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

Tissue penetration - protein binding Int J Clin Pharmacol Ther. 2003 Jun;41(6):267-74. 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. 2001 May;47(5):729-30.   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. 2003 Apr;15(2):139-42. 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. 2003 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. 2003 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. 2003 Jun;41(6):267-74. 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. 2003 Apr;15(2):139-42. 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.

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

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

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

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

Tissue concentrations Tissue specific brain, prostate, muscles, lung…. plasma muscle subcutan. t. healthy patients microdialysis I. Tegeder et al. Clin Pharmacol Ther. 2002 71(5):325 Imipenem Compartment specific extracellular intracellular intracellular compartments Patient specific  Activity

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

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)

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)

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)

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

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

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)

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

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

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

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

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. Take home message: Consider free levels Distrust tissue homogenates Enjoy the meeting