General principles in treatment of common drug poisoining

General Principles In
Treatment of Poisoning &
Management of Common drug
poisoning
Dr.Vinay Bajaj
JR1
Dept of Pharmacology

Overview
• Introduction
• General principles in Rx of poisoning
• Management of common drug poisoning
 Paracetamol
 Salicylates
 Organophosphates
 Barbiturates
 Atropine
 Iron
 Morphine
• Summary
General Principles in Rx of Poisoning & common drug poisoning
2

Introduction
 Poison:
Substance which when administered,inhaled or
ingested,is capable of acting deleteriously on human
body
 Thus,Almost anything is a poison
 Medicine in a toxic dose= Poison
 Poison in a small dose=Medicine
General Principles in Rx of Poisoning &
common drug poisoning
3
In law,real difference between a medicine & poison
is the intent with which it is given

General Principles In
Rx of Poisoning

Outline
1.Stabilization
2.Evaluation
3.Decontamination
4.Poison elimination
5.Antidote administration
6.Nursing & psychiatric care

Stabilization
• Initial survey should always be directed at
assessment & correction of life threatening
problems,if present
• Attention must be paid to the airway, breathing,
circulation, and depression of the CNS (the ABCD of
resuscitation)

Airway & Breathing
 Symptoms of airway obstruction:
Dyspnoea, air hunger, & hoarseness
 Signs : stridor, intercostal & substernal retractions,
cyanosis, sweating, and tachypnoea
 Increasing metabolic acidosis in the presence of a
normal PaO2 suggests a toxin or condition that either
1.Decreases oxygen carrying capacity (e.g. carbon
monoxide) OR
2.Reduces tissue oxygen (e.g. cyanide)

Assisted ventilation
Indications:
The immediate need for assisted ventilation has to be
assessed clinically, but the efficiency of ventilation
can only be gauged by measuring the blood gases
 Retention of carbon dioxide (PaCO2 > 45 mmHg)
 hypoxia (PaO2 < 70 mmHg) inspite of oxygen being
given by a face mask

9
Toxic respiratory depression

Circulatory failure
Management:
■ Correct acidaemia, if present
■ Elevate foot end of the bed (Trendelenberg position)
■ Insert a large bore peripheral IV line (16 gauge or
larger) & administer a fluid challenge of 200 ml of
saline. Observe for improvement in blood pressure
over 10 minutes. Repeat the fluid bolus if BP fails to
normalise and assess for signs of fluid overload.
10

■ In patients, who do not respond to initial fluid
challenges,monitor central venous pressure and hourly
urinary output
■ Vasopressors of choice include dopamine &
norepinephrine
■ Obtain an ECG in hypotensive patients and note rate,
rhythm, arrhythmias, and conduction delays

Cardiac arrhythmias
 Lignocaine & amiodarone are generally first line
agents for stable monomorphic ventricular
tachycardia, particularly in pts with underlying
impaired cardiac function
 Unstable rhythms require cardioversion
 Atropine may be used when severe bradycardia is
present

13
Drugs/Toxins induced arrhythmias

CNS Depression
This is generally defined as an unarousable lack of
awareness with a rating of less than 8 on Glasgow
Coma Scale
Management:
Till recently it was recommended that in every case
where the identity of the poison was not known, the
following three antidotes (called the Coma Cocktail)
must be administered (IV):
■ Dextrose—100 ml of 50% solution
■ Thiamine (Vitamin B1)—100 mg
■ Naloxone—2 mg
14

 There is an increasing dissatisfaction among
toxicologists with regard to the true benefits of the
coma cocktail, and the view is gaining ground that it
has no place in practice
 All patients with depressed mental status should
receive 100% oxygen in a mask (high flow—8 to 10
litres/min).

Evaluation
In all those poisoned patients where there appears to
be no immediate crisis, a detailed & thorough clinical
examination should be made with special reference to
the detection & treatment of any of the following
abnormalities :
 Hypothermia
 Hyperthermia
 Acid-base disorders
 Convulsions
 Electrolyte disturbances

Decontamination
 This is with reference to skin/eye decontamination,
gut evacuation and administration of activated
charcoal
 EYE
Irrigate copiously for at least 15 to 20 minutes with
normal saline or water. Do not use acid or alkaline
solutions.

