A-C abx Flashcards
What are aminoglycosides?
‘MYCIN’
amikacin, gentamicin, neomycin sulfate, streptomycin, and tobramycin.
When MUST serum concentrations be measured for aminoglycosides?
obesity
high doses
cystic fibrosis
elderly
renal impairment - can accumulate as they are primarily excreted renally
What are the MHRA warnings for aminoglycosides?
increased risk of deafness in patients with mitochondrial mutations
- consider genetic testing if recurrent or long term treatment needed
- need continuous monitoring of renal and auditory function, as well as hepatic and laboratory parameters
When are aminoglycosides contraindicated?
Myasthenia gravis - aminoglycosides may impair neuromuscular transmission
What are the red flags for amino glycoside use?
Ototoxicity and nephrotoxicity
- nephrotoxicity occurs most commonly in patients with renal impairment, who may require reduced doses
- monitoring is particularly important in the elderly.
Can aminoglycosides be used in pregnancy?
Avoid use unless essential
- risk of auditory or vestibular nerve damage in the infant when used in the second and third trimesters of pregnancy
- monitor serum concentrations
When should monitoring for serum concentration occur for aminoglycosides?
normal renal function
- after 3 or 4 doses of a multiple daily dose regimen and after a dose change
- for multiple daily dosing: 1 hours post dose (peak) and just before the next dose (trough)
How should dose adjustments be made following serum concentration monitoring of aminoglycosides?
trough too HIGH - increase dose interval
peak to HIGH - decrease dose
moderate renal impairment - increase dose interval
severe renal impairment - decrease dose
What medications should be avoided with aminoglycosides?
drugs that cause ototoxicity
- cisplatin
- loop diuretics
- vancomycin
- vinca alkaloids
drugs that cause nephrotoxicity
- ARBs/ACEi
- NSAIDs
- metformin
What should the peak and trough levels of gentamicin be?
for multiple daily dosing:
- peak: 5–10 mg/litre
- trough: less than 2 mg/litre.
What are cephalosporins?
cefalexin, cefixime (only ORAL drug), ceftazidime, ceftriaxone, cefadroxil
- are structurally related to penicillin
- may be avoided in penicillin allergy due to cross sensitivity (10% for 1st/2nd gen and 2-3% for 3rd gen)
What is the age restriction for chloramphenicol?
OTC - must be 2 years +
On Rx - any age
MHRA states - benefits outweigh risks, can be used
Can chloramphenicol be used in pregnancy or breastfeeding?
Oral use - avoid in pregnancy
Risk of neonatal ‘grey-baby syndrome’ if used in third trimester.
Oral use - avoid in breastfeeding
It may cause bone-marrow toxicity in infant
When is clindamycin contraindicated?
diarrhoeal states
- DISCONTINUE
- risk of clostridium difficile infection
What are the side effects of clindamycin?
diarrhoea - DISCONTINUE
abdominal pain
skin reactions
What are red flags associated with clindamycin use?
antibiotic-associated colitis
- can be FATAL
- abdominal pain, recurrent diarrhoea, mucus or blood in faeces, fever
- DISCONTINUE
c.difficile infection
- severe diarrhoea
- DISCONTINUE
What medications can make C.difficile infection more likely?
4C’s
- clindamycin
- ciprofloxacin (fluoroquinolone)
- cephalosporins
- penicillins
What should be monitored in clindamycin use?
monitor liver and renal function if treatment exceeds 10 days.
