FLUOROQUINOLONES: from Structure to Activity and Toxicity
FLUOROQUINOLONES: from structure to activity and toxicity
F. Van Bambeke, Pharm. D. & P. M. Tulkens, MD, PhD Unité de Pharmacologie Cellulaire et Moléculaire Université Catholique de Louvain, Brussels, Belgium
SBIMC / BVIKM
www.sbimc.org - www.bvikm.org www.md.ucl.ac.be/facm www.isap.org soon... Mechanism of action of fluoroquinolones: the basics...
PORIN
DNA
Topo DNA gyrase isomerase
Gram (-) Gram (+) 2 key enzymes in DNA replication:
DNA gyrase
bacterial DNA is supercoiled Ternary complex DNA - enzyme - fluoroquinolone
DNA GYRASE catalytic subunits COVALENTLY CLOSED CIRCULAR DNA
FLUOROQUINOLONES: DNA GYRASE ATP binding subunits 4 stacked molecules
(Shen, in Quinolone Antimicrobial Agents, 1993) Resistance to fluoroquinolones: the basics
decreased efflux pump permeability
DNA mutation of DNA gyrase Topo isomerase the enzymes
Gram (-) Gram (+) Fluoroquinolones are the first entirely man-made antibiotics: do we understand our molecule ?
R5 O R COOH 6
R7 X8 N
R1
Don’t panic, we will travel together…. Chemistry and Activity
This is where all begins... The pharmacophore common to all fluoroquinolones
BINDING TO DNA
R5 O O R C 6 - BINDING TO O BINDING TO THE ENZYME THE ENZYME
R7 X8 N
R1
AUTO-ASSEMBLING DOMAIN (for stacking) From chloroquine to nalidixic acid...
nalidixic acid N CH3 O O HN CH 3 C - O chloroquine CH N N Cl N 3 C2H5 1939 O O C O- 1962 Cl N
1958 C2H5
7-chloroquinoline (synthesis intermediate found to display antibacterial activity) Nalidixic acid *
a • typical chemical features of
O O fluoroquinolones (a, b, c) BUT a naphthridone C - O- b (N at position 8: )
H C N N 3 • limited usefulness as drug C H 2 5 • narrow antibacterial spectrum c (Enterobacteriaceae only) • short half-life (1.5h) • high protein binding (90%)
* Belg. pat. 612,258 to Sterling Drugs, 1962 From nalidixic acid to the 1st fluoroquinolone (1 of 4)
nalidixic acid oxolinic acid *
O O 1. modify naphthyridone O O into quinolone C - O C O O-
O H3C N N N
C2H5 C2H5
shows reduced protein binding...
* Ger. pat. to Warner Lambert, 1967 * quinoleine From nalidixic acid to the 1st fluoroquinolone (1 of 4)
nalidixic acid flumequine * 2. discovery of O O O O flumequine * C F C - O- O
N H3C N N C2H5 CH3
shows weak but broad Gram(-) activity
* Ger pat. to Rikker Labs, 1973 * benzo-quinolizine From nalidixic acid to the 1st fluoroquinolone (1 of 4)
nalidixic acid pipemidic acid * O O O O 3. introduce a C - C - N O O piperazine * N N N H3C N N HN C2H5 C2H5
shows longer half-life...
