Inhaled Salmeterol/Fluticasone Propionate

Salmeterol/fluticasone propionate, administered twice daily via a multidose dry powder inhaler (Seretide/Advair Diskus®, Seretide Accuhaler®) or metered-dose hydrofluoroalkane (chlorofluorocarbon-free) inhaler (Seretide Evohaler®), is a combination of the long-acting β₂-adrenoceptor agonist (β₂-agonist) [LABA] salmeterol and the corticosteroid fluticasone propionate.

Maintenance therapy with combined salmeterol/fluticasone propionate is at least as effective in improving lung function and symptoms and is as well tolerated in patients with asthma as concurrent salmeterol plus fluticasone propionate. In patients previously receiving as-required short-acting β₂-agonists (SABAs) or inhaled corticosteroids, salmeterol/fluticasone propionate was significantly more effective in providing asthma control than fluticasone propionate and in improving lung function and asthma symptoms than inhaled corticosteroids (at equivalent or higher dosages), salmeterol or montelukast (as monotherapy or in combination with fluticasone propionate). Salmeterol/fluticasone propionate was more effective in improving asthma symptoms than adjusted-dose budesonide/formoterol in patients with uncontrolled asthma despite treatment with inhaled corticosteroids with or without a LABA in a well designed 1-year study. In pharmacoeconomic analyses, salmeterol/fluticasone propionate compared favourably with inhaled corticosteroids and mono- or combination therapy with oral montelukast. Salmeterol/fluticasone propionate is, therefore, an effective, well tolerated and cost-effective option for the maintenance treatment of patients with asthma.

The pharmacokinetics of salmeterol and fluticasone propionate administered concomitantly using the same inhaler are generally similar to those of the two agents administered separately. The absolute bioavailability of fluticasone propionate is 10–30% of the inhaled dose. Salmeterol is extensively metabolised by hydroxylation, whereas fluticasone propionate is metabolised by the cytochrome P450 (CYP) isoenzyme CYP3A4 to an inactive metabolite. Drug interactions between fluticasone propionate and potent CYP3A4 inhibitors may occur.

Combined salmeterol/fluticasone propionate was as least as effective in improving lung function and asthma symptoms as the two agents administered using separate inhalers in adults, adolescents and children (aged 4–11 years).

Significantly more patients receiving twice-daily salmeterol/fluticasone propionate than those receiving twice-daily fluticasone propionate achieved totally controlled asthma in a large 1-year study in patients with asthma of varying severity. Moreover, in 12- or 24-week studies in asthmatic patients previously receiving as-required SABAs or inhaled corticosteroids, improvements from baseline in lung function and asthma symptoms were significantly greater with salmeterol/fluticasone propionate than with monotherapy with inhaled corticosteroids, salmeterol or montelukast, or combination therapy with montelukast plus fluticasone propionate. In several studies, this was achieved at substantially lower corticosteroid dosages. In addition, salmeterol/fluticasone propionate provided more effective protection against exercise-induced asthma than fluticasone propionate. In a well designed 1-year trial in patients with uncontrolled asthma despite receiving inhaled corticosteroids with or without a LABA, salmeterol/fluticasone propionate was more effective in improving asthma symptoms and preventing exacerbations than adjusted-dose budesonide/formoterol.

Twice-daily salmeterol/fluticasone propionate produced clinically meaningful improvements from baseline in asthma-related quality of life scores.

Salmeterol/fluticasone propionate was well tolerated in patients with asthma in trials of 4–52 weeks’ duration. The most frequently occurring adverse events were headache, throat irritation/cough, hoarseness/dysphonia and candidiasis. No significant differences in markers of systemic glucocorticoid activity were seen between patients receiving concurrent or combined salmeterol/fluticasone propionate 50μg/100μg or 50μg/500μg twice daily in 12- or 28-week studies, or between patients receiving salmeterol/fluticasone propionate 50μg/250μg or 50μg/500μg twice daily or the same nominal dosage of fluticasone propionate.

In pharmacoeconomic analyses from a healthcare payer perspective, salmeterol/fluticasone propionate was cost effective. It was associated with favourable incremental function- and symptom-based cost-effectiveness ratios relative to monotherapy with inhaled corticosteroids or oral montelukast in the UK, US and Sweden. Salmeterol/fluticasone propionate was cost saving relative to combination therapy with montelukast plus fluticasone propionate with regard to the cost per successfully treated patient in the US and with regard to the cost per successfully treated week, symptom-free day, symptom-free night and episode-free day in The Netherlands.