Application of PP in the pharmaceutical industry: safety cornerstone and functional innovation

PP (polypropylene), as a high-performance thermoplastic polymer, has become a core material in the pharmaceutical industry from drug packaging, medical devices to medical consumables due to its excellent biocompatibility, chemical stability, high temperature resistance, and processing flexibility. Its compliance has passed authoritative certifications such as China's GB 4806.7-2024 "National Food Safety Standard for Plastic Materials and Products in Contact with Food" (reference for pharmaceutical contact materials), EU Regulation No. 10/2011, and US FDA 21 CFR Part 177.1520. It does not contain harmful substances such as bisphenol A (BPA) and phthalates, and deeply meets the core requirements of the pharmaceutical industry for "safety, controllability, stable performance, and green environmental protection". It plays a key role in promoting the upgrading of pharmaceutical product quality and medical technology innovation.

1、 The core feature of PP adaptation to the pharmaceutical industry: precise matching of performance and requirements

PP can be widely used in the pharmaceutical field, essentially because its physical and chemical properties are highly compatible with the storage, processing, and clinical needs of pharmaceutical products, especially in the four dimensions of biological safety, chemical stability, high temperature resistance, and processing plasticity, forming irreplaceable advantages that far exceed traditional plastics such as PS (polystyrene) and PVC (polyvinyl chloride).

1. Biosafety: an absolute prerequisite for pharmaceutical applications

Medical contact materials are directly related to patient health, and the biosafety performance of PP has been rigorously validated

No harmful substance migration: The PP main chain is composed of saturated carbon carbon bonds, with a stable molecular structure and no easily breakable functional groups or residual monomers. At conventional medical temperatures (-20 ℃ to 120 ℃), harmful ingredients such as plasticizers, heavy metals, volatile organic compounds, etc. will not migrate into drugs, body fluids, or tissues. After long-term toxicology testing, its specific migration volume (SML) and total migration volume (OML) are far below the national standard limits, and it can be safely used in high-end pharmaceutical scenarios such as injections and implantable devices.

Excellent biocompatibility: When PP comes into contact with human tissues, blood, and mucous membranes, it will not cause immune rejection, cytotoxicity, or allergic reactions. The relative cell proliferation rate (RGR) is ≥ 90%, which meets the GB/T 16886.5-2017 biocompatibility standard. Its inert surface can reduce protein adsorption and bacterial adhesion, lower the risk of clinical infection, and meet the contact needs of multiple parts such as the oral cavity, blood vessels, and skin.

2. Chemical stability: ensuring the performance of drugs and devices

The chemical substances such as acidity, alkalinity, solvents, and disinfectants in the pharmaceutical environment are complex, and PP has significant advantages in corrosion resistance:

Corrosion resistance of drugs and excipients: PP has excellent tolerance to common medicinal ingredients (such as vitamins, antibiotics, alkaloids), excipients (such as ethanol, glycerol, polyethylene glycol), and acid-base buffer solutions (pH 2-12), without dissolution, swelling, or degradation, ensuring that the ingredients of the drug remain stable and the efficacy remains unchanged during the shelf life. For example, aspirin enteric coated tablets packaged in PP can avoid the decrease in content caused by the reaction between the drug and the packaging.

Anti disinfection and sterilization treatment: PP can tolerate mainstream disinfection methods in the pharmaceutical industry, including high-temperature steam sterilization (121 ℃, 20min), ethylene oxide (EO) sterilization, and gamma ray irradiation sterilization. The mechanical property retention rate after sterilization is ≥ 85%, and there is no harmful substance precipitation, meeting the sterile requirements of disposable medical devices.

3. High temperature resistance: suitable for processing and clinical scenarios

The production and use of pharmaceuticals often involve high-temperature processes, and the heat resistance of PP solves the key pain points:

Processing and sterilization compatibility: PP has a melting point of about 160-170 ℃, and can be continuously used at temperatures up to 100-120 ℃. It can tolerate drug filling (such as 60-80 ℃ hot oil solution), high-temperature sterilization and other processes, and has stable dimensions after molding without deformation or cracking. For example, after steam sterilization at 121 ℃, the body of PP infusion bottles still maintains complete sealing.

