
Tularemia	5mg/kg/day IV/IM once daily x 10 days	Active disease
Urethritis in men	240 mg IM x 1	CTX Contraindicated

Pediatric Dosing

Indications by Disease

Disease	Dose	Context
Acute cystitis	2.5mg/kg IV q8hrs	Pediatric Inpatient
Endocarditis	1mg/kg IV q8hrs	Pediatric Empiric
Pediatric fever of uncertain source	4mg/kg/dose	Neonatal 0-14 days with Ampicillin
Plague	2.5mg/kg IV/IM q8hrs x 10 days	Pediatric Active Disease
Pyelonephritis	2.5mg/kg IV q8hrs	Pediatric Inpatient
Tularemia	2.5mg/kg IV/IM q8hrs x 10 days	Pediatric Active Disease

Special Populations

• Pregnancy Rating: D
• Lactation: Probably safe
• Renal Dosing
  • Adult
    • Conventional interval dosing
      • CrCl 10-50: give q12-48h
      • CrCl <10: give q48-72h
      • Hemodialysis: give 1-1.7mg/kg after dialysis
    • Extended interval dosing
    • CrCl 30-60: increase dosing interval based on levels
    • CrCl <30: avoid use
  • Pediatric
    • Conventional interval dosing
      • CrCl 30-50: give q12-48h
      • CrCl: 10-29: Give q18-24h
      • CrCl <10: give q48-72h
      • Hemodialysis/peritoneal dialysis: give 2mg/kg after dialysis
    • Extended interval dosing
    • CrCl 30-60: increase dosing interval based on levels
    • CrCl <30: avoid use
• Hepatic Dosing (Adult & Pediatric)
  • Not defined

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• Ototoxicity
• Nephrotoxicity
• Prolongation of neuromuscular blockers

Common

• Nausea/vomiting
• Irritation at injection site

Pharmacology

• Half-life:2-3 hours
• Metabolism:
• Excretion: Urine excretion
• Mechanism of Action: Binds to 30S and 50S ribosomal subunits, disrupting mRNA translation and interfering with bacterial protein synthesis

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	R
	Strep. Pneumoniae	R
	Viridans strep	X1
	Strep. anginosus gp	X1
	Enterococcus faecalis	S
	Enterococcus faecium	S
	MSSA	S
	MRSA	R
	CA-MRSA	X1
	Staph. Epidermidis	I
	C. jeikeium	R
	L. monocytogenes	S
Gram Negatives	N. gonorrhoeae	R
	N. meningitidis	R
	Moraxella catarrhalis	S
	H. influenzae	S
	E. coli	S
	Klebsiella sp	S
	E. coli/Klebsiella ESBL+	S
	E coli/Klebsiella KPC+	R
	Enterobacter sp, AmpC neg	S
	Enterobacter sp, AmpC pos	S
	Serratia sp	X1
	Serratia marcescens	S
	Salmonella sp	X1
	Shigella sp	S
	Proteus mirabilis	X1
	Proteus vulgaris	S
	Providencia sp.	X1
	Morganella sp.	X1
	Citrobacter freundii	X1
	Citrobacter diversus	X1
	Citrobacter sp.	X1
	Aeromonas sp	X1
	Acinetobacter sp.	R
	Pseudomonas aeruginosa	S
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	R
	Yersinia enterocolitica	S
	Francisella tularensis	S
	Brucella sp.	S+'
	Legionella sp.	X1
	Pasteurella multocida	X1
	Haemophilus ducreyi	X1
	Vibrio vulnificus	I
Misc	Chlamydophila sp	R
	Mycoplasm pneumoniae	R
	Rickettsia sp	R
	Mycobacterium avium	X1
Anaerobes	Actinomyces	R
	Bacteroides fragilis	R
	Prevotella melaninogenica	R
	Clostridium difficile	R
	Clostridium (not difficile)	X1
	Fusobacterium necrophorum	R
	Peptostreptococcus sp.	R

Key

• S susceptible/sensitive (usually)
• I intermediate (variably susceptible/resistant)
• R resistant (or not effective clinically)
• S+ synergistic with cell wall antibiotics
• U sensitive for UTI only (non systemic infection)
• X1 no data
• X2 active in vitro, but not used clinically
• X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
• X4 active in vitro, but not clinically effective for strep pneumonia

See Also

• Antibiotics (Main)