Insecticides
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Questions and Answers

How do chemical insecticides primarily affect the target organisms?

  • By inhibiting their respiratory systems
  • By blocking their digestive systems
  • By poisoning their nervous systems (correct)
  • By interfering with their reproductive systems

    • Which of the following is a potential site of action of insecticides?

  • Interference with membrane transport of sodium, potassium, calcium, and chloride ions (correct)
  • Enhancement of selective enzymatic activities
  • Facilitation of ion transport through nerve endings
  • Promotion of neurotransmitter release at muscle endings

    • What is a possible effect of insecticides on nerve endings?

  • Decrease in production of neurotransmitters
  • Neutral effect on neurotransmitter activity
  • Increase in release and/or persistence of neurotransmitters (correct)
  • Stimulation of new neurotransmitter pathways

    • What is a common potential action of classes of insecticides on the nerve axon and terminal portions?

    <p>Interference with membrane transport</p> Signup and view all the answers

    What contributes to the persistence of organochlorine insecticides in the environment?

    <p>High lipid solubility and slow rates of degradation</p> Signup and view all the answers

    Which class of insecticide includes DDT and its analogues?

    <p>Chlorinated ethane derivatives</p> Signup and view all the answers

    What characteristic makes organochlorine insecticides chemically stable?

    <p>Low volatility</p> Signup and view all the answers

    Which compound belongs to the class of hexachlorocyclohexanes?

    <p>Gamma Lindane</p> Signup and view all the answers

    What is the primary metabolite of DDT in humans?

    <p>Dichlorodiphenyldichloroethylene (DDE)</p> Signup and view all the answers

    Where are the highest concentrations of DDT found in the body?

    <p>Adipose tissue</p> Signup and view all the answers

    How is DDT excreted from the body?

    <p>Bile, urine, and milk</p> Signup and view all the answers

    Which isomer of DDT is responsible for its insecticidal activity?

    <p>p,p-DDT</p> Signup and view all the answers

    Which mechanism describes the alteration of porous channels through which sodium ions pass?

    <p>Altering sodium ion channels by slowing down inactivation</p> Signup and view all the answers

    What effect does DDT have on the ability of calmodulin to transport calcium ions?

    <p>Inhibits calmodulin's ability to transport calcium ions</p> Signup and view all the answers

    What role do neuronal adenosine triphosphatases (ATPase) play in neuronal repolarization?

    <p>Play vital roles in neuronal repolarization</p> Signup and view all the answers

    How does DDT's reduction of potassium transport across the membrane impact neurons?

    <p>Interferes with the active transport of potassium out of the nerve axon</p> Signup and view all the answers

    What is one of the proposed sites of action of DDT?

    <p>Inactivating sodium channel closure</p> Signup and view all the answers

    How does DDT potentially affect the transport of potassium?

    <p>Reducing potassium transport through pores</p> Signup and view all the answers

    What is a suggested effect of DDT on calmodulin-calcium binding?

    <p>Inhibiting calmodulin-calcium binding</p> Signup and view all the answers

    Which of the following is a potential site of action of DDT?

    <p>Inhibiting sodium-potassium and calciummagnesium ATPases</p> Signup and view all the answers

    Which of the following is the earliest symptom of poisoning by DDT in humans?

    <p>Paresthesia of the mouth and lower part of the face</p> Signup and view all the answers

    What is the primary target for DDT toxicity based on the signs and symptoms of acute poisoning?

    <p>Nervous system</p> Signup and view all the answers

    According to animal data, how is DDT classified in terms of its potential impact on humans?

    <p>Human carcinogen</p> Signup and view all the answers

    Which organ or system is considered an important target for DDT in chronic exposure?

    <p>Liver</p> Signup and view all the answers

    Which class of organochlorine insecticides includes compounds that antagonize the action of the neurotransmitter GABA?

    <p>Class 3: Cyclodienes</p> Signup and view all the answers

    What is the γ isomer of benzene hexachloride known as?

    <p>Lindane</p> Signup and view all the answers

    Which compound is rapidly metabolized to dieldrin?

    <p>Aldrin</p> Signup and view all the answers

    What is the primary mechanism of neurotoxic action shared by the hexachlorocyclohexanes and cyclodiene insecticides?

