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Lorke DE, Nurulain SM, Hasan MY, Kuča K, Petroianu GA. Experimental and Established Oximes as Pretreatment before Acute Exposure to Azinphos-Methyl. Int J Mol Sci 2021; 22:3072. [PMID: 33802843 PMCID: PMC8002820 DOI: 10.3390/ijms22063072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/01/2021] [Accepted: 03/01/2021] [Indexed: 11/18/2022] Open
Abstract
Poisoning with organophosphorus compounds (OPCs) represents an ongoing threat to civilians and rescue personal. We have previously shown that oximes, when administered prophylactically before exposure to the OPC paraoxon, are able to protect from its toxic effects. In the present study, we have assessed to what degree experimental (K-27; K-48; K-53; K-74; K-75) or established oximes (pralidoxime, obidoxime), when given as pretreatment at an equitoxic dosage of 25% of LD01, are able to reduce mortality induced by the OPC azinphos-methyl. Their efficacy was compared with that of pyridostigmine, the only FDA-approved substance for such prophylaxis. Efficacy was quantified in rats by Cox analysis, calculating the relative risk of death (RR), with RR=1 for the reference group given only azinphos-methyl, but no prophylaxis. All tested compounds significantly (p ≤ 0.05) reduced azinphos-methyl-induced mortality. In addition, the efficacy of all tested experimental and established oximes except K-53 was significantly superior to the FDA-approved compound pyridostigmine. Best protection was observed for the oximes K-48 (RR = 0.20), K-27 (RR = 0.23), and obidoxime (RR = 0.21), which were significantly more efficacious than pralidoxime and pyridostigmine. The second-best group of prophylactic compounds consisted of K-74 (RR = 0.26), K-75 (RR = 0.35) and pralidoxime (RR = 0.37), which were significantly more efficacious than pyridostigmine. Pretreatment with K-53 (RR = 0.37) and pyridostigmine (RR = 0.52) was the least efficacious. Our present data, together with previous results on other OPCs, indicate that the experimental oximes K-27 and K-48 are very promising pretreatment compounds. When penetration into the brain is undesirable, obidoxime is the most efficacious prophylactic agent already approved for clinical use.
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Affiliation(s)
- Dietrich E. Lorke
- Department of Anatomy and Cellular Biology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - Syed M. Nurulain
- Bio Science Department, COMSATS Institute of Information Technology, Bio Sciences Block, CUI, Park Road, Tarlai Kalan, Islamabad 45550, Pakistan;
| | - Mohamed Y. Hasan
- Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, UAE University, Al Ain P.O. Box 15551, United Arab Emirates;
| | - Kamil Kuča
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62/26, 500 03 Hradec Kralove, Czech Republic;
| | - Georg A. Petroianu
- Department of Pharmacology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates;
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Lenina OA, Zueva IV, Zobov VV, Semenov VE, Masson P, Petrov KA. Slow-binding reversible inhibitor of acetylcholinesterase with long-lasting action for prophylaxis of organophosphate poisoning. Sci Rep 2020; 10:16611. [PMID: 33024231 PMCID: PMC7538863 DOI: 10.1038/s41598-020-73822-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/22/2020] [Indexed: 12/02/2022] Open
Abstract
Organophosphorus (OP) compounds represent a serious health hazard worldwide. The dominant mechanism of their action results from covalent inhibition of acetylcholinesterase (AChE). Standard therapy of acute OP poisoning is partially effective. However, prophylactic administration of reversible or pseudo-irreversible AChE inhibitors before OP exposure increases the efficiency of standard therapy. The purpose of the study was to test the duration of the protective effect of a slow-binding reversible AChE inhibitor (C547) in a mouse model against acute exposure to paraoxon (POX). It was shown that the rate of inhibition of AChE by POX in vitro after pre-inhibition with C547 was several times lower than without C547. Ex vivo pre-incubation of mouse diaphragm with C547 significantly prevented the POX-induced muscle weakness. Then it was shown that pre-treatment of mice with C547 at the dose of 0.01 mg/kg significantly increased survival after poisoning by 2xLD50 POX. The duration of the pre-treatment was effective up to 96 h, whereas currently used drug for pre-exposure treatment, pyridostigmine at a dose of 0.15 mg/kg was effective less than 24 h. Thus, long-lasting slow-binding reversible AChE inhibitors can be considered as new potential drugs to increase the duration of pre-exposure treatment of OP poisoning.
