RU2737505C1 - Stent with polymer coating medical article - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to implantable vascular medical devices for local delivery of a therapeutic agent, and discloses a medical product of a stent with polymer coatings. Stent includes metal base with diameter of 16 mm and length of 30 mm in open state, is woven from single wire of 280 mcm-thick TiNi alloy, having shape memory effect, wherein the stent is coated with a continuous coating of a non-bioresorbable polysiloxane polymer, which provides reliable adhesion to the base, wherein for applying the polysiloxane, a method is used for dipping into a solution with additive 4 wt. % of a cold curing catalyst, rate of extracting the stent from the container with polymer is 0.5 mm/s, and a biodegradable coating which is a polyglycolide containing a drug which is applied on the inner surface of the stent by spraying through a nozzle.

EFFECT: stent is characterized by longevity, wide range of operational properties and high biocompatibility due to complex multicomponent structure of created material and can be used for prevention and treatment of stenosis.

1 cl, 1 ex

Description

The invention relates to medicine, namely to implantable vascular medical devices for local delivery of a therapeutic agent or several agents, and can be used for the prevention and treatment of stenosis.

Known invention is a double stent (RU2 706 532 C1, publ. 11/19/2019), consisting of an external stent, a polymer layer located on the inner surface of the external stent, an internal stent located on the inner side of the polymer layer specified above and an internal polymer layer located on the inside of the inner stent. This design is intended for high-quality connection of the polymer layer with the metal base of the product, and also implies increased forces of radial expansion in relation to single walls of standard designs, in cases where there is a clinical need for this.

The disadvantage of this invention is indicated in the invention itself, namely, due to the multilayer structure, implying two metal frames, an increased thickness of the structure appears, which is proposed to be reduced by using thinner metal stents. However, a decrease in the thickness of the original stents will lead to a decrease in the radial expansion forces of the final product according to the invention, which raises the question of the advisability of using thicker single metal stents that provide the necessary radial expansion forces than the two stents proposed in the invention, since thicker versions of single stents in thickness walls can be equal to double walls using thin stents, but the former will be more cost effective.

There is a known invention, a method of applying a continuous coating on a stent and a stent obtained by the said method (RU 2 458 708 C2, IPC A61L 27/34, publ. 20.08.2012), which describes a continuous coating of a stent with a polymer, namely, a solution to the problem of reliable fixation of the polymer layer to the metal frame products. It is proposed to apply the polymer in two stages, in the first stage, the application is not continuous, but covering only the metal frame, being in fact a primer layer, in the second stage, a continuous coating is applied, which binds to the first coating layer.

The disadvantage of this patent is the additional manufacturing step that can be avoided by using polymers with high adhesive properties, such as polysiloxane.

As a prototype, the patent (US No. 6258121 B1. Class A61F 2/06, publ. 10.07.2001) was chosen, which describes a two-layer polymer coating with an active substance paclitaxel. The first layer of the coating consists of a mixture of two polymers: polyethylene oxide polylactide, a rapidly degrading material. The second layer is a slowly disintegrating material consisting of a mixture of polylactide and polycaprolactone, and paclitaxel is used as an active substance, which suppresses the development of restenosis after plastic surgery on vessels.

The disadvantages of this invention are the use of polylactide as a biocompatible coating, in which, when the product is used in the human body, the release of lactic acid monomers occurs, accompanied by significant acidification of tissues (pH shift 3.2-3.4). Polylactide does not differ in heat resistance and when heated over 50 ° C, polylactide products are deformed, and, as a consequence, they cannot be sterilized using thermal methods. The resorption period of polylactide is less than 2 weeks. To increase the strength, temperature and biocompatible properties, polylactide is modified with the addition of polyglycolic acid and other processing aids. This makes the coating difficult.

The objective of the invention is to provide a stent that is optimal in the treatment of some vascular diseases.

The technical result is a stent product consisting of a TiNi metal base, a solid non-bioresorbable polymer, a bioresorbable polymer polyglycolide with an embedded drug.

The technical result is achieved by the fact that in a medical device a polymer-coated stent consisting of a stent with a metal base with a shape memory effect, namely, a TiNi alloy, which has a continuous coating of a non-bioresorbable polymer, which provides reliable adhesion to the base, to which the inner the side is coated with a bioresorbable coating containing the drug. Durability, a wide range of performance properties and high biocompatibility can be provided by a complex multicomponent structure of the created material. The use of TiNi as a basis for biomedical products will provide them with minimization of the traumatic effect of the operation by reducing the size in the transport position, reducing the section of the mechanism of their delivery to the restored organ, coincidence in geometric parameters with the curved sections of the prosthetic organ, and improved mechanical characteristics. The introduction into the composition of the composite material of a shell made of a biodegradable biopolymer material (polyglycolide) will provide medical devices with the possibility of local therapeutic effects due to the controlled release of drugs for a given time. At the same time, the choice of a drug is practically unlimited. The formation of a biodegradable polymer shell (polysiloxane) under the biodegradable layer will provide an increase in the area for applying a drug coating, preventing the penetration of the affected tissues through the walls of the stent.

TiNi alloys have mechanical properties that are close to the characteristics of living tissues - superelasticity and compliance with the law of retardation, which led to its use in medicine, as well as the shape memory effect, which makes it possible to produce from it products that independently change their shape as a result of any action. In particular, these properties determine its use for creating self-expanding stents, which are recognized as more convenient and safer for implantation into the human body than those made from other materials.

Polyglycolide is noted as a very promising material for medical use with extremely high biocompatibility, hydrophilicity, sufficient elasticity and strength, has a biological origin (a derivative of lactic acid) and, upon degradation, decomposes to carbon dioxide and water, while having a structure suitable for fixing inside its volume drug molecules of various nature.

Polysiloxane (thermoplastic silicone, block copolymer of polydimethylsiloxane and polyurethane) is a heat-resistant polymer that does not dissolve in water and aqueous solutions. The rigid organic block provides high mechanical strength in a wide temperature range, and the elastic block provides excellent elastomeric properties, elasticity at low temperatures, gas permeability (does not retain oxygen and carbon dioxide molecules), high resistance to UV radiation. It has high adhesion to various materials and can be used as an adhesive. Does not contain volatile substances, stable and shelf-stable for unlimited time. Dyeing and recyclable. Suitable for creating both non-resorbable continuous shells for the entire product, and surface layers on material samples of any geometric configuration.

An example of a specific implementation of the invention:

A stent with a diameter of 16 mm and a length of 30 mm in the open state was taken as a basis, braided from a single strand of wire with a thickness of 280 μm of TiNi alloy. For the deposition of the first polymer, the method of dipping into a polysiloxane solution with the addition of 4 mass% cold curing catalyst was used. For the most uniform coating, the rate of stent extraction from the container with the polymer was chosen 0.5 mm / s. The dipping was carried out 3 times in a row. After complete curing of the polysiloxane by spraying through a nozzle, polyglycolide with the drug heparin was sprayed on the inner surface of the stent.

Claims (1)

A medical product is a polymer-coated stent, characterized by the fact that a stent with a metal base 16 mm in diameter and 30 mm long in the open state is woven from a single strand of wire with a thickness of 280 μm of TiNi alloy with a shape memory effect, while the stent is coated with a continuous coating of non-bioresorbable polymer of polysiloxane, providing reliable adhesion to the base, while the method of dipping into a solution with the addition of 4 wt% cold curing catalyst is used to apply polysiloxane, the rate of stent extraction from the container with the polymer is 0.5 mm / s, and a biodegradable coating, which is a polyglycolide containing a drug that is sprayed onto the inner surface of the stent through a nozzle.