common poisons 20

8/14/2019 Common Poisons 20

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The Common Poison

Intoxication


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Ethyl Alcohol(Ethanol)

1. Its the most widely used drug in the world.

2. The most deaths cause by the chronic effects

of alcohol or others reasons (such as motorvehicle accidents, craniocerebral injury,congenital anomalies) being linked to alcohol.

3. Alcohol beverage contain 0.5~95% alcohol .


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4. Alcohol is rapidly absorbed from all themucosal surfaces of the gastrointestinal tract. Fooddelays the absorption of alcohol, alcohol isabsorbed faster on an empty stomach.

5. Alcohol is soluble in water, it is present in thebody tissue in direct relation to the amount of water content of the tissue or fluid.


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6. Alcohol is metabolized in the liver. Over

90% of the ethanol ingested is oxidized tocarbon dioxide and water, and the remaining5~8% is excreted as ethanol in the breath,

urine, and perspiration.7. For nonalcoholics, the rate of elimination

from the blood varies between about

11~25mg/100ml/hour. Alcoholics are able toeliminate alcohol at a faster rate.


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8. The effects of ethanol is on the nervous system.

Symptoms: reduced inhibition of highernervous center decrease in attentivenessconfusion, staggering gait stupor, comadeath

9. Most deaths caused by acute alcoholintoxication occur with blood alcohol levels of

400mg% or greater.


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Symptoms

There are three phases of intoxication2. Stage of excitement3. Stage of incoordination4. Stage of coma


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1.stage of excitement--feeling of well being and a certain slight

excitation.-the action, speech and emotions are less

controlled due to lowering of inhibition normallyexercised by the higher centres of the brain.- increase confidence and lack of self control


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2. Stage of incoordination-when the alcohol content of the blood attains a

level of 150-250 mg/100ml the sense of perception and skilled movements are affected.The increased loss of inhibitory action of thehigher centers causes an alteration of in theconduct of individual.He may become carefree,cheerful, ill-tempered, irritable, excitable,quarrelsome, sleepy and so on.

-nausea and vomoting are common


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3. Stage of comain this stage the motor and sensory cells are

deeply affected, speech becomes thick andslurring, coordination is markedly affected,causing the patient to become giddy, stagger and

possibly fall.the person passes into a stage of coma with stertorous breating.


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Micturation syncope

It is a condition which occurs usually after heavy beer drinking

When a person rises from bed in the middleof night to pass urine, he losesconsciousness during the act of urination,

probably due to sudden upright posture.


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Munich beer heart

It is a condition in which cardiac dilatationand hypertrophy is seen due to excessiveand prolonged beer drinking.


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Corrosive Substances

Classification 1.Strong inorganic acid: sulfuric,hydrochloric, nitric acid.

2.The most common organic acid:phenol(carbolic acid), lysol, and cresol.

3.The strong alkalis: sodium and potassiumhydroxide, ammonia.


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The principal mechanism of injury bythis group of substances is thedestruction of tissue at sites of directcontact.

The different corrosive agents havedifferent actions on soft tissues

1. Strong acids act by dehydrating thetissues, coagulating the proteins, andconverting haemoglobin to haematin.


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2.the soft, slippery slime is thecharacteristic appearance by causticsoda.

3. Carbolic acid tends to stiffen thetissues and bleach them; Lysol is asoapy solution of phenol and cresols.


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Sulphuric acid poisoning

Pure sul acid is a heavy,odourless,colorless,non-fuming,hygroscopic, oily liquid.

Signs and symptoms-the lips r usually swollen and excoriated

and brown and black streaks may be found

extending from the angles of the mouth tothe sides of the chin and sometimes to thefront of the neck due to flow of the acids.


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There is corrosion of mucous membrane of mouth,throat and esophagus, immediate burning pain,stridor, drooling, odynophagia.

Epigastric pain soon spread all over the abdomenand thorax.

The nausea and vomiting occurs The vomit is brown or black, mucoid and strongly

acid Thirst is intense, but any attempt to drink cause

vomiting


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There may be edema of glottis which causesasphyxia.

