Nasal Sprays: Overview and Formulation

• Nasal sprays are designed for local actions (e.g., congestion relief) or systemic delivery (e.g., hormone administration).

• Effective formulations require attention to drug properties, device considerations, and appropriate excipients.

Nasal Sprays

Key Formulation Considerations

Drug Properties:

• Solubility: Enhanced with solubilizers for aqueous/organic vehicles.

• Stability: Protect against light, oxygen, and pH-related degradation.

Particle/Droplet Size:

• Optimal Size: 10–100 µm for nasal deposition; 1–10 µm for pulmonary targeting.

Viscosity:

• Balance: Improves residence time but may affect droplet size.

pH and Isotonicity:

• pH: Near physiological (5.5–6.5) to avoid irritation.

• Isotonicity: Prevents mucosal damage.

Bioadhesive Polymers:

• Enhance residence time (e.g., cellulose derivatives, chitosan).

Penetration Enhancers:

• Facilitate drug absorption (e.g., cyclodextrins, surfactants).

Preservatives & Stabilizers:

• Prevent microbial growth (e.g., benzalkonium chloride).

• Antioxidants and chelating agents (e.g., ascorbic acid, disodium EDTA) stabilize formulations.

Propellants:

• Used in metered-dose sprays; consider environmental impact.

Device Considerations:

• Influence droplet size, spray pattern, and dosing.

Excipients in Nasal Spray Formulations

1. Solvents: Purified water, saline.

2. Thickeners/Viscosity Modifiers: Hydroxypropyl methylcellulose.

3. Buffers: Citric acid, phosphate buffers.

4. Isotonicity Agents: Sodium chloride.

5. Surfactants: Polysorbate 80 for solubilization.

6. Antioxidants: Sodium metabisulfite, ascorbic acid.

7. Chelating Agents: Disodium EDTA.

8. Emollients: Light mineral oil for soothing.

9. Propellants: For metered-dose delivery.

Nasal spray formulations focus on achieving efficacy, stability, and patient comfort while ensuring optimal drug delivery.