From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Sublingual nitroglycerin is not recommended for tachysystole (excessive uterine contractions during labor) as it is not an approved indication, and terbutaline is the preferred medication, typically given as 0.25 mg subcutaneously. The use of nitroglycerin for tachysystole is not well-supported by evidence, and its potential side effects, such as hypotension, headache, and reflex tachycardia, require close maternal monitoring 1.
Alternative Options
- Intravenous nitroglycerin may be used at doses of 50-100 mcg IV bolus, which can be repeated every 3-5 minutes as needed, with a maximum cumulative dose of 500 mcg.
- If sublingual nitroglycerin must be used in an emergency situation where other options aren't available, a dose of 400 mcg (0.4 mg) could be considered, but this is off-label and not standard practice.
Mechanism of Action and Side Effects
Nitroglycerin works by relaxing smooth muscle, including uterine muscle, through nitric oxide release. Side effects include hypotension, headache, and reflex tachycardia, which require close maternal monitoring. Blood pressure should be checked before administration and regularly afterward, as significant hypotension can compromise placental perfusion. Nitroglycerin has a rapid onset (1-3 minutes) but short duration of action (about 5-10 minutes), so repeated dosing may be necessary if contractions recur 2.
Evidence-Based Recommendations
The most recent and highest quality study on this topic is a Cochrane review from 2018, which found that there is insufficient evidence to determine the effects of tocolytics for uterine tachysystole or suspected fetal distress during labor 1. However, the review suggests that terbutaline may be a more effective tocolytic than nitroglycerin, with fewer side effects. Another study from 2007 found that terbutaline resulted in lower median contraction frequency per 10 minutes and reduced tachysystole compared to nitroglycerin 3.
Key Points
- Terbutaline is the preferred medication for tachysystole.
- Nitroglycerin may be used in emergency situations, but its use is not well-supported by evidence.
- Close maternal monitoring is necessary when using nitroglycerin due to its potential side effects.
- The most recent and highest quality study on this topic is a Cochrane review from 2018, which found that there is insufficient evidence to determine the effects of tocolytics for uterine tachysystole or suspected fetal distress during labor.