English Translation

The preparation method of drug-coated balloon coatings directly affects drug loading capacity, release rate and coating stability. Different preparation processes have their own advantages and disadvantages, adapting to diverse clinical requirements and production scenarios. This article elaborates on the procedures, characteristics and application examples of seven mainstream preparation processes, providing a reference for process selection.

There are various preparation methods for drug-coated balloon coatings, each with unique process characteristics, applicable scenarios and technical key points. The seven mainstream preparation processes are analyzed in detail as follows:

1 Solvent Evaporation Method (Direct Crystalline Coating)

Process Procedures: Drug dissolution (paclitaxel dissolved in organic solvents such as acetone and ethanol) → Coating (ultrasonic spraying or dip coating) → Solvent evaporation (rapid evaporation under controlled temperature and humidity, with drugs deposited in microcrystalline form) → Post-treatment (heat treatment or mechanical compression to enhance adhesion).

Characteristics: Carrier-free design with drugs directly exposed on the surface, enabling fast drug release; solvent selection, coating speed and drying conditions need to be optimized to prevent excessive drug crystallization or coating peeling.

Application Example: Some early-generation drug-coated balloons (e.g., PACCOCATH® technology).

2 Carrier Matrix Blending Coating

Process Procedures: Drug-carrier mixing (paclitaxel mixed proportionally with hydrophilic carriers such as iopromide and urea, and dissolved in solvent to form a homogeneous solution) → Coating (ultrasonic spraying) → Drying and curing (low-temperature or vacuum drying to form a matrix film) → Stability treatment (adding antioxidants or adjusting pH value).

Characteristics: The carrier can regulate the drug release rate (e.g., iopromide facilitates rapid drug release); compatibility between drugs and carriers must be ensured to avoid phase separation.

Application Example: SeQuent Please® balloon (paclitaxel + iopromide).

3 Microstructure Loading Technology

Process Procedures: Surface microfabrication (laser etching, micro-embossing or 3D printing to create micropores and grooves on the balloon surface) → Drug filling (injecting paclitaxel solution/powder into microstructures and fixing via capillary action or vacuum adsorption) → Sealing treatment (covering with PLGA degradable film or water-soluble protective layer).

Characteristics: Microstructures reduce drug loss during delivery; mechanical stress during balloon expansion destroys the protective layer to achieve burst drug release.

Application Example: Nanoimprint lithography is adopted to fabricate microstructures in some experimental balloons.

4 Nanoparticle/Liposome Encapsulation Method

Process Procedures: Drug encapsulation (paclitaxel encapsulated in PLGA nanoparticles or liposomes) → Coating preparation (dispersing drug-loaded nanoparticles in solvent and spin-coating with precision dispensing equipment) → Crosslinking and curing (fixation via ultraviolet light or chemical crosslinking agents).

Characteristics: Nano-carriers prolong drug release duration and improve cellular uptake efficiency; the process is sophisticated with strict control over particle size and dispersion uniformity required.

5 Multi-layer Coating Technology

Process Procedures: Bottom layer (adhesive layer coated with polyurethane, silica gel, etc.) → Middle layer (drug layer loaded with paclitaxel by solvent evaporation or carrier blending method) → Outer layer (water-soluble protective layer coated with PEG).

Characteristics: The layered design enables precise regulation of drug release kinetics; the process is complex and requires multiple rounds of coating and drying procedures.

6 Freeze-drying Coating

Process Procedures: Drug solution preparation (paclitaxel mixed with excipients such as mannitol and dissolved in water or organic solvents) → Pre-freezing (rapid freezing below -80°C after coating) → Vacuum drying (solvent removed by sublimation under low pressure to form a porous drug layer).

Characteristics: The porous structure improves drug loading capacity and reduces solvent residue; the freeze-drying rate must be strictly controlled to avoid structural collapse.

7 Electrospinning Coating (Efficacy Not Yet Verified)

Process Procedures: Spinning solution preparation (paclitaxel blended with polymers such as PCL and PLGA and dissolved in volatile solvent) → Electrospinning (nanofibers formed under high-voltage electric field and deposited on the balloon surface) → Post-treatment (heat treatment or crosslinking to enhance stability).

Characteristics: Nanofiber membranes feature large specific surface area to accelerate drug release; low equipment cost, with precise control over parameters such as voltage and flow rate required.

The seven preparation processes are based on different technical logics to meet the diversified demands of drug-coated balloon coatings. From the traditional solvent evaporation method to the cutting-edge nano-encapsulation method, the iteration of processes drives the performance improvement of drug-coated balloons. Selecting an appropriate preparation process based on clinical needs, production costs and technical maturity is the key to high-quality manufacturing of drug-coated balloons.