The macrolide family...

Transcription

1 1

2 The macrolide family... erythromycin roxithromycin clarithromycin dirithromycin telithromycin azithromycin the last one!! josamycin spiramycin miocamycin 2

3 Erythromycin: activity Erythromycin A : mostly Gram (+) organisms Plus: Legionella p. Chlamydia spp. Mycoplasma spp. Mycobacterium avium 3

4 Erythromycin - MIC distributions of isolates that lack resistance mechanisms Mg/L >64 S.aureus n n n n Coag-neg staph n n n S.saprophyticus n n n Streptococcus_A n n n Streptococcus_B n n n Pneumococci n n n Strept misc n n n n Enterococcus n n n n n Listeria n n n Corynebacteria n n n Bacillus spp n n n H.influenzae n n n n n AST M.catarrhalis n n n B.pertussis n n n n P.multocida n n n L. pneumophila n n n n Camp. jejuni n n n N.gonorrhoeae n n n n N.meningitidis n n n n M.pneumoniae n n n n Borr. burgdorferi n n n SRGA and SRGA- M, , G Kahlmeter & B.lsson-Liljequist 4 +

5 Erythromycin: the problems Erythromycin A Instability in acid media 14 atoms Keto in C9 Alcohol in C6 5

6 H 3 C H 9 CH 3 H H 3 C H CH 3 Erythromycin: details of acid the degradation H 3 C H 3 CH 2 C 1 CH 3 H 3 C (H 3 C) 2 N H H 3 C ERYTHRMYCIN CH 3 H H 3 C H 3 C H 3 CH 2 C 1 CH 3 CH 3 H CH 3 (H 3 C) 2 N H H 3 C CH 3 CH 3 CH 3 H 3 C H 3 CH 2 C H 3 C H H H 3 C 1 CH 3 CH 3 C H 3 C CH 3 (H 3 C) 2 N H H 3 C CH 3 H CH 3 8,9-anhydroerythromyin-6,9-hemi ketal H 3 C H erythromyin-6,9;9-12 -spiroketal 6

7 What have the chemists done to avoid acid-instability instability? 9-CH 2, 9 a -aza 9-N-oxime 6-methoxy 9-amino 7

8 What have the chemists done to avoid acid-instability instability? 6-methoxy clarithromycin Erythromycin A 9-N-oxime 9-amino erythromycylamine 9-CH 2, 9 a -aza 15 atoms roxithromycin dirithromycin azithromycin acid stability 8

9 Did these modifications change anything else in PK? clarithromycin roxithromycin higher tissue accumulation dirithromycin azithromycin dibasic much higher tissue accumulation pharmacokinetic differentiation 9

10 Did these modifications change anything else? Cytochrome P 450 interactions erythromycin A clarithromycin roxithromycin dirithromycin azithromycin 10

11 Drug interactions with macrolides The main problem due to interactions between some macrolides and the cytochrome P 450 system, especially the CYP3A subclass of enzymes Finally results in lowered metabolism of CYP3A-dependent drugs drug azi clari diri ery josa mid roxi spira théophyllin ND 0/+ 0 ciclosporin ND ND ND carbamazepin ND 0/+ ND /+ 0/+ midazolam 0 ++ ND ++ ND ND + ND warfarin 0 ND ND + ND ND 0 ND terfenadin 0 ++ ND +++ 0/+ ND 0 ND cisapride ND ++ ND ND ND 0 From Petitjean et al. N=undocumented Mainly considered as a class-effect, resulting from what is known for erythromycin, except for spira and azithromycin 11

12 Basic indications of (classical) macrolides in a world of no resistance erythromycin clarithromycin roxithromycin dirithromycin azithromycin Respiratory tract infections pharyngitis otitis sinusitis acute exacerbations of chronic bronchitis community acquired pneumonia legionellosis C. pneumoniae Mycobacterium avium (AIDS) Genital/cular infections chlamydiosis (C. trachomatis) syphilis donovanosis gonorhhea Gastric ulcer (H. pylori) 12

13 Which is the best? erythromycin clarithromycin roxithromycin dirithromycin azithromycin 13

14 But was has been the problem? erythromycin clarithromycin roxithromycin dirithromycin azithromycin Emergence of resistance Target modification: erm Efflux: Mef All are similarly affected 14

15 Mechanisms of macrolide resistance Ribosomal modification by methylase (erm genes) S. pneumoniae: erm(b) % of Ery-R strains in Europe S. pyogenes: erm(b) generally <50% of Ery-R strains erm(a) Ribosomal modification by mutation (rrna, proteins) ccasional in Ery-R S. pneumoniae Rare in Ery-R S. pyogenes (up to 18% in Eastern Europe) The only mechanism or highly prevalent in H. pylori, Campylobacter, M. avium Drug efflux (mef genes) <25% in Ery-R S. pneumoniae >50% in Ery-R S. pyogenes (up to 95%) 15