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Affiliation(s)
- Oksana A Lenina
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center "Kazan Scientific Center of the Russian Academy of Sciences", Arbuzov str., 8, Kazan, Russian Federation, 420088
| | - Irina V Zueva
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center "Kazan Scientific Center of the Russian Academy of Sciences", Arbuzov str., 8, Kazan, Russian Federation, 420088
| | - Vladimir V Zobov
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center "Kazan Scientific Center of the Russian Academy of Sciences", Arbuzov str., 8, Kazan, Russian Federation, 420088
- Kazan Federal University, 18 Kremlyovskaya str, Kazan, Russia, 420008
| | - Vyacheslav E Semenov
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center "Kazan Scientific Center of the Russian Academy of Sciences", Arbuzov str., 8, Kazan, Russian Federation, 420088
| | - Patrick Masson
- Kazan Federal University, 18 Kremlyovskaya str, Kazan, Russia, 420008
| | - Konstantin A Petrov
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center "Kazan Scientific Center of the Russian Academy of Sciences", Arbuzov str., 8, Kazan, Russian Federation, 420088.
- Kazan Federal University, 18 Kremlyovskaya str, Kazan, Russia, 420008.
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Combined Pre- and Posttreatment of Paraoxon Exposure. Molecules 2020; 25:molecules25071521. [PMID: 32230733 PMCID: PMC7180863 DOI: 10.3390/molecules25071521] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/19/2020] [Accepted: 03/25/2020] [Indexed: 02/01/2023] Open
Abstract
AIMS Organophosphates (OPCs), useful agents as pesticides, also represent a serious health hazard. Standard therapy with atropine and established oxime-type enzyme reactivators is unsatisfactory. Experimental data indicate that superior therapeutic results can be obtained when reversible cholinesterase inhibitors are administered before OPC exposure. Comparing the protective efficacy of five such cholinesterase inhibitors (physostigmine, pyridostigmine, ranitidine, tacrine, or K-27), we observed best protection for the experimental oxime K-27. The present study was undertaken in order to determine if additional administration of K-27 immediately after OPC (paraoxon) exposure can improve the outcome. METHODS Therapeutic efficacy was assessed in rats by determining the relative risk of death (RR) by Cox survival analysis over a period of 48 h. Animals that received only pretreatment and paraoxon were compared with those that had received pretreatment and paraoxon followed by K-27 immediately after paraoxon exposure. RESULTS Best protection from paraoxon-induced mortality was observed after pretreatment with physostigmine (RR = 0.30) and K-27 (RR = 0.34). Both substances were significantly more efficacious than tacrine (RR = 0.67), ranitidine (RR = 0.72), and pyridostigmine (RR = 0.76), which were less efficacious but still significantly reduced the RR compared to the no-treatment group (paraoxon only). Additional administration of K-27 immediately after paraoxon exposure (posttreatment) did not further reduce mortality. Statistical analysis between pretreatment before paraoxon exposure alone and pretreatment plus K-27 posttreatment did not show any significant difference for any of the pretreatment regimens. CONCLUSIONS Best outcome is achieved if physostigmine or K-27 are administered prophylactically before exposure to sublethal paraoxon dosages. Therapeutic outcome is not further improved by additional oxime therapy immediately thereafter.
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Lorke DE, Nurulain SM, Hasan MY, Kuča K, Petroianu GA. Oximes as pretreatment before acute exposure to paraoxon. J Appl Toxicol 2019; 39:1506-1515. [PMID: 31264735 DOI: 10.1002/jat.3835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 05/15/2019] [Accepted: 05/16/2019] [Indexed: 11/11/2022]
Abstract
Organophosphates, useful agents as pesticides, also represent a serious danger due to their high acute toxicity. There is indication that oximes, when administered before organophosphate exposure, can protect from these toxic effects. We have tested at equitoxic dosage (25% of LD01 ) the prophylactic efficacy of five experimental (K-48, K-53, K-74, K-75, K-203) and two established oximes (pralidoxime and obidoxime) to protect from mortality induced by the organophosphate paraoxon. Mortalities were quantified by Cox analysis and compared with those observed after pretreatment with a strong acetylcholinesterase inhibitor (10-methylacridine) and after the FDA-approved pretreatment compound pyridostigmine. All nine tested substances statistically significantly reduced paraoxon-induced mortality. Best protection was conferred by the experimental oxime K-48, reducing the relative risk of death (RR) to 0.10, which was statistically significantly superior to pyridostigmine (RR = 0.31). The other oximes reduced the RR to 0.13 (obidoxime), 0.20 (K-203), 0.21 (K-74), 0.24 (K-75) and 0.26 (pralidoxime), which were significantly more efficacious than 10-methylacridine (RR = 0.65). These data support the hypothesis that protective efficacy is not primarily due to cholinesterase inhibition and indicate that the tested experimental oximes may be considered promising alternatives to the established pretreatment compound pyridostigmine.
