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H. Thiermann and F. Worek

Bundeswehr Institute of Pharmacology and Toxicology, 80937 Munich, Germany

Toxicology Symposium of the Low Lands

9th June 2017 Ghent, Belgium Nerve Agents and other Organophosphorus Compounds

G - Agents

Tabun (GA), Sarin (GB), Cyclosarin (GF), Soman (GD) (and Analogs)

V - Agents

VX, Russian VX (VR), Chinese VX (CVX) (and Analogs)

OP- Pesticides

Diethyl-type, Dimethyl-type, hundreds of other compounds! Characteristics of Poisoning by Nerve Agents

Generally assumed: patients exposed up to 5x LD50

Inhalative G-Type Nerve Agent Poisoning - Immediate onset of cholinergic crisis - Short persistence of nerve agent in the body

Percutaneous V-type Nerve Agent Poisoning - Prolonged onset of cholinergic crisis - Persistence of nerve agent over several days in the body Effects of Organophosphorus Compounds

Mechanism: - inhibition of AChE - accumulation of ACh - disturbance of cholinergic functions Clinical Challenge of Nerve Agent Poisoning

Signs and symptoms Nerve agent poisoning Slight Moderate Severe Miosis / lacrimation Local fasciculations Hypersalivation / sweating Nausea Vomiting / defacation / emiction Bronchocontriction / bronchorrhoe Bradycardia / circulatory depression Respiratory depression Convulsions Coma Worek et al. Arch Toxicol 2016 Effects of Organophosphorus Compounds

Mechanism: - inhibition of AChE - accumulation of ACh - disturbance of cholinergic functions

Life threatening effects: - bronchoconstriction/ bronchorrhoea (muscarine receptors) - central respiratory arrest (muscarine and nicotine receptors) - peripheral respiratory arrest (nicotine receptors) ChE Check Mobile for on-site Confirmation of the Clinical Diagnosis

Acetylthiocholine

AChE BChE

AS-1397

Acetate Thiocholine

+ DTNB

5-Mercapto-2-nitrobenzoate + TNB- Ellman et al. Biochem Pharmacol 1961 Med C- Special Diagnostics/ Reconnaissance / Verification and Analysis

Biomedical verification of exposure to chemical agents ► chemical warfare agents ► degradation products ► metabolites and adducts Peculiarities in Treatment of Chemical Agent Poisoning Self – Protection; Working under aggravated conditions; Protection of medical units; Latency period. Decontamination of victims with signs and symptoms

ouvry.com

Compare: Thiermann et al. Chem Biol Interact 2013; Rosman et al. Annal Intern Med 2014 Atropine for Nerve Agent Poisoning

Military doctrine: autoinjectors for self and buddy aid Enhanced first aid and clinical care by medical personnel)

Aggressive atropine dosing Recommended German regimen 2 mg, i.m. followed by consecutive doubling the dose (4 – 8 – 16 - 32 mg) and finally infusion at field hospital Criteria Clear chest on auscultation; heart rate >80 beats/min; pupils no longer pinpoint; dry skin (axilla); systolic blood pressure >80 mmHg

Thiermann et al. Chem Biol Interact, 2013; according to Eddleston et al. Crit Care 2004 and J Toxicol ClinToxicol 2004. For review see: Thiermann et al. Treatment of Nerve Agent poisoning In:Chemical Warfare Toxicology, Volume 2: Management of Poisoning, © The Royal Society of Chemistry 2016 Development of Oximes

Synthesis of thousands 2017 of oximes since the Oximes in use or in early 1950ies advanced development

- Monopyridinium oximes 2-PAM 1955 - Bispyridinium oximes TMB-4 1958 - Asymmetric oximes MMB-4 1959 - Substituted pyridinium oximes Obidoxime 1959 - Uncharged oximes HI-6 1968 Effects of Obidoxime in a Patient with Parathion Poisoning Patient: 56-year old, female

Emergency situation: Unconscious, cardiovascular resuscitation

Clinical course: As the clinical course situation remained critical for about 4 days without obidoxime, the regimen was started