16 Correlation between erythromycin MICs and resistance mechanisms No. of strains mefe+ ermb ermb mefe none >64 Erythromycin MIC (ug/ml) Nagai ICAAC 2000, abstr #

17 The Alexander Project 1999: S. pneumoniae, Macrolide Resistance Europe 20% Russia 7% USA 33% Mexico 22% Brazil 4.0% Israel 23% Kenya 0.5% Saudi Arabia 18% Singapore 55% Japan 78% Hong Kong 82% South Africa 13% Resistance defined as erythromycin MIC 1mg/L 17

18 Distribution of erythromycin-resistance phenotypes among pneumococci from 8 different European countries ( ) Country (total N of isolates) Belgium (59) Finland (651) France (48) Germany (102) Greece (140) Italy (85) Norway (8) Spain (109) ref overall % of distribution of resistance phenotype erythromycin-resistance MLS B M other

19 Bronchitis pneumonia sinusitis otitis Resistance to macrolides in Greece S. pneumoniae S. pyogenes Pharyngitis

20 Inhibition of Protein Synthesis (1) Inhibition of peptidyl transferase activity 30S Domain V 5S rrna Domain II Pocket: peptidyl transferase site 50S Erythromycin A 2058 V erm mef 5S rrna 752 -cladinose II Modified from Bryskier (FDA presentation of KETEK ) 20

21 Telithromycin 21

22 Resistance: a semi-rational answer... erythromycin A C 3 -descladinose ketolides lateral basic hydrophobic chain to increase activity C 6 -methoxy for acid-stability telithromycin Target modification: erma Efflux: Mef E 22

23 Inhibition of Protein Synthesis (2) Inhibition of peptidyl transferase activity 30S Domain V 5S rrna Domain II Pocket: peptidyl transferase site 50S Erythromycin A 2058 V V Telithromycin 2058 erm mef 5S rrna -cladinose 5S rrna 752 II II 752 From Bryskier, FDA presentation of KETEK 23

24 MIC 50 [µg/ml] of wild type and mutant strains Erythromycin Telithromycin S. pyogenes (WT) (ermtr ind.) (ermtr const.) (ermb ind.) (ermb const.) (mef) S. pneumoniae (WT) (ermb const.) (mef) >64 >64 >64 8 0,03 >64 2 0,08 0,06 0,25 0, ,5 0,008 0,06 0,125 24

25 Telithromycin Telithromycin, the first ketolide, was designed to overcome erythromycin A resistance within Gram (+) positive cocci and take advantage of PK improvements of clarithromycin Side chain for improved activity R 9 CH 3 To avoid chemical instability C 11 C 12 carbamate for anchoring N D - desosamine New chemical class (3 keto) active against ermr 25

26 Pharmacokinetics of telithromycin (as submitted to the FDA; april 2001) 800 mg 800 mg (single dose) (7 days) C max (mg/l) 1.9 (42) 2.3 (31) C 24h (mg/l) 0.03 (45) 0.07 (72) AUC 24h (mgxh/l) 8.3 (31) 12.5 (43) t 1/2 (h) 7.2 (39) 9.8 (20) The company has declared that activity of telithromycin is driven by C max /MIC and by AUC 24h /MIC ratios 26

27 Pharmacodynamics of telithromycin (as based on FDA submission; april 2001) rganism MIC 90 C max /MIC 90max AUC 24h /MIC 90max S. pneumoniae < S. pyogenes < H. influenzae M. catarrhalis 0.12 L. pneumophila C. pneumoniae M. pneumoniae Activity will be good for MIC 0.25 mg/l, but may become problematic for higher MICs 27

28 Which are the sensivities of S. pneumoniae towards telithromycin in Belgium in 2000? 100 Ery-S Ery-r % of strains MIC (mg/l) PK/PD limit of sensitivity (0.25 mg/l) MIC 90 for Ery-s strains: < But MIC 90 for Ery-r strains: Verhaegen & Verbist, Acta Clin. Belg. 2001, 56:

29 Macrolides: : the 16 atoms family Erythromycin A Instability in acid media 14 atoms Carbomycin A / Spiramycins 16 atoms Intrinsically acid-stables 29

30 Macrolides: : the 16 atoms family 30

31 Properties of the 16 atoms family spiramycin josamycin miocamycin Carbomycin A / Spiramycins 16 atoms But, usually, lower intrinsic activities Low cyt P450 interactions Non ermb inducers Non mefe substrates Intrinsically acid-stables 31

32 Macrolides: : the present family picture Erythromycin A clarithromycin roxithromycin dirithromycin azithromycin PK telithromycin? spiramycin josamycin miokamycin erm mef mef 32