* Ger. Pat. to Roger Bellon, 1974 * pyrido-2-3-pyrimidine From nalidixic acid to the 1st fluoroquinolone (1 of 4)
combine all 3 O O nalidixic acid 2 features *... F C O- O O
C - N O N HN 1 CH3 H3C N N C2H5 1978 3 broader Gram(-) activity less protein binding (50%) longer half-life (3-4h)
* Belgian patent 863,429, 1978 to Kyorin * 6-fluoro-7-pyrimidino-quinoleine From norfloxacin to the other 1st generation fluoroquinolones: pefloxacin norfloxacin
OO
F C O-
N N HN CH3
Add a methyl OO
C to still increase F - O- half-life
N N N CH3 CH 3 * Ger. pat. 2,840,910 to pefloxacin * Roger Bellon/Dainippon,1979 From norfloxacin to the other 1st generation fluoroquinolones: ofloxacin
norfloxacin
OO tricyclic compound
F C (as in flumequine but - O morpholine ring)
N N HN CH3
O O O O F C O-- F C O-- N N N N N O H3C N CH3 H3C CH3 pefloxacin ofloxacin* * Eur. pat. Appl. 47,005 to Daiichi, 1982 From norfloxacin to the other 1st generation fluoroquinolones: ciprofloxacin norfloxacin ciprofloxacin * O O
F C cyclopropyl to O O O- increase potency F C O- N N HN N N CH3 HN
O O O
F C -- F O O
C N N N N O-- N N O H C CH H3C 3 3 CH3
pefloxacin ofloxacin * Ger. pat. 3,142,854 to Bayer AG, 1983 "1st generation" fluoroquinolones
norfloxacin ciprofloxacin
O O O O F C - C O F - O
N N N N HN HN CH3 cyclo piperazine propyl
O O O O F C -- C O F - O-
N N N N N N H3C CH3 O methyl H3C CH3
pefloxacin ofloxacin morpholine The "first generation" of fluoroquinolones
1960 1970 1980
t1/2 activity • Nalidixic acid • Norfloxacin 3-4 h ++ • Oxolinic acid • Pefloxacin 11 h + • Cinoxacin • Ofloxacin improved 6 h ++ • Pipemidic acid • Ciprofloxacin anti Gram (-) 3-4 h +++ activity • Fleroxacin • Rufloxacin From ofloxacin to levofloxacin...
Ofloxacin is a racemic mixture
O O
C N F - O- H Levofloxacin is the pure (-) S isomer * N N O N O H3C CH3 CH3
The active form of ofloxacin is the (-) S isomer
* Eur. pat. 206,283 to Daiichi, 1987 The present "first generation" of fluoroquinolones ...
1960 1970 1980
t1/2 activity • Nalidixic acid • Norfloxacin 3-4 h ++ • Oxolinic acid • Pefloxacin 11 h + • Flumequine • Ofloxacin improved 6 h ++ • Pipemidic acid • Ciprofloxacin anti Gram (-) 3-4 h +++ activity • Fleroxacin • Rufloxacin
• Levofloxacin 6 h ++++ twice as active as ofloxacin per g How to improve the chemotherapeutic usefulness of the "first generation" fluoroquinolones
1. Maintain broad Gram(-) activity
“2d generation” 2. Improve Gram(+) activity
3. Acquire activity against anaerobes
“3d generation” The “second generation” fluoroquinolones
1960 1970 1980 1990 2000
a • Temafloxacin • Gram (-); • Sparfloxacin b • Grepafloxacin c • improved Gram (+) • Gatifloxacin d
anti-anaerobe
a: Toyama, 1988 (?) ; b: Dainippon, 1985-1987; c: Otskuda, 1989; d: Kyorin, 1988 The “third generation” fluoroquinolones
1960 1970 1980 1990 2000
• Clinafloxacin a • Trovafloxacin b anti-Gram (-) anti-Gram (+) • Moxifloxacin c anti-anaerobe • Gemifloxacin d
a:Kyorin, 1987; b: Pfizer, 1993; c: Bayer, 1994; d: LG Chemical Ltd., S. Korea, 1994-98 1. maintenance of anti - Gram (-) activity
Gram (-) NH2
R5 O F COOH piperazine
N Gram (-) R7 C N N MIC
R1 R bulky group
Cl, F halogen MIC O-CH3 methoxy Gram (-) activity (E. coli)
I II
O O CH3 O O CH3 O O F C F C F C O- O- O-
H3C H3C N N N N N N HN HN HN H 3 CO
ciprofloxacin grepafloxacin gatifloxacin 0.125 - 0.5 0.06 - 2 0.06 2. improving Gram (+) activity (S. pneumoniae)
Gram (+) CH3
R5 O
pyrimidine F COOH N Gram (+) F
H 2N R7 X8 N MIC F R1 bulky group
N Gram (+) if X = C naphthyridone 8 Cl, F halogen MIC
O-CH3 methoxy Activity against S. pneumoniae
I II NH2 OO III O O F C F C O- O- H3C N N N N HN HN F H CO 3
H3C O O sparfloxacin moxifloxacin F C O- 0.125 - 0.5 0.01 - 0.5
CH3 O O O O N N HN F C F C O- O-
H C 3 H N N N N N HN F F ciprofloxacin + H3N 0.5 - 2 H
F F temafloxacin trovafloxacin 0.5 - 1 0.007 - 0.25 3. obtaining activity against anaerobes ...
