Buprenorphine, cannabis, and other periop challenges

It's no mystery why substance use is a growing issue in perioperative care, according to Karna Sundsted, MD, FACP, an assistant professor and the hospital internal medicine medical director for perioperative and consultative medicine at Mayo Clinic in Rochester, Minn.

“As we're seeing more and more patients with substance use disorders, chronic pain syndromes, or just regular substance use on general hospital services, the same holds true in our surgical population,” she told attendees at Mayo Clinic Hospital Medicine: Managing Complex Patients in Arizona in November 2023.

It's also unsurprising that physicians can struggle with how to handle surgical patients already on opioids or other analgesics, when perioperative medication management as a field has had uncertainty.

“It's historically been tough. We're limited by lack of consensus and high-quality outcome data,” said Dr. Sundsted. “With that, there's been substantial variation in clinical practice, and that's even true within the same institution.”

The good news is that some help began to arrive in 2021, as the Society for Perioperative Assessment and Quality Improvement (SPAQI) released the first of nine consensus statements on perioperative management of medications, including a paper focused specifically on preoperative use of opioids and other analgesics.

Dr. Sundsted reviewed that guidance and offered her advice on other challenging drugs to handle, including gabapentin and cannabis, during her perioperative medicine talk.

The SPAQI consensus statement on opioids offers detailed information on specific drugs, “some really palatable summary tables that are helpful in the hospital setting,” she said.

For example, the consensus recommends continuing antispasmodics whenever possible in surgical patients, to avoid the risk of withdrawal, rebound hypertension, or other effects, but seriously considering discontinuation of centrally acting muscle relaxants, because they can interact with sedatives and anesthetic agents in the perioperative period.

Of course, there's also advice on how to handle patients on chronic opioids. “This can be a challenging population because their pain levels are ratcheted up. They come in with higher pain scores, slower time to pain resolution, and higher opioid requirements,” said Dr. Sundsted. And the answer is not to try to get the patient off opioids.

“The decision to make broad sweeping changes in medication regimen is best left to when they're stable and to the outpatient providers who know them best,” said Dr. Sundsted. “The bottom line is typically to continue opioids in the perioperative setting and anticipate the need to use higher-than-typical doses of adjunct opioids.”

That said, there are a few important considerations with specific medications.

For starters, tramadol and codeine are prodrugs, metabolized by CYP2D6. “So anything that inhibits that enzyme is going to reduce conversion to the active metabolite and efficacy,” she said. “Likewise, a reminder that some of these are serotonergic, right?” Combining methadone, tramadol, or fentanyl with any other drug that increases serotonergic activity risks toxicity.

Perioperative meperidine management is complicated enough that you may not want to tackle it yourself. “It's tricky, and we need to individualize it. Expert consultation can be helpful,” she said.

When preparing a patient for surgery, don't forget to check whether they're taking any nonprescription medications. “Our patients with chronic pain or other somatic symptom burden may turn toward alternative medicine,” said Dr. Sundsted. The proper time to stop herbs and supplements ranges from two weeks to a few days before surgery, but there are some to worry about more than others.

“I'm picking on St. John's wort,” she said, noting that it is both serotonergic and an inducer of CYP3A4. In general, the risks of continuing herbs and supplements through surgery include issues like inhibited platelet activation, hepatotoxicity, and drug interactions.

In contrast, experts are now thinking that it's better not to stop buprenorphine before surgery. “Over the last several years, management has really evolved,” said Dr. Sundsted. If patients are taking less than 16 mg of buprenorphine a day, with or without naloxone, keep them on it, she advised, directing her audience to papers published in 2021 by The BMJ and in 2019 by Pain Medicine.

Larger doses pose more of a quandary. “There is practice variation in what we should do for patients who are on greater than 16 mg. Some suggest we should taper it down to a 16 mg-dose preoperatively,” said Dr. Sundsted. It's also less certain on what dose patients should be maintained perioperatively and how to handle buprenorphine in patients expected to have severe pain or prolonged hospitalization. “That becomes a more complex case,” she said. “Consider potentially getting pain medicine involved.”

