1. Tissue concentrations Protein binding
12th ISAP Educational Workshop, Copenhagen 2005
Tissue concentrations Protein binding
Ursula Theuretzbacher Center for Anti-Infective Agents, Vienna

2. Tissue penetration - protein binding
Int J Clin Pharmacol Ther Jun;41(6):
Pharmacokinetics and tissue penetration of pefloxacin plus metronidazole after administration as surgical prophylaxis in colorectal surgery. Gascon AR, Gutierrez-Aragon G, Hernandez RM, Errasti J, Pedraz JL.
High tissue concentrations!??
J Antimicrob Chemother May;47(5):
  Tissue penetration of a single dose of levofloxacin intravenously for antibiotic prophylaxis in lung surgery. von Baum H, Bottcher S, Hoffmann H, Sonntag HG.
J Chemother Apr;15(2):
Ceftriaxone (1 g intravenously) penetration into abdominal tissues when administered as antibiotic prophylaxis during nephrectomy. Leone M, Albanese J, Tod M, Savelli V, Ragni E, Rossi D, Martin C.
Andrologia Oct;35(5):331-5.
Antibiotic therapy--rationale and evidence for optimal drug concentrations in prostatic and seminal fluid and in prostatic tissue. Naber KG, Sorgel F.
Helicobacter Aug;8(4):294-9.
Gastric juice, gastric tissue and blood antibiotic concentrations following omeprazole, amoxicillin and clarithromycin triple therapy. Nakamura M, Spiller RC, Barrett DA, Wibawa JI, Kumagai N, Tsuchimoto K, Tanaka T.
Int J Clin Pharmacol Ther Jun;41(6):
Pharmacokinetics and tissue penetration of pefloxacin plus metronidazole after administration as surgical prophylaxis in colorectal surgery. Gascon AR, Gutierrez-Aragon G, Hernandez RM, Errasti J, Pedraz JL.
J Chemother Apr;15(2):
Ceftriaxone (1 g intravenously) penetration into abdominal tissues when administered as antibiotic prophylaxis during nephrectomy. Leone M, Albanese J, Tod M, Savelli V, Ragni E, Rossi D, Martin C.

3. Tissue penetration - protein binding
Where is the pathogen ?
Where is the antibiotic ?
Active concentration (protein binding!)

4. Where is the pathogen? pneumococci, enterobacteria
blood capillary
extracellular fluid
cells
Legionella, mycobacteria
Mycoplasma, Bordetella
Chlamydia, Rickettsia, Ehrlichia
Salmonella, Staph. aureus
Shigella, Listeria
Chlamydia, Legionella
intracellular
pneumococci, enterobacteria, Haemophilus

5. Where is the antibiotic?
Eng`s principle of medical procedures: „The easier it is to do, the harder it is to change.“
blood capillary
interstitial fluid
cells
homogenates, biopsies
intravascular
extra-, intracellular
Bound + free fraction
70-80%
20-30%
macrolides
fluorquinolones
high concentrations
ß-lactams
aminoglycosides
low concentrations

6. Site of Infection Pneumonia ELF, AM, blood Bronchitis
Barrier
KU Medical Center
Pneumonia
ELF, AM, blood
Bronchitis
bronchial secretions
Sinusitis
sinus secretions
Otitis media
middle ear fluid

7. Tissue concentrations
Tissue specific brain, prostate, muscles, lung….
plasma
muscle
subcutan. t.
healthy
patients
microdialysis
I. Tegeder et al. Clin Pharmacol Ther (5):325
Imipenem
Compartment specific
extracellular intracellular
intracellular compartments
Patient specific
 Activity

8. Tissue concentration: pulmonary
Telithromycin, pulmonary disposition
Total concentrations (g/ml) 1
0,6
0,06
Muller-Serieys et al. AAC 2001, 45 (11)

9. Tissue concentration: pulmonary
g/ml
Clarithromycin: 2x 500mg, 4 days
Azithromycin: 1x 500mg /1x 250mg, 4 days 4 8 12 24 h
K Rodvold et al. AAC, 1997, 41 (6)