Clinical heating safety: PP is one of the few medical plastics that can be safely used for microwave heating. Some modified PP can withstand short-term high temperatures of 130 ℃ and is suitable for oral preparation heating, medical dressing hot compress and other scenarios. There is no harmful substance release during the heating process.

4. Processing and cost advantages: supporting large-scale applications

The pharmaceutical industry has strict requirements for production efficiency and cost control, and the characteristics of PP are perfectly adapted:

Strong process flexibility: PP can be produced through injection molding, blow molding, extrusion, thermoforming, spinning and other processes to produce a variety of products ranging from micrometer sized syringe components to large medical device casings. The injection molding process can achieve high-precision molding (with a dimensional tolerance of ± 0.01mm), and is suitable for precision components such as syringe barrels and infusion drippers; The extrusion process can produce films and pipes to meet packaging and conduit requirements.

Cost and environmental balance: The cost of PP raw materials is only 70% of PET and 50% of PC, and the processing energy consumption is low (the molding temperature is 30-50 ℃ lower than PET), significantly reducing the production cost of enterprises; At the same time, PP can be recycled (recycling label "No. 5"), and after purification, recycled PP can be used for the outer packaging of non direct contact drugs, which is in line with the green development trend of the pharmaceutical industry.

2、 The core application of PP in the field of pharmaceutical packaging: full dosage form protection system

Packaging is the main application scenario of PP in the pharmaceutical industry, accounting for over 65%. Based on the drug form (solid, liquid, semi-solid) and dosage form characteristics, targeted packaging solutions are formed to provide full cycle guarantee for drug quality.

1. Solid formulation packaging: the core barrier for moisture and oxidation prevention

Solid preparations such as tablets, capsules, and granules are easily affected by moisture and oxygen. PP packaging achieves precise protection through innovative forms:

Bubble wrap packaging (PTP): PP hard sheet is the core substrate of bubble wrap packaging, with a thickness of 0.2-0.4mm, and forms an independent drug cavity after heat sealing with aluminum foil. Its advantages lie in: firstly, strong barrier properties, with a water vapor transmission rate of ≤ 1g/(m ² · 24h) and an oxygen transmission rate of ≤ 5cm ³/(m ² · 24h · 0.1MPa), which can extend the shelf life of drugs to 1-3 years; Secondly, it has good formability and can be stamped into different specifications of medication chambers, suitable for low-dose tablets and capsules; Thirdly, it has high transparency, making it easy to observe whether the appearance of the drug is damaged or discolored. For example, the blister packaging of antihypertensive and hypoglycemic drugs uses PP hard tablets to ensure accurate dosage and stable efficacy.

Bottled packaging: injection molded PP bottles are suitable for large capacity solid preparations, such as vitamin tablets, traditional Chinese patent medicines and simple preparations granules, etc. The bottle body adopts a screw cap or anti-theft cap design, matched with a silicone sealing ring, with excellent sealing performance; Some high-end medicine bottles are equipped with a desiccant compartment to further reduce the humidity inside the bottle (relative humidity ≤ 30%) and prevent the drugs from absorbing moisture and clumping. The weight of PP medicine bottles is only 1/5 of glass bottles of the same capacity, and the transportation damage rate is less than 0.1%, significantly reducing logistics costs.

2. Liquid formulation packaging: leakage prevention and compatibility guarantee

Oral liquid, syrup, topical detergent and other liquid preparations require extremely high sealing and chemical compatibility in packaging, and PP packaging is perfectly compatible:

Oral liquid bottle: Blow molded PP bottles are the mainstream packaging for oral liquids and syrups, with a capacity of 5-100mL. Their inner walls are smooth and not easily adsorbed with medicinal ingredients such as polysaccharides and alkaloids, ensuring accurate dosage; The bottle body has strong impact resistance and does not break when dropped at a height of 1.5m, avoiding contamination from liquid leakage; The bottle mouth is designed as a spiral mouth or press type, suitable for dispensing devices such as droppers and measuring cups, making it convenient for patients to access. For example, the PP bottle of children's cough syrup adopts anti misoperation bottle cap and graduated measuring cup, balancing safety and convenience.

