___________________________________________________________________________ Antibiotics Review
THE AMINOGLYCOSIDES
Agent
Adult Dosing Range
Pediatric Dosing Range
Route
Common Side Effects
Comments
Amikacin 5 mg/kg every 8 hrs or 7.5 mg/kg every 12 hrs Gentamicin 3–5 mg/kg/day in divided doses every 8 to 12 hrs, or 5–7 mg/kg once daily Neomycin 4–12 g/day in 4 to 6 divided doses for 5 to 6 days, or 4 g/ day for an indefinite period
15–22.5 mg/kg/day every 8 hrs OR 15–20 mg/kg/dose every 24 hours Infants: 2–2.5 mg/ kg/dose every 6 to 8 hrs 50–100 mg/kg/day in 3 to 4 divided doses
IV, IM Renal failure,
Predisposition to auditory/vestibular nerve damage may be genetic; check family history. Check serum levels. Doses are based on lean body mass; maintenance dose is based on calculation with creatinine clearance. Additional dose adjustments are needed in renal failure. Used as a bowel prep for surgery. Is also formulated in some topical eye, ear, and skin preparations. Boxed warning: Risk factors for nephrotoxicity include pre-existing renal impairment, elderly patients, concomitant. May cause ototoxicity; symptoms may be irreversible and may not become evident until after therapy is complete. This is the most ototoxic of aminoglycosides; levels must be monitored closely. Can cause neuromuscular blockade and respiratory paralysis, especially when given soon after muscle relaxants or anesthesia. Effects of nondepolarizing muscle relaxants can be increased. Total body weight (as opposed to ideal body weight) should be used for underweight patients.
vestibular nerve damage, auditory nerve damage
IV, IM, topical
PO, topical
Systemic absorption is possible, resulting in the same side effects as amikacin.
Plazomicin 15 mg/kg once daily for 4-7 days
N/A
IV
Renal failure
Streptomycin 15–30 mg/kg/day or 1–2 g daily
20–40 mg/kg/day every 6 to 12 hrs in divided doses Max: 1 g/dose or 2 g/day
IM Renal failure,
vestibular nerve damage, auditory nerve damage
Tobramycin 1–2.5 mg/kg every 8 to 12 hrs. or 4–7 mg/kg once daily dose
<5 yrs: 2.5 mg/kg every 8 hrs >5 yrs: 2–2.5 mg/kg every 8 hrs
IV, IM inhalation solution, ophthal- mic oint-
Renal failure, vestibular nerve damage, auditory nerve damage
ment or solution
Prescribing information is given for comparison purposes only. The higher dosage ranges reflect dosages for more severe infections. Please consult the manufacturer’s package insert for the antibiotic for complete prescribing information, maximum dosages, and indications. Source: [6; 16] Table 4
PHARMACOKINETICS The aminoglycosides are effective for the treatment of aerobic gram-negative bacilli, such as Klebsiella species, Enterobacter , and P. aeruginosa . There is very little activity against anaerobes and gram-positive organisms, so combination therapy with a beta-lactam, vancomycin, or other agents active against gram- positive organisms and anaerobes is commonly used. The ami- noglycosides are indicated for infections caused by susceptible organisms of the urinary tract, respiratory tract, skin and soft tissues, and sepsis due to gram-negative aerobic bacilli.
The binding site for aminoglycosides on the rRNA of the ribosome may also be altered, reducing binding. In addition, mutations that cause reduced uptake of aminoglycosides have been documented [81]. To combat resistances and overcome the relative natural resis- tance of enterococcus, other agents that target the cell wall are often used in conjunction with the aminoglycosides. Damage to the cell wall from the additional agents may be bactericidal in some cases and makes the cell wall more permeable to the aminoglycosides [82].
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