10. Tissue concentration: middle ear
Acute otitis media, concentrations in middle ear fluid
Ceftibuten: 9mg/kg
Cefixime: 8mg/kg
Azithromycin: 10mg/kg
g/ml 14
cell-free 12
4 h
12 h
24 h
Ceftibuten
with cells 10 8 6
cell-free 4
Cefixime
with cells
Azithromycin
with cells
cell-free 2
F Scaglione et al. Br J Clin Pharmacol 1999, 47 (3)

11. Tissue concentration: middle ear
Haemophilus influenzae
Concentration in middle ear (mean, g/ml)
Bacteriologic eradication (after 4-5 days of therapy)
9,5 (amoxycillin 25 mg/kg dose, 3h)
87% (amoxycillin/clavulanic acid 45/6,4mg/kg/day)
5,1 (20mg/kg single dose, 2h)
48%
3,5 (10mg/kg day 1, 5mg/kg days 2-5)
47% (39%)
MIC s
s: NCCLS susceptible
0,5 2
amox/clav
cefaclor
Placebo!
azithromycin
R Dagan et al: AAC 2000, 44 (1) R Dagan et al: Pediatr Inf Dis J 2000, 19 (2) DM. Canafax et al: Pediatr Inf Dis J 1998, 17 (2) T Eden et al: Scand J Infect Dis 1983, Suppl, 39 JO Klein, CID 1994,19 (5)

12. Protein binding free drug bound serum interstitial fluid
non-specialized tissues
specialized tissues
diffusional barriers
transport pump
equilibrium
small reservoirs
large reservoirs

13. Protein binding affects distribution tissue penetration clearance
interactions
S Tawara et al. AAC 1992, 36 (1)
activity!

14. Protein binding: Effect on Penetration of ß-Lactams into Rabbit Peripheral Lymph
Correlation between protein binding and penetration
100 75
% Penetration of total drug (AUC lymph/AUC plasma 50 25 25 50 75
100
Plasma binding %
G Woodnutt et al. AAC 1995, 39 (12)

15. Protein binding Telithromycin Ertapenem
Mean time-versus-concentration profiles of total and free telithromycin in plasma, muscle, and subcutis (800 mg p.o.)
Relationships between EC50 and % human serum for E. cloacae (•) and S. aureus ()
R. Gattringer et al. AAC 2004 (48) 4650
DE Nix et al. AAC 2004 (48) 3419

16. Protein binding
Azoles
D. Andes: Infect Dis Clin N Am 2003 (17) 635

17. Protein Binding: Cefotaxime - Ceftriaxone
g/ml
35%
95% h
F Scaglione et al. JAC 1990, 26, Suppl A

18. Protein binding >90% >70% >30% >10% <10%
Oxacillin, ceftriaxone, ertapenem, teicoplanin, daptomycin, televancin, fusidic acid, rifapentine
>70%
Cefazolin, rifampicin, oritavancin
>30%
Penicillin G, cefixime, cefotaxime, erythromycin, clarithromycin, azithromycin, telithromycin vancomycin, linezolid
>10%
Amoxicillin, piperacillin cefpodoxime, cefuroxime, ceftazidime, imipenem ciprofloxacin, levofloxacin, gatifloxacin, metronidazole
<10%
Meropenem, doripenem, aminoglycosides, fosfomycin

19. Summary: tissue concentration – protein binding
Tissue penetration:
Precondition for activity
Site of infection  location of antibiotic
Don`t mix separated pharmacokinetic compartments (homogenates!), results may be misleading!
Protein binding:
Free drug is active
Highly protein bound drugs have reduced antibacterial effect in vitro (with albumin)
Don’t correlate MIC (measured in protein-free media) with total concentrations
Protein binding influences tissue penetration
Drugs with high protein binding are not generally less clinically active

20. Take home message: Consider free levels Distrust tissue homogenates
Whitehead`s rule: Seek simplicity, and distrust it.
Take home message:
Consider free levels
Distrust tissue homogenates
Enjoy the meeting