External liquid packaging: PP bottles or PP/PE composite pipes are used for packaging external detergents and disinfectants, such as iodine, physiological saline, etc. The chemical resistance of PP can prevent chemical corrosion of the packaging, and the extrusion design of the composite pipe is easy to control the dosage and avoid waste; Some products are made of light resistant PP material (with added carbon black masterbatch) to prevent photosensitive drugs (such as hydrogen peroxide solution) from decomposing under light.

3. Semi solid formulation packaging: balance of sealing and extrusion properties

Semi solid preparations, such as ointment, cream, gel, etc., need to take into account both storage sealing and use extrudability. PP composite packaging is an ideal choice:

Composite hose: PP/aluminum/PE composite hose is the core packaging of semi-solid preparations. The outer layer of PP provides strength and printability, the aluminum layer blocks oxygen and ultraviolet rays, and the inner layer of PE comes into direct contact with drugs, with good flexibility. The hose can achieve precise extrusion with a residual amount of less than 5%, and the nozzle can be designed in the form of a pointed or flat mouth, suitable for scenarios such as skin application and intracavitary drug delivery. For example, the hormone ointment and hemorrhoid gel for dermatology use PP composite hose to ensure that the drug will not be oxidized or deteriorated within the warranty period.

Canned packaging: Large capacity semi-solid preparations (such as 50-500g medical Vaseline, burn ointment) are packaged in PP wide mouthed cans, with the can body and lid sealed by threads for good sealing; The diameter of the can mouth is ≥ 5cm, which is convenient for cotton swabs to dip or apply directly, and the PP material is easy to clean and can be repeatedly opened and used.

3、 The application of PP in the field of medical devices and consumables: the material basis for clinical safety

PP, with its biocompatibility and mechanical properties, is widely used in medical devices, disposable consumables, and other fields, covering the entire process of diagnosis, treatment, and nursing, and is an important guarantee for clinical safety.

1. Disposable medical consumables: the core carrier for preventing cross infection

Disposable consumables need to meet the requirements of sterility, safety, and low cost. PP is the preferred material, accounting for more than 40% of disposable medical consumables raw materials:

Injection and infusion consumables: injection molded PP syringe barrels, infusion set droppers, and catheter fittings, with high dimensional accuracy (inner diameter tolerance ± 0.02mm) and good transparency, making it easy for medical staff to observe the status of bubbles and medication; The chemical inertness of PP can prevent reactions with the drug solution, such as during the injection of penicillin and cephalosporin antibiotics, the PP syringe has no adsorption phenomenon, ensuring accurate dosage. In addition, the PP infusion tube is made of medical grade PP material, which is soft, bending resistant, and has a stable infusion flow rate.

Nursing consumables: PP is used to make medical trays, urine bags, drainage bags and other nursing consumables. PP tray is resistant to high temperature sterilization and can be reused more than 50 times; The urine bag is made of PP film and PE valve, with good sealing and leakage prevention. The bag body is printed with a scale for easy monitoring of urine volume; The PP buckle of the drainage bag has high strength and can bear 5kg, suitable for clinical mobility needs.

2. Diagnostic and testing consumables: accuracy and stability guarantee

Diagnostic testing has strict requirements for the accuracy and stability of consumables, and the processing accuracy of PP can meet the requirements:

Laboratory consumables: PP centrifuge tubes, PCR reaction tubes, and colorimetric dishes are the core consumables in biological laboratories. PP centrifuge tube has a centrifugal force resistance of ≥ 15000g, does not deform after high-temperature sterilization, and is suitable for separating samples such as blood and urine; The PCR reaction tube has a uniform wall thickness (± 0.01mm), good thermal conductivity, and can achieve rapid temperature rise and fall (rate ≥ 5 ℃/s) to ensure amplification efficiency; The transmittance of the colorimetric dish is ≥ 85%, without optical interference, ensuring accurate detection results. For example, the inner wall of the PP sampling tube for COVID-19 nucleic acid detection is silane treated to avoid nucleic acid adsorption and improve the detection rate.

