Salmeterol Xinafoate

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Cat Number

API94749083

CAS Number

94749-08-3

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Product Detail Description Scientific Support Customer Q&A

CAS Number

94749-08-3

EINECS

638-765-3

Storage

Store at room temperature

Synonyms

Salmeterol 1-hydroxy-2-naphthoate; GR 33343 G; DTXSID1045798; 6EW8Q962A5; DTXCID9025798

Molecular Formula

C36H45NO7

Molecular Weight

603.7

Smiles

C1=CC=C(C=C1)CCCCOCCCCCCNCC(C2=CC(=C(C=C2)O)CO)O.C1=CC=C2C(=C1)C=CC(=C2O)C(=O)O

Appearance

White to off-white crystalline powder

Melting Point

137-138℃

Boiling Point

603℃

Relative Density

1.112

General Description

Salmeterol xinafoate is a long-acting beta-2 adrenergic agonist (LABA) administered by oral inhalation for the maintenance treatment of asthma and chronic obstructive pulmonary disease (COPD). The xinafoate salt enhances the drug's lipophilicity, allowing for prolonged duration of action. It is available in dry powder inhalers and metered-dose inhalers, often in fixed-dose combinations with inhaled corticosteroids.

Mechanism of Action

Salmeterol selectively binds to and activates beta-2 adrenergic receptors on airway smooth muscle cells, stimulating intracellular adenylate cyclase to increase cyclic AMP production. Elevated cyclic AMP activates protein kinase A, which phosphorylates multiple targets leading to smooth muscle relaxation and bronchodilation. The long duration of action, exceeding 12 hours, results from the drug's high lipophilicity and membrane partitioning, allowing sustained receptor occupancy and activation.

Application

It is indicated for the maintenance treatment of asthma in patients aged four years and older, as well as for the management of COPD including chronic bronchitis and emphysema. It is not indicated for acute bronchospasm due to its slow onset of action. Due to an increased risk of asthma-related death seen in a large safety trial, salmeterol should never be used as monotherapy in asthma without concurrent use of an inhaled corticosteroid. Dosing is typically twice daily.

This real‑world matched cohort study compared fluticasone propionate/salmeterol delivered via pressurized metered‑dose inhaler (pMDI) versus dry powder inhaler (DPI) in COPD patients. At the 500 μg/day fluticasone dose, pMDI users had fewer moderate/severe exacerbations than DPI users (adjusted rate ratio 0.71; 95% CI 0.54–0.93). At the 1000 μg/day dose, exacerbation rates did not differ, but pMDI users had lower odds of needing a long‑acting muscarinic antagonist (LAMA) prescription. The authors suggest that at the lower ICS dose, the pMDI’s more efficient lung delivery translates into better clinical outcomes, whereas higher ICS dose may overcome DPI delivery inefficiencies.

Fig. 1 Comparison of outcomes between pMDI and DPI, in the 500 μg/d cohort. (Jones R, et al., 2017)

References

Jones R, et al. The comparative effectiveness of initiating fluticasone/salmeterol combination therapy via pMDI versus DPI in reducing exacerbations and treatment escalation in COPD: a UK database study. Int J Chron Obstruct Pulmon Dis. 2017; 12:2445-2454.

Does Salmeterol Xinafoate require refrigerated storage as a long-acting beta agonist?

No, it is stable at controlled room temperature (15-25°C). Refrigeration is not required but avoid excessive heat above 30°C to prevent degradation.

Is Salmeterol Xinafoate sensitive to light and moisture?

Yes, it is both photosensitive and hygroscopic. Store in original, tightly sealed, light-resistant containers with desiccant to maintain potency for inhalation use.

What is the stability of Salmeterol Xinafoate in dry powder inhaler formulations?

It shows good stability when blended with lactose and packaged in moisture-protective blister strips. We provide compatibility and stability data for DPI development.

How is the impurity salmeterol keto analog monitored?

This oxidative degradation product is quantified using a stability-indicating HPLC method, ensuring it remains within acceptable limits for inhalation-grade API.