general principles in treatment of common drug poisoining

General Principles In Treatment of Poisoning & Management of Common

drug poisoning

Dr.Vinay BajajJR1

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


In law,real difference between a medicine & poison is the intent with which it is given

General Principles In Rx of Poisoning

General Principles in Rx of Poisoning & common drug poisoning

Outline1.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 ofresuscitation)


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 anormal 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 ventilationIndications: 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



Toxic respiratory depression

Circulatory failureManagement:■ 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.


■ 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



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


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).


EvaluationIn all those poisoned patients where there appears tobe no immediate crisis, a detailed & thorough clinicalexamination should be made with special reference tothe detection & treatment of any of the followingabnormalities : Hypothermia Hyperthermia Acid-base disorders Convulsions Electrolyte disturbances


Decontamination

This is with reference to skin/eye decontamination, gut evacuation and administration of activated charcoal

EYEIrrigate 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 ipecacIn recent years owing to doubts being raised as toits 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

themanagement 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.



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



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.



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 weightpolyethylene glycol)

These are safe and efficacious, withoutproducing 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

ParacetamolClinical 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 reportedwhere-in an individual has consumed large doses ofparacetamol 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) forcerebral 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-inducedhepatic 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 isunusual

c. Complications—Metabolic acidosis, pulmonaryoedema, 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 pseudosepsissyndrome characterised by fever, leukocytosis, hypotension, and multi-organ system failure: ARDS, acute renal failure and coagulopathy (DIC)


Salicylates must not be therapeutically administeredto children under 15 years of age, especially if theyare suffering from chicken pox or influenza. There isa serious risk of precipitating Reye’s syndrome whichcan 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 afteringestion, since toxic doses of salicylates often causepylorospasm 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 Poisoning1. 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 thatthe patient should be undressed & washed thoroughlywith 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. Suctionsecretions. Endotracheal intubation and mechanicalventilation may be necessary. Monitor pulse oximetry or arterial blood gases to determine need forsupplemental 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 ofbelladonna/datura plant

• Dry mouth, difficulty in swallowing & talkingDilated 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 bodytemperature. 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


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


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, naloxoneshould be repeated every 1–4 hours, accordingto the response.


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 worsewith time as newer drugs and chemicals are developed invast numbers


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 General Principles in Rx of Poisoning &

common drug poisoning 57


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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