Sublocade, the once-monthly buprenorphine injection for opioid use disorder, has a terminal half-life of 43 to 60 days, making it the longest-lasting injectable medication in its class. But “how long it lasts” depends on what you’re really asking: how long each dose works, how often you need injections, or how long the drug stays in your body after you stop. Each answer is different, and all three matter.
How Long Each Injection Works
Each Sublocade injection is designed to deliver buprenorphine steadily for about one month. When the liquid is injected under the skin of your abdomen, it solidifies into a small depot (a pea-sized lump) that slowly releases medication as the material biodegrades. The polymer breaks down into lactic acid and glycolic acid, both of which your body naturally metabolizes. The lump at the injection site typically dissolves within about four weeks.
Maintenance injections are given at least 26 days apart. If you miss your scheduled dose, delays of up to two weeks beyond the normal window aren’t expected to cause a noticeable dip in how well the medication works. For people on the standard 100 mg monthly dose who need to cover a gap (extended travel, for example), a single 300 mg dose can bridge a two-month period before returning to the regular schedule.
Dosing Schedule and What to Expect
Treatment typically starts with two monthly 300 mg injections. After that, your provider may lower the dose to 100 mg monthly for ongoing maintenance. The second injection can be given as early as one week after the first if clinically needed, but from that point on, every injection must be spaced at least 26 days apart.
There’s flexibility built into the schedule. You don’t need to hit an exact calendar date each month. The long half-life gives a cushion that shorter-acting forms of buprenorphine (like sublingual tablets or films) don’t offer, which is one of the main practical advantages of Sublocade for people who find daily dosing difficult to maintain.
How Long Buprenorphine Stays in Your Body After Stopping
This is where the numbers get much larger than most people expect. Because the depot releases medication so gradually, buprenorphine can remain in your system for months, even after your final injection. In most people, it takes roughly 172 to 300 days (about 6 to 10 months) before no trace of buprenorphine is detectable in the blood.
Urine tests pick it up even longer. Patients will test positive for buprenorphine for up to 38 months after their last Sublocade injection, according to the manufacturer’s patient alert card. That’s over three years. This is important to know if you’re subject to drug testing for any reason, since a positive buprenorphine result long after treatment ends doesn’t mean you’ve taken anything recently.
Why This Matters for Pain Management
Because buprenorphine partially blocks opioid receptors, its lingering presence affects how your body responds to opioid pain medications. The FDA label advises that anyone who has received Sublocade within the past six months should be treated with non-opioid pain relief whenever possible. If you need surgery or emergency care, this is critical information for your medical team. Carrying a patient alert card that notes your most recent injection date can prevent confusion in an emergency room.
The same long tail also means that drug interactions and other buprenorphine-related effects can persist for several months after your last dose. Your provider should monitor you during this period, particularly for signs of withdrawal as the medication slowly clears.
Factors That Affect How Quickly It Clears
Not everyone metabolizes Sublocade at the same rate. Body weight plays a role: the body clears buprenorphine faster in larger individuals, and both clearance rate and absorption speed from the depot are influenced by BMI in the pharmacokinetic models used during development.
Sex also affects how quickly the drug absorbs from the injection site. In FDA modeling, men and women showed different absorption rate constants from the depot, though the clinical significance of this difference in everyday treatment isn’t dramatic enough to require different dosing.
Liver function is another variable. Buprenorphine is processed by the liver, and people with moderate to severe liver impairment can have significantly higher blood levels of the drug. Studies on sublingual buprenorphine tablets showed that moderate liver impairment increased drug exposure by 64%, and severe impairment increased it by 181%. Because Sublocade bypasses the digestive system and goes directly into the bloodstream, the impact of liver problems is expected to be somewhat smaller than with oral forms, but dedicated studies on Sublocade in liver-impaired patients haven’t been conducted. If you have liver disease, your provider will likely monitor you more closely.
The Gradual Taper Effect
One of the distinctive features of Sublocade is what happens when you stop. Unlike sublingual buprenorphine, where blood levels drop quickly after you stop taking daily doses, Sublocade creates a slow, built-in taper. The depot continues releasing medication for months, so buprenorphine levels decline gradually rather than dropping off a cliff. For many people, this makes discontinuation smoother than stopping other forms of buprenorphine, though experiences vary and monitoring is still important during this period.
The practical takeaway: a single Sublocade injection provides about one month of active treatment, but the drug’s presence in your body extends far beyond that, with detectable levels lasting anywhere from six months to over three years depending on the type of test and how many injections you’ve received.