Usage and Importance of Aminoglycosides

• It is important to understand that certain drugs are resistant to aminoglycosides and the best treatment options offered by aminoglycosides.
• There are several important drug interactions and adverse reactions that must be noted when using aminoglycosides. 
• The nurse has an important role in the administration and education of aminoglycosides.
  

Aminoglycosides are commonly used antibiotics (to kill bacteria or stop their synthesis) that are often used in hospitals for severe infections.  

Aminoglycosides are bactericidal, meaning they kill bacteria.  They are mostly active against: 

• gram-negative bacilli 
• some aerobic gram-positive bacteria 
• mycobacteria 
• some protozoa
  

The most commonly aminoglycosides that are currently used include: 

• amikacin sulfate 
• gentamicin sulfate 
• kanamycin sulfate 
• neomycin sulfate 
• netilmicin sulfate 
• paromomycin sulfate 
• streptomycin sulfate 
• tobramycin sulfate 

Aminoglycosides act against susceptible organisms by binding to the 30S subunit – a specific ribosome in the microorganisms which interferes with protein synthesis, leading to bactericidal actions. 

Drug Interactions and Adverse Reactions of Aminoglycosides 

Drug Interactions

The following drug interactions can occur with aminoglycosides: 

• Carbenicillin and ticarcillin reduce the effects of amikacin, gentamicin, kanamycin, neomycin, streptomycin, and tobramycin.  When giving penicillin with aminoglycosides, penicillin should be given first and separately.  
• If amikacin, gentamicin, kanamycin, neomycin, streptomycin, and tobramycin are administered with neuromuscular blockers, the neuromuscular blockade increases, which results in increased muscle relaxation and respiratory distress.  Therefore, one must exercise caution if the patient has to undergo anesthesia and is taking aminoglycosides.  

Adverse Reactions

The most common and serious adverse drug reactions with aminoglycoside therapy are as follows:  

• neuromuscular reactions ranging from peripheral nerve toxicity to neuromuscular blockade 
• ototoxicity 
• renal toxicity 
  

The symptoms of ototoxicity (damage to the ears) can be masked when given with oral antiemetics.  Moreover, the damage is increased with loop diuretics.  Hearing loss is variable and may be reversible.  

Toxicity to the kidneys can result in renal failure; therefore, one must monitor kidney functions with aminoglycoside therapy.  The risk of renal toxicity also increases when amikacin, gentamicin, kanamycin, or tobramycin is administered with cyclosporine, amphotericin B, or acyclovir.  

It is important to not give other potentially nephrotoxic drugs, such as vancomycin, with aminoglycoside therapy.  

Do not give warfarin with aminoglycoside therapy, especially gentamicin, because it can decrease the excretion rate of warfarin, resulting in increased serum levels, which increases the chances of bleeding.  Consult with the physician or the pharmacist first to adjust the dose accordingly.  

Do not give aminoglycosides with neuromuscular agents because it can lead to respiratory depression.  

Toxicity to the neurologic system results in peripheral neuropathy with numbness and tingling of the extremities; therefore, one must check the patient for peripheral neuropathy with aminoglycoside therapy.  

Other adverse effects of oral aminoglycosides are as follows: 

• nausea
• vomiting
• diarrhea

The Nursing Role and Processes With Aminoglycosides

Nurse Assessment

• Obtain a patient’s allergy record.  Ask him/her if they have had an allergic reaction to any antibiotic previously.  
• Before starting the therapy, have culture and sensitivity tests done.  One can start the therapy before the arrival of the test results.  To check the drug’s efficacy, one can repeat these tests.  If the organism is not sensitive to aminoglycosides, change the antibiotic.  
• Assess the patient’s vital signs, electrolyte levels, hearing ability, and renal function studies before and during therapy. 
• Before starting therapy and during therapy, weigh the patient daily and review baseline renal function studies.  If any changes are noted, inform the prescriber to adjust the dose.  
• Assess the patient for drug interactions and adverse reactions.  Take a complete medication and health history from the patient.  
• Assess both the patient and family’s knowledge of drug therapy. 

Key Nursing Diagnoses

With aminoglycoside therapy, one needs to be mindful of the following nursing diagnoses: 

• Risk for injury related to the adverse effects of the drug 
• Risk for infection related to drug-induced superinfection  
• Risk for fluid volume deficit related to adverse gastrointestinal reactions 

Planning and Outcome Goals

• The patient’s risk of injury will be minimized. 
• The patient’s risk of superinfection will be minimized. 
• The patient’s fluid volume will remain within normal limits, monitored by vital signs, intake, and output.
  

Implementation

With aminoglycoside therapy, implement the following: 

• Hydrate the patient well to avoid a chemical reaction in the renal tubes.  
• Do not add or mix other drugs with the infusion, especially penicillin, as they inactivate the drug.  If one needs to administer another drug through an intravenous route with aminoglycosides, stop the primary drug temporarily and restart it once the other one is completed.   
• Check the expiration date before the administration of the drug.  
• Follow the manufacturer’s instructions for the reconstitution, dilution, and storage of drugs. 
• Before administering oral suspensions, shake them well.  
• For intramuscular drug administration, use a large muscle mass, such as the ventral gluteal, and administer it deep down into the muscle.  To minimize tissue injury, rotate the injection sites.  Also, apply ice cubes to provide pain relief.   
• Rapid IV administration can cause neuromuscular blockade; therefore, infuse the drug continuously or intermittently for over 30 to 60 minutes for adults and over 1 to 2 hours for infants.  However, dilution volume for children is determined individually. 
• If any signs or symptoms of decreased renal function in the patient or decreased hearing ability is present, inform the healthcare provider promptly. 
• Keep in mind that therapy shall be administered for 7 to 10 days.  However, if the patient does not improve in 3 to 5 days, it should be stopped.  Culture and sensitivity tests should be obtained again.  
• Make sure that the patient is well hydrated and has taken enough fluid to prevent chemical reactions in the renal tubes.  
• With gentamicin therapy, draw blood to check for the peak level 1 hour after intramuscular injection and 30 minutes to 1 hour after intravenous infusion.  To obtain a trough level, draw a sample just before the next dose.  Peak gentamicin levels above 12 mcg/mL and trough levels above 2 mcg/mL may increase the risk of toxicity.  Keep a record of all samples with time and date.  Be sure not to use a heparinized tube to collect blood samples because it interferes with the results. 

Evaluation

• The patient maintains an adequate hearing level and renal function as was present before the start of therapy.  
• The patient has recovered completely from the infection and does not show any signs or symptoms of remaining infection.   
• The patient maintains adequate hydration. 

The Bottom Line

Aminoglycosides act by interfering with the protein synthesis of the bacteria.  Aminoglycoside therapy can affect the patient’s renal functions and hearing levels because it poses a risk of nephrotoxicity and ototoxicity.   

If any of these symptoms are noted, it is important for the medical provider to be notified promptly in an effort to offer guidance on lowering the dosage or discontinuing the medication.

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