Standard Operating Procedure for Formation of Solid Lipid Nanoparticles (SLNs)
1) Purpose
This SOP provides the steps for preparing solid lipid nanoparticles (SLNs), which are used in drug delivery systems for improving the bioavailability of poorly soluble drugs.
2) Scope
This SOP applies to laboratory personnel involved in the preparation of SLNs using the hot and cold homogenization methods.
3) Responsibilities
- Operators: Responsible for accurately preparing SLNs according to this SOP.
- QA: Ensures SLNs meet the required specifications for particle size, stability, and drug encapsulation.
4) Procedure
4.1 Preparation of Lipid Phase
4.1.1 Lipid Selection
- 4.1.1.1 Select a solid lipid suitable for the drug to be encapsulated (e.g., glyceryl monostearate, Compritol).
4.1.2 Melting the Lipid
- 4.1.2.1 Melt the solid lipid at a temperature 5–10°C above its melting point.
4.2 Drug Incorporation
4.2.1 Drug Loading
- 4.2.1.1 Dissolve or suspend the drug in the molten lipid phase and stir until the drug is uniformly dispersed.
4.3 Formation of SLNs
4.3.1 Emulsification
- 4.3.1.1 Add the molten lipid-drug mixture to an aqueous phase containing a surfactant (e.g., Poloxamer 188) under high-speed stirring to form an emulsion.
- 4.3.1.2 Use a high-pressure homogenizer to reduce the particle size.
4.3.2 Cooling
- 4.3.2.1 Cool the emulsion to room temperature, allowing the solid lipid to recrystallize, forming SLNs.
4.4 Washing and Collection of SLNs
4.4.1 Centrifugation
- 4.4.1.1 Centrifuge the SLN suspension at 10,000 g to collect the nanoparticles and wash with distilled water.
4.5 Particle Size Measurement
4.5.1 DLS Analysis
- 4.5.1.1 Use dynamic light scattering (DLS) to measure particle size and ensure that SLNs meet the required size specifications (typically 50–300 nm).
4.6 Storage
4.6.1 Storage Conditions
- 4.6.1.1 Store the SLN suspension in sterile, sealed containers at 4°C to maintain stability.
5) Abbreviations, if any
- DLS: Dynamic Light Scattering
6) Documents, if any
- SLN Formation Logbook
7) References, if any
- SLN formulation protocols for drug delivery
8) SOP Version
Version 1.0
Annexure
SLN Formation Logbook Template
| Date | Batch Number | Lipid Type | Particle Size | Encapsulation Efficiency | Operator Initials | QA Initials |
|---|---|---|---|---|---|---|
| DD/MM/YYYY | Batch Number | Lipid Type | Size in nm | % Encapsulation | Operator Name | QA Name |
