Classification by organ-tissue tropism (Part 1)
Neurotropic poisons This is an extensive group of substances that selectively affect the nervous system. Their impact leads to severe consequences: profound mental disorders occur, convulsive syndromes and paralysis develop. The list of representatives is extremely wide. It includes narcotic substances (cocaine, opium, lysergic acid diethylamide), sleeping pills, as well as alcohol and its various surrogates. Organophosphorus compounds (OPCs), such as chlorofophos and karbofophos, the alkaloids nicotine and anabasine, and isoniazid derivatives possess a strong neurotropic effect. In addition, this group includes carbon monoxide and chemical warfare nerve agents (sarin, VX, BZ).
Cardiotropic poisons These toxins have a specific tropism for the heart muscle. Their main pathological manifestation is impaired myocardial contractility and cardiac arrhythmias. In severe poisonings, toxic myocardial dystrophy develops. Typical representatives include cardiac glycosides, barium and potassium salts, as well as dangerous plant poisons found in quinine and aconite.
Pulmonotoxic poisons The target of these substances is the respiratory system. Toxic exposure leads to the development of acute respiratory failure (RF) and the formation of toxic pulmonary edema. Classical representatives of pulmonotoxicans include nitrogen oxides and chemical warfare choking agents, such as phosgene and diphosgene.
Classification by organ-tissue tropism (Part 2)
Hepatotropic poisons Substances in this group selectively destroy liver cells. The result of their exposure is toxic hepatopathy, which predictably progresses to hepatic failure (HF). Hepatotropic poisons include chlorinated hydrocarbons (e.g., dichloroethane), phenols, and aldehydes. Poisonous mushrooms, primarily the death cap (Amanita phalloides), pose a particular danger.
Nephrotoxic poisons These compounds are filtered by the kidneys and cause direct damage to them. Toxic nephropathy develops, resulting in renal failure. The list of nephrotoxics includes heavy metal salts, ethylene glycol, and oxalic acid.
Hemoglobinotropic poisons This group of toxins interferes with the vital processes of oxygen transport and utilization by the blood. Pathological effects include hemolysis (destruction) of erythrocytes, as well as the formation of pathological hemoglobin forms — methemoglobinemia and carboxyhemoglobinemia. Similar disorders are caused by aniline and its derivatives, nitrites, arsine, hydrocyanic acid and its derivatives. This same category includes carbon monoxide and the chemical warfare agent cyanogen chloride.
Skin-resorptive poisons The specific feature of these substances lies in the combined nature of the lesion. They cause pronounced local changes in the form of inflammation and tissue necrosis at the site of contact, after which they are absorbed into the bloodstream and provoke severe general toxic phenomena. Skin-resorptive poisons include concentrated acids and alkalis, dichloroethane, hexachlorane, arsenic and its compounds, as well as mercury (corrosive sublimate). Among chemical warfare agents, mustard gas and lewisite possess such an action.
Diagnostics and treatment principles
Diagnosis and emergency care The key goal of diagnosis in suspected poisoning is the identification of specific symptoms characteristic of the specific toxin's effect on the body. Understanding which exact poison caused the lesion is of critical importance, as this is necessary to formulate adequate treatment principles and methods.
Upon detecting signs of poisoning, urgent emergency measures are required. The first and most important step is the urgent hospitalization of the victim to a specialized medical facility. Delivery of the patient to specialized toxicology centers, where all conditions for targeted care are available, is considered the optimal option.
General principles of poisoning treatment The main goal of all therapeutic measures is complete detoxification of the body. To achieve this, three main approaches are implemented in toxicology: etiotropic, pathogenetic, and symptomatic.
The main directions of treatment include:
- Active detoxification — a set of measures aimed at the most intensive elimination of toxic substances from the bloodstream and tissues.
- Specific (antidote) therapy — administration of drugs capable of neutralizing a specific poison or blocking its action.
Briefly: answers to topical questions
What active detoxification methods are used in acute poisoning?
In acute poisoning, active detoxification methods aimed at removing the toxin already entered into the systemic circulation are used. These include:
- Forced diuresis — stimulation of natural excretion; may include intravenous administration of a large volume of fluid and the use of potent diuretics.
- Hemosorption — blood perfusion through a detoxifier with a sorbent.
- Hemodialysis — a method using an "artificial kidney" machine.
- Plasmapheresis — removal of plasma with replacement of the removed volume with saline solutions or fresh frozen plasma.
- Peritoneal dialysis.
- Exchange blood transfusion — replacement of the recipient's blood with donor blood; especially relevant for hemolytic poisons.
What specific antidotes are used in organophosphorus poisoning?
In organophosphorus poisoning, specific antidotes acting on receptors or enzymes are used. The following groups of drugs are applied:
- Atropine — an M-anticholinergic drug that eliminates symptoms of parasympathetic system excitation. It acts as a competitive antagonist and prevents the binding of acetylcholine to receptors.
- Cholinesterase reactivators — drugs whose action is aimed at reactivating and restoring the activity of enzymes inhibited by the toxin.
What is the mechanism of methemoglobin formation in nitrite poisoning?
The mechanism of methemoglobin formation in nitrite poisoning consists of the oxidation of hemoglobin. Nitrites act as strong oxidizing agents that change the charge of the iron ion within hemoglobin from ferrous () to ferric (). As a result of this process, methemoglobin is formed — a stable compound of hemoglobin with oxygen. Excess nitrites block normal oxidative processes and the blood's ability to transport oxygen to tissues, leading to the development of methemoglobinemia.
For quick memorization of toxin targets, use the association: Nerves, Heart, Lungs, Liver, Kidneys, Blood, Skin (Neuro-, Cardio-, Pulmono-, Hepato-, Nephro-, Hemoglobino-, Skin-resorptive).
Class and exam questions
What principle underlies the classification of poisons?
The classification is based on the selective toxic effect of substances — their organ-tissue tropism, i.e., the ability to predominantly affect certain body systems.
What pathological effects are characteristic of hemoglobinotropic poisons?
They cause impaired oxygen transport and utilization. This manifests as erythrocyte hemolysis, as well as the development of methemoglobinemia and carboxyhemoglobinemia.
What is the main goal of diagnosing poisonings?
The main goal is to identify specific symptoms of a particular toxin's exposure. This is critically important for choosing the correct treatment methods and antidotes.
What are the main areas of treatment for poisoning?
Treatment is based on active detoxification (intensive elimination of toxins) and the administration of specific antidote therapy within the framework of etiotropic, pathogenetic, and symptomatic approaches.
What else to study on this topic
- Mechanisms of development of toxic myocardial dystrophy
- Pathogenesis of methemoglobinemia and carboxyhemoglobinemia
- Active detoxification methods in a hospital setting
- Specific (antidote) therapy for organophosphate poisoning
- Toxic hepatopathy and hepatic failure
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