Toxicology
Introduction

Toxicology is a science dealing with properties, action,
toxicity, fatal dose, detection, estimation and treatment
of poisons.

Toxinology refers to toxins produced by living organism
which are dangerous to man. Like poisonous plant,
venom of snake, spider, scorpion.
Contd…….

Poison is a substance, which if introduced in living
body, or brought in contact with any part through, will
produce ill health or death, by its constitutional or local
effects or both.

Some poison are harmless in small quantity but
produce death if large quantity is used.
Classification of poison according to
symptoms they produces( mode of action)
A. Corrosive:1. Strong acids :- sulphuric acid, nitric acid,
hydrochloric acid, acetic acid, carbolic acid,
oxalic acid, salicylic acid.
2. Strong alkalis :- sodium hydroxide or caustic
soda, potassium hydrochloride, ammonium
hydrochloride.
3. Metallic salts :- zinc chloride, potassium
cyanide, ferric chloride, chromates of alkalis,
bichromates of alkalis , Mercuric chloride etc
Contd…..
B. Irritants :1. Inorganic:a. Non-metallic:- phosphorus, halogen.
b. Metallic:- arsenic, antimony, mercury,
copper, lead, zinc, silver.
2. Organic:a. Vegetables:- castor oil, cotton oil.
b. Animals:- snake venom, insect bites.
c. Mechanical:- glass powdered, diamond dust.
Contd…..
C. Systemic:1. Cerebral:a. CNS depressants:- alcohols, general
anesthetics, opioid analgesic, hypnotics,
sedatives.
b. CNS stimulants:- cyclic antidepressants,
amphetamine.
c. Deliriant:- Dhatura, belladonna, cannabis,
cocaine.
2. Spinal:- nux vomica (strychnine), gelsemium.
3. Peripheral:- conium, curare.
3. Peripheral:- conium, curare.
4. Cardiovascular:- aconite, quinine,
tobacco , HCN, oleander, nicotine etc
5. Nephrotoxic : Oxalic acid, mercury,
cantharides.
6. Hepatotoxic: Phosphorous, carbon,
tetrachloride, chloroform
Contd……..
D. Miscellaneous :1. Insecticides:a. Organ phosphorus compounds:i. Alkyl phosphates:Hexaethyl tetra phosphate (HETP),
Tetraethyl pyrophosphate (TEPP),
Octamethyl pyro-phosphoramide (OMPA)
ii. Aryl phosphates:- parathion, diazinon.
b. Chlorinated hydrocarbons:- endrine, D.D.T. and
gamaxin.
2. Antihistamines
3. Food poisons:- Cl. Botulism, Mushroom poisoning.
Route of administration of poison:1.
2.
3.
4.
5.
Inhalation in gaseous or vapor form.
Injection into blood vessels(IV)
Intramuscular, subcutaneous and intradermal injection.
Application to a wound(Ulcer)
Introduction like oral, nasal, rectal, urethral, vaginal.
Route of elimination of poison:1.
2.
3.
4.
Kidney
Skin
Bile, milk, saliva, mucous and serous secretion.
Unabsorbed portion by vomit and faeces.
Factors modifying the action of poison
1.Quanity:- Greater the quantity more severe would be
symptoms of poison and usually rapid would be fatal.
2. Form of poison:- The action of poison is influences by
the form in which it is administered.
a. Physical state:- gas, liquid or solid.
b. Chemical combination:- for e.g. arsenic is not
poisonous but its salt arsenious oxide is poisonous.
c. Mechanical combination:- for e.g. small dose of
concentrated mineral acid produces corrosive action
but same dose largely diluted with water is harmless.
3. Mode of administration:- The rapidity of action of a
poison depends upon the route of administration, rate
of absorption and the mode in which it is introduce into
the system. The route of administration may be
enumerated as follows in order of rapidity of action:a. Inhalation
b. Intravenous
c. Intramuscular, subcutaneous, intradermal,rectal
d. Oral
4. Condition of body:a. Age:
b. Habit:- action of certain poison decrease with
habituate. An addict can tolerate larger dose than a
non addict. Like alcohol, morphine.
Antidotes
These are the substances which prevent or neutralize or
counteract the action of poison.
Reasons of use of antidotes:1. The poison may not be completely removed by gastric
lavage or the procedure is contraindicated.
2. The poison is already absorbed.
3. The poison has been administered other than ingestion.
Classification of antidotes:1. Mechanical antidotes or physical antidote.
2. Chemical antidotes
3. Physiological or pharmacological antidotes
4. Serological antidote
1. Mechanical antidotes:- acts by preventing absorption
of poisons.
a. Activated charcoal
b. Demulcents:- egg albumin, fats, oil.
2. Chemical antidotes:-they counteract the action of
poison by forming harmless compound, when
brought in contact with them.
a. Sodium sulphate for lead poisoning
b. Copper sulphate for phosphorus poisoning.
c. Ferric oxide for arsenic poisoning.
d. KMNO4 for Opium and OPC
3. Physiological antidotes:- these are the agents
which act on the tissue of the body and produce
symptoms exactly opposite to those caused by
poisons. E.g.:
a) Atropine, Pralidoxime for OPC
b) Paracetamol poisoning: N-acetyl cystine
c) Opioids poisoning: Naloxone
d) Dhatura Poisoning: Neostigmine.
e) Strychnine Poisoning: Barbiturates.
4. Serological antidote: Anti-snake venom
Universal antidotes:- it is an antidotes that is used in
those cases where the nature of the ingested poison in
not known.
It has following composition:
Activated powder charcoal or burnt toast---2 parts (absorbent)
Magnesium oxide---1 part 9neutralises if poison is acid)
Tannic acid or strong tea----1 part( precipitates alkalis)
Stomach wash/gastric lavage by Boas or Ewald’s tube
Chelating agent:These are soluble organic compound which fix metallic
ions into their molecular form and make them inactivate.
They form chelate with metallic poisons those are freely
available in the circulation and their early excretion from
the body through kidney.e.g.:1. EDTA(ethylene diamine tetra acetic acid):-for lead.
2. Desferrioxamine:-for acute and chronic iron poisoning.
3. Bemigride:- barbiturate poisoning
4. Nalorphine:- morphine, heroine poisoning.
5. Penicillamine (Cuprimine): Free metals
6. Dimercaprol: For arsenic, mercury, copper, bismuth,
gold.
Principle of management of poisoning

