A-C abx

Question 1

What are aminoglycosides?

Answer 1

‘MYCIN’
amikacin, gentamicin, neomycin sulfate, streptomycin, and tobramycin.

Question 2

When MUST serum concentrations be measured for aminoglycosides?

Answer 2

obesity
high doses
cystic fibrosis
elderly
renal impairment - can accumulate as they are primarily excreted renally

Question 3

What are the MHRA warnings for aminoglycosides?

Answer 3

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

Question 4

When are aminoglycosides contraindicated?

Answer 4

Myasthenia gravis - aminoglycosides may impair neuromuscular transmission

Question 5

What are the red flags for amino glycoside use?

Answer 5

Ototoxicity and nephrotoxicity
- nephrotoxicity occurs most commonly in patients with renal impairment, who may require reduced doses
- monitoring is particularly important in the elderly.

Question 6

Can aminoglycosides be used in pregnancy?

Answer 6

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

Question 7

When should monitoring for serum concentration occur for aminoglycosides?

Answer 7

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)

Question 8

How should dose adjustments be made following serum concentration monitoring of aminoglycosides?

Answer 8

trough too HIGH - increase dose interval
peak to HIGH - decrease dose

moderate renal impairment - increase dose interval
severe renal impairment - decrease dose

Question 9

What medications should be avoided with aminoglycosides?

Answer 9

drugs that cause ototoxicity
- cisplatin
- loop diuretics
- vancomycin
- vinca alkaloids

drugs that cause nephrotoxicity
- ARBs/ACEi
- NSAIDs
- metformin

Question 10

What should the peak and trough levels of gentamicin be?

Answer 10

for multiple daily dosing:
- peak: 5–10 mg/litre
- trough: less than 2 mg/litre.

Question 11

What are cephalosporins?

Answer 11

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)

Question 12

What is the age restriction for chloramphenicol?

Answer 12

OTC - must be 2 years +
On Rx - any age

MHRA states - benefits outweigh risks, can be used

Question 13

Can chloramphenicol be used in pregnancy or breastfeeding?

Answer 13

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

Question 14

When is clindamycin contraindicated?

Answer 14

diarrhoeal states
- DISCONTINUE
- risk of clostridium difficile infection

Question 15

What are the side effects of clindamycin?

Answer 15

diarrhoea - DISCONTINUE
abdominal pain
skin reactions

Question 16

What are red flags associated with clindamycin use?

Answer 16

antibiotic-associated colitis
- can be FATAL
- abdominal pain, recurrent diarrhoea, mucus or blood in faeces, fever
- DISCONTINUE

c.difficile infection
- severe diarrhoea
- DISCONTINUE

Question 17

What medications can make C.difficile infection more likely?

Answer 17

4C’s
- clindamycin
- ciprofloxacin (fluoroquinolone)
- cephalosporins
- penicillins

Question 18

What should be monitored in clindamycin use?

Answer 18

monitor liver and renal function if treatment exceeds 10 days.