NSAID-induced gastropathy and GI damage
The primary cause of gastric mucosal damage is the non-selective inhibition of the COX-1 enzyme. This leads to a sharp drop in the synthesis of protective prostaglandins (PgE2, PgI2). As a result, an imbalance between aggressive and protective factors occurs: hydrochloric acid secretion increases, while mucus and bicarbonate production decreases.
Clinically, this manifests as mucosal ulceration and a high risk of gastrointestinal bleeding. For effective pharmacoprophylaxis, synthetic prostaglandin analogues (misoprostol) or proton pump inhibitors (omeprazole) are used. Switching to selective COX-2 inhibitors (e.g., celecoxib) also reduces risks. The use of enteric-coated forms is of little efficacy.
Effects on hemostasis
Drugs of this group reliably reduce platelet aggregation ability. In laboratory tests, this is reflected as an increase in bleeding time.
It is important to remember that the antiplatelet effect does not disappear instantly—it persists for several days after complete drug withdrawal. This feature is critically important to consider when preparing patients for surgical interventions to avoid severe hemorrhagic complications.
Respiratory system and "aspirin-induced asthma"
Blockade of the cyclooxygenase pathway of arachidonic acid metabolism leads to the activation of an alternative cascade—the lipoxygenase pathway. This causes massive overproduction of leukotrienes, which provoke pronounced bronchial spasm.
In addition, drugs affect the acid-base balance:
- In therapeutic doses, they stimulate respiration by increasing alveolar ventilation.
- Toxic doses depress the respiratory center, leading to CO2 accumulation and the development of combined respiratory and metabolic acidosis.
Pediatric use
The use of salicylates (aspirin) in children against the background of viral infections, such as influenza or chickenpox, is an absolute contraindication. Such a combination can provoke Reye's syndrome—an extremely dangerous, life-threatening condition.
The pathology is characterized by acute hepatic encephalopathy, rapid progression, and fatty infiltration of the liver and brain, with a high mortality rate. In pediatric practice, the drugs of choice for fever reduction are exclusively paracetamol and ibuprofen.
Pharmacokinetics and dose-dependency
Drugs are rapidly absorbed from the stomach and small intestine, reaching peak concentration (Cmax) in 1–2 hours, and are capable of crossing the blood-brain barrier. The spectrum of action strictly depends on the daily dose:
- Low doses (80–325 mg/day) provide an antiplatelet effect.
- Medium doses (500–1500 mg/day) provide antipyretic and short-term analgesic action.
- High doses (more than 3000 mg/day) are necessary to achieve an anti-inflammatory effect.
At therapeutic dosages, elimination follows linear kinetics with a half-life of about 3 hours. At high doses, enzymes become saturated, kinetics changes, and the half-life can increase up to 15 hours.
Briefly: answers to topical questions
What renal side effects does long-term intake of non-selective NSAIDs cause?
Long-term NSAID intake can cause renal dysfunction associated with altered glomerular filtration. NSAIDs are also classified as nephrotoxic drugs and can be a triggering factor for hepatorenal syndrome.
Which drugs, besides celecoxib, belong to the group of selective COX-2 inhibitors?
In addition to celecoxib, rofecoxib is classified as a selective drug in the literature.
What cardiovascular complications are associated with the long-term use of coxibs?
The use of coxibs is associated with an increased risk of arterial hypertension, myocardial infarction, stroke, and thromboembolism.
What severe hematological reactions, unrelated to platelets, can metamizole sodium cause?
Systematic and long-term use of metamizole sodium is associated with a high risk of hematopoietic suppression. Severe hematological reactions include leukopenia and agranulocytosis.
How to remember the mechanism of "aspirin-induced asthma": COX is blocked — arachidonic acid goes the "Left" way (via Lipoxygenase), forming Leukotrienes, which Break breathing (cause bronchospasm).
Class and exam questions
Why drinking milk with pills does not protect against ulcers?
Milk provides only a short-term buffering effect, but does not prevent the systemic drop in protective prostaglandin levels. Moreover, calcium ions can secondarily stimulate hydrochloric acid secretion.
How long does the bleeding risk persist after drug discontinuation?
The decrease in platelet aggregation ability and prolongation of bleeding time persist for several days, which is critically important to consider before surgical operations.
How to safely reduce fever in a child with a viral infection?
In pediatrics, only paracetamol and ibuprofen are permitted during viral infections. The use of salicylates is strictly contraindicated due to the risk of developing fatal Reye's syndrome.
What else to study on this topic
- Nonlinear pharmacokinetics at high doses
- Mechanisms of metabolic acidosis development in overdose
- Comparative characteristics of selective COX-2 inhibitors
- Pharmacological properties of synthetic prostaglandin analogues
- Pathogenesis of hepatic encephalopathy in Reye's syndrome
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