Fate of poison
Some of the poison is lost in vomitus or stools, the
remaining are absorbed to pass to the liver, then to the general
circulation, where it is distributed to the target tissues. Then
some of the poison is eliminated via the kidney, sweat, milk,
bile or if volatile in expired air.
Once emergency procedures have been performed and the
poisoned patient is stabilized, or at least is out of immediate
danger, additional steps can be taken to remove the poison,
prevent a delay absorption, enhance excretion, or administer a
specific antidote.
Toxicokinetic considerations
I- Methods to reduce or prevent absorption
A- Gatrointestina1 decontamination
Demulcents
May plants and chemicals cause oral and gastric mucosa
irritation but no serious toxicity. Management for these acute
ingestion may include ice cream, milk, or another soothing
agent to reduce irritation. Egg whites, which serve as a source of
readily available protein, have been given for corrosive
intoxications.
Dilution
The initial procedure generally recommended when ever
ingestion of a poison is suspected is dilution. Water is the best
and only fluid that should be used. The amount recommended is
generally 1 to 2 cupfuls for a child and 2 to 3 cupfuls for an
adult. however, fluids should never he forced. Offer the patient a
quantity that can be comfortably taken. Excessive liquid may
distend the stomach wall, causing premature evacuation into the
duodenum, and making it more difficult to remove the
In cases of ingestion of solid dosage forms such as tablets or
capsules, dilution is not universally recommended. In this case
dilution promotes dissolution of the medication and actually
increases absorption.
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A general rule is that nothing should be administered orally
to an unconscious patient.
Water is given to accomplish at least two functions:
1- It helps reduce the gastric irritation induced by many ingested
poisons.
2- It adds bulk to the stomach that may be needed later for
emesis. Ipecac-induced emesis is more effective if there is
fluid or bulk present in the stomach. Milk provides dilution
and is also a demulcent.
Emesis:
Ipecac has been in use for several hundred years.
Chemically-induced emesis generally accepted to be a first-line
procedure in the management of poisonings because it can be
easily administered at home.
Conditions in which emesis should not be attempted.
Do not induce vomiting if the poison is a:
* Convulsant.
* Hydrocarbon.
* Corrosive acid or alkali.
Do not induce vomiting if the patient:
* Is Unconscious or comatose.
* Has severe cardiovascular disease or, emphysema, or
extremely weakened blood vessels.
* Is under 6 months of age.
If the victim is unconscious danger exists that vomitus may
be aspirated into the lungs. If the poison is a convalsant. forced
emesis may precipitate seizures.
For petroleum, this substance can be readily aspirated into
the lungs during emesis, and may cause chemical pneumonitis.
If the ingested poison is corrosive, emesis should be
avoided because it may induce further damage to the esophagus
as the substance is brought up. Children under 6 months of age
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should not receive syrup of ipecac unless supervised by a
physician. Their gag reflex is poorly developed and emetic may
cause choking with aspiration.
* Methods:
1- Mechanical: Done by touching the back of the oropharynx
by the index finger or handle of a spoon. This may be
difficult in children and the uncooperative patients.
2- Drugs:
1- Syrup of Ipecac: This is the drug of first choice for emesis as
it can be administrated at home thus cutting short time before
evacuation the contents of the stomach. Active constituents
(emetine and cephaline).
Action: its action occurs through an early and late phase.
Early: Local irritation of gastro-intestinal tract within 30
minutes.
Late: After 30 minutes due to direct stimulation of the
chemoreceptor trigger zone hence the second dose should be
given only after 20-30 minutes.
Dose: 30 ml for adults, 20 ml for children 5-12 years, 15 ml
for children 1-5 Years, 10 ml for children less than 1 year to 6
months.
Procedures:
1- Give the appropriate dose of the syrup according to the age,
then after 10-15 minutes give 2-3 glasses of water.
2- Wait for 20-30 minutes, if no emesis occurs repeat the step
number one and ask the patient to sit up and if able let him
walk around.
3- If no vomiting occurs do not repeat the dose and do gastric
lavage.
Adverse effects: These are rare:
1- Persistent vomiting these delaying the administration of
activated charcoal.
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2- Protracted forcible vomiting may result in hemorrhagic
gastritis.
3- Drowsiness, tremors, convulsions, muscle weakness and
diarrhea.
4- If the dose is repeated may get cardiac arrhythmia.