Diagnostic equipment components: PP is used for the housing and test strip holder of portable diagnostic equipment such as blood glucose meters and blood lipid analyzers. Its impact resistance can protect internal precision components, and the surface is easy to clean and disinfect, making it suitable for home and clinical scenarios; The detection chip base of some devices is made of PP material, which is injection molded with high temperature resistance to ensure a tight fit between the chip and the base and avoid detection errors.

3. Treatment and rehabilitation equipment: dual support of function and experience

Treatment and rehabilitation equipment need to balance functional implementation and patient experience, and the modified properties of PP can meet diverse needs:

Orthopedics and sports rehabilitation equipment: Modified PP (reinforced with glass fiber) is used for orthopedic splints, braces, and walking aid components. Its strength is close to aluminum alloy (tensile strength ≥ 40MPa), and its weight is only one-third of aluminum alloy, making it easy for patients to wear and move; The surface is smooth and free of burrs, which can prevent skin wear and tear, and is resistant to sweat corrosion, with a service life of ≥ 2 years. For example, PP splints for fracture patients can be shaped according to the shape of the limbs, with good fixation effect and high comfort.

Oral and ophthalmic instruments: PP is used to make invisible denture bases and ophthalmic surgical instrument handles. The biocompatibility of medical grade PP can avoid irritation to the oral mucosa and ocular surface; The invisible denture base is made of transparent PP material, which has good aesthetics and moderate elasticity, and can provide continuous correction force; The PP material of the ophthalmic instrument handle has strong anti slip properties, making it easy for doctors to operate and resistant to disinfectant immersion, ensuring sterility.

4、 Innovative development of PP in the pharmaceutical industry: functional upgrading and green transformation

With the advancement of pharmaceutical technology and the upgrading of environmental protection needs, PP is developing towards functionalization, high-end, and green direction through innovation in modification, compounding, and recycling technologies, expanding its application boundaries.

1. Modified PP technology: meets high-end pharmaceutical needs

Develop high-performance PP materials through chemical modification or addition of functional additives, suitable for high-end pharmaceutical scenarios:

Antibacterial PP: Packaging and consumables made by adding antibacterial agents such as silver ions and zinc oxide nanoparticles have a surface antibacterial rate of ≥ 99%, which can inhibit the growth of Escherichia coli and Staphylococcus aureus and reduce the risk of hospital infections. For example, antibacterial PP infusion sets and dressing change trays can reduce microbial contamination in clinical use; Antibacterial PP bottles can extend the shelf life of sterile drugs.

High barrier PP: Developed by blending or nanocomposite with EVOH (ethylene vinyl alcohol copolymer), high barrier PP with oxygen permeability ≤ 1cm ³/(m ² · 24h · 0.1MPa) can replace glass for injection packaging and reduce transportation costs. For example, high barrier PP pre filled syringes can store biological agents (such as insulin, vaccines) with a shelf life of up to 2 years.

Degradable PP: Degradable PP medical consumables such as surgical sutures and wound dressing substrates are made by adding degradable ingredients such as starch and PBAT (polybutylene adipate terephthalate). They can be completely degraded within 6-12 months in the body or natural environment, avoiding secondary pollution.

2. Pharmaceutical grade application of regenerated PP: a new path for green development

With the promotion of the "dual carbon" policy, the pharmaceutical grade application of recycled PP has become a hot topic. Through precise recycling and purification technology, recycled PP can be used for packaging and equipment of non direct contact drugs:

Recycling and purification process: Adopting the "sorting cleaning melting filtration modification" process, impurities and pollutants in PP waste are removed, and the mechanical properties and purity of regenerated PP can reach medical grade standards (ash content ≤ 0.05%, heavy metal content ≤ 1ppm). For example, recycled PP infusion bottles can be purified and made into pharmaceutical packaging boxes and instrument trays, achieving resource recycling.