The following principle should be followed in case of
poisoning:-
1. Removal of unabsorbed poison from the body:a. If inhaled:-take pt. to fresh air. Give oxygen and
artificial respiration if necessary.
b. If bitten or injected:- immediately apply tight band
above the wound. Release in every 10 minutes for
20-30 second to prevent gangrene.
c. If local application:- it should be washing with water.
d. If ingested:- stomach wash/ gastric lavage within 3 hr.
2. Administration of antidotes
3. Prevention of absorption into the system:- by
a. Renal excretion can be improved by plenty of fluid,
diuretics.
b. Increasing diaphoresis ( Perspiration) using
neostigmine, pilocarpine
c. By dialysis.
d. By chelating agents
4. Treatment of general symptoms:Pain, shock, peripheral circulatory collapse, electrolyte
imbalance.
Initial Management of the
poisoned patient (ABCD’s)
•
•
•
•
First, the airway should be cleared of vomitus or any
other obstruction and an oral airway or endotracheal
tube inserted if needed.
Breathing should be assessed by observation and
oximetry and, if in doubt by measuring arterial blood
gases patients with respiratory insufficiency should be
intubated and mechanically ventilated
Circulation should be assessed by continuous
monitoring of pulse rate, blood pressure , urinary
output. An intravenous line should be placed and
blood drawn fro serum glucose and other routine
determinations
Dextrose to treat hypoglycemia (0.5gm/kg)
History & Physical Exam
 Lab




and Imaging procedures:
Arterial Blood Gases
Electrolytes: Sodium, Potassium, Chloride,
Bicarbonate
Renal Function Tests: Blood Urea,
Creatinine
Electrocardiogram
Decontamination
 Decontamination
procedure should be
undertaken simultaneously with initial
stabilization, diagnostic assessment and
lab evaluation
 Decontamination involves removing
toxins from the skin or GIT
A) Skin
 Contaminated
clothing should be
completely removed and double bagged
to prevent illness in health care providers
and for possible lab analysis
 Wash contaminated skin with soap and
water
B) GIT
Emesis: Emptying of stomach in conscious children
1.
–
Syrup: Ipecac (6-12 months 10 ml single dose and >1
yr 15 ml) *repeated in 20 mins for those more than 1 yr.
Gastric Lavage:
2.
–
0.9% saline , Left Lateral position
Activated Charcoal
Catharsis: Laxative and purgatives
3.
4.
–
–
Mannitol (1-2 gm/kg)
Magnesium or sodium sulfate (200-300 mg/kg)
* Specific Antidotes*
 CONTRAINDICATION
OF GASTRIC
LAVAGE:
1. Very old patients with esophageal
varices.
2. Poisoning with corrosives: danger of
perforation of stomach.
3. Convulsant poisons: attempt of using
tube may lead to convulsions
4. Comatosed patients : risk for aspiration
CONTRAINDICATION OF
EMESIS
 Corrosives
and volatile poisons.
 Comatose patients.
 Heart disease patients.
 Pregnant women.
 Kerosene : may cause aspiration
pneumonia.