2- Soap solution: Soapy water solution may be used as an
alternate emetic. Use only slandered Dish washing liquid or
lotion soap 2 tablespoons in a glass of water. Do not use
powdered laundry or dishwasher detergent or liquid dish
washing concentrate as these products are corrosives. There
is no other accepted safe alternative to the syrup of ipecac.
3- Apomorphine: Dose: 5 mg subcutaneously. It is morphine
derivative that produces quick emetic action within 1-3
minutes through direct central action by stimulation of the
central trigger zone.
Advantages:
1- Its action is reliable and more effective than syrup Ipecac.
2- It can be used along with orally administered activated
charcoal, whereas syrup of ipecac should be given at least 30
min before activated charcol.
* Disadvantages:
1- It must be freshly prepared as it is unstable in solution.
2- It must be given by injection.
3- It is not readily available and it should only be administered
by qualified medical personnel.
Adverse effects: include CNS depression, respiratory
depression, and hypotension. Apomorphine should be avoided
with ingested poisons which produce CNS depression.
To overcome the effect of protracted emetic action,
respiratory depression, and sedative properties, some physicians
administrate a narcotic antagonist, such as naloxone, shortly
following onset of emesis.
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Gastric Lavage
Gastric lavage is a process of washing out the stomach with
solutions, including water, sodium bicarbonate, calcium salts,
tannic acid. Lavage is indicated when poisons must be quickly
removed from the stomach or when emesis is contraindicated.
The patient is placed on the left side to permit pooling of
gastric contents and to reduce the risk of aspiration and the
chance of gastric emptying. Also, the patient’s head should be
lower than the rest of the body, the largest diameter tube should
be used.
Indications:
* Semiconscious.
* Unconscious child or adult.
* Loss of gag reflex.
* Ipecac induced emesis is infective or contraindicated.
Lavage is usually begun using tap water or normal saline.
Saline is recommended in children to prevent electrolyte
imbalance. aliquots of 50 to 100 ml in children and 200 to 300
ml in adults should be instilled and recovered. Generally, 5 liters
are required to clean the stomach.
Lavage is not always a procedure of the first choice for
removing ingested poisons and ‘may be associated with
numerous risks.
Risk:
* The tube may be accidentally inserted into the trachea.
* Improperly used, lavage can incite a greater risk of aspiration
of solution.
*Aspiration pneumonia secondary to emesis with unprotected
airway.
*Laryngospasm with cyanosis.
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* The tube may cause perforation of the stomach or hasten its
emptying time into the intestine.
If a cool lavaging solution is used too rapidly, the body
temperature may be lowered.
Adsorbents
Activated charcoal
It is a highly adsorbent and harmless material made from
distillate of wood pulp. It is the best in management of mild
ingestions.
Mechanism of action: Activated charcoal reduces
absorption in the stomach and intestine. Poison diffuse through
the numerous pores on the charcoal surface and from tight
chemical bonds. This charcoal-chemical complex then passes
out of the body.
Indications: All poisons except:
1- Alkali
2- Cyanide
3-D.D.T.
4- Iron salts
5-Malathion
6- Water-insoluble compounds.
Contralndications:
1- Absence of the bowel sounds
2- Intestional obstruction.
Adverse effects:
1. Constipation, can be prevented if given with cathartics.
2- Distention of the stomach with potential risk of pulmonary
aspiration.
3. Many new products add sorbitol to the mixture so repeated
doses may lead to excessive diarrhea, dehydration in children
and elderly.
Time Interval: For maximal effect, it should be administered
within 30 minutes of the poison except in:
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a- Drugs that slow the gastric emptying, sedative, etc. Here
charcoal can be given up to 6-8 hours following poison
ingestion.
b- Following salicylate ingestion, can be given 9-10 hours
later, as it sticks to gastric mucous membrane
c- Drugs that have enterohepatic circulation.
Dose: Generally speaking it should be in ratio of 10: I by weight
charcoal to drug if the amount of drug is known.
Recommended doses are 50-60 g. (1 g per kg) that might be
increased to 100-120 g. for adults 15-30 g. for childern.
Administration: Activated charcoal !s unsightly and readily
adsorbs materials from air water when mixed and allowed to
stand, so about 250 ml. water are added to the powder then
vigorously shaken to form a slurry or soup then it is
administered directly from a slurry or soup then it is
administered directly from the container. One or two repeated
doses may be given at 2 hours interval to ensure adequate gut
decontamination.
Drawbacks:
a- The substance leaves a grtiy sensation in the mouth.
b- Discolours the gums, mouth, and sticks to the throat.