Compliance application scenarios: The European Union has approved the use of recycled PP for drug packaging and medical device transport boxes, and China has also specified the usage standards for recycled plastics in GB 4806.7-2024. It is expected that the usage rate of recycled PP in the pharmaceutical industry will reach 20% by 2025, reducing the consumption of raw plastics by 300000 tons per year.

3. Integration of PP and cutting-edge technology: material support for innovative healthcare

The integration of PP with 3D printing, intelligent sensing and other technologies promotes medical technology innovation and expands application boundaries

3D printing customized medical devices: Medical grade PP powder can be 3D printed using selective laser sintering (SLS) technology to customize medical devices such as maxillofacial restorations, dental implant guides, hearing aid housings, etc. The printing product has high accuracy (size error ≤ 0.1mm), perfectly fits the patient's anatomical structure, and improves the treatment effect. For example, 3D printed PP restorations can achieve personalized appearance restoration for patients with congenital maxillofacial deformities.

Intelligent medical consumables: temperature and humidity sensors are integrated on PP substrate to make intelligent wound dressings, intelligent infusion sets, etc. For example, the PP substrate of intelligent wound dressings can monitor the temperature and humidity of the wound in real time, and the data is wirelessly transmitted to the nurse station to achieve wound infection warning; The PP dropper of the intelligent infusion set is equipped with a flow sensor that can automatically alert the completion of infusion, avoiding the risk of air embolism.

5、 Challenges and coping strategies of PP application in the pharmaceutical industry

Despite the significant advantages of PP, it still faces challenges in high-end applications, recycling, and other areas, which need to be addressed through technological breakthroughs and industry collaboration

1. Main challenges

High end modified materials rely on imports: The core technologies of high-end materials such as high barrier PP and antibacterial PP (such as nanocomposite technology and antibacterial agent dispersion technology) are monopolized by foreign companies, and domestic products have gaps in barrier properties and antibacterial persistence. High end pharmaceutical packaging still relies on imports, with an import dependence rate of ≥ 30%.

The recycling system is incomplete: pharmaceutical PP waste is difficult to process before recycling due to the possibility of residual drugs or biological pollutants; Moreover, different types of PP (ordinary PP, modified PP, composite PP) are mixed, resulting in high separation and purification costs. The pharmaceutical grade utilization rate of regenerated PP is only 10%.

Lagged standard system: The lack of standards for 3D printed PP medical devices and recycled PP pharmaceutical applications, as well as inconsistent product safety evaluation methods, have hindered the process of innovative product launch.

2. Response strategies

Strengthen core technology research and development: collaborate with industry, academia, and research to tackle key technologies such as nanocomposites and long-term fixation of antibacterial agents, and improve the localization rate of high-end PP materials; Establish a PP material performance database to provide precise material selection solutions for different pharmaceutical scenarios.

Building a pharmaceutical PP recycling system: Establishing a closed-loop system of "production use recycling", medical institutions classify and collect PP waste, and professional enterprises carry out disinfection, sorting, and purification; Introduce subsidy policies for regenerated PP pharmaceutical applications to reduce recycling costs for enterprises.

Improve standards and regulations: accelerate the development of national standards for 3D printed PP medical devices and recycled PP pharmaceutical packaging, clarify performance indicators and safety evaluation methods; Strengthen cross departmental regulatory collaboration to ensure the safety and controllability of innovative products.

6、 Summary: PP - the core material for safety and innovation in the pharmaceutical industry

From the full cycle protection of drug packaging, to the safety guarantee of clinical consumables, and to the technical support of innovative healthcare, PP deeply integrates into the entire chain of the pharmaceutical industry with its core advantages of "safety compliance, stable performance, and controllable cost". Its biological safety ensures the safety of patient medication and treatment, chemical stability ensures drug quality and device performance, and processing flexibility supports the diversified needs of pharmaceutical products. In the future, with the integration of modification technology, recycling technology, and cutting-edge medical technology, PP will achieve greater breakthroughs in high-end pharmaceutical packaging, customized medical devices, green medicine, and other fields, becoming a key force in promoting high-quality development of the pharmaceutical industry.