RESUMEN
【Objective】 To eliminate the insoluble particles in the drug and the particles produced by breaking the glass during intravenous or intramuscular injection. 【Methods】 We established a type of liquid medicine filter for preventing insoluble particles in this study. The front end of the filter body was conical and the back end was a filtering one. The filter body consisted of a filter block and a floating plug arranged inside the filter block. A filter chamber was formed inside the filter block， and a ring-shaped filter membrane was set in the filter chamber. When the injector pumped liquid， the float plug moved to the top of the float plug channel of the filter block， and the liquid entered the filter cavity from the blind hole of the float plug. When the syringe discharged liquid， the float plug was far away from the top of the float plug channel of the filter block， and the liquid in the filter cavity entered the blind hole of the float plug through the annular filter membrane and the peripheral channel of the filter block. 【Results】 The filtration rates of 5‒6 μm particles in standard solution of 5 μm latex particles by nuclear pore membrane， polyethersulfone membrane and nylon membrane were 96.9%， 97.1% and 96.2%， respectively. The filtration rate of 3‒4 μm particles in the standard solution of 3 μm latex particles could reach 98.1%. 【Conclusion】 The filter can filter the particles， which precipitate in the drug， thus achieving the effect of filtration and ensuring the safety of patients.