Chapter 87 - Aminoglycosides: Bactericidal Inhibitors or Protein Synthesis

What are the big adverse affects to look out for when using aminoglycosides?

****Aminoglycosides can cause serious injury to the inner ear and kidney. (ototoxicity and nephrotoxicity) also: -hypersensitivity reactions -neuromuscular blockade -Blood dyscrasias (abnormally low levels of WBCs)

What are the three main aminoglycosides we talked about in class?

-Gentamicin -tobramycin -Amikacin

Are aminoglycosides bactericidal or bacteriostatic?

Bactericidal.

What type of bacterium are aminoglycosides used to treat?

Gram-negative bacilli

What do we need to pay attention to with peak and trough levels?

Peak levels must be high enough to kill bacteria; trough levels must be low enough to minimize toxicity.

Before administering an aminoglycoside, it is most important for the nurse to assess the patient for a history of what? A) Myasthenia gravis B) Asthma C) Hypertension D) Diabetes mellitus

The answer is A, Aminoglycosides can inhibit neuromuscular transmission, causing flaccid paralysis and potentially fatal respiratory depression. These drugs should be used with extreme caution in patients with myasthenia gravis.

A nurse is administering a daily dose of tobramycin at 1000. At which time should the nurse obtain the patient's blood sample to determine the trough level? A) 0800 B) 0900 C) 1130 D) 1200

The answer is B, Trough levels determine the lowest level between doses. Blood is drawn just before the next dose is administered when a divided dose is used or 1 hour before the next dose if a single daily dose is used.

The nurse knows that there is an increased risk of ototoxicity in a patient receiving an aminoglycoside if which level is high? A) Concentration B) Trough C) Peak D) Dose

The answer is B, When trough levels remain elevated, aminoglycosides are unable to diffuse out of inner ear cells, thus exposing the cells to the medication for an extended time. Prolonged exposure (ie, high trough levels), rather than brief exposure to high levels, underlies cellular injury.

How do aminoglycosides and broad-spectrum penicillins interact?

There is a beneficial response. It has been shown that if you ad an aminoglycoside to a broad-spectrum penicillin, you would get a higher kill on the bacteria (synergy)

What is the "trough level?"

Trough is the lowest level of medication in the blood stream.

Because aminoglycosides are narrow-spectrum antibiotics, what bacteria do they cover?

Aerobic gram-negative bacilli

What is the a "peak level?"

It determines how much of the bacteria is killed. Peak level is the highest amount of medication in the blood stream.

When administering an aminoglycoside to a patient with myasthenia gravis, it is most important for the nurse to assess what? A) Deep tendon reflexes B) Breath sounds C) Eyelid movement D) Muscle strength

The answer is B, Aminoglycosides can inhibit neuromuscular transmission, causing potentially fatal respiratory depression. Patients with myasthenia gravis (MG) are at an increased risk. Deep tendon reflexes, eyelid movement, and muscle strength are important assessments for a patient who has MG, but they are not as important as airway and breathing ability.

A patient who is receiving an aminoglycoside (gentamicin) has a urinalysis result with all of these findings. Which finding should a nurse associate most clearly with an adverse effect of gentamicin? A) White blood cells (WBCs) B) Glucose C) Ketones D) Protein

The answer is D, Aminoglycoside-induced nephrotoxicity usually presents as acute tubular necrosis. Symptoms of concern are protein in the urine, dilute urine, and elevation of the serum creatinine and blood urea nitrogen (BUN) levels. WBCs, glucose, and ketones are not specifically related to gentamicin use.

A patient who is receiving an aminoglycoside develops flaccid paralysis and impaired breathing. Which medication does the nurse anticipate administering? A) Magnesium sulfate [Epsom salt] B) Potassium chloride [K-Dur] C) Sodium bicarbonate [Citrocarbonate] D) Calcium gluconate [Kalcinate]

The answer is D, Flaccid paralysis and impaired breathing are signs of impaired neuromuscular transmission, which may occur with aminoglycosides, especially if they are administered concurrently with a neuromuscular blocking agent. Impaired transmission can be reversed with intravenous infusion of a calcium salt (calcium gluconate). Magnesium sulfate, potassium chloride, and sodium bicarbonate do not reverse impaired neuromuscular transmission caused by aminoglycosides.

Are aminoglycosides broad-spectrum or narrow-spectrum?

Aminoglycosides are narrow-spectrum antibiotics.