Cautions: It should not be given within 30 minutes of syrup
of Ipecac unless the patient has already vomited.
If both have to be given, ipecac should precede charcoal
because emetine and cephaline (comprising 90% of the active
emetic alkaloidal content) are adsorbed on to the activated
charcoal hence inhibiting their action. Apomorphine can be
combined with it if immediate emetic action is needed.
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Cathartics
Saline cathartics are preferred when catharsis is desired to
remove toxic substances from the GI tract.
Common used cathartics and recommended dose
Cathartic
Dose
Child
adult
Magnesium sulifate
250mg/kg
5-10 g.
Magnesium citrate
4 ml/kg
300 ml.
Sodium sulfate
250 mg/kg
150 g.
Sorbitol
1.5g/kg
1.5g/kg
Catharsis should not be attempted when the poison is
strongly corrosive, the patient has electrolyte distubance or
bowel sounds are absent. A side from a few exceptions,
including castor oil for phenol intoxication and mineral oil for
fat-soluble vitamin overdoses, no other stimulant or lubricant
cathartic should be recommended. Additionally, magnesiumcontaining cathartics should not be given to persons with
compromised renal function because of the possibility of
causing CNS depression due to accumulation of high
concentrations of magnesium in the serum. Sodium contalning
cathartics are, likewise, best avoided by persons with congestive
heart failure.
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B- Topical decontamination
I- Skin decontamination:
There are certain rules that should be followed here:
a- Rapid decontamination is needed specially if the poison is
a corrosive or is easily absorbed from the skin.
b- Care should be taken when handling patients, clothes or
any article which is contaminated to avoid any hazard to
any person handling the patients, so, protective gloves and
glasses should be worn.
c- Rapid removal of contaminated clothes after their being
flushed with water.
* Methods of decontamination:
1- Wash contaminated areas as well as exposed areas with warm
water or saline not forgetting careful washing of the skin,
behind ears, under nails, and skin folds.
2- Topical agents for chemical exposure could be used e.g.:
Phenol: Can apply olive oil any oil.
Phosphorus: use 2 % copper sulphate solution.
Oxalic acid: Soak the affected area with solution of calcium
gluconate.
Organophosphonis: soap water.
3- No creams, ointments, or occlusive bandages should be
placed over the contaminated area. These will
II- Eye decontamination: The more quick the decontamination
the better the results as the eye is a very sensitive organ
specially the cornea. Usually the eye is affected by a
corrosive so, the first aime is to applay anesthetic drops if
present e.g. Cocaine HCI (Xylocaine).
This will help easy irrigation of the eyes which should be
with large amounts of water. This is done either by placing the
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patient in supine position under the tap water or If at hospital
use an intravenous tube in order to direct a continuous stream of
water from nasal bridge to the medial aspect of the eye. Amount
used at least one liter. Irrigation should continue until pH of
tears returns to normal. After first aid treatment the patient
should be referred to an ophthalmologist .
2- Methods to increase elimination of toxic agents.
a-Forced diuresis.
Forced diuresis is employed to help remove chemicals from
the blood. It is useful when compounds or active metabolites are
eliminated by the kidney and diuresis enhance excretion. The
procedure is based on increasing the volume of flow of uiine
tough the renal tubules so that the chemical may be more
quickly eliminated. The objective is to maintain a urine output
of 300 to 500 mI/hr. Manitol increases urinary output through
Osmotic attraction. Furosemide reduces the reabsorption in the
descending limb of Henle’s loop.
Forced diuesis is beneficial for some but not all chemicals.
Chemicals which are not normally reabsorbed by the kidney will
not be significantly lowered in concentration with forced
diuresis.
Examples of substances removed by forced diuresis:
Amphetamine, alcohol, aniline, barbiturates (long acting),
Bromide, ethylene glycol, isoniaside, Lithium, penecillin,
Quindine, salicylates, strychnine and sulfonamides.
Examples of substances not removed by forced diuresis:
Acetoaminophen, barbiturates (short and medium acting),
glutethimide, phenothiazine, tricycic antidepressents.
At best, forced diuresis may increase excretion of a
chemical twofold. A better procedure is to couple this with
acidification or alkalinization of the urine so that ion-trapping is
greater. Ascorbic acid or ammonium chloride will acidify urine
and sodium bicarbonate accomplishes alkinization.
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Dialysis and Hemoperfusion
The following procedures are limited in use. However, they
are being employed more frequently as adjuncts to management
of severely intoxicated patients.