Teeth are chalky white. Tonge becomes swollen, sodden and black. The abdomen becomes distended and very

tender The eyes r usually sunken and pupils

usually dilated


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Arsenic poisoning


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arsenic compounds. arsenious oxide,

sodium and potassium arsenites, arsenicsulphides and so on.

The mechanism of poisoning

Arsenic compounds interfere withcellular respiration by combining with thesulphydryl groups of mitochondrialenzymes, especially pyruvate oxidase andcertain phosphatases.


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Its particular target is vascular endothelium,leading to increase permiability, tissue edema and

hemorrhage, especially in the intestinalcanal.Locally it causes irritation of the mucousmembranes and remotely depression of thenervous system

Arsenate causes its toxicity by uncouplingmitochondrial oxidative phosphorylation.

It interferes with glycolysis


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The form of poisoning

1. The fulminent typemassive doses < 3-5 gm> of arsenic when

rapidly absorbed causes death in 1 to 3

hours from shock and peripheral vascularfailure.all the capillaries are markedlydilated, especially in the splanchnic area

with marked fall of blood pressure. Arsenicalso has direct action on heart muscle


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2. The gastrointestinal form is a more common type of arsenic poisoning.

Symptoms usually appear half to one hour after

ingestion but may be delayed many hours especiallywhen it is taken with food

Signs and symptoms of this type include Constriction in the throat and difficuilty in swallowing.

vomiting, burning pain in the abdomen, cramps, anddiarrhea. Stool is dark colored and bloody at the begining


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Carbon monoxide


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The sources of carbon monoxide: coal

gas, the exhaust fumes of internalcombustion engines, smoke fromconflagrations, and the fumes from

defective heating appliances (furnace,stove, or water heater),explosion inmines.

Carbon monoxide has an affinity forhaemoglobin that is between 200~300

times greater than oxygen.


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It displaces oxygen from its combinationwith haemoglobin and forms a relatively

stable compound known ascarboxyhaemoglobin. It reduces oxygen content of the blood, and

hence that of the tissues. It acts as a chemical asphyxiant and

produces death due to anaemic anoxia.


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HbCO saturation levels of blood relate

to the clinical symptom.HbCO (%) The clinical symptoms

< 10% absent or mild

15%~30% fatigue, loss of attention,headache30%~50% confused to subject

faint on exertion

> 50% unconsciousness or death

The specific cherry-pink colour of theskin and blood


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They r esters of phosphoric acid and formtwo series of compound

2. Alkyl phosphates-tetron, dimefox,

malathion,trichlorfon etc

2. Aryl phosphates-parathion,paraoxon, methyl parathion,

chlorthion etc


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It is absorbed by inhalation through theskin, mucous membrane and the GI tract.

It is metabolised in liver and excretion of metabolites occurs through urine


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Common organic phosphates: parathion,malathion, dichlorvos and so on

All of these substances have aparasympathomimetic effect and act ascholinesterase inhibitors, acetylcholinebuilds up neuromuscular junctions andother neurotransmitter sites, resulting inhyperexcitability of both voluntary andinvoluntary muscle.


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Cyanide


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Cyanide inhibits the action of cytochrome oxidase, carbonic anhydraseand other enzyme system.It blocks thefinal step of oxidative phosphorilation andprevents the formation of ATP and its use

as energy source.Cyanide acts byreducing the oxygen carring capacity of the blood and by combining the ferric

iron atom of intracellular cytochromeoxidase, preventing the uptake of oxygenfor cellular respiration


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Cyanide gas is absorbed rapidly fromrespiratory system and the acid and cyanide

salts from the stomach.Acid is alsoabsorbed from skin.absorbtion is delayed if it is taken on a full stomach or with much

wine. It is mainly excreted in the urine, a small

amount excreted in the breath.


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The colours of the blood is bright reddue to excess oxyhaemoglobin.

The signs and symptoms are manifestedcollapse, rapid pulse, gasping respiration,convulsions and death.

common poisons 20

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