Toxic effects of drugs used in the ICU. Nitroprusside, nitroglycerin, and angiotensin-converting enzyme inhibitors.

Sodium nitroprusside causes cyanide poisoning at currently recommended infusion rates. Serum thiocyanate concentrations are of no value in detecting cyanide poisoning caused by nitroprusside. Methemoglobinemia in those patients receiving intravenous nitroglycerin may seriously impair oxygen delivery and is not always accompanied by cyanosis in anemic patients. Angiotensin-converting enzyme inhibitors are responsible for a plethora of adverse effects, including renal insufficiency, hypotension, angioedema, cough, and increased insulin sensitivity.