    <p>Blocking GABA-induced uptake of chloride ions</p> Signup and view all the answers

    What is the mechanism of action shared by hexachlorocyclohexanes and cyclodiene insecticides?

    <p>Antagonism of GABA receptors</p> Signup and view all the answers

    Which compound is the γ isomer of benzene hexachloride?

    <p>Lindane</p> Signup and view all the answers

    Which class of insecticides includes chlordane, dieldrin, and aldrin?

    <p>Cyclodienes</p> Signup and view all the answers

    What is the primary mechanism of neurotoxic action for organochlorine insecticides?

    <p>Antagonism of GABA receptors</p> Signup and view all the answers

    What is the primary effect of endogenous GABA binding to its receptors?

    <p>Opening of chloride channels resulting in hyperpolarization</p> Signup and view all the answers

    What is the primary action of Lindane and cyclodienes on the chloride channel?

    <p>Blocking the opening of chloride channels</p> Signup and view all the answers

    What is the result of inhibiting Na+,K+-ATPase and Ca2+,Mg2+ ATPase by Class 2 and Class 3 insecticides?

    <p>Accumulation of intracellular free Ca2+</p> Signup and view all the answers

    What is the primary effect of GABA antagonists like Lindane and cyclodienes on neurotransmission?

    <p>Inhibition of neurotransmitter release</p> Signup and view all the answers

    What is the primary target for the toxicity of Lindane and cyclodienes?

    <p>Central nervous system</p> Signup and view all the answers

    What is the main difference in symptoms of poisoning between DDT and Lindane/cyclodienes?

    <p>Tremor</p> Signup and view all the answers

    What effect do cyclodienes have on the liver upon chronic exposure?

    <p>Enlargement</p> Signup and view all the answers

    Where do Lindane and cyclodienes tend to bioaccumulate?

    <p>Adipose tissue</p> Signup and view all the answers

    What is the primary target for the toxicity of Lindane and cyclodienes?

    <p>Central Nervous System</p> Signup and view all the answers

    What is a prominent aspect of poisoning by Lindane and cyclodienes?

    <p>Tremor</p> Signup and view all the answers

    What is the effect of cyclodienes on the liver upon chronic exposure?

    <p>Liver enlargement</p> Signup and view all the answers

    Where do Lindane and cyclodienes tend to bioaccumulate?

    <p>Adipose tissue</p> Signup and view all the answers

    What is the primary manifestation of chlordecone toxicity?

    <p>Tremors</p> Signup and view all the answers

    What is believed to be the mechanism of chlordecone neurotoxicity?

    <p>Inhibition of catecholamines</p> Signup and view all the answers

    What effect does chlordecone have on the liver?

    <p>Induces hepatic drug metabolizing enzymes</p> Signup and view all the answers

    What reproductive effect has been observed in chlordecone-exposed workers?

    <p>Low or absent sperm count</p> Signup and view all the answers

    Which of the following best defines an endocrine disruptor?

    <p>A chemical that interferes with the production of natural hormones</p> Signup and view all the answers

    Which compound has estrogenic properties and can act as an agonist at estrogen receptors?

    <p>o,p-isomer of DDT</p> Signup and view all the answers

    What is the primary negative effect of the metabolite p,p-DDE on androgen receptors?

    <p>Inhibits androgen binding</p> Signup and view all the answers

    Which category of insecticides includes compounds with weak estrogenic activity?

    <p>Organochlorine insecticides</p> Signup and view all the answers

    What is the definition of an endocrine disruptor?

    <p>A chemical that affects the transport, binding, and action of natural hormones in the body</p> Signup and view all the answers

    What is the primary mechanism of action of the o,p-isomer of DDT?

    <p>Acts as an agonist at estrogen receptors</p> Signup and view all the answers

    Which compound has estrogenic properties and can act as an agonist at estrogen receptors?

    <p>o,p-isomer of DDT</p> Signup and view all the answers

    What do organochlorine compounds with weak estrogenic activity primarily affect?

    <p>Reproduction and development</p> Signup and view all the answers

    How does the oral administration of anion-exchange resin (cholestyramine) affect the fecal excretion of chlordecone?

