Drug delivery implants could change the way we approach chronic conditions

There’s a trend in medicine toward using implants to deliver medication over long periods of time. If applied to chronic pain management, it stands to wholly reorganize the field. This is one place where just throwing more technology at the problem has actually produced a visible improvement in patient outcomes. The practice of giving medicine using indwelling, passive delivery methods was pioneered and refined for contraception. We’d been administering medication with patches, for example, for a while and had pretty good results, both with birth control and nicotine. Insulin pumps for Type 1 diabetics, too, have been streamlined and improved.

Contraceptive implants like Norplant, Implanon, and Nexplanon are in a class of their own. They’re intended to dwell inside the body, delivering medication at a constant, steady rate over a long period of time without requiring power or refills. They’re a major step forward from IUDs, which are T-shaped and sit in the uterus; Nexplanon, in particular, is a flexible, matchstick-sized rod that gets implanted under the skin of the arm so there’s no risk of uterine damage if you get kicked in the stomach (one of the scariest sticker-shock risks of an IUD). Nexplanon is the most effective method of contraception on the market, not because of what drug it uses, but because it’s free of user intervention. There are no pills to remember to take, so the dose gets delivered perfectly, every time, for the whole time the implant is in the patient’s system.

Hormonal medications aren’t the only kind of drug that stands to benefit from a better vehicle for administration, though. What about psych meds or painkillers? There exist implant-based treatment options for mood disorders like bipolar disorder and schizophrenia, so that instead of having to remember to take meds, patients just feel right, all the time. Serum levels don’t change, so the medication’s effect doesn’t wax and wane. Most recently, the FDA approved a Nexplanon-like implant called Probuphine, meant to deliver a controlled dose of buprenorphine over a period of six months. Never a pill to take nor a prescription to fill.

Implants like Nexplanon and Probuphine can provide certainty in a lot of different ways. They take away the need to hide away high-test meds where children can’t get into them, and that’s not just painkillers — bad things happen if your kid eats all your SSRIs or Xanax, too, and nobody needs more reasons to keep poison control on speed-dial.  They eliminate the possibility that a patient’s pain meds could be sold, stolen, or otherwise fall into the wrong hands. They firmly legitimize the actions of a person seeking pain relief on the long term, by providing near-perfect dose control and no grey area whatsoever for abuse.

But what might be most important is that an implant takes away the volitional aspect of taking pills as needed to manage one’s own pain. The anticipation attachment is never made, because the dose doesn’t wax and wane, so the pain control is constant. Patients never have to deal with waking up without painkillers in their system, so they never have to make the choice to increase their tolerance by taking extra meds just because they hurt so much. Implants that manage pain meds could cut the legs out from under a nascent pain medication habit. Remember Dr. House? How different would his life have been if he’d never developed a Vicodin habit? Without increasing one’s use of painkillers, abuse is so much more difficult to entrench as a habit. No doctor-shopping. No endlessly increasing doses of painkillers just to keep down the same pain. And after things have calmed down from whatever required pain management, Probuphine, the buprenorphine implant, can help long-term opioid users ramp down their use. It can even be used to kick heroin addiction.

Not every drug will work as an implant. Short-term medications don’t need a long-term, indwelling implant. Some things are irritating to tissue. There are some things that just won’t persist at physiological pH for that long in an unchanged state, too. Drugs that can last for a year or three sitting in a cool, dry closet don’t just sit inert in the body’s acidic, constantly moving fluid environment. But this method of delivery will be an important sea change in how we approach long-term medication.

Top image credit: Probuphine implant, Braeburn Pharmaceuticals