Toxicology: Antidotes, Elimination, and Chemical Analysis

Posted on Jan 19, 2025 in Biotechnology

Antidote Treatments

The objective is to neutralize toxins absorbed into the blood and tissues.

Chemical Antidotes: These convert a toxic substance into a non-toxic compound. For example, glucose + CnH = Heptose, and sodium thiosulphate + metal = sulfur compounds.
Chelating Agents: These compounds combine with metals and metalloids, forming water-soluble, nonionic chelates that are usually less toxic or non-toxic. Examples include BAL for As, Hg, Cr, Au; and Cobalt EDTA for Cyanides.
Replacement Therapy: This approach attempts to counteract the toxic effect by correcting the metabolic disorders it causes. For example, ethyl alcohol (5% IV) neutralizes the toxic effects of methanol or ethylene glycol, preventing the production of toxic metabolites. Vitamin B6 neutralizes the neurotoxic effect of isoniazid.
Biological Antidotes: These are serums that neutralize the toxic effects of substances with antigenic character, such as botulinum toxin, snake venom, and fungi.
Physiological Antidotes: These counteract the toxic effect by exerting an antagonistic action. Examples include the use of strychnine and barbiturates, or atropine and pilocarpine.

These treatments aim to minimize the duration of action of toxins and should be used in conjunction with other methods.

Respiratory Elimination: Artificial respiration helps evacuate unabsorbed toxins, eliminating them via the respiratory route and maintaining respiratory function.
Renal Elimination: This involves three methods:
- Osmotic Diuresis: Instilling more than 3 liters of iso- or hypertonic solution, such as mannitol or ureamanitol. Requires normal cardiac and renal function.
- Diuretics: Using safe and active diuretics like hydrochlorothiazide.
- Urinary Alkalinization: Administering serum bicarbonate to favor the excretion of weak acids.
Extrarenal Elimination: Directly removing toxins from the blood, essential if the kidneys are damaged. Methods include:
- Exchange Transfusion: Replacing the blood.
- Peritoneal Dialysis: Using the peritoneum to filter blood.
- Intestinal Elimination: Using purgatives and enemas to stimulate defecation.

This involves the separation of toxins from biological material.

Gaseous or Volatile Toxins: These are moved from the sample by heat, distillation, micro-Conway diffusion cell, or headspace techniques.
Inorganic or Mineral Toxins: These are firmly bound to organic matter and can only be separated by calcination (burning) or oxidation of organic matter. They can also be removed by forming chelates with substances like As, Cu, and Pb.
Volatile Organic Toxins: These are extracted using organic solvents immiscible in water, such as ether. This separation is achieved by acidifying or alkalinizing the sample. For general analysis, the sample is divided into four parts, with the fourth part reserved for further analysis or counter-analysis. Extraction can be performed using non-polar or polar solvents with a pH change of the sample, or by chromatographic methods and capillary electrophoresis.

After separating the sample, the toxins are identified and quantified.

Technical Guidance: These serve as screening methods, and their results cannot be used to issue a report. Examples include paper chromatography, immunoassays, and spectrophotometry.
Confirmatory Techniques: These verify the results obtained by the previous group or are used directly. Good laboratory practice recommends identifying toxins using two techniques with different physical-chemical bases, such as gas chromatography, liquid chromatography, high-pressure or resolution chromatography, with the safest being integrated gas chromatography-mass spectrometry.

Techniques can also be classified as instrumental or non-instrumental.