    <p>It enhances fecal excretion by 18 fold</p> Signup and view all the answers

    What is the rationale for the use of cholestyramine in increasing fecal excretion of chlordecone?

    <p>It interrupts enterohepatic circulation and reduces reabsorption of chlordecone</p> Signup and view all the answers

    What is the primary impact of cholestyramine on the biological half-life of chlordecone?

    <p>It shortens the biological half-life of chlordecone</p> Signup and view all the answers

    How does cholestyramine potentially reduce chlordecone reabsorption in the intestinal tract?

    <p>By reducing biliary – enterohepatic circulation of chlordecone</p> Signup and view all the answers

    What is the primary rationale for using cholestyramine to increase fecal excretion of chlordecone?

    <p>Interrupting enterohepatic circulation of chlordecone</p> Signup and view all the answers

    What effect does cholestyramine potentially have on chlordecone reabsorption in the intestinal tract?

    <p>Reducing reabsorption by interrupting enterohepatic circulation</p> Signup and view all the answers

    What is the primary impact of cholestyramine on the biological half-life of chlordecone?

    <p>Shortening the biological half-life</p> Signup and view all the answers

    Where does cholestyramine retain the bound chlordecone to increase fecal excretion?

    <p>Gastrointestinal lumen</p> Signup and view all the answers

    What is the common mechanism of action shared by the two types of insecticides?

    <p>Inhibition of acetylcholinesterase (AChE)</p> Signup and view all the answers

    What do the esters of phosphoric or phosphorothioic acid and the esters of carbamic acid have in common?

    <p>Shared mechanism of hydrolysis sensitivity</p> Signup and view all the answers

    What is the role of X in the general structure of OP insecticides?

    <p>Serves as a leaving group when phosphorylating AChE</p> Signup and view all the answers

    What are R1 and R2 in the general structure of OP insecticides typically composed of?

    <p>Alkyl or alkoxy groups</p> Signup and view all the answers

    What is the most sensitive to hydrolysis in the general structure of OP insecticides?

    <p>The leaving group</p> Signup and view all the answers

    Which chemical class of insecticides includes esters of carbamic acid?

    <p>Organophosphate insecticides</p> Signup and view all the answers

    What is the common mechanism of action for the agents comprising a type of insecticide ?

    <p>Phosphorylation of acetylcholinesterase (AChE)</p> Signup and view all the answers

    What are R1 and R2 in the general structure of OP insecticides primarily composed of?

    <p>Alkyl or alkoxy groups</p> Signup and view all the answers

    What is the common mechanism of action shared by the two types of insecticides?

    <p>Inhibition of acetylcholinesterase (AChE)</p> Signup and view all the answers

    Which chemical class of insecticides includes esters of carbamic acid?

    <p>Carbamate insecticides</p> Signup and view all the answers

    What contributes to the persistence of organochlorine insecticides in the environment?

    <p>Resistance to chemical hydrolysis</p> Signup and view all the answers

    What is the primary impact of cholestyramine on the biological half-life of chlordecone?

    <p>Decreases the biological half-life</p> Signup and view all the answers

    What is the primary metabolic bioactivation process for compounds containing a sulfur bound to phosphorus?

    <p>Oxidative desulfuration mediated by cytochrome P450 enzymes (CYPs)</p> Signup and view all the answers

    Which enzymes are primarily responsible for the oxidative desulfuration of compounds containing sulfur bound to phosphorus?

    <p>Cytochrome P450 enzymes (CYPs)</p> Signup and view all the answers

    What type of analog is formed during the oxidative desulfuration of compounds containing sulfur bound to phosphorus?

    <p>Oxon</p> Signup and view all the answers

    Where does the oxidative desulfuration of compounds containing sulfur bound to phosphorus predominantly take place?

    <p>Liver</p> Signup and view all the answers

    What happens to the AChE enzyme following the reaction with an organophosphorus ester?

    <p>It forms a transient intermediate complex and becomes phosphorylated, leading to irreversible inhibition</p> Signup and view all the answers

    What is the effect of inhibiting Na+,K+-ATPase and Ca2+,Mg2+ ATPase by Class 2 and Class 3 insecticides?

