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Toxicology – Nitrates and Nitrites
Source
Nitrates such as nitroglycerin and isosorbide dinitrate are commonly used in the treatment of coronary artery disease due to their vasodilatory effects. Nitrites, including amyl, butyl, and isobutyl nitrite, are often misused recreationally as inhalants and may be marketed under misleading labels such as “poppers,” cleaners, or deodorizers.
Typical Presentation
Individuals may present after inhaling these substances recreationally, often experiencing rapid onset of flushing, headache, and palpitations shortly after exposure.
Clinical Features
Common findings include headache, facial flushing, tachycardia, and hypotension due to vasodilation. In some cases, especially with nitrite exposure, methemoglobinemia may develop, leading to reduced oxygen delivery, cyanosis, and symptoms of hypoxia.
Mechanism of Action
Both nitrates and nitrites act as potent vasodilators, causing relaxation of vascular smooth muscle and resulting in decreased blood pressure with compensatory increase in heart rate. They can also oxidize hemoglobin to methemoglobin, impairing oxygen transport—this effect is more pronounced with nitrites.
Management
Treatment includes removal from exposure and supportive care. Intravenous fluids may be used for hypotension. In cases of methemoglobinemia, methylene blue (1–2 mg/kg IV) is the treatment of choice.
Key Points
Source
Nitrates such as nitroglycerin and isosorbide dinitrate are commonly used in the treatment of coronary artery disease due to their vasodilatory effects. Nitrites, including amyl, butyl, and isobutyl nitrite, are often misused recreationally as inhalants and may be marketed under misleading labels such as “poppers,” cleaners, or deodorizers.
Typical Presentation
Individuals may present after inhaling these substances recreationally, often experiencing rapid onset of flushing, headache, and palpitations shortly after exposure.
Clinical Features
Common findings include headache, facial flushing, tachycardia, and hypotension due to vasodilation. In some cases, especially with nitrite exposure, methemoglobinemia may develop, leading to reduced oxygen delivery, cyanosis, and symptoms of hypoxia.
Mechanism of Action
Both nitrates and nitrites act as potent vasodilators, causing relaxation of vascular smooth muscle and resulting in decreased blood pressure with compensatory increase in heart rate. They can also oxidize hemoglobin to methemoglobin, impairing oxygen transport—this effect is more pronounced with nitrites.
Management
Treatment includes removal from exposure and supportive care. Intravenous fluids may be used for hypotension. In cases of methemoglobinemia, methylene blue (1–2 mg/kg IV) is the treatment of choice.
Key Points
- Nitrites are more likely than nitrates to cause methemoglobinemia.
- These substances are sometimes misused for their short-lived vasodilatory and sensory effects
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