Skin
Cutaneous absorption is a common occurrence especially
with reference to industrial and agricultural substances
such as phenol, hydrocyanic acid, aniline, organic metallic
compounds,phosphorus, & most of the pesticides
 The following measures can be undertaken to minimise
absorption :
 Corroded areas should be irrigated copiously with water or
saline for at least 15 minutes
 Remove all contaminated clothes or cover with clean
bedsheet

GUT
The various methods of poison removal from the
gastrointestinal tract include:
Emesis■
Gastric lavage■
Catharsis■
Activated charcoal■
Whole bowel irrigation.■

Emesis
 The only recommended method of inducing a poisoned
patient to vomit is administration of syrup of ipecac
In recent years owing to doubts being raised as to
its actual efficacy and safety. The current consensus is
that syrup of ipecac must NOT be used, except in
justifiable circumstances
 Indications: Conscious and alert poisoned patient who has
ingested a poison not more than 4 to 6 hours earlier

Gastric lavage
 Gastric lavage should not be employed routinely in the
management of poisoned patients. There is no certain
evidence that its use improves outcome, while the
fact that it can cause significant morbidity is
indisputable.
 Lavage should be considered only if a patient has
ingested a life-threatening amount of a poison and
presents to the hospital within 1 to 2 hours of
ingestion.

22
Solutions for gastric lavage

Catharsis
• It means purification
• Achieved by purging the gastrointestinal tract (particularly the
bowel)
• Recommended saline cathartics are Magnesium citrate,
Magnesium sulfate, Sodium sulfate
• In saccharides, Sorbitol (D-glucitol) is the cathartic of choice in
adults because of better efficacy than saline cathartics

Activated charcoal
• A number of studies have documented clearly the efficacy
of activated charcoal as the sole decontamination measure
in ingested poisoning
• Decreases the absorption of various poisons by adsorbing
them on to its surface
• Contraindications—
Absent bowel sounds or proven ileus

25
Adsorption of toxins to activated charcoal

Whole bowel irrigation (Whole Gut lavage)
• Increasingly recommended for late presenting
overdoses when several hours have elapsed since
ingestion
• It involves the instillation of large volumes of a
suitable solution into the stomach in a nasogastric
tube over a period of 2 to 6 hours producing
voluminous diarrhoea
• Previously,saline was recommended for the procedure
but it resulted in electrolyte and fluid imbalance.
26

 Today, special solutions are used such as
1.PEG-ELS ( i.e. polyethylene glycol and electrolytes
lavage solution combined together, which is an
isosmolar electrolyte solution) &
2. PEG-3350 (high molecular weight
polyethylene glycol)
 These are safe and efficacious, without
producing any significant changes in serum
electrolytes, serum osmolality, body weight, or
haematocrit.

Elimination
The various methods of eliminating absorbed poisons from
the body include the following:
 Forced Diuresis
 Extracorporeal techniques
Haemodialysis
Haemoperfusion
Peritoneal dialysis
Haemofiltration
Plasmapheresis
Plasma perfusion

Antidote administration
• In majority of cases of acute poisoning, all that is
required is intensive supportive therapy
• Specific antidotes are rarely necessary, besides the
fact that only a few genuine antidotes exist in actual
practice, though there is no denying to the results
that can be achieved with some of them in
appropriate circumstances

Management of
Common drug poisoning

Paracetamol
Clinical features:
1.Acute Poisoning:
a. Stage I (1/2 hr to 24 hrs): Anorexia, vomiting,
sweating,malaise
b. Stage II (24 to 72 hrs): Relatively symptom-free.
There may be right upper quadrant pain. Liver
function tests may be abnormal.
c. Stage III (72 to 96 hrs): Hepatic necrosis sets in
with coagulation defects, jaundice, & encephalopathy.
Renal failure & myocardial damage are frequently
present.

d. Stage IV (4 days to 2 wks): If the patient survives
the IIIrd stage, complete resolution of hepatic
damage is the rule
2. Chronic Poisoning:
This is uncommon, but cases have been reported
where-in an individual has consumed large doses of
paracetamol over a period of time for relief of
chronic pain which resulted in toxic hepatitis.

Treatment
 Children who have an unobtainable history or in
whom a large amount of paracetamol is suspected to
have been ingested (>200mg/kg) should be referred
to a health care facility for a 4-hour paracetamol
serum level determination
 Stomach wash: useful only in cases of very early
presentation (<1 hour)
 Activated charcoal can adsorb paracetamol, but it
can also adsorb the antidote (N-acetylcysteine) &
hence must be administered earlier to 4 hours post-
ingestion

 Supportive measures:
a. 10 to 20% dextrose for hypoglycaemia.
b. Vitamin K if PT is elevated.
c. Fresh-frozen plasma if there is overt bleeding.
d. Mannitol (0.5 gm/kg given over 10 minutes) for
cerebral oedema.
e. H2 antagonists to prevent upper GI haemorrhage.
Do not give sedatives, benzodiazepines, or NSAIDs.