    <p>Decreased excitability of neurons</p> Signup and view all the answers

    How does DDT's reduction of potassium transport across the membrane impact neurons?

    <p>It increases excitability of neurons</p> Signup and view all the answers

    What is the primary impact of GABA antagonists like Lindane and cyclodienes on neurotransmission?

    <p>Decreased inhibition of neurotransmission</p> Signup and view all the answers

    What happens to the AChE enzyme following the reaction with an organophosphorus ester?

    <p>It forms a transient intermediate complex that hydrolyzes with the loss of the substituent group</p> Signup and view all the answers

    What is the primary impact of cholestyramine on the biological half-life of chlordecone?

    <p>It decreases the biological half-life of chlordecone</p> Signup and view all the answers

    What is the common mechanism of action for the agents comprising a type of insecticide?

    <p>Inhibition of acetylcholinesterase (AChE) activity</p> Signup and view all the answers

    What are R1 and R2 in the general structure of OP insecticides primarily composed of?

    <p>Functional groups that enhance enzyme reactivation</p> Signup and view all the answers

    What is the primary impact of inhibiting AChE by organophosphates (OPs)?

    <p>Overstimulation of muscarinic and nicotinic cholinergic receptors</p> Signup and view all the answers

    What is the primary consequence of AChE inhibition at cholinergic synapses?

    <p>Overstimulation of muscarinic and nicotinic receptors</p> Signup and view all the answers

    What is the primary result of AChE inhibition by organophosphates (OPs) in the body?

    <p>Increased activity of cholinergic receptors</p> Signup and view all the answers

    What is the consequence of AChE inhibition by organophosphates (OPs) at cholinergic synapses?

    <p>Overstimulation of muscarinic and nicotinic receptors</p> Signup and view all the answers

    What effect can be expected from the stimulation of muscarinic receptors of the parasympathetic autonomic nervous system?

    <p>Increased sweating and salivation</p> Signup and view all the answers

    What is believed to be the primary cause of death when respiratory failure occurs due to exposure to certain substances?

    <p>Paralysis of respiratory muscles</p> Signup and view all the answers

    Which effect is associated with the action of chlordecone in the intestinal tract?

    <p>Increased reabsorption</p> Signup and view all the answers

    What symptoms can result from the effects of substances on the CNS?

    <p>Convulsion and coma</p> Signup and view all the answers

    What is the hallmark of severe organophosphate (OP) poisoning?

    <p>Respiratory failure</p> Signup and view all the answers

    Which symptoms are observed most often in mild and moderate OP poisoning?

    <p>Miosis</p> Signup and view all the answers

    What are the first signs to appear in OP poisoning?

    <p>Muscarinic</p> Signup and view all the answers

    What is a hallmark of severe chlordecone poisoning?

    <p>Gastrointestinal symptoms</p> Signup and view all the answers

    What is the primary means of replacing the activity of irreversibly inhibited AChE?

    <p>Synthesis of new enzyme</p> Signup and view all the answers

    What facilitates the dephosphorylation of AChE in the therapy of OP poisoning?

    <p>Hydroxylamine derivatives (oximes)</p> Signup and view all the answers

    What is the impact of aging on phosphorylated AChE?

    <p>Makes the enzyme irreversibly inhibited</p> Signup and view all the answers

    What determines the rate of aging of phosphorylated AChE and the need for enzyme replacement?

    <p>Nature of the alkyl group</p> Signup and view all the answers

    What effect would the presence of P–O–C bonds have on aging ?

    <p>Aging would occur rapidly</p> Signup and view all the answers

    What type of bonds in P–R would prevent aging ?

    <p>P–C</p> Signup and view all the answers

    In what form of P-R bonds would aging not be possible?

    <p>P–C</p> Signup and view all the answers

    What type of P-R bonds are associated with rapid aging?

    <p>P–O–C</p> Signup and view all the answers

    What is the primary feature of the Intermediate Syndrome in organophosphate (OP) poisoning?

    <p>Marked weakness of respiratory and limb muscles</p> Signup and view all the answers

    What is the mortality rate due to respiratory paralysis and complications in the Intermediate Syndrome?

