Methemoglobin levels following sublingual nitroglycerin in human volunteers.

Sublingual nitroglycerin 0.8 mg every five minutes for a total of 4.8 mg was administered to 11 healthy volunteers. One volunteer had to withdraw due to a hypotensive bradycardic reaction after 2.4 mg. In the remaining subjects, methemoglobinemia over the next hour never significantly increased from baseline levels, reaching a peak of only 0.71%. We conclude that commonly used doses of sublingual nitroglycerin do not induce significant methemoglobinemia and that nitroglycerin would not be useful in the treatment of cyanide poisoning.