Dialysis and hemoperfusion should never replace more
specific antidotes.
They would not be necessary for a patient with an acute
opioid overdose because of the availability of the specific
antidote. naloxone.
These procedures would be of little value in treating acute
ingestions of cylotoxic poisons such as cyanide which produce
toxic effects very rapidly, often within minutes. Dialysis is
governed by the laws of osmosis. A diffusible chemical
dissolved in water partitions across a semipermeable membrane
and the solution moves from an area of higher concentration (i.e,
the blood) to one of lower concentration (i.e., a dialyzing
solution).
* Peritoneal dialysis
Peritoneal dialysis is the most easily performed method, and
is associated with the lowest risk for causing complications.
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The procedure is undertaken by inserting a tube through a
small incision made in the mid-abdomen area into peritoneum.
The peritoneal membrane serves as the semipermeab1e
(dialyzing) membrane. In this way, the dialyzable chemical
diffuses from the blood across the peritoneal membrane into the
dialyzing fluid (moves from an area of larger to lower
concentration). A warmed dialyzing solution (up to 2 L for
adults and 1 L for children) is introduced into the peritoneal
cavity over a period of 15 to 20min. The fluid is left in place for
45 to 60 min for equilibration to occur, then removed. A fresh
solution is reintroduced and the process repeated. Up to 30 L.or
more of dialysis fluid may be used.
Composition of dialysis solution:
The dialysis solution of the fluid normally consists of a
balanced electrolyte solution. The osmotic pressure of the fluid
is maintained above that of the fluid with dextrose. By making
the dialysis fluid hypertonic, there should be an increased
recovery of water soluble chemicals.
For chemicals that are highly protein-bound, addition of
albumin to the dialyzing solution may be helpful to increase
recovery.
The dialysis solution may also be modified by adjusting pH.
For example, in acute phenobarbital ingestion, using an alkline
solution may considerably increase total drug recovery.
Some dialysis procedures use lipids such as peanut oil to
attract chemicals such as glutathmide that are highly lipidsoluble.
In general. peritoneal dialysis is 5 to 10 times less efficient
than hemodialysis. it is not the procedure of choice when rapid
removal of toxic substances is needed. On the other hand,
pentoneal dialysis does not require elaborate equipment and
need little medical supervision. It seems to be more generally
applicable for acute ingestions in children, because of their large
peritoneal surface area in relation to body size. Also a child’s
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abdominal wall is much easier to penetrate than trying to isolate
an appropriate vein in a small arm.
Complication of peritoneal dialysis include:
abdominal pain; intraperitoneal bleeding; intestinal, bladder,
liver, or spleen perforation; peritonitis ; water and electrolyte
imbalance; and protein loss.
Hemodialysis:
The same basic principles apply to hemodialysis for
peritoneal dialysis an in vivo (peritoneal) membrane is utilized,
whereas in hemodialysis,. a cellophane bag (ailificial kidney)
forms a semipermeable membrane.
Two catheters are inserted into the patient’s femoral vein,
about 2 inches apart. Blood is pumped from one catheter
through the dialysis unit, across the semipermeable membrane,
and returned through the other catheter. The procedure is usually
continued for 6-8 hr. The solublized chemical diffuses across the
semipermeable membrane into the dialysis solution. Clearance
of the toxic agent is based on the differences in osmotic and
concentration gradients.
The chemicals which can removed by hemodialysis:
must have low molecular weight and small molecular size to
passively diffuse across the dialyzing membrane. Hemodialysis
is less effective for drugs that are highly protein-bound.
Complications - include clotting, hvpotension, convulsions,
arrhythmia, infection, sod hematologic defect.
Hemperfusion
Hemperfusion is significantly more effective than peritoneal
dialysis and hemodialysis for removing intoxicating compounds.
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Particularly those which arc lipid- soluble or protein bound, or
those which for other reason are poorly dialyzable.
The ability of activated charcoal to adsorb toxic substances
has been recognized for many years. Numerous analytical
procedures have used anion exchange resins. Regardless of the
type of adsorbent used, blood is withdrawn via an artriovenous
or venovenous shunt and passed directly over the adsorbing
material contained in sterile columns. The procedure is a simple
one, and column are commercially available.
Primary complications include trapping of white blood cells
and platelets and microembolization. These problems have been
largely eliminated with newer systems.
Common
poisonous
substances
removed
by
hemoperfusion:
Barbiturates,
sedatives,
analgesics.
Antidepressents, Alcohols and digoxin and procainamide.
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