R5 O F COOH
F R7 X8 N
R1 F bulky group
N if X8 = C naphthyridone O-CH3 methoxy Activity against B. fragilis
OO CH3 O O I II III F C F C O- O-
H3C N N N N HN
HN H CO H 3 CO 3 O O
F C gatifloxacin moxifloxacin O- 0.25 - 8 0.25 - 8
N N HN O O O O F C F C O- O- H ciprofloxacin N N N N N N N 2 - 128 F H3CO + H3N H CH HN2 2 gemifloxacin trovafloxacin F 0.5 - 64 0.125 - 8 Is there a SAR for emergence of resistance ?
The "Mutant Prevention Concentration" *
"When Mycobacterium bovis BCG and Staphylococcus aureus were plated on agar containing increasing concentrations of fluoroquinolone, colony numbers exhibited a sharp drop, followed by a plateau and a second sharp drop.
The plateau region correlated,vith the presence of first-step resistant mutants. Mutants were not recovered at concentrations above those required for the second sharp drop, thereby defining a mutant prevention concentration (MPC).
A C8-methoxy group lowered the MPC for an N-1-cyclopropyl fluoroquinolone" Is there a SAR for emergence of resistance ? Bactericidal activity of FQs against Mycobaterium bovis
CH O O MIC (99) 3 F C - 1 O H5C2 N N 10-2 HN R
10-4
10-6 PD160793 PD161148 MPC (10) R = OCH3 R = H 10-8
Fraction of of Fraction survivors 10-10 MIC 99 0.25 0.8 MPC 10 0.9 9 0.01 0.10 1.00 10.00 MPC/MIC 3.6 12
FQ concentration Dong et al; AAC 43:1756-1758 Fluoroquinolones with a C8-methoxy
I II III
O O CH3 O O O O F C F C F C O- O- O-
H3C N N N N N N HN HN HN H CO H 3 CO 3
ciprofloxacingatifloxacin moxifloxacin Toxicity
This is where all may fail... Frequent side effects of fluoroquinolones: is there a SAR ?
COMPLEXATION WITH METALLIC IONS (Fe, Al, Mg, Ca)
PHOTOTOXICITY
DRUG INTERACTIONS: INHIBITION OF cyt P450 (1A2)
? CNS TOXICITY (BINDING TO GABA RECEPTOR) ? GASTRO-INTESTINAL DISCOMFORT ? CARTILAGE and MUSCULOSQUELETAL TOXICITY SAR of frequent side effects
R
R Ca++, Al+++, Fe++ N N complexation HN HN R
Binding to R R5 O Penetration GABA receptor All FQs in CNS F COO-
N R X N cipro, 7 8 grepa ...
Inhibition of P450 R 1
sparflo, C flero, lomeflo F Inhibition of P450 Phototoxicity Fluoroquinolones with low or no drug interactions..
Trova O O Gati O O F C O- F C O- H H3C N N N N N F HN H + 3N H CO H 3
F O O Moxi
Grepa CH3 O O F C O- F C O- N N HN H3C N N H CO 3 HN Fluoroquinolones with high phototoxicity ...
O O
F C O-
O O OO N N F C F C N - - CH2CH2F O O H3C F H3C N N N N HN HN Fleroxacin a F Cl CH3
NH2 O O b c F C Lomefloxacin Bay 3118 O- H3C N N HN F
H3C
Sparfloxacin a: Kyorin, 1981; b: Hokuriku, 1985; c: Bayer, 1994 Rare side effects of fluoroquinolones:
RENAL TOXICITY crystalluria, hematuria, interstitial nephritis, acute renal failure
CARDIAC TOXICITY (QT prolongation, Torsades de pointe)
HEPATOTOXICITY ? temafloxacin syndrome / trovafloxacin syndrome Rare side effects of fluoroquinolones: cardiac toxicity
Torsade de pointes: paroxysm of ventricular tachycardia in which the electrocardiogram shows a steady undulation in the QRS axis in runs of 5 to 20 beats with progressive changes in direction. It is a most severe type of arythmia which may cause death. It is most often associated with and preceeded by a prolongation of the QT interval.
moxifloxacin: 7 sparfloxacin: 15
fluoxetine: 2 grepafloxacin: 10 cisapride + clari: 25 terfenadine: 46
0 change in QTc prolongation (msec) 50
20 msec: population risk Cardiac toxicity QT prolongation: is there any SAR ?
