Types of Overdose
Toxic effects are directly related to the concept of overdose, in which an excessive concentration of a drug forms in the tissues. There are two main mechanisms for the development of this condition:
- Absolute overdose. Occurs due to a direct violation of the dosing regimen. The patient is administered a dose that exceeds established maximum single, daily, or cumulative limits. As a result, the concentration of the substance predictably reaches dangerous levels.
- Relative overdose. Develops during the administration of standard therapeutic doses. The problem lies in the pathology of elimination organs. Impaired hepatic detoxification or renal excretion prevents the drug from being eliminated on time. Prolonged treatment with drugs prone to accumulation (cumulation) significantly increases the risk of relative overdose.
Organotoxicity (Target Organ Damage)
Excessive amounts of a drug target specific physiological systems, causing severe functional impairment. The most characteristic clinical examples include:
- Central Nervous System (CNS). The main danger lies in the depression of vital centers in the medulla oblongata. A classic example is complete respiratory arrest during opioid overdose.
- Cardiovascular System. Excess amounts of certain drugs disrupt electrical impulse propagation in the myocardium. A similar effect is typical of toxic doses of cardiac glycosides.
- Liver (Hepatotoxicity). The liver bears the brunt of drug metabolism. Toxic exposure, for example to Paracetamolum, can lead to severe hepatic impairment up to massive necrosis.
- Hematopoietic System (Hematotoxicity). Drugs can suppress bone marrow hematopoiesis. The use of analgesics such as Metamizolum natrium carries a risk of leukopenia and agranulocytosis.
Specific Types of Toxicity
A special group includes effects affecting the genetic apparatus and fetal development. The administration of any medications to pregnant women requires strict medical supervision due to the risk of developmental anomalies or fetal death.
- Fetotoxic effect. Negative impact of a drug on the fetus in the later stages of pregnancy. During this period, organ formation (organogenesis) is already complete, so the substance directly affects the functioning systems of the fetus. For example, anticoagulants reduce clotting and create a bleeding risk for the newborn. Sulfonylurea derivatives provoke severe hypoglycemia, and neurotropic agents (alcohol, drugs, hypnotics) severely depress the child's CNS.
- Mutagenic effect. The ability of a substance to cause permanent mutations. The drug attacks germ cells during gametogenesis and somatic cells of the developing embryo, altering their genetic code.
- Carcinogenic effect. The property of a drug to provoke the development of malignant neoplasms (cancer).
Safety Requirements for New Drugs
Pharmacology imposes strict safety requirements on new molecules. During preclinical research stages and prior to clinical introduction, embryotoxic, teratogenic, fetotoxic, mutagenic, and carcinogenic properties of a developing drug must be excluded. If a drug demonstrates such effects, its widespread clinical use is prohibited.