TOXICOLOGY

POISON:
A compound, which in relatively small amount with the help of a chemical action, can cause death or disability. So toxicology is the science of adverse effects of chemicals on living organisms. The principles of poison treatment are as follows.

1. IDENTIFICATION OF POISON: Since there are few selective antagonists, this is not useful as expected.
2. REMOVAL OF POISON:
a. EXTERNAL POISON:
i. Wash with water
ii. Remove the contact.
iii. Apply appropriate antidote e.g. NaHCO3, Vinegar, alcohol, etc, etc.
b. POISON FROM GUT:
i. BY EMESIS: This method is applied in conscious patient only; especially some solid is given for emesis. Expiration must be considered if the patient does not vomit. Apomorphine HCl i/v, Ipecac syrup etc, etc are used as emetics. Emetics are contra-indicated in situation like consciousness (aspiration of GI contents may occur), corrosive material poisoning (strong alkali, strong acids poisoning, emesis likelihood to increase gastric perforation and further necrosis of the esophagus). If the patient has ingested a CNS stimulant, further stimulation associated with vomiting may precipitate convulsions. If the patient has ingested petroleum distillate, regurgitating hydrocarbon can be aspirated readily and cause chemical pneumonitis.
ii. GASTRIC ASPIRATION AND LAVAGE: This procedure can be used in unconscious patients. Gastric lavage is accomplished by inserting a tube in stomach and washing with water or a harmless solvent to remove the unabsorbed poison. Lavage may be useful as long as three hours after the ingestion of poison and if gastric emptying has been delayed, lavage may be useful as long as 12 hours after the ingestion. Unlike emesis, it is used for patients who are hysterical, ametized or otherwise not co-operative.
iii. PREVENTION OF FURTHER ABSORPTION:
From An Injection Site: Stop flow of drug by compression using some tourniquet.
From Gut: Specific antidote, which combine chemically with poison may be used. It is important in case of acids and alkalis but it is probably ineffective in most substances except iron whose antidote is “Deferoxamine”. Non-specific antidote: Demulcents like milk, eggs, kaolin, flour and water, activated charcoal and castor oil may be used. Saline purgatives may be used when patient is unconscious.
iv. SPECIFIC PHARMACOLOGICAL ANTIDOTE: Atropine antihistamines nalorphine and chelating agents
v. NON-SPECIFIC PHARMACOLOGICAL ANTIDOTE: Anticonvulsants in case of convulsants and analeptics in case of narcotic poisoning.
CHELATING AGENTS:
Chelating agent is any