Tissue concentrations Protein binding Ursula Theuretzbacher Center for Anti-Infective Agents, Vienna 14th ISAP Educational Workshop, Nice 2006

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. Helicobacter Aug;8(4): 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. Tissue penetration - protein binding 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. 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 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. Andrologia Oct;35(5): Antibiotic therapy--rationale and evidence for optimal drug concentrations in prostatic and seminal fluid and in prostatic tissue. Naber KG, Sorgel F. 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!??

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

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

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

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

Concentrations In The Lung Zeitlinger et al. AAPS Journal. 2005; 7(3): E600-E608

Tissue concentration: pulmonary Telithromycin, pulmonary disposition 10,60,060 Muller-Serieys et al. AAC 2001, 45 (11) Total concentrations (  g/ml)

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

Tissue specific brain, prostate, muscles, lung….  Activity Tissue concentrations Patient specific Compartment specific extracellular intracellular intracellular compartments

Tissue concentrations - patients healthy plasma muscle subcutan. t. patients I. Tegeder et al. Clin Pharmacol Ther (5):325 Imipenem 500mg Microdialysis in muscle, subcutaneous tissue

Levofloxacin 500 mg Microdialysis in lung Hutschala D et al: AAC 2005, 49: 5107 Concentration in plasma Concentration in pulmonary interstitial fluid Concentrations In The Lung – Cardiac Surgery Lung: unbound AUC tissue /MIC ratio  1-4 for pseudomonas unbound AUC tissue /MIC ratio  PK/PD

Concentration at site of infection  activity Joukhadar C et al: AAC 2005, 49: 4149 Time-kill curves for P. aeruginosa (MIC 0.12, 0.5, 2 mg/l) Interstitial fluid of subcutaneous adipose tissue (warmed + reference tissue) Ciprofloxacin 200 mg Increase of Microcirculatory Blood Flow

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%) Tissue concentration: middle ear Haemophilus influenzae 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) Placebo! MICs s s s s: NCCLS susceptible 0,5 2 2 amox/clav cefaclor azithromycin

Protein binding small reservoirs large reservoirs free drug bound seruminterstitial fluid non-specialized tissuesspecialized tissues diffusional barriers transport pump equilibrium

Protein binding affects Distribution Tissue penetration Clearance Interactions Ertapenem Relationships between EC50 and % human serum for E. cloacae () and S. aureus (  ) DE Nix et al. AAC 2004 (48) 3419 Activity

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

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

Protein binding R. Gattringer et al. AAC 2004 (48) 4650 Mean time-versus-concentration profiles of total and free telithromycin in plasma, muscle, and subcutis (800 mg p.o.) Telithromycin

Protein binding>90% 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% Meropenem, doripenem, aminoglycosides, fosfomycin >10% Amoxicillin, piperacillin cefpodoxime, cefuroxime, ceftazidime, imipenem ciprofloxacin, levofloxacin, gatifloxacin, metronidazole

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

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