Icosorbide Mononitrate

Question 1

Drug class?

Answer 1

Nitrates

Question 2

How does it work?

Answer 2

Organic nitrates (including glyceryl trinitrate, isosorbide dinitrate and isosorbide mononitrate) are potent relaxers of smooth muscle. They have a powerful effect on vascular smooth muscle. Low concentrations dilate both arteries and veins.

Venous dilatation pools blood in the periphery leading to a decrease in venous return, central blood volume, and ventricular filling volumes and pressures. Cardiac output may remain unchanged or it may decline as a result of the decrease in venous return. Arterial blood pressure usually declines secondary to a decrease in cardiac output or arteriolar vasodilatation, or both. A modest reflex increase in heart rate results from the decrease in arterial blood pressure. Nitrates can dilate epicardial coronary arteries including atherosclerotic stenoses.

Question 3

Indications?

Answer 3

Angina Pectoris

Question 4

Contra-indications?

Answer 4

Acute myocardial infarction with low filling pressures, hypertrophic obstructive cardiomyopathy, constrictive pericarditis, cardiac tamponade, aortic/mitral stenosis and severe anaemia, hypovolaemia, conditions causing raised intracranial pressure (e.g. cerebral haemorrhage, head trauma) and closed-angle glaucoma. Severe cerebrovascular insufficiency or hypotension are contraindications to use.

Question 5

Side-effects?

Answer 5

Most of the adverse reactions are pharmacodynamically mediated and dose dependent.
Headache is very common (>10%). The incidence of headache usually disappears after 1-2 weeks of treatment.
Immune system disorders - Allergic dermatitis, exfoliative dermatitis.
Nervous system disorders - Headache, restlessness, somnolence, pituitary haemorrhage.
Cardiac disorders - Tachycardia, bradycardia - these symptoms generally disappear during long-term treatment.
Vascular disorders - Flushing, dizziness, orthostatic hypotension - these symptoms generally disappear during long-term treatment. Pallor. Circulatory collapse (sometimes accompanied by bradyarrhythmia, bradycardia and syncope). Severe hypotension may lead to enhanced angina pectoris symptoms.
Respiratory, thoracic and mediastinal disorders - Hypoxia.
Gastrointestinal disorders - Nausea, vomiting, diarrhoea
Skin and subcutaneous tissue disorders - Hyperhidrosis, pruritus.
Musculoskeletal and connective tissue disorders - Myalgia.
General disorders and administration site conditions - Asthenia.

Question 6

Possible interactions?

Answer 6

The hypotensive effect of nitrates will be increased if used together with phosphodiesterase type-5 inhibitors (e.g. sildenafil). This might lead to life threatening cardiovascular complications.

Any medication which may cause hypotension may have its hypotensive effects potentiated by concurrent administration of Chemydur 60XL Tablets (e.g. alcohol, antihypertensives, vasodilators, calcium channel blockers, and diuretics).