Rational Polypharmacy for Patients with Chronic Pain

Phoenix—Patients with chronic pain have numerous treatment options, including several analgesic prescription drugs. Combining medications is also a popular strategy, although clinicians should be mindful of pharmacokinetic risks, according to Jeffrey Fudin, PharmD, clinical pharmacy specialist, Stratton Veterans Affairs Medical Center, Albany, New York.

Dr. Fudin, who spoke at the AAPM meeting, said clinicians could consider polypharmacy with medications such as opioid agonists, acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), antidepressants, and anticonvulsants. He described rational polypharmacy as facilitating the use of ≥1 drugs to minimize adverse effects, increase adherence, and spare opioids; maintaining analgesic efficacy by combining long-acting and short-acting drugs; and increasing efficacy by using ≥2 drugs with different mechanisms of action.

Switching chronic pain patients from 1 opioid to another provides more effective analgesia, according to Dr. Fudin, though the response varies among patients. This method is particularly effective for patients experiencing adverse effects or toxicity with their current opioids, developing a tolerance for the opioids or opioid hyperalgesia, or having poorly controlled pain that cannot be lessened by increasing the dosage.  

In August, Dr. Fudin and Kathryn Shaw, PharmD, published an article in Practical Pain Management that compared 8 online opioid conversion calculators. They found that some of the calculators included dosage tables that help clinicians, though they warned that the calculators should be used with caution.

“Opioid calculators may serve as useful tools when converting from 1 opioid to another, but all conversions need to be double-checked by the end user for accuracy,” Drs. Fudin and Shaw noted. “There is significant and potentially dangerous inconsistency in certain calculated doses among various online calculators, most particularly with fentanyl and methadone.”

During the session, Dr. Fudin cited data from the Centers for Disease Control and Prevention (CDC) that found 2% of prescriptions for opioid analgesics were for methadone in 2012; however, methadone accounted for approximately one-third of opioid overdose deaths. In 2009, 6 times as many people died of methadone overdoses compared with in 1999. In its report, the CDC noted that there were >4 million methadone prescriptions for chronic pain statistics in 2009, and the insurance companies typically list methadone as a preferred drug on their formularies.

Dr. Fudin recommended that clinicians be careful with opioids and evaluate issues such as respiratory depression, chronic obstructive pulmonary disease, gastrointestinal (GI) side effects, urinary retention, and constipation. He added that using sertraline with codeine can increase sedation, agitation, and serum codeine levels and decrease morphine levels. In addition, NSAIDs may be beneficial because of their prostaglandin inhibition and anti-inflammatory activity, but they can be risky for individuals >50 years of age, those who have GI disorders, those who have concomitant heparin or aspirin use, or those who have bleeding risk.

According to Dr. Fudin, healthcare professionals should implement rational polypharmacy only if the benefits outweigh the risks and must respect drug–drug interactions and understand therapeutic challenges of various populations and age groups.—Tim Casey