3.12 Aminoglycosides

Aminoglycosides are a potent broad spectrum of antibiotics that are useful for treating severe infections. Many aminoglycosides are poorly absorbed in the GI tract; therefore, the majority are given IV or IM. Aminoglycosides are potentially nephrotoxic and neurotoxic. They should be administered cautiously. Blood peak and trough levels should be performed to titrate a safe dose for each patient.

Indications: Streptomycin is used for streptococcal endocarditis and a second line treatment for tuberculosis. Neomycin is used in the treatment of hepatic encephalopathy as adjunct therapy to lower ammonia levels and is also used as a bowel prep for colon procedures.

Mechanism of Action: Aminoglycosides are bactericidal and bind with the area of the ribosome known as the 30S subunit, inhibiting protein synthesis in the cell wall and resulting in bacterial death (see Figure 3.9).^[1] Aminoglycosides may be given with beta-lactam medications to facilitate transport of aminoglycoside across the cellular membrane, resulting in a synergistic effect and increasing drug effectiveness.

Special Administration Considerations: Aminoglycosides can result in many adverse effects for the patient and, therefore, the nurse should monitor the patient carefully for signs of emerging concerns. Peak and trough levels are used to titrate this medication to a safe dose. Aminoglycosides can be nephrotoxic (damaging to kidney), neurotoxic (damaging to the nervous system), and ototoxic (damaging to the ear). Nurses should monitor the patient receiving aminoglycosides for signs of decreased renal function such as declining urine output and increasing blood urea nitrogen (BUN), creatinine, and declining glomerular filtration rate (GFR). Indications of damage to the neurological system may be assessed as increasing peripheral numbness or tingling in the extremities. Additionally, the patient should be carefully assessed for hearing loss or hearing changes throughout the course of drug administration.

Patient Teaching & Education: Patients receiving aminoglycosides should be advised to monitor for signs of hypersensitivity and auditory changes.  This may include tinnitus and hearing loss.  Patients may also experience accompanying vertigo while on the medication.  Patients should be advised to drink plenty of fluids while taking the medication.  Female patients should notify their provider if pregnancy is planned or if they are actively breastfeeding.^[2]

Now let’s take a closer look at the medication grid for streptomycin and gentamycin in Table 3.12.^[3]

Table 3.12 Streptomycin and Gentamycin Medication Grid

Critical Thinking Activity 3.12a

Using the above grid information, consider the following clinical scenario question:

A patient is admitted with streptococcal endocarditis and the nurse is preparing the morning dose of streptomycin. The lab has not yet arrived to obtain the trough level, and the drug is now overdue to be given. What is the nurse’s next best response?

Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.