CLASSES OF ABX: AMINOGLYCOSIDES Flashcards
Aminoglycoside examples
Amikacin
Gentamicin
Neomycin
Streptomycin
Tobramycin
MOA
- Irreversibly bind to 30s ribosomes
- Inhibit protein synthesis
What organisms are ahminoglycosides active against?
SOME Gram-POSITIVE
MANY Gram-NEGATIVE organisms.
What aminoglycosides are active against Pseudomonas aeruginosa?
Amikacin, gentamicin and tobramycin
How are AG administered
- via injection: OD or multiple (2-3 divided doses)
- not absorbed from the gut
Which AG is not administered via injection?
Neomycin
- too toxic
- PO/ topical
Which AG can be absorbed via nebuliser/ inhalation poweder?
Tobramycin
- via injection, nebuliser, inhalation powder
What aminoglycoside is active against Mycobacterium tuberculosis?
Streptomycin
Gentamicin has broad spectrum but is inactive against
anaerobes
when gentamicin is used as blind therapy of undiagnosed serious infections it is usually given in conjunction with…
a penicillin or metronidazole or both
a patient has gentamicin resistant enteroccal endocarditis. which AG do you give instead
streptomycin
Indication
- In combination therapy for:
o Endocarditis
o Septicaemia
o meningitis
o other CNS infections - biliary-tract infection
- prostatitis
- pneumonia.
Side effects
- OTO/NEPHROTOXICITY
- N+V
- AAC
- Peripheral neuropathy
- Electrolyte disturbances.
Contraindication
- Avoid in pregnancy
- Obese patients
- Avoid using in conjunction with ototoxic drugs
- Avoid using in conjunction with drugs that cause renal impairment
Contraindications for all ahminoglycosides by injection
Myasthenia gravis (aminoglycosides may impair neuromuscular transmission)
why is it myasthenia gravis contraindicated for all aminoglycosides by injection
AG may impair neuromuscular transmission
Aminoglycosides and pregnancy
- Auditory or vestibular nerve damage in 2nd and 3rd trimesters
- Greater risk with streptomycin
- Less risk with gentamicin and tobramycin but their use should be avoided unless essential
- Monitor serum conc if you do give it
Aminoglycosides and obese patients
o Use ideal body weight
o Based on height to calculate parenteral dose
What are examples of other ototoxic drugs
o e.g. cisplatin
o loop diuretics (furosemide, spironolactone, bumetanide, torasemide)
o vancomycin
o vinca alkaloids (vinblastine, vincristince, vindesine, vinfluine
therapeutic drug monitoring of gentamicin - serum amino glycoside conc should be measured in all pt receiving parenteral aminoglycosides and MUST be determined in the following pt (3)
obesity
high doses being given
CF
elderly
How often should you monitor serum-aminoglycoside concentrations
- after 3 or 4 doses, then every 3 days
- after a dose change
When should you monitor renal function
Assess renal function BEFORE starting and DURING treatment
Monitor auditory and vestibular function DURING treatment
WHEN (not how often) should you take blood samples of serum AG conc for multiple daily dose regimens
to get peak conc: take blood samples ~1h after IM or IV admin
to get trough conc: take blood samples just before next dose is due
Multiple daily dose regimen (peak)
5-10mg/L