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Affiliation(s)
- Dietrich E Lorke
- Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, University Park GL 495 D, Florida International University, Miami, Florida.,College of Medicine and Health Sciences, Department of Anatomy and Cellular Biology, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Syed M Nurulain
- Department of Bio Science, COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Mohamed Y Hasan
- Department of Pharmacology & Therapeutics, College of Medicine and Health Sciences, UAE University, United Arab Emirates
| | - Kamil Kuča
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic
| | - Georg A Petroianu
- Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, University Park GL 495 D, Florida International University, Miami, Florida
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Abstract
Standard therapy of Organophosphorus Compound (OPC) poisoning with
oxime-type acetylcholinesterase (AChE) reactivators is unsatisfactory. New bispyridinium
oximes have therefore been synthesized. This review summarizes in vitro characteristics
of established (pralidoxime, obidoxime, trimedoxime, HI-6) and experimental (K-)oximes,
and compares their protective efficacy in vivo, when administered shortly after exposure
to Diisopropylfluorophosphate (DFP) and three OPC pesticides (ethyl-paraoxon, methylparaoxon,
azinphos-methyl) in the same experimental setting.
In addition to reactivating cholinesterase, oximes also inhibit this enzyme; strongest
AChE inhibition (IC50 rat blood: 1-9 µM) is observed in vitro for the oximes with a xylene
linker (K-107, K-108, K-113). AChE inhibition is weakest for K-27, K-48 and HI-6 (IC50
>500 µM). Intrinsic AChE inhibition of oximes in vitro (IC50, rat) is strongly correlated with their LD50 (rat):
oximes with a high IC50 (K-27, K-48, pralidoxime, obidoxime) also show a high LD50, making them relatively
non-toxic, whereas oximes K-107, K-108 and K-113 (low IC50 and LD50) are far more toxic.
When given in vivo after OP exposure, best protection is conferred by K-27, reducing the relative risk of death
to 16-58% of controls, which is significantly superior to pralidoxime in DFP-, ethyl-paraoxon- and methylparaoxon-
exposure, and to obidoxime in ethyl-paraoxon- and methyl-paraoxon-exposure. Marked reduction in
mortality is also achieved by K-48, K-53, K-74 and K-75, whereas K-107, K-108 and K-113 have no or only a
very weak mortality-reducing effect. K-27 is the most promising K-oxime due to its strong reactivation potency,
weak cholinesterase inhibition and high LD50, allowing administration in large, very efficacious dosages.
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Affiliation(s)
- Dietrich E. Lorke
- Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, University Park GL 495 D, 11200 SW 8th St, Miami 33199, Florida , United States
| | - Georg A. Petroianu
- Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, University Park GL 495 D, 11200 SW 8th St, Miami 33199, Florida , United States
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Lorke DE, Petroianu GA. The Experimental Oxime K027-A Promising Protector From Organophosphate Pesticide Poisoning. A Review Comparing K027, K048, Pralidoxime, and Obidoxime. Front Neurosci 2019; 13:427. [PMID: 31191210 PMCID: PMC6547910 DOI: 10.3389/fnins.2019.00427] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/15/2019] [Indexed: 11/13/2022] Open
Abstract
Poisoning with organophosphorus compounds (OPCs) is a major problem worldwide. Standard therapy with atropine and established oxime-type enzyme reactivators (pralidoxime, obidoxime) is unsatisfactory. In search of more efficacious broad-spectrum oximes, new bispyridinium (K-) oximes have been synthesized, with K027 being among the most promising. This review summarizes pharmacokinetic characteristics of K027, its toxicity and in vivo efficacy to protect from OPC toxicity and compares this oxime with another experimental bisquaternary asymmetric pyridinium aldoxime (K048) and two established oximes (pralidoxime, obidoxime). After intramuscular (i.m.) injection, K027 reaches maximum plasma concentration within ∼30 min; only ∼2% enter the brain. Its intrinsic cholinesterase inhibitory activity is low, making it relatively non-toxic. In vitro reactivation potency is high for ethyl-paraoxon-, methyl-paraoxon-, dichlorvos-, diisopropylfluorophosphate (DFP)- and tabun-inhibited cholinesterase. When administered in vivo after exposure to the same OPCs, K027 is comparable or more efficacious than pralidoxime and obidoxime. When given as a pretreatment before exposure to ethyl-paraoxon, methyl-paraoxon, DFP, or azinphos-methyl, it is superior to the Food and Drug Administration-approved compound pyridostigmine and comparable to physostigmine, which because of its entry into the brain may cause unwanted behavioral effects. Because of its low toxicity, K027 can be given in high dosages, making it a very efficacious oxime not only for postexposure treatment but also for prophylactic administration, especially when brain penetration is undesirable.
