Glycopeptides Flashcards
GLYCOPEPTIDES:
What are TWO common indications?
- Complicated skin and soft tissue, bone and joint infections.
infective endocarditis and other infections caused G-positive organisms where infection is severe and or penicillins cannot be used
- Vancomycin - c-diff colitis
GLYCOPEPTIDES:
What is the spectrum of activity?
Narrow spectrum
G-positive bacteria e.g
S.spp(MRSA)
Strepp spp
c.diff
(inactive against G-negative)
GLYCOPEPTIDES:
What is the mechanism of action?
Inhibits growth and cross linking of peptidoglycan chains
This inhibits synthesis of the cell wall in gram-positive bacteria causing cell lysis
GLYCOPEPTIDES:
What is the mechanism of resistance?
Gram-negative bacteria have a different cell wall structure, so no active in G-positive
Acquired resistance through bacterial modification of cell wall structure to prevent antibiotic binding.
GLYCOPEPTIDES:
What are important side effects of vancomycin?
-Pain and thrombophlebitis
-Red man syndrome
cutaneous reactions
Who would need to be prescribed with caution?
Immune-mediated hypersensitivity
Hepatic impairment-(increased risk of ototoxicity)
Nephrotoxicity- reduced renal function
- neonates
-older adults
Renal excreted and may accumulate in renal impairment.
Pregancy (only if essential)
What are important interactions?
Increased risk of ototoxicity/ nephrotoxicity when prescribed with
loop diuretic
aminoglycosides
NSAIDs
Ciclosporins
What are dosages for parenteral administration?
Vancomycin:
15-20mg/kg
8-12 hrly
Teicoplanin:
6-12mg /kg
daily (after 12 hr initial loading dose) (long half life 100-170 hours)
What is the route of administration?
Parenteral as it is not absorbed from the GI tract.
For C.diff 125mg 6 hourly for 10 days oral
IV should be diluted <5mg/ml in glucose 5% or NaCl 0.9%
Why must vancomycin NOT be given IM?
Risk of muscle necrosis
What rate should vancomycin be given?
Vancomycin no faster tha 10mg/min and over 60 minutes to reduce the risk of flushing syndrome
What are symptoms of red man syndrome?
What causes it?
An infusion-related reaction peculiar to vancomycin.
pruritus, an erythematous rash that involves the face, neck, and upper torso.
Less frequently, hypotension and angioedema can occur.
What are monitoring requirements?
Pre-dose (trough) plasma levels
(10-15mg/ml or 15-20mg/ml endocarditis)
dose should be adjusted to keep trough level concentration high enough for therapeutic effect whilst avoiding toxicity
How is safety monitored?
by enquiry about hearing changes and daily measurement of renal function.
Platelet and leukocyte counts should be monitored in prolonged courses.
What is second line option for c.diff if vancomycin is ineffective?
fidaxomicin but very expensive (1350 per course)