AChE activity of red blood cells Neuromuscular transmission prior to Obidoxime

600 Obidoxime 500 RBC-AChE in vivo 400 RBC-AChE in vitro 300 200 mU/µmol Hb after Obidoxime 100 0 0 12 24 36 48 Hours Reactions Occurring at AChE with an OP and an Oxime

OP enzyme leaving groupinhibited enzyme

X + AChE-OH X + ACHE

RNOH H2OH2O

AChE-OH CH3-CH2OH AChE-OH + + +

R ACHE

oxime induced aging spontaneous reactivation reactivation Kinetic-Based Computer Model

ki (1) [E] + [OP] [EP]

1000 ka 150 Toxicokinetics (2) [EP] + H2O [EP'] Pharmacokinetics 100 100 10 ks VX (nM) (3) [EP] + H2O [E] + [P] HI (µM) 6 50 1

0.1 0 KD kr 0 100 200 300 400 500 0 100 200 300 400 500 (4) [EP] + [OX] [EPOX] [E] + [POX] min min

kr * [OX] kobs = KD + [OX]

d[E]  ki * [OP] * [E]  ks * [EP]  kobs * [EP  EPOX] dt d[EP]  ki * [OP] * [E]  ks * [EP]  kobs * [EP  EPOX]  ka * [EP] dt

Worek et al. TAP 2005 The Use of Kinetic Constants, Pharmacokinetic and Toxicokinetic Data for Prediction of AChE-Activity in Human Poisoning 20 100 Patient: Obidoxime Paraoxon 80 [nM] Paraoxon A 45-year old, male 15 60 Emergency situation: 10 40 Unconscious, severe signs and 5 symptoms of cholinergic crisis. Obidoxime [µM] 20 1.5 mg of atropine, intubation and initiation of artificial ventilation. 0 0

Clinical course: 400

2 bolus doses of obidoxime together 300 with an atropine infusion at the local hospital. Transfer to the ICU of 200 Technical University, Munich. AChE: measured The patient recovered uneventfully. 100 AChE (mU/µmol Hb) (mU/µmol AChE AChE: calculated 0 Worek et al. TAP 2005 0 24 48 72 96 120 144 Time p.i. (h) Reactivation of OP Inhibited AChE with Oximes

Paraoxon Sarin VX

100 100 Obidoxim 100 2-PAM HI 6 10 10 MMB 4 10

1 1 1 half-time (min) half-time half-time (min) half-time (min)

0.1 0.1 0.1 10-7 10 -6 10 -5 10-4 10 -3 10 -2 10 -1 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 -7 10 -6 10 -5 10-4 10 -3 10 -2 10-1 oxime (M) oxime (M) oxime (M) VR GF Tabun

100 100 100

10 10 10

1 1 1 half-time (min) half-time (min) half-time (min)

0.1 0.1 0.1 10 -7 10 -6 10 -5 10-4 10 -3 10 -2 10-1 10 -7 10 -6 10 -5 10-4 10 -3 10 -2 10-1 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 oxime (M) oxime (M) oxime (M)

Compare: Thiermann et al. Chem Biol Interact 2013 and Tox Lett 1999; modified by using data from Aurbek et al. Toxicolgy 2006; Bartling et al. Toxicolgy 2007 Worek et al. Tox Lett 2011 Calculated Plasma Concentration of Oximes after i.m. Injection

Obidoxime Pralidoxime

50 50

40 40 250 mg 600 mg PAM 30 220 mg 30 350 mg P2S

20 20

10 10 concentration (µM) concentration (µM)

0 0 0 120 240 360 480 600 0 120 240 360 480 600 time (min) time (min)

Calculated according to Erdmann et al. Dtsch Med Wschr 1965 and Sidell et al. J Pharm Sci 1972; Translation of Clinical Findings from Human Poisoning to an Animal Model

Poisoning by dimethoate (oral) and treatment with 2-PAM

100 ACHE in vivo 75 ACHE calc

50 ACHE (%) 25

0 100 200 300 400 500 600 700 800 time (min) 50 80 40

60 30

40 20 2-PAM (µM)

10 Omethoate (µM) 20 2-PAM Omethoate 0 100 200 300 400 500 600 700 800 0 100 200 300 400 500 600 700 800 time (min) time (min) Worek et al. Chem Biol Interact. 2010 Is there a Correlation between RBC-AChE- Activity and Clinical Status? A parathion poisoned patient was treated with obidoxime. The cholinesterase status and NMT were monitored during treatment at the ICU.