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Affiliation(s)
- Dietrich E Lorke
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, United States.,Department of Anatomy and Cellular Biology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Georg A Petroianu
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, United States
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Lorke DE, Petroianu GA. Reversible cholinesterase inhibitors as pretreatment for exposure to organophosphates. A review. J Appl Toxicol 2018; 39:101-116. [PMID: 30027640 DOI: 10.1002/jat.3662] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 06/06/2018] [Indexed: 01/04/2023]
Abstract
Organophosphorus compounds (OPCs), inhibitors of acetylcholinesterase (AChE), are useful agents as pesticides, but also represent a serious health hazard. Standard therapy with atropine and established oxime-type enzyme reactivators (pralidoxime, obidoxime) is unsatisfactory. Better therapeutic results are obtained, when reversible AChE inhibitors are administered before OPC exposure. This review summarizes the history of such a pretreatment approach and sums up a set of experiments undertaken in search of compounds that are efficacious when given before a broad range of OPCs. The prophylactic efficacy of 10 known AChE inhibitors, either already used clinically for different indications (physostigmine, pyridostigmine, ranitidine, tiapride, tacrine, amiloride, metoclopramide, methylene blue) or developed for possible therapeutic use in the future (7-methoxytacrine, K-27) was compared, when administered before exposure to six chemically diverse OPCs in the same experimental setting: ethyl-paraoxon, methyl-paraoxon, diisopropylfluorophosphate, terbufos sulfone, azinphos-methyl and dicrotophos. The experimental oxime K-27 was the most efficacious compound, affording best protection, when administered before terbufos sulfone, azinphos-methyl and dicrotophos, second best before ethyl- and methyl-paraoxon exposure and third best before diisopropylfluorophosphate administration. This ranking was similar to that of physostigmine, which was superior to the Food and Drug Administration-approved pretreatment for soman with pyridostigmine. Tiapride, amiloride, metoclopramide, methylene blue and 7-methoxytacrine did not achieve protection. No correlation was observed between the IC50 of the reversible AChE inhibitors and their protective efficacy. These studies indicate that K-27 can be considered a very promising broad-spectrum prophylactic agent in case of imminent organophosphate exposure, which may be related to its AChE reactivating activity rather than its AChE inhibition.
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Affiliation(s)
- Dietrich E Lorke
- Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Georg A Petroianu
- Department of Cellular Biology & Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
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Chronic Manganese Toxicity Associated with Voltage-Gated Potassium Channel Complex Antibodies in a Relapsing Neuropsychiatric Disorder. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15040783. [PMID: 29669989 PMCID: PMC5923825 DOI: 10.3390/ijerph15040783] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/13/2018] [Accepted: 04/16/2018] [Indexed: 01/26/2023]
Abstract
Heavy metal poisoning is a rare but important cause of encephalopathy. Manganese (Mn) toxicity is especially rare in the modern world, and clinicians’ lack of recognition of its neuropsychiatric manifestations can lead to misdiagnosis and mismanagement. We describe the case of a man who presented with recurrent episodes of confusion, psychosis, dystonic limb movement and cognitive impairment and was initially diagnosed with anti-voltage-gated potassium channel (VGKC) complex limbic encephalitis in view of previous positive autoantibodies. His failure to respond to immunotherapy prompted testing for heavy metal poisoning, which was positive for Mn. This is the first report to examine an association between Mn and VGKC antibodies and the effects of Mn on functional brain activity using functional near-infrared spectroscopy (fNIRS).
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