    <p>15-40%</p> Signup and view all the answers

    What is one hypothesis for the cause of muscle weakness in the Intermediate Syndrome?

    <p>Muscarinic receptor desensitization</p> Signup and view all the answers

    What is the primary treatment for the Intermediate Syndrome?

    <p>Supportive intervention only</p> Signup and view all the answers

    When does the Intermediate Syndrome typically develop after OP poisoning?

    <p>One to several days after poisoning</p> Signup and view all the answers

    What is the usual recovery period in surviving patients with the Intermediate Syndrome?

    <p>Up to 15 days</p> Signup and view all the answers

    What is a common symptom of Organophosphate-Induced Delayed Polyneuropathy (OPIDP)?

    <p>Tingling of the hands and feet</p> Signup and view all the answers

    When do the signs and symptoms of Organophosphate-Induced Delayed Polyneuropathy (OPIDP) typically occur?

    <p>2-3 weeks after exposure</p> Signup and view all the answers

    What is the primary impact of AChE (Acetylcholinesterase) inhibition by organophosphates (OPs) in the body?

    <p>Impaired nerve signal transmission</p> Signup and view all the answers

    Which of the following is a sign of Organophosphate-Induced Delayed Polyneuropathy (OPIDP)?

    <p>Progressive muscle weakness</p> Signup and view all the answers

    What is the necessary percentage of NTE phosphorylation for OPIDP to be initiated?

    <p>70%</p> Signup and view all the answers

    What is the target enzyme for OPIDP?

    <p>Neuropathy target esterase (NTE)</p> Signup and view all the answers

    Which type of compounds can cause OPIDP?

    <p>Compounds that inhibit NTE and undergo aging reaction</p> Signup and view all the answers

    What is the primary impact of organophosphates (OPs) on NTE?

    <p>Phosphorylation and aging of NTE</p> Signup and view all the answers

    What is the primary reason for the distinctive difference in neurotoxicity action between carbamic acid esters and organophosphates?

    <p>The rate of decarbamylation is rapid for carbamic acid esters but slow for organophosphates.</p> Signup and view all the answers

    What distinguishes carbamic acid esters as poor substrates for the cholinesterase enzymes compared to organophosphates?

    <p>They form a carbamylated enzyme through a fast process.</p> Signup and view all the answers

    What distinguishes organophosphates as frequently considered to be irreversible inhibitors of AChE?

    <p>The rate of dephosphorylation is exceedingly slow.</p> Signup and view all the answers

    What characterizes the distinct difference in neurotoxic action between carbamic acid esters and organophosphates?

    <p>Organophosphates have a higher rate of decarbamylation.</p> Signup and view all the answers

    What distinguishes carbamate insecticides from most organophosphorus compounds?

    <p>They are rapidly biotransformed in vivo</p> Signup and view all the answers

    What is the primary difference between the signs and symptoms of acute intoxication by carbamate insecticides and organophosphorus compounds?

    <p>Duration and intensity of toxicity</p> Signup and view all the answers

    What is the reason for the extensive toxicologic short-term toxicity following acute administration of carbamate insecticides?

    <p>Rapid biotransformation in vivo</p> Signup and view all the answers

    What is the primary reason for fatalities occurring in humans due to carbamate insecticide toxicity?

    <p>Higher toxicity of the compounds</p> Signup and view all the answers

    What is the primary indicator of the severity of organophosphorus ester poisoning?

    <p>Erythrocyte AChE inhibition</p> Signup and view all the answers

    What immediate action is required in response to life-threatening signs of anticholinesterase poisoning?

    <p>Initiating artificial respiration and suctioning</p> Signup and view all the answers

    What should be monitored in cases of anticholinesterase poisoning, in addition to the status of the patient?

    <p>Arterial blood gases and cardiac function</p> Signup and view all the answers

    What is a consequence of extensive nervous system involvement in anticholinesterase poisoning?

    <p>Hypoxemia requiring immediate artificial respiration</p> Signup and view all the answers

    What is a good indicator of the severity of organophosphorus ester poisoning?

