Aminoglycosides

Question 1

Chimically?

Answer 1

Chimically aminoglycosides consist of two or more amino sugars joined by aGlycosidic bond to ahexose nuclues usually situated in the center . this hexose is either streptidine or 2 deoxystreptamine

Question 2

Sourses ?

Answer 2

Natural drugs obtained from different types of bacteria and fungi .

Question 3

Sourse of streptomycin ?

Answer 3

Sterptomyces griseus

Question 4

Sourse of Neomycin ?

Answer 4

Sterptomyces fradie

Question 5

Sourse of Kanamycin ?

Answer 5

Sterptomyces kanamycetieus

Question 6

Sourse of Gentamycin ?

Answer 6

Microspora

Question 7

Mechanism of action ?

Answer 7

Aminoglycoside are rapidly bactericidal antibiotics . act by entering into cytoplasm of the bacterial cell where they bind to polysomes and interfer with protein biosynthesis by causing misreading and premature termination of translation of mRNA

Question 8

Spectrum ?

Answer 8

Is mainly confined to gram negative bacilli

Question 9

Mention same aminoglycosides ?

Answer 9

Gentamycin 
Sterptomyces
Kanamycin 
Tobramycin 
Amikacin

Question 10

Antimicrobial spectrum ?

Answer 10

Pseudomonas aeruginosa 
Escheria coli 
Enterobacter spp
Klebsella spp 
Sderralia spp 
Proteus mirabilis 
Enterococcus foecalis 
Staphllococcus aureus

Question 11

Pharmacokinetics ?

Answer 11

Aminoglycoside are poorly absorbed by GIT because of their high polarity ( only less than 1% is absorbed ) they are inactivated in the intestine , so the aminoglycoside are administered parentrally where they are rapidly absorbed . with exception of sterptomycin binding of aminoglycoside to plasma protein is negligible , so their distribution in body tissues is very low . they can’t penetrat BBB and should be injected intrathecally to attain effective concentration in CSF. Excretion of aminoglycoside is urinary

Question 12

Adverse reactions ?

Answer 12

1- Ototoxicity :- adminstration of aminoglycosides results in both vestibular and auditory dysfuntion.this occurs due to accumulationin the perilymph and endolymph of inner ear . ototoxicity is irreversible and is due to destruction of vestibular or Cochlear sensory cells .
2-Nephrotoxicity :- result due to accumulation of aminoglycosides in the proximal tubular cells . Reflected by proteinurea and appearance of granular casts . GFR is reduced after days of beginning treatment . Severe acute necrosis may occur , mild increase in plasma creatinine is detected
3- Neuromuscular blockade:- occur on adminstration of large doses , relatively uncommon .
4- Streptomycin cause Optic dysfunction in form of enlargement of blind spot and peripheral neuritis .
5- Mild adverse effects include : skin rash ,eosinophilia and exfoliative dermatitis

Question 13

Amikacin ( Amikin )?

Answer 13

Abroad spectrum aminoglycosides. Is resistant to aminoglycosides- inactivating enzyme . Used for bacteria resistant to gentamycin .

Question 14

Dose of Amikacin ?

Answer 14

15mg/kg body weight (in sigle or divided doses ) for at least 5 days

Question 15

What is antibactereial spectrum of Neomycin ?

Answer 15

Broad spectrum

Question 16

What is therapentic uses of neomycin ?

Answer 16

Sensitive infections in skin and mucous membranes ( incombination with erythromycin ) for prepration of bowel for surgeory

Question 17

Dose of neomycin ?

Answer 17

4-12 grams

Question 18

The high dose of neomycin is dangerous ?

Answer 18

The high dose is not dangerous because no absorption takes place and the action is local .

Question 19

ather name of Kanamycin?

Answer 19

Kantrax

Question 20

Kanamycin ?

Answer 20

Can be administered orally or parentrally . Use of kanamycin is limited because it antibacterial spectrum is the least compared to other aminoglycosides

Question 21

Uses of kanamycin?

Answer 21

1- treatment of tuberculosis if bacteria is resistant to other anti T.B.
2- used orally for prophlaxis in cases of hepatic coma

Question 22

Dose of kanamycin in TB ?

Answer 22

1 g daily

Question 23

Dose of kanamycin in prophlaxis ?

Answer 23

4-6 grams daily ( in divided doses ) for 36 to 27 hours

Question 24

Therapeutic Uses of streptomycin ?

Answer 24

Therapentic uses of streptomycin are now restricted to :
1- bacterial endocarditis : in combination with penicillins
2- tuberculosis : in combination with isoniazed
3- plague

Question 25

Dose of streptomycin?

Answer 25

1 gram daily for 2-3 month ( for TB )
1 gram daily for 4 weeks ( for endocarditis)
1-4 grams daily for 7-10 days ( for plague )

Question 26

Spectrum of gentamycin ?

Answer 26

Important in treatment of many serious Gram negative bacillary infections

Question 27

Uses of gentamycin ?

Answer 27

1- sensitive complicated urinary tract infections usually in combination with a B lactam
2- pneumonia : effective in pneumonia caused by various Gram- negative bacilli . should be after sensitivily test . given in combination with a B - lactam
3- useful in meningitis caused by gram negative bacilli should be administered intrathecally
4- topical uses : given in topical forms ( ointments , creams , eye ( ear ) drops or oimtments ) for treatment of infections caused by sensitive bacteria

Question 28

Dose of gentamycin in UTI ?

Answer 28

80 mg every 8 hourse for at least 3 days

Question 29

Dose of gentamycin in pneumonia?

Answer 29

80 mg 8 hourly for at least 3 days

Question 30

Dose of gentamycin in meningitis?

Answer 30

30 mg per CSF every 24 hours