A patient is receiving an aminoglycoside (tobramycin) antibiotic. A nurse asks the patient to choose daily meal selections, to which the patient responds, "Oh, dear, I don't want another IV." The nurse makes which assessment about the patient's response? A) Some hearing loss may have occurred. B) The confusion is due to the hospital stay. C) A nutrition consult most likely is needed. D) The patient has a family history of dementia.

The answer is A, The patient's comment suggests that the person did not hear the instructions. Aminoglycoside antibiotics can cause ototoxicity. The first sign may be tinnitus (ringing in the ears), progressing to loss of high-frequency sounds. Audiometric testing is needed to detect it. Nutrition, confusion, and a family history of dementia do not address the problem of possible hearing loss associated with aminoglycosides.

Before administering gentamycin, it is most important for the nurse to assess the patient for a history of what? A. Hypertension B. Myasthenia gravis C. Diabetes mellitus D. Asthma

The answer is B, Aminoglycosides must be used with caution in patients with renal impairment, pre-existing hearing impairment, and myasthenia gravis, and in patients receiving ototoxic drugs (especially ethacrynic acid), nephrotoxic drugs (for example, amphotericin B, cephalosporins, vancomycin, cyclosporine, nonsteroidal anti-inflammatory drugs [NSAIDs]), and neuromuscular blocking agents.

The nurse is reviewing laboratory values from a patient who has been prescribed gentamicin. To prevent ototoxicity, it is most important for the nurse to monitor which value(s)? A. Serum creatinine and blood urea nitrogen levels B. Trough drug levels of gentamicin C. Peak drugs levels of gentamicin D. Serum alanine aminotransferase and aspartate aminotransferase levels

The answer is B, To minimize ototoxicity, trough levels must be sufficiently low to reduce exposure of sensitive sensory hearing cells. The risk of ototoxicity is related primarily to persistently elevated trough drug levels rather than to excessive peak levels.

The patient is ordered daily divided doses of gentamycin. The patient received an intravenous dose of gentamycin at 4:00 PM which finished infusing at 4:30 PM. When should the nurse obtain the peak level? A. 4:30 PM B. 5:00 PM C. 5:30 PM D. 6:00 PM

The answer is B, When using divided daily doses, draw blood samples for measuring peak levels 1 hour after IM injection and 30 minutes after COMPLETING an IV infusion. When a single daily dose is used, measuring peak levels is unnecessary. Draw samples for trough levels just before the next dose (when using divided daily doses) or 1 hour before the next dose (when using a single daily dose).

A nurse monitors a patient who is receiving an aminoglycoside (gentamicin) for symptoms of vestibular damage. Which finding should the nurse expect the patient to have first? A) Unsteadiness B) Vertigo C) Headache D) Dizziness

The answer is C, Gentamicin causes irreversible ototoxicity, which results in both impaired hearing and disruption of balance. Headache is the first sign of impending vestibular damage (balance) and may last 1 to 2 days. Unsteadiness, vertigo, and dizziness appear after headache.

Which enteral aminoglycoside would the nurse expect to be ordered preoperatively for a patient having intestinal surgery? A) Gentamicin B) Tobramycin C) Amikacin D) Neomycin

The answer is D, In general, aminoglycosides are poorly absorbed in the gastrointestinal (GI) tract. Neomycin is given orally to suppress bowel flora before surgery of the intestine and is not used parenterally because of its high nephrotoxicity and ototoxicity. Gentamicin, tobramycin, and amikacin are administered parenterally only.

The nurse is caring for a patient receiving intravenous gentamicin for a severe bacterial infection. Which assessment finding by the nurse indicates the patient is experiencing an adverse effect of gentamycin therapy? A. Blurred vision B. Hand tremors C. Urinary frequency D. Tinnitus

The answer is D, Ototoxicity can result from accumulation of the drug in the inner ear. Early signs that should be reported include tinnitus or headache. Other major adverse effects include nephrotoxicity and neuromuscular blockade.

Which statements about ototoxicity and aminoglycosides does the nurse identify as true? (Select all that apply.) A) The risk of ototoxicity is related primarily to excessive peak levels. B) The first sign of impending cochlear damage is headache. C) The first sign of impending vestibular damage is headache. D) Ototoxicity is largely irreversible. E) Use of aminoglycosides for less than 10 days is recommended to avoid ototoxicity.

The answers are C, D, and E. The risk of ototoxicity with aminoglycoside use is related primarily to excessive trough levels. The first sign of impending vestibular damage is headache. The first sign of cochlear damage is tinnitus. The other two statements are true.