 Antidote therapy
N-acetylcysteine (NAC): gives maximum protection
against hepatotoxicity when administered within 10
hours of paracetamol overdose, but can be given with
(lesser) benefit upto 36 hours
Indications
1. Paracetamol ingested is more than 100 mg/kg.
2. Likelihood exists of paracetamol-induced
hepatic failure

Salicylates
Acute Poisoning:
a. Early : Nausea, vomiting, sweating,tinnitus, vertigo &
hyperventilation due to respiratory alkalosis.
disorientation,hyperactivity, slurred speech, ataxia,
and restlessness may be early findings in patients
with severe toxicity
b. Late—Deafness, hyperactivity, agitation, delirium,
convulsions, hallucinations, hyperpyrexia. Coma is
unusual
c. Complications—Metabolic acidosis, pulmonary
oedema, rhabdomyolysis, cardiac depression,
thrombocytopenic purpura

2. Chronic Poisoning (Salicylism):
 This is characterised by slow onset of confusion,
agitation, lethargy, disorientation, slurred speech,
hallucinations, convulsions, and coma
 Sometimes “salicylism” presents as pseudosepsis
syndrome characterised by fever, leukocytosis,
hypotension, and multi-organ system failure: ARDS,
acute renal failure and coagulopathy (DIC)

 Salicylates must not be therapeutically administered
to children under 15 years of age, especially if they
are suffering from chicken pox or influenza. There is
a serious risk of precipitating Reye’s syndrome which
can be fatal
 Main feature: onset of hepatic failure &
encephalopathy

Treatment
• Patients with major signs or symptoms (metabolic
acidosis,dehydration, mental status changes, seizures,
pulmonary oedema) should be admitted to the
Intensive Care Unit regardless of serum salicylate
level
• Minor symptoms only (i.e. nausea, tinnitus) following
acute overdose may be managed in the emergency
department with decontamination and alkaline
diuresis if the salicylate level is shown to be declining

• Stomach wash may be beneficial upto 12 hours after
ingestion, since toxic doses of salicylates often cause
pylorospasm and delayed gastric emptying.
• Activated charcoal (AC): It is said to be very
efficacious in the treatment of salicylate poisoning
since each gram of AC can adsorb 550 mg of the
drug. A 10:1 ratio of AC to salicylate ingested appears
to result in maximum efficiency.
The initial dose of AC can be combined with a
cathartic to enhance elimination.

• Urinary alkalinisation:Alkalinisation of both blood and
urine can be achieved with I.V sodium bicarbonate
• Haemodialysis: It is very effective in salicylate
poisoning & must always be considered in the
presence of cardiac or renal failure, intractable
acidosis, convulsions, severe fluid imbalance, or a
serum salicylate level more than 100 mg/100 ml.
• Supportive measures: Correction of fluid
overload,dehydration,metabolic acidosis,convulsions
etc

OP Poisoning
1. Acute Poisoning:
a. Cholinergic Excess:
• Muscarinic effects: bronchoconstriction with
wheezing and dyspnoea,cough, pulmonary oedema,
vomiting, diarrhoea,abdominal cramps, increased
salivation, lacrimation, sweating, bradycardia,
hypotension,miosis, & urinary incontinence
• Nicotinic effects: Muscle weakness, fatiguability,
and fasciculations are very common.

b. CNS Effects—Restlessness, headache, tremor,
drowsiness, delirium, slurred speech, ataxia &
convulsions.Coma supervenes in the later stages
 Death usually results from respiratory failure due to
weakness of respiratory muscles, as well as
depression of central respiratory drive.
 Chronic Poisoning:
Those who are engaged in pesticide spraying of crops.
The following are the main features—
a. Polyneuropathy: paraesthesias, muscle cramps,
weakness, gait disorders.
b. CNS Effects : drowsiness, confusion, irritability,
anxiety

