Warnings:
In cases of recent myocardial infarction or acute heart failure, treatment with the preparation should be carried out cautiously under strict medical surveillance and/or haemodynamic monitoring.
Removal of the patch should be considered as part of the management of patients who develop significant hypotension.
Precautions:
This patch should be used with caution in patients with
• Severe hepatic or renal impairment
• Hypothyroidism
• Hypothermia
• Malnutrition
• A recent history of myocardial infarction
• Hypoxaemia or a ventilation/perfusion imbalance due to lung disease or ischaemic heart failure.
• Arterial Hypoxaemia due to severe anaemia (including G6PD deficiency induced forms), because in such patients the biotransformation of nitroglycerin is reduced.
• Alveolar hypoventilation a vasoconstriction occurs within the lung to shift perfusion from areas of alveolar hypoxia to better ventilated regions of the lung (Von Euler–Liljestrand mechanism).
• Angina pectoris, myocardial infarction, or cerebral ischaemia frequently suffer from abnormalities of the small airways (especially alveolar hypoxia).Under these circumstances vasoconstriction occurs within the lung to shift perfusion from areas of alveolar hypoxia to better ventilated regions of the lung. As a potent vasodilator, nitroglycerin could reverse this protective vasoconstriction and thus result in increased perfusion of poorly ventilated areas, worsening of the ventilation/perfusion imbalance, and a further decrease in the arterial partial pressure of oxygen.
• Methemoglobinemia
Following treatment with GTN, methemoglobinemia has been reported. Treatment of methaemoglobinemia with methylene blue is contraindicated in patients with glucose-6-phosphate deficiency or methemoglobin-reductase deficiency (see also section 4.9).
The patch is not indicated for use in acute angina attacks. In the event of an acute angina attack, sublingual treatment such as a spray or tablet should be used.
As with all nitrate preparations withdrawal of long-term treatment should be gradual by replacement with decreasing doses of long acting oral nitrates.
Also when transferring the patient on long-term therapy to another form of medication, nitroglycerin should be gradually withdrawn and overlapping treatment started.
If the patches are not used as indicated (see Section 4.2) tolerance to the medication could develop.
Patients should be warned not to discontinue or interrupt GTN patch therapy in order to use phosphodiesterase inhibitor-containing products (e. g. sildenafil, vardenafil, tadalafil).
During treatment with GTN alcohol should be avoided as it may potentiate the hypotensive and vasodilating effect of GTN (see section 4.5).