    <p>Erythrocyte AChE levels</p> Signup and view all the answers

    What is the immediate action required for life-threatening signs of anticholinesterase poisoning?

    <p>Initiating artificial respiration</p> Signup and view all the answers

    What should be monitored as a consequence of the extensive involvement of the entire nervous system in anticholinesterase poisoning?

    <p>Arterial blood gases</p> Signup and view all the answers

    What is the primary indicator of severe organophosphate (OP) poisoning?

    <p>Inhibition of erythrocytic AChE</p> Signup and view all the answers

    What is the recommended action for all cases of anticholinesterase poisoning?

    <p>Immediate hospitalization</p> Signup and view all the answers

    Which enzyme's inhibition is a good indicator of the severity of organophosphorus ester poisoning?

    <p>Plasma acetylcholinesterase (AChE)</p> Signup and view all the answers

    What is required to maintain a patent airway in cases of life-threatening signs in anticholinesterase poisoning?

    <p>Immediate artificial respiration and suctioning via an endotracheal tube</p> Signup and view all the answers

    What should be monitored as a consequence of the extensive involvement of the entire nervous system in anticholinesterase poisoning?

    <p>Arterial blood gases and cardiac function</p> Signup and view all the answers

    What is the role of diazepam in the treatment of organophosphorus and/or carbamate intoxications?

    <p>Relieving mental anxiety associated with exposure</p> Signup and view all the answers

    What is the antidotal therapy for organophosphorus ester insecticide poisoning usually based on?

    <p>Analysis of serum pseudocholinesterase</p> Signup and view all the answers

    What is the primary impact of AChE (Acetylcholinesterase) inhibition by organophosphates (OPs) in the body?

    <p>Overstimulation of muscles and nerves</p> Signup and view all the answers

    What characterizes the distinct difference in neurotoxic action between carbamic acid esters and organophosphates?

    <p>The reversibility of AChE inhibition</p> Signup and view all the answers

    What is the primary reason for using frequent small doses of atropine in cases of mild signs and symptoms of anticholinesterase poisoning?

    <p>To counteract the muscarinic effects and some CNS effects of accumulating Ach</p> Signup and view all the answers

    What is the supplementary treatment for moderate to severe nicotinic symptoms in cases of anticholinesterase poisoning?

    <p>Priming with pralidoxime chloride or P2S</p> Signup and view all the answers

    What is the primary consequence of AChE inhibition by organophosphates (OPs) at cholinergic synapses?

    <p>Accumulation of acetylcholine at cholinergic synapses</p> Signup and view all the answers

    What is the status that must be monitored continuously in cases of anticholinesterase poisoning?

    <p>Disappearance of secretions and mydriasis</p> Signup and view all the answers

    What is the primary requirement for a reactivating molecule for AChE inhibition?

    <p>A rigid structure containing a quaternary ammonium group and an acidic nucleophile</p> Signup and view all the answers

    What is the therapeutic action of oxime compounds based on?

    <p>Reactivation of AChE</p> Signup and view all the answers

    What contributes to the irreversible inhibition of AChE by organophosphorus esters?

    <p>Presence of good 'leaving groups' that phosphorylate AChE</p> Signup and view all the answers

    What aids in the rapid dephosphorylation of the phosphorylated enzyme?

    <p>Various nucleophilic agents containing a substituted ammonium group</p> Signup and view all the answers

    What is the practical limitation on the usefulness of oxime reactivators?

    <p>Inability to reactivate 'aged' AChE</p> Signup and view all the answers

    What is the product of the oxime reaction with either the phosphorylated enzyme or with free, unbound organophosphorus ester?

    <p>Phosphorylated oxime</p> Signup and view all the answers

    What happens to the phosphorylated enzyme in 'aged' AChE?

    <p>Becomes tightly bound to the reactive site</p> Signup and view all the answers

    What is the nature of the reaction between oxime and the phosphorylated enzyme or free, unbound organophosphorus ester?

    <p>Equilibrium reaction</p> Signup and view all the answers

    What should be administered repeatedly over several days if the absorption, distribution, and/or metabolism of the organophosphorus ester is delayed in the body?