1. Acute Poisoning:
a. Decontamination:
 If skin spillage has occurred, it is imperative that
the patient should be undressed & washed thoroughly
with soap & water
 If ocular exposure has occurred, copious eye
irrigation should be done with normal saline or
Ringer’s solution. If these are not immediately
available, tap water can be used
Treatment

b. Antidotes:
 Atropine—It is a competitive antagonist of
acetylcholine at the muscarinic postsynaptic
membrane & in the CNS & blocks the muscarinic
manifestations of organophosphate poisoning
 Oximes—The commonest is pralidoxime, which is a
nucleophilic oxime that helps to regenerate
acetylcholinesterase at muscarinic, nicotinic, & CNS
sites

c. Supportive Measures:
 Administer IV fluids to replace losses
 Maintain airway patency and oxygenation. Suction
secretions. Endotracheal intubation and mechanical
ventilation may be necessary. Monitor pulse oximetry
or arterial blood gases to determine need for
supplemental oxygen
 The following drugs are contraindicated:
parasympathomimetics, phenothiazines,
antihistamines

Barbiturates
 Poisoning is mostly suicidal,rarely accidental
 Characterized by respiratory failure,cardiovascular
collapse,coma & renal failure
 Treatment : Gastric lavage,artificial respiration &
forced alkaline diuresis with mannitol & sodium
bicarbonate

Atropine
• Belladonna poisoning may occur due to drug
overdose or consumption of seeds & berries of
belladonna/datura plant
• Dry mouth, difficulty in swallowing & talking
Dilated pupil, photophobia, blurring of near vision,
palpitation, psychotic behaviour, ataxia, delirium,
visual hallucinations,Hypotension, weak & rapid pulse,
cardiovascular collapse with respiratory depression
• Convulsions & coma occur only in severe poisoning

Treatment
• If poison has been ingested, gastric lavage should be
done with tannic acid
• The patient should be kept in a dark quiet room. Cold
sponging or ice bags are applied to reduce body
temperature. Physostigmine 1–3 mg s.c. or i.v.
antagonises both central & peripheral effects

Iron
• Has a direct corrosive action on the stomach &
proximal small bowel
• Once absorbed, produces shock, metabolic acidosis,
liver failure& death
• Initially, GI symptoms prevail with persistent
vomiting, abdominal pain& hemorrhage
• A quiescent phase may be observed, followed by
shock, coma, metabolic acidosis& liver failure

Treatment
• Management of iron poisoning includes gastric lavage
with normal saline
• The treatment of choice is the antidote
desferrioxamine, which chelates free serum iron in
the plasma to form ferrioxamine
• Indications :
 All critical patients who present with coma, shock, or
hemorrhage
 All patients with a serum iron level higher than 500
mg/dL
 Patients who are symptomatic with a serum iron > 300
mg/dL General Principles in Rx of Poisoning &
53

Morphine
• It may be accidental, suicidal or seen in drug abusers.
The human lethal dose is estimated to be about 250
mg
• Stupor or coma, flaccidity, shallow & occasional
breathing, cyanosis, pinpoint pupil,fall in BP & shock;
convulsions may be seen in few, pulmonary edema
occurs at terminal stages, death is due to respiratory
failure
54

Treatment
• Consists of respiratory support & maintenance of BP
(i.v.fluids, vasoconstrictors)
• Gastric lavage should be done with pot. permanganate
to remove unabsorbed drug
• Specific antidote: Naloxone 0.4–0.8 mg i.v.
repeated every 2–3 min till respiration picks up,
is the specific antagonist of choice
 Due to short duration of action, naloxone
should be repeated every 1–4 hours, according
to the response.
55

Summary
 It has been estimated that some form of poison directly
or indirectly is responsible for more than 1 million
illnesses worldwide annually, and this figure could be just
the tip of the iceberg since most cases of poisoning
actually go unreported, especially in India
 The incidence of poisoning in India is among the
highest in the world: it is estimated that more than
50,000 people die every year from toxic exposure
 The causes of poisoning are many—civilian and industrial,
accidental and deliberate. The problem is getting worse
with time as newer drugs and chemicals are developed in
vast numbers General Principles in Rx of Poisoning &
56

References:
 Goodman and Gilman's -12th
The Pharmacological basis of
therapeutics
 Modern medical toxicology,4th
edition- VV Pillay
 Principles of pharmacology-HL Sharma & kk sharma
 Principles & practice of forensic medicine,2nd
edition- B
umadethan
 Parikh’s Textbook of medical jurispudence,forensic
medicine & toxicology- 7th
edition
57

58
Next topic- Pharmacotherapy of Shock
By- Dr.Bhagyashree mohod
Date: 29/12/16

General principles in treatment of common drug poisoining

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