⚠️ Warnings
Formoterol should not be used as first-line therapy in asthma, as its action alone is insufficient for this purpose. Patients treated for asthma should receive maintenance doses of anti-inflammatory corticosteroids in addition to formoterol and should not discontinue them, even if formoterol administration alleviates symptoms. Formoterol may be added to therapy when corticosteroids are insufficiently effective; however, it must never be initiated during severe exacerbations or worsening of asthma. Deterioration of asthma control may occur during treatment, but patients must not discontinue treatment on their own and should remain under continuous medical supervision. Conversely, if the medicinal product alleviates asthma symptoms, the physician may consider reducing the dose. The lowest effective dose of formoterol should always be used as the disease progresses. The maximum daily doses must not be exceeded.
Particular caution should be exercised when using formoterol in patients with: severe arterial hypertension, severe heart failure, ischaemic heart disease, cardiac arrhythmias (particularly third-degree atrioventricular block), idiopathic subvalvular aortic stenosis, hypertrophic obstructive cardiomyopathy, thyrotoxicosis, and in the presence of phaeochromocytoma, aortic aneurysm, known or suspected QTc interval prolongation, as well as in patients taking medicinal products that affect the QTc interval (as formoterol may cause prolongation of this interval). In patients with pre-existing cardiac disease, particular caution should be exercised during concomitant use of formoterol and theophylline. Due to the hyperglycaemic effect of formoterol, blood glucose monitoring is recommended in patients with diabetes mellitus. Formoterol may also cause severe hypokalaemia — particular caution and monitoring of serum potassium levels are recommended, as hypoxia in severe acute asthma may increase the risk of hypokalaemia (concomitant treatment with xanthine derivatives, corticosteroids, and diuretics may potentiate hypokalaemia).
As with any inhaled medicinal product, the use of formoterol carries a risk of paradoxical bronchospasm, which manifests as a sudden worsening of wheezing and dyspnoea. In such cases, a rapid-acting bronchodilator should be administered immediately and formoterol should be discontinued.