600 RBC-AChE in vivo Reactivatability

400 86.4 h

mU/µmol Hb 200

0 0 24 48 72 96 Hours 93.7 h 60

40

20 94.6 h Obidoxime (µmo/l)

0 0 24 48 72 96 Hours Eyer et al. Clincal Toxicology 2009 Patient-Oriented Therapy by Using the Cholinesterase Status Cholinesterase Status: • AChE and BChE activity • Reactivatability of AChE – Reactivatability at all – Aging • Persistence of poison load Treatment: • Appropriate oxime • Oxime as long as substantial ChE Status Monitor reactivation may be expected – Given reactivatability – Persistence of active poison • Oxime stop: – Reactivation achieved and no poison load – Complete aging – Increase of BChE activity Translation of Findings from OP-Pesticide- Poisoning to Nerve Agent-Poisoning

Male York-Landrace cross swine (about 20 kg)

Poisoning:

3 x LD50 VX, p.c.

Treatment:

HI-6 (12.7 mg/kg) / Atropine sulfate (0.05 mg/kg) i.m., according to signs and symptoms

Field laboratory diagnosis:

AChE activity on-site

Plasma sampling for laboratory analysis:

HI-6, VX Treatment of a Percutaneously VX Poisoned Pig

22 cm

22 cm 8 cm

100 10000

80 1000 60 100 40

VX [pM] VX(+) pM AChE (% ) 10 20 VX(-) pM

0 1

0 60 120 180 240 300 360 0 60 120 180 240 300 360 time [min] time [min] Alternative Approaches for Therapy of Nerve Agent Poisoning O F O P Nu Enhanced O elimination by scavengers

Cyclodextrins Cyclodextrines as Small Molecular Scavengers in Nerve Agent-Poisoning

VX

Tabun Sarin Cyclosarin 2-O-(3Carboxyl-4 -iodosobenzyl)-ß -cyclodextrin

Wille et al. Toxicology 2009, Zengerle et al. J Org Chem 2011, Müller et al. Toxicol Lett 2011; 2013 a,b Treatment of a GF Poisoned Guinea Pig with with 6-OxP-CD

Anesthetized (Medetomidine – Fentanyl – Midazolam) Cannulated A. carotis and V. jugularis ß-CD (6-OxP-CD; 100 mg/kg i.v. at -5 min) Cyclosarin (100 µg/kg s.c.; ~2LD50 at 0 min) No post-exposure treatment

GF 100 µg/kg s.c.

0 - 10 11 - 20 21 - 30 45 60 70 90 120

6-OxP -CD 100 mg/kg i.v. 5 min prior to GF 100 µg/kg s.c.

0 - 10 11 - 20 21 - 30 45 60 70 90 120

Worek et al. Toxicol Lett 2014 Cyclodextrines as Small Molecular Scavengers in Nerve Agent-Poisoning

VX

Tabun Sarin Cyclosarin 2-O-(3Carboxyl-4 -iodosobenzyl)-ß -cyclodextrin

Wille et al. Toxicology 2009, Zengerle et al. J Org Chem 2011, Müller et al. Toxicol Lett 2011; 2013 a,b Sulfonatocalix[4]arenes as Small Molecular Scavengers in VX-Poisoning

Detoxification of VX with Calixarenes containing hydroxamic acid was about 3500 times faster when compared with spontaneous hydrolysis

Calixarene-derivates were decorated with substituents in order to achieve fast detoxification in water

Schneider et al. Angew Chem Int Ed Engl 2016 Treatment of VX Poisoned Guinea Pigs with PTE C23

Anesthetized (Medetomidine – Fentanyl – Midazolam) Cannulated A. carotis and V. jugularis VX (18 µg/kg s.c.; ~2LD50 at t = 0 min) PTE C23 (5 mg/kg at t = 5 min) No post-exposure treatment

18 µg/kg VX s.c. (~2LD50) Signs 0 -20 21 -40 41 -60 90 120 150 180

Salivation /

Bronchorrhoe

Convulsions

Altered respiration

Respiratory

depression

18 µg/kg VX s.c. (~2LD50) followed by 5 mg/kg PTE i.v. after 5 min Signs 0 -20 21 -40 41 -60 90 120 150 180

