Trends in Prescription Drug Abuse: 'Bridging Medications'

Michael G. O'Neil, PharmD

Disclosures

May 28, 2013

Question

Outside of approved traditional opioid maintenance programs, I've heard that some drug addicts are using prescription drugs for "bridging." What is this practice, and which prescription drugs may be involved?

Response from Michael G. O'Neil, PharmD
Professor, Department of Pharmacy Practice; Consultant, Drug Diversion and Substance Abuse, South College School of Pharmacy, Knoxville, Tennessee

The epidemic of unintended prescription drug overdoses continues to spread across the United States. The medications being abused and misused in these tragic events are often opioids and benzodiazepines.

A lesser known phenomenon involves use of other prescription medications to minimize physiologic withdrawal until individuals can obtain their next "chemical high" with their drug of choice. This practice is commonly referred to as "bridging." Traditionally, the term "bridging" has been used in medication-assisted addiction treatment centers while stabilizing patients. Unfortunately, this terminology has gained a new meaning at the street level. Recognizing bridging behaviors may help clinicians identify patients with the disease of addiction or potential medication adverse effects.

Individuals with the disease of drug addiction who are not in recovery, referred to as "active addicts," spend a significant amount of time preoccupied with drug-seeking behavior or finding ways to minimize the severity of drug withdrawal between highs. Individuals addicted to opioids or benzodiazepines use escalating doses in order to attain the desired euphoria. Continuous abuse and dose escalation leads to a tolerance of the sedative and euphoric effects of these medications. When chronic ingestion of opioids or benzodiazepines is abruptly discontinued, physiologic withdrawal is predictable and potentially life-threatening.

Opioid withdrawal is frequently characterized by diarrhea, vomiting, anxiety, tachycardia, sweating, abdominal cramping, and muscle cramping. Although none of these symptoms are life-threatening by themselves, in combination with other comorbidities, such as heart disease or seizure disorders, they may lead to poor outcomes.[1]

Benzodiazepine withdrawal has a higher incidence of risk. Common benzodiazepine withdrawal symptoms include but are not limited to seizures, high anxiety levels, agitation, tremors, paranoia, muscle cramping, diaphoresis, and tachycardia.[2]

Active addicts experiencing withdrawal from an opioid or benzodiazepine agree that it is a miserable experience frequently causing several days of complete incapacitation. These distressing physiologic and emotional effects may result in bridging behavior. Minimizing the effects of drug withdrawal becomes almost as critical as obtaining the high.

Methadone is an approved agent for treating opioid addiction. Methadone is frequently abused both on the streets and as a bridging agent. For active opioid addicts, methadone is a poor euphoric agent. However, euphoria is frequently reported in opioid-naive individuals. Use of methadone, a synthetic opioid with a prolonged pharmacokinetic half-life, helps to minimize the severity of opioid withdrawal until active addicts achieve their next high. Because of the volume of methadone prescribing for chronic pain management, it can often be obtained from street sources.

Buprenorphine and buprenorphine/naloxone also are approved agents for treating opioid addiction and may be abused and misused for bridging by opioid addicts.[3] These agents usually do not produce euphoria. Although agonist/antagonist effects of buprenorphine may induce physiologic withdrawal in individuals using or abusing opioids chronically, individuals may benefit from the mu receptor activity from buprenorphine that minimizes withdrawal symptoms once significant drug withdrawal has started.

Tramadol, a synthetic codeine analog, is approved for mild to moderate analgesia. Both tramadol and its metabolite have weak mu receptor activity. It is easy to acquire and cheap to purchase on the street, and abuse has been reported.[4,5] As a bridging agent, tramadol may be used by active opioid addicts to minimize withdrawal. Of particular concern, exceeding the recommended maximum daily dosage of tramadol increases the risk for seizures.

Benzodiazepine addicts use other agents to bridge their highs. Gabapentin is an anticonvulsant agent that has many medical uses but is commonly used to treat neuropathic pain. Gabapentin has not been recognized as a drug of abuse owing to its nonscheduled drug status, but reports of abuse have surfaced.[6,7] Because of its sedative and anxiolytic properties as well as its intermediate half-life, gabapentin is used by active addicts to minimize withdrawal effects from benzodiazepines.

Recognizing addictive behaviors may be difficult, even in the best of clinical situations. Individuals who may be bridging frequently request early refills or report theft of these agents. Active addicts may also fake pain symptoms and specifically request these particular agents for their pseudopain management. Active addicts may also test positive on drug screens for buprenorphine, methadone, gabapentin, or tramadol.

Treating, monitoring, and detecting active drug addiction is often difficult. Recognizing bridging behaviors may be one more tool for managing the disease of drug addiction.

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