Aminoglycosides (high risk) Flashcards
lit 5 aminoglycosides and outline some of the characteristics of this group
1) Amikacin, Gentamicin, Tobramycin (also active against Pseudomonas aeruginosa)
2) Neomycin (Toxic for systemic use)
3) Streptomycin (Mycobacterium tuberculosis)
4) All are bactericidal and active against some Gram-positive and many Gram-negative organisms.
Are aminoglycosides absorbed from the gut?
Not absorbed from the gut and must therefore be given by injection for systemic infections
1) which aminoglycoside is the drug of choice in the UK and how is its dose calculated?
2) how many days should treatment not exceed with this drug?
1) Gentamicin- calculated on the basis of the patient’s weight and renal function and serum-gentamicin concentrations
2) if possible should not exceed 7 days
Tobramycin has similar activity to gentamicin. It is slightly more active against Ps. aeruginosa. what condition is this drug administered via nebuliser for?
for the treatment of chronic pulmonary Ps. aeruginosa infection in cystic fibrosis
which aminoglycoside is more stable than gentamicin to enzyme inactivation?
1) Amikacin- used in the treatment of serious infections caused by gentamicin-resistant Gram-negative bacilli.
Once daily administration of aminoglycosides is more convenient, and in many cases has largely superseded multiple-daily dose regimens. which patients should once daily doses be avoided in?
1) Endocarditis due to Gram-positive bacteria also HACEK endocarditis
2) Burns of more than 20% of BSA
3) CrCl < 20 mL/minute
4) Insufficient evidence to recommend a once daily, high-dose regimen of an aminoglycoside in pregnancy.
Serum concentrations of aminoglycosides must be determined in which individuals?
1) Elderly
2) Obesity
3) Cystic fibrosis
4) If high doses are being given
5) Renal impairment
When used for the ‘blind’ therapy of undiagnosed serious infections what is Gentamicin usually combined with?
1) with a penicillin or metronidazole (or both).
2) because its inactive against anaerobes and has poor activity against haemolytic streptococci and pneumococci.
aminoglycosides are used to treat severe infections, particularly those caused by Gram-negative aerobes. list the indications for these drugs
1) Severe sepsis- even if source unidentified
2) Pyelonephritis and complicated UTI
3) Biliary and other intraabdominal sepsis
4) Endocarditis
(Topical aminoglycosides (e.g. neomycin) are used to treat Bacterial skin, eye or external ear infections)
what is the Spectrum of activity for aminoglycosides?
1) Gram-negative aerobic bacteria.
2) should be combined with penicillin and/or metronidazole when the organism is unknown.
Outline the MoA of aminoglycosides
1) Bactericidal- bind irreversibly to bacterial ribosomes and inhibit protein synthesis.
2) Aminoglycosides enter bacterial cells via an oxygen-dependent transport system. Streptococci and anaerobic bacteria do not have this transport system
list the important adverse effects caused by aminoglycosides, are these reversible?
1) nephrotoxicity and ototoxicity-
2) Nephrotoxicity presents as reduced urine output and rising serum creatinine and urea and is potentially reversible.
3) Ototoxicity is often not noticed until after resolution of the acute infection, when the patient may complain of hearing loss, tinnitus and/or vertigo. Ototoxicity may be irreversible.
Who should aminoglycosides be used in caution with?
1) Renally excreted- monitoring and dose adjustment is essential particularly in neonates, elderly patients and
those with renal impairment.
2) impair neuromuscular transmission avoid in those with myasthenia gravis
3) Pregnancy: risk of vestibular nerve damage in infant when used in 2nd and 3rd trimester. greatest with streptomycin
list some of the important interactions with regards to aminoglycosides
1) Ototoxicity more likely if co-prescribed with loop diuretics (e.g. furosemide) or vancomycin
2) Nephrotoxicity is more likely if a co-prescribed with ciclosporin, platinum chemotherapy, cephalosporins or vancomycin
what patient and carer advice is given to those taking aminoglycosides?
check if patient has noticed any change in their hearing, ringing in their ears or dizziness and advise them to let you know if this occurs
