Glyceryl trinitrate (GTN) is prescribed for chest pain associated with angina. Tablet and spray formulations are referred to as short-acting preparations. This is because the effect of the medicine lasts for around 20-30 minutes. They are used to provide rapid relief from the pain as and when it happens. They can also be used for when the pain is expected to happen, such as before exercise that is likely to cause chest pain (for example, before climbing stairs). Other formulations which contain GTN are skin patches and ointment. These are longer-acting nitrates, as the medicine in these preparations works for a longer period of time. They are often referred to as transdermal nitrates. They are prescribed to prevent the pain from developing.
This is a companion discussion topic for the original article at https://patient.info/medicine/glyceryl-trinitrate-for-angina-gtn-glytrin-nitrolingual