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Here is a list of nine aminoglycoside antibiotics.
1. Streptomycin:
1. Isolated from streptomyces griseus in 1943.
2. Very soluble in water.
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3. Stable compared with penicillin.
4. Pure dry powder remain full potency at room temperature for at least 2 years.
5. Intestinal absorption poor.
6. Used in the treatment of enteritis.
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7. Slow absorption from I/M route.
8. Peak level achieves about 60-90 min of I/M administration.
9. Mainly active against gram negative organism.
10. Resistance develop through mutation, decreased cellular uptake and decreased cell permeability to antibiotic.
Clinical Use:
1. Tuberculosis
2. Brucellosis
3. Tularemia
4. Glanders
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Dose:
Parenteral
5-10 mg/kg I/M oral
20 mg/kg
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Intramammary, 100 mg/quarter in lactating cow and 500 mg/quarter in dry cow.
Used in combination with procaine penicillin for the treatment of Gram positive and Gram negative organism. Synergistic effect.
2. Gentamicin:
1. Isolated from Micromonospora Purpurea.
2. The commercial preparation consists of a mixture of gentamicin C1, C1a and C2.
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3. Oral absorption low.
4. Protein bound activity low.
5. Absorption rapid following I/M route.
6. Biological half life 75-110 min.
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7. Excretion by glomerular filtration.
8. Less amount available in CSF, prostate and eye.
9. One half to one third of serum level found in milk, bronchial secretion and other body fluids.
10. Effective against Pseudomonas, E. Coli, Salmonella, Klebsiella, Proteus, Staphylococcus, Shigella, Neisseria.
11. Organisms resistant to gentamicin also be resistant to neomycin, streptomycin, framycetin and kanamycin. Many strains resistant to other aminoglycoside sensitive to gentamicin.
12. Cause toxicity mainly affects vestibular function resulting impairment of balance.
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13. Cause renal damage also.
14. Cause respiratory paralysis due to neuromuscular blockade which can be treated by parenteral calcium or by anticholinesterase agents.
15. Cross placental barrier leading to potential foetal damage.
Clinical Use:
1. Urinary tract, respiratory tract and soft tissue infection.
2. Otitis, metritis, eye infection.
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Dose:
5 mg/kg twice on the first day of treatment followed by once daily.
3. Neomycin:
1. Isolated from Streptomyces fradiae.
2. Used as sulphate.
3. White or slightly yellow crystalline powder, soluble in water, highly stable.
4. About 3% absorption through oral route.
5. No absorption from the skin.
6. Highly effective for treatment of enteric infection due to gram negative organisms.
7. Peak blood level within 1 hr of I/M injection.
8. Appreciable amounts present from 4 to 8 hr.
9. Penetrates blood brain, pleural and peritoneal barriers after I/M administration.
10. Excreted rapidly by the kidney.
11. Causes loss of hearing due to irreversible damage to the auditory, division of the eighth cranial nerve.
12. Causes kidney damage.
13. Effective against Salmonella, E. Coli, Klebsiella, Proteus, Enterobacter.
Clinical Use:
1. Urinary infections due to coliforms and skin, eye and ear infection.
2. Scour in calves and piglets.
3. Mastitis-along with penicillin.
4. Solutions for dressing wounds and eyes.
5. Ointment for superficial conditions like otitis, corneal ulcer, conjunctivitis, keratitis, abscess and dermatitis.
Dose: 10 mg/kg orally.
2.5 mg/kg parenterally.
4. Kanamycin:
a. Antibacterial activity similar to that of neomycin.
b. Use for similar purposes.
c. Topical preparation for ear infection and oral preparation for enteric infection.
d. Not absorbed from the intestine.
e. Antibacterial activity against E. Coli, Salmonella, Klebsiella.
f. Residues persist for longer period in kidney tissue.
g. Parenteral administration may cause permanent damage to the cochlear and vestibular portions of the 8th cranial nerve.
Clinical Use:
necrotic enteritis, pneumonia, diarrhoea, haemorrhagic dysentery and atrophic rhinitis in swine; L Coli, Strep, fecalis, Staph aureus and Proteus infection in dog; Colibacillosis in chickens; bovine mastitis.
Dose:
15 mg/kg/ day in 3 divided doses I/M.
5. Tobramycin:
1. Related structurally to kanamycin.
2. Highly effective against Pseudomonas spp.
6. Spectinomycin:
a. Limited gram-positive and somewhat better gram negative activity.
b. Bacteriostatic against most bacteria and mycoplasma.
c. Protein binding activity low.
d. Lipid solubility low.
e. Absorb after oral and parenteral route.
f. Excretion by glomerular filtration.
g. Effective against E. Coli, Salmonella, Pasteurella and Mycoplasma (CRD in poultry).
Clinical Use:
a. Mycoplasmal infection in Poultry.
b. Colibacillosis in poultry and pigs.
c. E. Coli mastitis in cattle.
Dose:
Pig – 11-44 mg/kg orally.
Dog- 5.5-11 mg/kg twice daily I/M.
22 mg/kg twice daily orally.
7. Amikacin:
a. Water soluble acylated derivative of kanamycin.
b. Resistant to most bacterial enzymes.
c. Poor absorption from intestine.
d. Excretion via kidney.
e. Toxicity on hearing, balance and kidney function.
f. Effective against E. Coli, Proteus, Klebsiella, Pseudomonas, Serratia, Citrobacter.
Clinical Use:
a. Infection resistant to other aminoglycoside.
b. Drug of choice for burn infected with resistant Pseudomonas.
c. M. tuberculosis (99% strain inhibited).
d. Uterine infection caused by Gram negative bacteria in mares.
8. Netilmicin:
1. Latest aminoglycoside antibiotic.
2. Similar to gentamicin and tobramycin in its pharmacokinetic properties and dosage.
3. Effective against aerobic gram negative bacilli.
4. Not metabolized by the majority of the aminoglycoside inactivating enzymes.
Clinical Use:
1. Serious infections due to susceptible Enterobacteriaceae and other aerobic gram negative bacilli.
9. Framycetin:
1. Framycetin- neomycin B.
2. Properties like neomycin.
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3. Not absorbed from intestine.
Clinical Use:
1. Enteritis.
2. Topical antibiotic for the treatment of otitis externa in the dog.
Untoward effects of the aminoglycoside antibiotics.
Ototoxicity:
Vestibular and auditory dysfunction. Progressive accumulation of these drugs in the perilymph and endolymph of the inner ear → diffusion back into the blood flow → half lives 5-6 times longer in the otic fluid → destruction of vestibular or cochlear sensory cells → retrograde degeneration of the auditory nerve → irreversible hearing loss.
Nephrotoxicity:
Accumulation and avid retention of antibiotics in the proximal tubular cells → damage manifested by the excretion of enzymes of the renal tubular brush border → defect in renal concentrating ability, mild proteinuria and the appearance of hyaline and granular casts → glomerular filtration decreased.
Symptoms:
low concentrating ability, proteinuria, hypokalemia, acute renal acidosis.
Neuromuscular:
Reduced pre-junctional release of acetyl choline which may lead to muscular paralysis.
Others:
Enlargement of blind spot, optic neuritis.