Salivation /

Bronchorrhoe

Convulsions

Altered respiration

Respiratory

depression

18 µg/kg VX s.c. (~2LD50) followed by 2 mg/kg PTE i.v. after 5 min Signs 0 -20 21 -40 41 -60 90 120 150 180 © 2014 by InstPharmToxBw

Salivation / Worek et al. Toxicol Lett 2014 Bronchorrhoe Oximes in OP-poisoning – Hope and Despair

160

140

120 ) -1 100 min 80 -1

60 (mM r2 k 40

20

0 HI 6 HI HLö 7 VX VR DFP Sarin Tabun MFPCh methyl Obidoxime Paraoxon- Butylsarin Cyclosarin Pralidoxime Fenamiphos Paraoxon-ethyl Methamidophos Worek et al. Biochem Pharmacol, 2004; Worek et al. Toxicology, 2016, Worek et al. Chem Biol Interact, 2016 Alternative Approaches for Therapy of Nerve Agent Poisoning O F O P Nu Enhanced O elimination by scavengers

Cyclodextrins

Enzymes, e.g. PON1, PTE

Modulation of nicotinic ACh- receptors

Goldsmith et al. Arch Toxicol ,2016 Wille et al. Tox Lett, 2016 Ashani et al. Chem Biol Interact, 2016 Restoration of Nerve Agent Blocked Muscle Force

Human intercostal Horizontal 4-chamber-organ bath muscle with stimulation-electrodes

Muscle-force after electrical field stimulation (25 Hz)

Seeger et al. Toxicology 2012 Interaction of MB 327 with Human Nicotinic Acetylcholine Receptors (7)

Functionality: Whole cell recording by automated patch clamp platform

Agonist Modulators

Nicotine PNU 120596 MB327 Scheffel et al. 2017 to be published Interaction of MB 327 with Nicotinic Acetylcholine Receptors (Muscle-type)

Membrane preparation of Torpedo californica electric organ (muscle-type nAChR)

N N 2I

MB327 PTM0001 PTM0002 • Affinity on [³H]epitatidine • Functionality based on solid binding sites supported membranes (SSM)

Niessen et al. Chem Biol Interact 2013, Niessen et al. Tox Lett 2016, Niessen at al. 2017 to be submitted Therapeutic Approach in Nerve Agent-Poisoning

Self protection Prompt reactivation of inhibited AChE - even in the absence of severe signs and symptoms - prolonged oxime treatment

Atropine for muscarinic signs and symptoms

Benzodiazepines for treatment and/or prevention of seizures

Supportive therapy artificial ventilation, sedation, cardiovascular stabilisation Outlook: Alternative Therapeutic Approach in Nerve-Agent Poisoning Binding and enhanced elimination by scavengers:

small molecular scavengers human BChE / & oxime human AChE / & oxime PON1; PTE

Receptor active compounds Summary and Recommendations

Don’t wait for symptoms to develop!

Determine AChE activity in case of possible exposure as soon as possible!

Administer atropine according to signs and symptoms!

Administer an effective reactivating oxime when AChE activity has dropped even in the absence of clinical signs and symptoms!

Maintain oxime therapy as long as the organophosphorus compound is persisting in the body! Acknowledgement

T. Zilker D. Kiderlen K. Wanner F. Eyer B. Fichtl T. Wein R. A. Hatz J.E.H. Tattersall N. Felgenhauer P. Eyer S. Rappenglück M. Eichhorn C.M. Timperly R. Pfab M. Radtke M. Lindner A.C. Green H. Friess M. Bird R. Bumm A.L. Mihaljevic

J. Mikler I. Hill K. Niessen T. Seeger D. Tawfik K. Weatherby G. Reiter H. John M. Goldsmith T. Wille M. Koller Y. Ashani G. Heyes G. Engl J.L. Sussman T. Hannig S. Kirchner S. Eckert S. Kämpfer S. Kubik N. Herkert L. Schnitzler M. Zengerle S. Muschik N. Boos A. Bierwisch M. Eddleston C. Scheffel C. Wübbeke C. Schneider