Glyceryl trinitrate infusion

A 74-year-old man developed Wernicke s encephalopathy, which required treatment with intravenous thiamine after discontinuation of the glyceryl trinitrate infusion. 

Raynaud s phenomenon may be helped by nifedipine, reserpine (an a-adrenoceptor blocker, in low doses) and also by topical glyceryl trinitrate indeed any vasodilator is worth trying in resistant cases enalapril (ACE inhibitor) seems to lack efficacy. In severe cases, especially patients with ulceration, intermittent infusions over several hours of the endogenous vasodilator, prostacyclin (epoprostenol), achieves long-lasting improvements in symptoms. 

Besides its usual indications, topical glyceryl trinitrate has been used to prevent intravenous infusion failure because of phlebitis and extravasation, which occur in 30-60% of patients and can cause discomfort and harm, such as pulmonary embolism, septicemia, and increased mortality. Local application of glyceryl trinitrate patches was efficacious in several studies (11) the mechanism is probably vasodilatation and increased capillary flow. Glyceryl trinitrate is safe, since it causes only skin rashes and transient headache. 

A paradoxical increase in pulmonary vascular resistance has been reported after intravenous infusion of glyceryl trinitrate, and care is needed when giving potent vasodilators to patients with idiopathic pulmonary hypertension (91). 

Ethanol has also been implicated as the cause of acute gout in four patients with unstable angina who received intravenous infusions of glyceryl trinitrate (104). 

The pressure-lowering effect of a step-wise intravenous infusion of glyceryl trinitrate was significantly increased in 12 healthy volunteers treated for 4 days with sildenafil (Viagra) 25 mg tds episodes of symptomatic hjrpotension were also more frequent with sildenafil (113). When sublingual glyceryl trinitrate was used, the reduction in systolic blood pressure was four-fold greater in association with sildenafil. 

The effects of heparin were reduced by the infusion of glyceryl trinitrate in some studies, but other studies have failed to confirm this interaction. On balance, the evidence favours there being no clinically important interaction. No interaction has been seen with heparin and isosorbide dinitrate or molsidomine. 

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