Medical implants are devices that are placed on the inside or surface of the body with the purpose of delivering medication, monitoring body conditions, or supporting organ health. When most people think of implantables, they think of drug pumps used to deliver insulin in the treatment of diabetics. This form of implantables are typically programmable “active” devices which require regular resupply of the medication through an access port.

Another type of implant is a drug delivery device that, when placed inside the body, releases drugs at a defined rate and for a defined period. These technologies enable the sustained release of drugs through a small non-mechanical subcutaneous implant device, and provide long-term, “passive” release without the need for replenishment. Typically found as thin flexible rods, these delivery systems are particularly effective for the delivery of highly potent drugs such as hormones. Commercial examples include implants for contraception and the treatment of prostate cancer. One significant advance in recent years is the addition of sustained release drug implants that dissolve over time and do not require removal of the implant – reducing the number of procedures required and the potential for complications such as infections.

Benefits of Sustained Release Drug Implants

For over a decade there has been an increasing convergence between implantable devices and drug therapies, including devices that deliver drugs. Sustained release drug implants offer several advantages over conventional drug delivery options. First, implantable devices allow targeted, localized therapy where the drug is most needed. This may also allow for significantly lower doses of a drug which can minimize potential side effects and reduce the impact on the kidneys and liver. Second, implantable devices allow for sustained release of a therapeutic agent. Both pills and injections produce Active Pharmaceuticals Ingredient (API) concentrations that rapidly rise and then exponentially decay as the body dilutes, metabolizes, and/or excretes the pharmaceutical compounds. By contrast, sustained release drug implants can slowly and steadily release the API at a controllable, optimal rate within the therapeutic window. The last and perhaps most important advantage is patient compliance, as the treatment regimen associated with an implantable device is generally less burdensome than pills or injections, and patients won’t forget to administer the medication. These implants offer prolonged delivery of treatment ranging from weeks to years.

Materials for Sustained Release Drug Implants

Injection molding, a manufacturing method used for making everything from car parts to kids’ toys, is also utilized to make life-saving medical devices, including those inserted or implanted into patients’ bodies.

As you would expect, there are key material considerations for products used in drug delivery such as biocompatibility, the ability of the material to control release of the API, stability, durability, and the ability to naturally degrade over time if necessary.

Medical grade silicones have long been a material of choice for drug delivery given their range of available durometers, extreme chemical inertness and biocompatibility, excellent tear and heat resistance make it ideal for parts that need to remain in the human body for extended periods of time. Ethylene vinyl acetate (EVA), polyurethanes and acrylate hydrogels have also been utilized in select applications. Another option is to use a biodegradable material such as poly(lactic-co-glycolic acid), or PLGA, to controllable release the drug while essentially “dissolving away” by hydrolysis. While new material development for drug delivery remains an active field of research, injection molding is expected to continue to play a significant role in the manufacturing of drug delivery devices due to its ability to produce high volumes at low prices while meeting tight dimensional tolerances.

Recent Innovations in Sustained Release Drug Delivery Devices

The development of novel sustained release drug implants is an area of significant research and advances in recent years. Below are a few notable innovations that give a glimpse into the future of this exciting and relatively new field.

  • Contraception has long been an area where implantable devices have been utilized. Recently, a grant was awarded to Inflammasome Therapeutics for the development of a long-term bioerodible birth control implant. After being implanted under the skin, the device will provide a constant and consistent low plasma level of the hormone levonorgestrel for a period of up to 2 years at which point it will fully dissolve and require no removal. This is a huge step as current contraception implantables require removal. This form of treatment is expected to be extended to other disease treatments sch as HIV and arthritis.
  • A huge area for research and development is nanomedicine, which entails targeted drug delivery in which particles attracted to disease cells directly treat those cells. For example, scientists at Houston Methodist Research Institute recently successfully delivered long-term medications via a nanochannel delivery system (nDS) implanted under the skin. The implant is remotely controlled using Bluetooth technology. Researchers are hopeful that these devices can allow for remote patient care and lower healthcare costs. Additionally, this technology would allow for patient treatment during off hours, such as at night, when some treatments are proven to be more effective.
  • Researchers recently created a new type of coating for drug delivery that can be activated externally, specifically with infrared radiation (IR). The coating is considered a hybrid stimulus-responsive system that will allow for more on-demand, localized treatment of a given area with sustained release drugs.

ProMed’s Implant Molding Capabilities

ProMed understands the importance of quality to your success, especially when it comes to implants. We have a history of manufacturing drug delivery products, which means we have the experience as well as robust systems and processes in place to handle your specific project needs! Our work has historically focused on molding silicone drug delivery devices using injection and compression molding techniques. In some cases, co-extrusion or over molding of a thin, drug-free layer has been used to enable more uniform release of drug from the implant.

We have a well-established pallet of durable and biodegradable polymeric materials that provide options for delivery of potent compounds such as hormones, opioids, antibiotics, and oncology drugs. We will assist in your material selection to help ensure all design requirements are met. Our manufacturing facilities and equipment are designed for a single purpose—to mold medical and implantable silicone, combination components, and bio-material grade plastics with uncompromising quality and service. We currently have four divisions that are located within two manufacturing sites. All are certified class 10,000 / ISO Class 7 cleanrooms.

Contact ProMed today at 763-331-3800 to discuss your next medical molding project.

The Development of Novel Sustained Release Drug Implants
Article Name
The Development of Novel Sustained Release Drug Implants
Recent developments and innovations in the field of novel sustained release drug delivery implants as well as the benefits of this technology.
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ProMed Molding
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