    <p>Pralidoxime</p> Signup and view all the answers

    What may alleviate severe muscle cramping, particularly in the extremities, caused by the repeated dosing of pralidoxime?

    <p>Oral or intravenous calcium solutions</p> Signup and view all the answers

    What binding by pralidoxime causes muscle spasms similar to those caused by the organophosphorus esters?

    <p>Calcium ions</p> Signup and view all the answers

    What is the primary treatment for severe muscle cramping, particularly in the extremities, caused by repeated dosing with pralidoxime?

    <p>Oral or intravenous calcium solutions</p> Signup and view all the answers

    What is the primary difference in the clinical treatment of carbamate toxicity compared to organophosphorus ester insecticide intoxication?

    <p>The use of oximes is contraindicated</p> Signup and view all the answers

    What did reports reveal about the use of pralidoxime in treating carbaryl intoxications?

    <p>The oxime enhanced the carbaryl-induced toxicity</p> Signup and view all the answers

    What is the important consideration regarding the treatment of anticholinesterase-type insecticide intoxications?

    <p>Vigorous treatment is ineffective in preventing neurotoxicity</p> Signup and view all the answers

    What is the similarity in the clinical treatment of carbamate toxicity and organophosphorus ester insecticide intoxication?

    <p>Both involve delayed-onset neurotoxicity</p> Signup and view all the answers

    What are pyrethrins?

    <p>Esters of chrysanthemic acid and pyrethric acid found in chrysanthemum flowers</p> Signup and view all the answers

    Which type of pyrethrins contains the -cyano substituent?

    <p>Esters containing the -cyano substituent</p> Signup and view all the answers

    What is the primary source of pyrethrins?

    <p>Chrysanthemum flowers</p> Signup and view all the answers

    What distinguishes pyrethrins from carbamate and organophosphorus insecticides?

    <p>They have a natural source in chrysanthemum flowers</p> Signup and view all the answers

    What impact do pyrethroids have on sodium channels?

    <p>They affect both the activation and inactivation of sodium channels, resulting in a hyperexcitable state</p> Signup and view all the answers

    What is the primary difference between type I and type II esters in relation to sodium channels?

    <p>Type I esters keep the channel open for seconds, while type II esters keep it open for milliseconds</p> Signup and view all the answers

    What is the effect of type II esters on sodium ion transport within neurons?

    <p>They modify the gating kinetics of sodium channels, causing a hypoexcitable state</p> Signup and view all the answers

    What is the impact of both type I and type II esters on sodium channels?

    <p>They modify the gating kinetics of sodium channels, resulting in a hyperexcitable state</p> Signup and view all the answers

    What is the potential effect of inhibiting Ca2, Mg2-ATPase by several agents such as permethrin, cypermethrin, and deltamethrin?

    <p>Increased intracellular calcium levels</p> Signup and view all the answers

    What is the action of Type II esters at relatively high concentrations in the mammalian brain?

    <p>Act on the GABA-gated chloride channels</p> Signup and view all the answers

    What is the potential consequence of Type II ester intoxication on seizures?

    <p>Increased likelihood of seizures</p> Signup and view all the answers

    What is the primary effect of inhibiting GABA-gated chloride channels in the mammalian brain?

    <p>Increased postsynaptic depolarization</p> Signup and view all the answers

    Which compound produces profuse salivation, coarse tremor progressing to clonic seizures?

    <p>Type II pyrethrins</p> Signup and view all the answers

    What is the primary adverse effect resulting from dermal contact with pyrethroids?

    <p>Paresthesia</p> Signup and view all the answers

    What is the hallmark of severe organophosphate (OP) poisoning?

    <p>Marked behavioral arousal</p> Signup and view all the answers

    What is the primary impact of GABA antagonists like Lindane and cyclodienes on neurotransmission?

    <p>Antagonize GABA receptors</p> Signup and view all the answers

    What is the primary reason for fatalities occurring in humans due to pyrethrin poisoning?

    <p>Respiratory paralysis</p> Signup and view all the answers

    What does piperonyl butoxide do when included in commercial forms of pyrethrins?

    <p>Inhibits the ability of insects to metabolize pyrethrins</p> Signup and view all the answers

    What may a patient also exhibit signs of, if pyrethrins are sold in hydrocarbon solution?