Also remember to talk to the patient about all of this. “This is a very vulnerable time for patients with opioid use disorder. They're concerned about everything from relapse to uncontrolled pain,” said Dr. Sundsted.

When making a plan for pain control in patients on buprenorphine, consider the typical pain severity and duration based on the type of surgery, the amount of tissue disruption, and any other expected painful sequelae such as paresthesias or muscle spasms, she recommended.

“You can consider dividing the doses of buprenorphine,” she said. Also look at adding high-affinity, full mu-opioid agonists, that is, hydromorphone or fentanyl, to try to achieve adequate analgesia.

Know that patients are going to require larger-than-normal doses of pain meds. “Of course, monitor for side effects or oversedation,” and have a plan for tapering as pain goes down, Dr. Sundsted added.

Finally, don't forget the other possible modes of analgesia, including blocks, acetaminophen, NSAIDs, neuromodulators, and nonpharmacologic strategies. Don't let patients' doubts about the last of those categories dissuade you, she said.

“Often, when we bring up things like massage, relaxation techniques, diaphragmatic breathing, and animal-assisted therapy to patients that have chronic pain, and in this case, acute-on-chronic pain, there's understandable skepticism.”

That doubt can sometimes be allayed by discussion of what might be going on with the patient's central nervous system. “I know that taking some extra minutes for patient education isn't always possible during a busy hospital service. But if we can educate patients on what is central sensitization, how is it impacting them, and what are the tools we have to combat it, that can be very powerful,” said Dr. Sundsted.

She uses the metaphor of pain being like a tiger that scares a person, and then even if the tiger goes away, the sympathetic nervous system of a patient with central sensitization will remain maladaptively activated; the nonpharmacologic strategies are a way to mitigate that.

In contrast, something that clinicians and patients maybe should be a little more scared of is gabapentin. “It's been widely adopted and promoted for opioid sparing,” said Dr. Sundsted, noting that it is among the most commonly prescribed drugs in the U.S.

Recent research has highlighted some reasons for concern. Older patients who received gabapentin before surgery had significantly higher risk of delirium, new antipsychotic use, and pneumonia in a cohort study published by JAMA Internal Medicine in September 2022.

Another study, published by the Journal of the American Geriatrics Society in August 2022, found that a fifth of Medicare patients who were prescribed gabapentin after surgery filled another prescription for it more than three months after discharge.

“It calls into question frequently adding gabapentin,” said Dr. Sundsted. “I don't think it's off the table, but I do think there are concerns with it.” Particularly in older patients, do a careful risk-benefit assessment, use the lowest effective dose, and explain that it is not intended as a long-term medication.

Dr. Sundsted's last topic was a drug that increasing numbers of Americans are using long term: cannabis. A 2017 study found that 10% of U.S. adults were consuming it at least monthly, and many states have expanded access since then, she noted.

The first step to managing cannabis perioperatively is knowing about it. “Patients don't volunteer this information, so I think it's good to ask,” she said. Use of cannabis poses a number of perioperative issues, as outlined in guidelines developed in 2023 by the American Society of Regional Anesthesia and Pain Medicine.

“Recent cannabis smoking and potentially other forms of ingestion increase perioperative cardiovascular risk. Cannabis users are at risk for increased postoperative pain,” said Dr. Sundsted. There are also potential cannabinoid drug interactions, including with warfarin and direct-acting oral anticoagulants.

However, the guidelines do not take a position for or against tapering cannabis before surgery, since on the flip side, patients who have abruptly discontinued use prior to surgery will be at increased risk for cannabis withdrawal syndrome.

“Patients who frequently use cannabis should be counseled on the potential negative effects on postop pain control,” she said, noting that clinicians should be prepared to use multimodal analgesia, including rescue medications as needed.

Low-dose, medically supervised cannabis use is less likely to cause problems, according to the guidelines, but definitely no one should have surgery within two hours of smoking cannabis because it increases risk of myocardial infarction, Dr. Sundsted concluded.