Mechanism of Action: Chemical Antagonism
The action of Natrii thiosulfas is a classic example of chemical antagonism in pharmacology. This phenomenon involves a direct chemical reaction between the administered substance (the antagonist) and the toxin present in the organism. This interaction creates new, pharmacologically inactive compounds incapable of damaging cells and tissues.
This process is fundamentally different from other types of drug interactions, such as physical interaction, ion exchange, or adsorption. The drug acts exclusively through a chemical reaction with poison molecules. Other known antidotes operate on a similar principle: for example, protamine sulfate binds to the anionic centers of heparin to neutralize its anticoagulant effect, or monoclonal antibodies bind cardiac glycosides into inactive complexes.
Pharmacological Effects and Indications
The primary effect of the drug is pronounced detoxification. Classified as an antidote, chelating agent, and absorbent, sodium thiosulfate is used to rescue patients from specific poisonings.
The main indication for its use is heavy metal poisoning. In clinical practice, it serves as a specific antidote for poisonings by:
- Arsenic
- Mercury
- Lead
Upon contact with these heavy metals, Natrii thiosulfas chemically binds to them. During the reaction, the toxic metal ions are converted into non-poisonous sulfites. These safe complexes lack toxicity and are subsequently eliminated from the body.
Formulations and Administration
For emergency care and detoxification therapy, it is essential to know the available drug formulations and routes of administration.
According to prescription references, Natrii thiosulfas is available in the following forms:
- Powder (used to prepare various dosage forms).
- Ampoules containing a 30% solution (available in 5 mL, 10 mL, and 50 mL volumes).
Administration: For heavy metal poisoning, the drug is administered strictly intravenously. The standard regimen involves the intravenous administration of 5 to 10 mL of a 30% solution.
(Note: While detailed adverse effects and contraindications are beyond the scope of this specific discussion on chemical antagonism, intravenous administration of antidotes always requires strict medical supervision).