H3CO
OCH3 HN N (H 2C) 3 O F cisapride H2N O Cl H N H N N (H 2C) 2 C OCH3 astemizole N OH
CH2
H F HO C N (H 2C) 3 C C(CH3)3 terfenadine OH Cardiac toxicity QT prolongation: is there any SAR ?
H3CO
OCH3
HN N (H 2C) 3 O F cisapride H2N O Cl ??? H3C F CH3 H N F CH 2 3 O O O N NH O N NH C C -O N -O N F CH3
sparfloxacin grepafloxacin Other severe toxicities
1992: 1999:
The temafloxacin syndrome: The trovafloxacin syndrome: hemolytic uraemic anemia serious hepatic events
• discoloured urine, fever • laboratory abnormallities • jaundice, nausea, vomiting • ALT, bilirubin, • abdominal pain encephalopathies • coagulopathy • necrotic inflammation • hepatic and renal dysfunction • 0.0056% incidence • 0.056% incidence • 5 transplants • 2 deaths • 6 deaths (multifactorial) withdrawn in June 1992 withdrawn / limited in June 1999 Which part of the molecule is the culprit ?
CH3 O O O O F C F C O- O- H C 3 N N H N N N HN F F H N+ 3 H
F F
withdrawn in June 1992 withdrawn / limited in June 1999 Pharmacokinetics
This is where people start sleeping.. SAR of pharmacokinetic parameters
R O cipro 5 grepa Bulky F COOH gati substituant gemi moxi t 1/2 R X N 7 8
R 1 flero, peflo, oflo, grepa, gati, trova, moxi, gemi N Vd Biodisponibility
gemi, trova SAR of main pharmacokinetic parameters: how to get a long half life
t 1/2 (h) no. of daily administrations oflo 5 - 7 2 x* N N peflo 10 2 x* H3C flero 9 - 13 1 x
H3C N grepa 10 - 12 1 x
HN N gati 13 1 x N H CO 3 gemi 8 1 x H N CH 2 2 trova 10 1 x H N moxi 12 1 x
+ N H3N HN H other FQ 3 - 6 2 x * higher MIC... SAR of main pharmacokinetic parameters: biodisponibility
O O biodisponibility F C O- trovafloxacin 90 % N N no data available for gemifloxacin
other FQ 60-90 % SAR of main pharmacokinetic parameters: volume of distribution
Vd (L/Kg) ciprofloxacin 3 O O
F C gatifloxacin 1.8 O- grepafloxacin 8 ? N gemifloxacin 1.5 moxifloxacin 2
other FQ 1- 1.5 Resistance: do not forget the correct dosing...
“Inadequate dosing of antibiotics is probably an important reason for misuse and subsequent risk of resistance. A recommendation on proper dosing regimens for different infections would be an important part of a comprehensive strategy. The possibility to produce such a dose recommendation based on pharmacokinetic and pharmacodynamic considerations will be further investigated in one of the CPMP working parties…”
European Agency of the Evaluation of Medicinal Products (London)
EMEA discussion paper on Antimicrobial resistance 3 January 1999 EMEA/9880/99 Pharmacokinetic parameters in relation with efficacy
Dose Cmax MIC for AUC MIC for (mg) (mg/l) pk/MIC=10 (mg.h/l) AUIC=125 norflo 400 (X2) 1.6 0.2 14 0.1 peflo 400 (X2) 4.6 0.4 108 1.0 cipro 500 (X2) 1.5 0.2 17 0.1 oflo 200 (X2) 3.1 0.4 66 0.4 levoflo 500 8.7 0.8 73 0.4 grepa 600 1.4 0.1 20 0.2 gati 400 4.5 0.4 28 0.2 trova 200 2.3 0.2 25 0.2 moxi 400 2.5 0.2 30 0.2 gemi 600 4 0.4 24 0.2 Indications of new fluoroquinolones
Consider local epidemiology, and do not believe it is always a first choice…
The use of the FQ should focus on infections in which • there is a differential benefit over conventional agents in terms of efficacy, safety, or cost; • in infections for which few alternative treatments exist, or • against organisms towards wich they are sufficiently active to prevent the rapid emergence of resistance. Shall we have a very bright future ?
or some problems ?