Aminoglycosides - Side Effects And Contraindications

Aminoglycosides are a group of strong antibiotics that are used to treat bacterial infections. They are also the main component in the treatment of pulmonary exacerbations of cystic fibrosis (approximately 30,000 individuals in the US and 70,000 worldwide are living with the life-threatening condition) slowing the decline in lung function.

Furthermore, this type of antibiotics is used for treating and preventing the infection’s complications after cardiothoracic surgery. They accomplish this by stopping bacteria from producing proteins (they bind to the 30S ribosome) needed for their survival.

List of aminoglycosides

They are structurally related amino sugars connected by glycosidic linkages. This class of antibiotics includes:

  • tobramycin;
  • gentamicin;
  • streptomycin – this is the first aminoglycoside and was discovered in 1944. Presently, streptomycin is used occasionally and largely as adjunctive therapy of multi-drug resistant tuberculosis;
  • neomycin;
  • kanamycin;
  • amikacin;
  • paromomycin;
  • netilmicin.

Of these antibiotics, tobramycin, gentamicin, and amikacin are the most usually recommended for systemic administration.

Uses 

All these prescription medications are used to treat different types of bacterial infections, particularly those caused by gram-negative aerobic bacteria, such as Mycobacterium tuberculosis, Salmonella, Pseudomonas, and Escherichia coli. In addition, they tend to work in synergy with cell wall–active antibiotics such as cephalosporins, PCNs, and vancomycin.

However, similar to all other antibiotics, they are not effective against the common cold, influenza (better known as flu), or other viral infections. They are also ineffective against viruses, anaerobic bacteria (bacteria which does not require oxygen for growth), and fungi. Lastly, only one type aminoglycoside – paromomycin is used against parasitosis (parasitic infection).

Dosage

The dose of these antibiotics is given depending on weight, age, and how well the kidneys of the patient are working. Moreover, because they need only a short interaction with bacteria to kill them, the concentration differs from patient to patient.

They are usually given into a vein as an injection or drip by a nurse in a hospital. Topical application over inflamed tissues results in minimal systemic absorption.

In specific clinical situations, like individuals with endocarditis (an infection of the endocardial surface of the heart), multiple dosing are commonly recommended. Nevertheless, single daily dosing of these antibiotics appears to be efficacious, safe, and cost-effective.

Excretion

They are mainly eliminated by the kidney through glomerular filtration (the kidneys filter the blood and remove excess fluids and wastes). This excretion method accounts for approximately 90% of the dose administered.

Common side effects of aminoglycosides antibiotics  

While antibiotics have restored health and saved lives in some cases, they can have side effects and hazards similar to any other prescription drugs. Furthermore, they are very strong antibiotics, therefore, their side effects can be quite serious, particularly when taken by IV or mouth.

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Side effects which are less frequently experienced include:

  • chills and fever;
  • skin rashes;
  • difficulty breathing;
  • shaking;
  • weakness;
  • drowsiness;
  • blindness;
  • prolongation of effects of neuromuscular blockers;
  • renal damage.

Renal function should be monitored during therapy with this medicine, nevertheless, no indicator of renal disease is barely sensitive to prevent continued damage once nephrotoxicity (toxicity in the kidneys) is detected.

Renal damage is associated with the accumulation of high concentrations of this type of antibiotics in the renal cortex. The risk of nephrotoxicity is increased in patients who are ingesting other prescription medicines which affect the kidneys and hearing, like – NSAIDS (nonsteroidal anti-inflammatory medications), certain diuretics (especially furosemide), naproxen, ibuprofen, or other antibiotics like – vancomycin.

Usual side effects include:

  • unsteadiness;
  • dizziness;
  • increased thirst;
  • urine output changes;
  • seizures;
  • muscle twitching;
  • nausea and vomiting;
  • decreased appetite,
  • cochlear damage (irreversible hearing loss);
  • they can also exacerbate weakness in individuals with myasthenia gravis (a chronic autoimmune neuromuscular disease that leads to varying degrees of skeletal muscle weakness), thus, it is recommended to completely avoid using this type of antibiotics in these patients.

Furthermore, these medicines have a post-antibiotic effect, in which bacterial cell killing continues for some period of time after the blood plasma concentration of the antibiotic has fallen below the so-called MIC – minimal inhibitory concentration (the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism). This means that antibiotics levels can drop below the minimal inhibitory concentration of targeted harmful bacteria for a longer period without decreasing efficacy.

Moreover, too much use of an antibiotic can make the bacteria antibiotic resistant. In addition, antibiotics also kill the good bacteria, named intestinal flora, which lives in the colon.

More importantly, according to recent studies, antibiotics destroy cells in the intestinal epithelium (the layer of cells that forms the luminal surface of both the large and small intestine). The intestinal epithelium facilitates glucose, water, and essential nutrients absorption. Therefore, you should be mindful of how you use antibiotics.

Note

Over the years, the use of this type of antibiotics has rapidly declined because there are other less harmful antibiotics which bring the same results.

References

http://accesspharmacy.mhmedical.com/

https://livertox.nih.gov/

https://bmcpsychiatry.biomedcentral.com/

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