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