Doxycycline
Class
Tetracycline
Dose
100mg q12h
Mechanism
Bacteriostatic
MoA
30S inhibitor
Inhibitis protein synthesis
Time v Concentration
Time >MIC
Post dose effect
Short
Spectrum
Covers
Doesn't Cover
Atypical Pathogens:
- Mycoplasma
- Chlamydia
- Rickettsia
- Lyme disease
- Q fever
- Anthrax
Staphylococcus
Streptococcus
Campylobacter
H Influenza
Neisseria gonorrhoeae & meningitidis
Clostridium
- Most difficult to treat Gram -ves (ie Pseudomonas)
- Enterococcus
- Legionella (only mild activity, which is why in ICU infections Azithromycin is employed)
Indications
Soft tissue infections
Lyme disease
Some Community-Acquired MRSA
Resp tract infections (but not ICU Pneumonia)
PK
A
Excellent close to 100%. Affected by milk!
D
Distributes widely
93% PPB
crosses placenta (contraindicated in pregnancy)
M
Minimal hepatic
E
Unchanged by glomerular filtration
A/E
Photosensitivity reactions
Children; binds Ca++ resulting in teeth discolouration & inhibition of bone growth
Steatosis
Severe gastritis (given with food or NJ tube)
Monitoring
LFTs