    <p>Hydrocarbon toxicity</p> Signup and view all the answers

    What is the primary impact of piperonyl butoxide on the activity of insects?

    <p>Enhances the insecticidal activity of pyrethrins</p> Signup and view all the answers

    What is the primary concern in organochlorine insecticide poisoning?

    <p>Respiratory failure and acidosis</p> Signup and view all the answers

    What is the recommended treatment to control convulsions in organochlorine insecticide poisoning?

    <p>Diazepam</p> Signup and view all the answers

    What is the effect of repetitive stimulation of the CNS in organochlorine insecticide poisoning?

    <p>Tremors and motor seizures</p> Signup and view all the answers

    In addition to general decontamination and supportive treatment, what medication may be administered to control the convulsions in organochlorine insecticide poisoning?

    <p>Phenobarbital</p> Signup and view all the answers

    Study Notes

    Chemical Insecticides

    • Chemical insecticides primarily affect target organisms by interfering with nerve impulses, disrupting ion channels and receptors, and altering enzyme function.
    • Potential sites of action include nerve endings, axon and terminal portions, and sodium and calcium channels.

    Organochlorine Insecticides

    • Organochlorine insecticides, including DDT and its analogues, are chemically stable due to their cyclic structure.
    • They persist in the environment due to their low biodegradability and high lipophilicity.
    • They can bioaccumulate in fatty tissues and biomagnify up food chains.

    DDT

    • DDT (dichlorodiphenyltrichloroethane) is an organochlorine insecticide that affects nerve endings, axon and terminal portions, and sodium and calcium channels.
    • Its primary metabolite in humans is DDE (dichlorodiphenyldichloroethylene).
    • Highest concentrations of DDT are found in fatty tissues, and it is excreted through the bile and feces.
    • The insecticidal activity of DDT is attributed to its p,p'-isomer.
    • DDT alters the transport of potassium, affecting neuronal repolarization, and binds to calmodulin, altering calcium ion transport.

    Hexachlorocyclohexanes

    • Hexachlorocyclohexanes, including Lindane (γ-hexachlorocyclohexane), are another class of organochlorine insecticides.
    • They antagonize the action of the neurotransmitter GABA, affecting chloride channels and leading to neuronal hyperexcitation.

    Cyclodiene Insecticides

    • Cyclodiene insecticides, including chlordane and aldrin, are organochlorine compounds that antagonize GABA receptors, affecting chloride channels.
    • They are rapidly metabolized to more toxic compounds, such as dieldrin.

    Endocrine Disruptors

    • Endocrine disruptors, including some organochlorine insecticides, interfere with hormone function, affecting reproductive and developmental processes.
    • p,p'-DDE, a metabolite of DDT, has anti-androgenic properties, affecting reproductive health.
    • Chlordecone, a cyclodiene insecticide, has estrogenic properties, acting as an agonist at estrogen receptors.

    Cholestyramine and Chlordecone

    • Cholestyramine, an anion-exchange resin, increases the fecal excretion of chlordecone by binding to it in the gut, reducing reabsorption and increasing elimination.

    Organophosphorus Insecticides

    • Organophosphorus insecticides, such as malathion and parathion, are esters of phosphoric or phosphorothioic acid.
    • They inhibit acetylcholinesterase (AChE), leading to an accumulation of acetylcholine, which overstimulates muscarinic and nicotinic receptors.
    • Inhibiting Na+,K+-ATPase and Ca2+,Mg2+ ATPase can lead to neurological and muscular effects.

    Toxicity and Symptoms

    • Symptoms of poisoning by DDT, Lindane, and cyclodienes include muscle weakness, tremors, and seizures, while chlordecone poisoning can cause tremors, muscle weakness, and liver damage.
    • Organophosphate poisoning can cause muscle weakness, fasciculations, and respiratory failure.
    • The primary impact of cholestyramine on the biological half-life of chlordecone is to reduce it.

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    Test your knowledge on the potential sites of action and modes of action of chemical insecticides. Learn about the interference with membrane transport of ions, enzymatic activities, and neurotransmitter release at nerve endings.

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