BMA Concise Guide to Medicine & Drugs

Glyceryl Trinitrate

Brand names Coro-Nitro, Deponit, Minitran, Nitro-Dur, Nitrolingual, Percutol, Rectogesic, Suscard, Transiderm-Nitro, and others

Used in the following combined preparations None

QUICK REFERENCE

Drug group Anti-angina drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed No (most preparations); yes (injection)

Available as generic Yes

GENERAL INFORMATION

Glyceryl trinitrate is a type of vasodilator known as a nitrate and is used to relieve the pain of angina attacks. It is available in short-acting forms (sublingual or buccal tablets, ointment, and spray) and long-acting forms (slow-release tablets and patches). The short-acting forms act very quickly to relieve angina. Glyceryl trinitrate is also given by injection in hospital for severe angina, heart failure, and to control high blood pressure. It may cause a variety of minor symptoms, such as flushing and headache, most of which can be controlled by adjusting the dosage. Glyceryl trinitrate is best taken for the first time while sitting, as fainting may follow the drop in blood pressure caused by the drug.

Glyceryl trinitrate may also be used topically to treat anal fissures.

INFORMATION FOR USERS

Follow instructions on the label. Call your doctor if symptoms worsen.

How taken/used Buccal tablets, sublingual tablets, injection, ointment, gel, skin patches, spray.

Frequency and timing of doses Angina prevention 3 x daily (buccal tablets); every 3–4 hours (ointment); once daily (patches). Angina relief Use buccal or sublingual tablets, ointment, or spray at the onset of an attack or immediately prior to exercise. Dose may be repeated within 5 minutes if further relief required. Anal fissure Every 12 hours for up to 8 weeks.

Adult dosage range Angina 2–15mg daily (buccal tablets); 5–15mg daily (patches); as directed (ointment). 0.3–1mg per dose (sublingual tablets); 1–3mg per dose (buccal tablets); 1–2 sprays per dose (spray). Anal fissure 3mg daily in 2 equal doses.

Onset of effect Angina 1–3 minutes (buccal and sublingual tablets and spray); 30–60 minutes (patches and ointment). Anal fissure 12 hours.

Duration of action 20–30 minutes (sublingual tablets and spray); 3–5 hours (buccal tablets and ointment); up to 24 hours (patches); up to 12 hours (anal fissure preparations).

Diet advice None.

Storage Keep sublingual tablets in an airtight glass container fitted with a foil-lined, screw-on cap in a cool, dry place out of the reach of children. Protect from light. Do not expose to heat. Discard tablets within 8 weeks of opening. Check label of other preparations for storage conditions.

Missed dose If your next dose is due within 6 hours, skip the missed dose and take your next scheduled dose as usual (buccal tablets); take as soon as you remember, or when needed. If your next dose is due within 2 hours, take a single dose now and skip the next (other preparations).

Stopping the drug Do not stop taking the drug without consulting your doctor.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause symptoms such as dizziness, vomiting, severe headache, sweating, fits, or loss of consciousness. Notify your doctor.

POSSIBLE ADVERSE EFFECTS

The most serious adverse effect is lowered blood pressure, which may cause dizziness, fainting, or collapse. If dizziness occurs, discuss with your doctor; if fainting or collapse occur, stop taking the drug and consult your doctor without delay. Other effects, such as headache and flushing, usually decrease in severity after regular use and can usually also be controlled by adjusting the drug dosage.

INTERACTIONS

Antihypertensive drugs and other anti-angina drugs These drugs increase the possibility of lowered blood pressure or fainting when taken with glyceryl trinitrate.

Sildenafil, tadalafil, and vardenafil The hypotensive effect of glyceryl trinitrate is increased significantly by these drugs; they should not be used with glyceryl trinitrate.

SPECIAL PRECAUTIONS

Be sure to consult your doctor or pharmacist before taking this drug if:

· You have any other heart condition.

· You have a lung condition.

· You have long-term liver or kidney problems.

· You have any blood disorders.

· You have glaucoma.

· You have thyroid disease.

· You have low blood pressure.

· You have anaemia.

· You have a recent head injury or stroke.

· You are taking other medicines.

Pregnancy Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding It is not known whether the drug passes into the breast milk. Discuss with your doctor.

Infants and children Not usually prescribed.

Over 60 No special problems.

Driving and hazardous work Avoid such activities until you have learned how glyceryl trinitrate affects you because the drug can cause dizziness.

Alcohol Avoid excessive intake. Alcohol may increase the risk of lowered blood pressure, causing dizziness and fainting.

PROLONGED USE

The effects of the drug usually become slightly weaker during prolonged use as the body adapts. Timing of the doses may be changed to prevent this effect. Preparations for anal fissures should not be used for more than 8 weeks.

Monitoring Periodic checks on blood pressure are usually required when the drug is used for angina.