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2. Introduction
• Aminoglycosides are antibiotics with amino sugars in
glycosidic linkages.
• They are derived from the soil actinomycetes of the
genus streptomyces (streptomycin, kanamycin,
tobramycin, neomycin) and the genus micromonospora
(gentamicin and netilmicin) - hence the difference in
spelling.
• Amikacin and netilmicin are semisynthetic products

3. Common Properties of
Aminoglycosides
1. Aminoglycosides are not absorbed orally (as they ionize
in solution) therefore they are given parenterally.
2. They remain extracellularly and penetration into CSF is
very poor.
3. They are excreted unchanged by the kidneys.
4. They are all bactericidal.

4. 5. They act by inhibiting bacterial protein synthesis.
6. They are mainly effective against gramnegative
organisms.
7. They produce variable degrees of ototoxicity and
nephrotoxicity as adverse effects.

5. • Antibacterial spectrum Aminoglycosides have a
narrow spectrum and are effective mainly against
aerobic gram-negative bacilli like E. coli, Proteus,
Pseudomonas, Brucella, Salmonella, Shigella and
Klebsiella.

6. Mechanism of action
• Aminoglycosides, being water-soluble penetrate the bacterial
cell membrane through aqueous pores and from there they
are taken up by an active transport process.
• Inside the cell, aminoglycosides bind to 30S ribosomes and
inhibit bacterial protein synthesis - block initiation of protein
synthesis, cause termination of protein synthesis and cause
addition of incorrect amino acids resulting in the synthesis of
abnormal proteins.

7. • Aminoglycosides are bactericidal.
Mechanism of action of aminoglycosides

8. • Higher the concentration, greater is the bactericidal
effect.
• A residual bactericidal effect—postantibiotic effect—
remains even after the plasma levels of
aminoglycosides fall.
• Hence, even though they have a short t½, they can
be given once a day

9. • Resistance to aminoglycosides is acquired by
1. Aminoglycoside inactivating enzymes.
2. Low affinity of ribosomes - acquired by mutation.
3. Decrease in permeability to the antibiotic.
• There is partial cross-resistance among
• various aminoglycosides.

10. Pharmacokinetics
• Aminoglycosides are not absorbed from the gut but
when instilled into body cavities or applied over large
wounds, they may get rapidly absorbed.
• Following IM injection peak levels are seen in 60
minutes.

11. • They are not bound to plasma proteins and do not
enter cells or cross barriers - mostly remain in the
vasculature.
• In patients with severe infection, plasma
concentration of aminoglycosides should be
determined to guide the treatment.

12. Adverse Effects
1. Ototoxicity is the most important toxicity. Both vestibular and
auditory dysfunction can occur depending on the dose and
duration. The aminoglycosides get concentrated in the
labyrinthine fluid of the inner ear and damage both cochlear
hair cells and vestibular sensory cells.

13. • As the cochlear cells cannot regenerate, there is progressive,
permanent deafness. The auditory nerve degenerates. Tinnitus
appears first, followed by deafness; elderly people are more
susceptible
• Stopping the drug can prevent further damage. Vestibular
dysfunction is manifested by headache, nausea, vomiting, dizziness,
vertigo, nystagmus and ataxia. Most symptoms subside in two
weeks except ataxia which may persist for1-2 years.

14. 2. Nephrotoxicity Aminoglycosides attain high concentration in
the renal cortex and cause damage to the renal tubules. This
results in loss of urine concentrating capacity, low GFR and
albuminuria. These effects are reversible. Most symptoms
subside in 2 weeks except ataxia which may persist for 1-2
years.

15. 3. Neuromuscular blockade Aminoglycosides have
curare-like effects and block neuromuscular
transmission.

16. Precautions in Using Aminoglycosides
1. Avoid concurrent use of other ototoxic drugs like
loop diuretics.
2. Avoid concurrent use of other nephrotoxic drugs like
amphotericin B, cephalothin and cisplatin.
3. Avoid concurrent use of curarimimetic drugs.

17. 4. To be used cautiously in elderly, in renal damage and in
combination with skeletal muscle relaxants.
5. Contraindicated in pregnancy because of risk of deafness
in the child.
6. Do not mix aminoglycosides with any other drug in the
same syringe.
7. Determination of plasma levels of aminoglycosides may
be needed in severe infections and in patients with renal
dysfunction.

18. Dose and routes of administration of
aminoglycosides
Aminoglycosides Doses Routes
Streptomycin
(STREPTONEX)
1-2 g/day IM
Gentamicin
(GARAMYCIN)
3-5 mg/kg/day in 3
divided doses
IM/IV
Tobramycin
(TOBRANEG)
3-5 mg/kg/day in 3
divided doses
IM/IV
Amikacin (AMICIN) 15 mg/kg/day in 2-3
divided doses
IM/IV
Netilmicin
(NETROMYCIN)
4-6 mg/kg/day in 2-
3 divided doses
IM/IV

19. • Streptomycin obtained from Streptomyces griseus is
mainly effective against aerobic gramnegative bacilli.
When used alone, bacteria, especially the tubercle
bacillus rapidly develops resistance to it.
• Streptomycin is the least nephrotoxic among
aminoglycosides.

20. Uses of Streptomycin
1. Tuberculosis
2. Subacute bacterial endocarditis (SBE)—
Combination of streptomycin and penicillin is
synergistic in this condition.
3. Plague, tularaemia and Brucellosis— Streptomycin
is given with a tetracycline

21. Uses of gentamycin
1. UTI Gentamicin is effective in uncomplicated UTI as it
is released for a long time from the renal cortex.
2. Pneumonia due to gram-negative organisms may be
treated with gentamicin + penicillin.
3. Osteomyelitis, peritonitis, septicaemia caused by
gram-negative organisms can be treated with
gentamicin.

22. 4. Meningitis due to gram-negative bacilli— gentamicin is
used with a III generation cephalosporin.
5. Gentamicin may be used in place of streptomycin in SBE.
6. Topical
• Gentamicin cream is used topically in burns and other
infected wounds.
• Gentamicin eye drops are used in the prevention and
treatment of bacterial conjunctivitis.

23. 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).

24. • 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.
• 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.