Aminoglycosides
What are they?
- Aminoglycosides are antibiotics
- Aminoglycosides act by inhibiting bacterial protein synthesis and are used against gram-negative bacteria such as E. coli, Proteus, and Pseudomonas
- Some gram positive cocci are resistant to aminoglycosides, therefore penicillin or cephalosporins are effective
- Aminoglycosides are used mostly for serious infections
- when administered with penicillins, the effects of aminoglycosides are decreased
Absorption
- They are not absorbed in the gastrointestinal tract
- They are not able to cross into the cerebrospinal fluid
- They cross through the given blood-brain barrier in children but not adults
- These are commonly via intramuscular and intravenous routes
- Two aminoglycosides given by oral route include neomycin and paromomycin
- used as a preoperative bowel antiseptic
- used in treating intestinal amebiasis and tapeworm infestation
Examples of aminoglycosides include: Gentamicin, Tobramycin, and Streptomycin
Gentamicin Sulfate
- used to treat infections caused by gram-negative organisms. It is used to treat inflammatory disease and it is effective against Staphylococcus aureus
- given intramuscular or intravenous
- side effects include anorexia, nausea, vomiting, rash, tremors, tinnitus, pruritus, and mnuscle cramps
- effective against pseudomonas aeruginosa
- given intravenous or intramuscular
- hearing changes and urinary output should be monitored. this aminoglycosides has fewer toxic effects than others
- streptomycin was the first aminoglycoside
- used with antituberculosis drugs
- ototoxicity is a major prblem with this drug
Dosage and Route
- Amikacin 15 mg/kg q 8 hr IM, IV
- Gentamicin 1 mg/kg q 8 hr IM, IV
- Streptomycin 1 g/day initially decreased to 1 g 2-3 times weekly IM
- Tobramycin 0.75-1.25 mg/kg q 6 hr
- ototoxicity
- nephrotoxicity- renal function, drug dose, and age are factors that determine this
- drug dosing is important with younger children and older adults
- prolonged use could result in superinfection
- serum aminoglycoside levels should be monitored to avoid adverse reactions
- hypersensitivity to aminoglycosides or bisulfites
- effects of aminoglycosides are decreased when given with a penicillin
- the drug action of oral anticoagulants may increase when taken together with aminoglycosides
- the risk of ototoxicity increases when ethacrynic acid is given simultaneously
- assess for infection (vital signs, wound appearance, sputum, urine, stool, WBC) at beginning of and throughout therapy
- obtain specimens for culture and sensitivity before initiating therapy
- monitor intake and output and daily weights to assess hydration status and renal function
- assess for signs of superinfection (fever, upper respiratory infection, vaginal itching or discharge, increasing malaise, diarrhea)
- evaluate eighth cranial nerve function by audiometry before and throughout therapy. hearing loss is usually in the high-frequency range
- monitor renal function by urinalysis, specific gravity, BUN, and creatinine before and throughout therapy
- may cause increased BUN, AST, ALT, serum alkaline phosphate, bilirubin, creatinine, and LDH concentrations
- monitor blood levels periodically. Draw blood for peak levels 1 hr. after IM injection and 30 min. after IV infusion is complete. Trough levels should be drawn just before next dose
- IM administration should be deep into well developed muscles. Alternate injection site
- Y-site compatibility and incompatibility should be considered
- in case if there is vestibular dysfunction, nausea, vomiting, headache, or fever then drug should be discontinued
- Instruct patient to report if there is loss of hearing feeling of fullness in head
- to report headache, dizziness, or renal impairment
- instruct patient to keep hydrated (1500 - 2000 ml/day) during therapy
- therapeutic response if there is absence of fever, draining wounds, etc.
Kee, J. L.,
Hayes, E. R., & McCuistion, L. E.
(2012). Pharmacology: A nursing process approach (7th ed.).
St. Louis, MO: Elsevier Saunders.
Pagkalis, S., Mantadakis, E., Mavros, M. N., Ammari, C., & Falagas, M. E.
(2011). Pharmacological Considerations for the Proper Clinical Use of
Aminoglycosides. Drugs, 71(17),
2277-2294. doi:10.2165/11597020-000000000-00000
I like the mention of the timing of levels. This is SO important. So many times in practice, something messes this up. The lab/nursing communication is critical so that pharmacists and providers can interpret the levels correctly. Elevated troughs are what are correlated with adverse outcomes (like acute renal impairment). For gent/tobra we try to keep the trough < 0.5-1. The use of once daily or extended dosing of aminoglycosides has become more popular and the norm. It's given as a single 5 or 7mg/dose and then getting a random level 6-14 hrs later and then referring to a published nomogram graph to determine what the frequency should be depending on how quickly it was cleared. Aminoglycosides are dosed using a dosing weight (between actual and ideal body weight) for obese patients. Using actual weight in obese patients could lead to dangerously high levels.
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