NITROCONTIN-2.6

Indications

• Angina pectoris
• Acute myocardial infarction
• Heart failure
• Hypertensive emergencies
• Control of blood pressure during surgery

Dosage

Children: Refer to BNF for Children for specific dosing information.

Adults: Refer to BNF for specific dosing information.

Mechanism of action

Nitroglycerin is converted to nitric oxide (NO) in the body, which activates guanylate cyclase, leading to increased levels of cyclic guanosine monophosphate (cGMP) in vascular smooth muscle cells. This results in smooth muscle relaxation and vasodilation, primarily affecting the veins, reducing preload, and decreasing myocardial oxygen demand. It also dilates coronary arteries, improving blood flow to ischemic areas of the heart.

Pharmacodynamics

The vasodilatory effects of nitroglycerin lead to decreased myocardial oxygen consumption and relief of angina symptoms. The onset of action varies depending on the route of administration; sublingual forms act rapidly while transdermal patches provide sustained release. Its effects are dose-dependent, with higher doses leading to more pronounced vasodilation and potential side effects such as hypotension.

Pharmacokinetics

Nitroglycerin is rapidly absorbed through the gastrointestinal tract and mucous membranes, with sublingual administration providing quick onset of action. It undergoes extensive first-pass metabolism in the liver, reducing bioavailability when taken orally. The half-life is short, approximately 5-7 minutes, necessitating repeated dosing or continuous infusion for sustained effects. It is primarily metabolized by hepatic enzymes and eliminated through urine.

Contra-indications

• Hypersensitivity to nitroglycerin or any of its components
• Severe anemia
• Increased intracranial pressure
• Hypotension
• Severe aortic stenosis
• Constrictive pericarditis
• Cardiomyopathy

Adverse effects

• Headache
• Dizziness
• Hypotension
• Reflex tachycardia
• Flushing
• Nausea
• Vomiting
• Syncope
• Skin rash

Interactions

• Sildenafil and other phosphodiesterase-5 inhibitors (risk of severe hypotension)
• Other antihypertensive agents (additive hypotensive effects)
• Alcohol (enhanced hypotensive effects)
• Ergotamine (may cause vasospasm)
• Tricyclic antidepressants (may enhance hypotensive effects)

Precautions

• Use with caution in patients with renal or hepatic impairment
• Monitor blood pressure regularly during therapy
• Caution in patients with a history of myocardial infarction
• Avoid abrupt withdrawal to prevent rebound angina
• Tolerance may develop with prolonged use

Pregnancy

Nitroglycerin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as there are no adequate and well-controlled studies in pregnant women.

Breast-feeding

Nitroglycerin is excreted in breast milk, and caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Keep out of the reach of children.

Formulations

• Sublingual tablets
• Transdermal patches
• Ointment
• Intravenous solution