15.2 Opioid Use Disorder Drugs

Opioid use disorder is a complex condition affecting the brain's reward system. Repeated opioid use leads to neuroadaptations, tolerance, and withdrawal symptoms when use is reduced. Understanding these mechanisms is crucial for effective treatment and care.

Treatment options include medications like methadone, buprenorphine, and naltrexone. These drugs work differently to reduce cravings and withdrawal symptoms. Nurses play a vital role in assessing patients, administering medications, and providing education on addiction treatments and recovery strategies.

Opioid Use Disorder

Mechanisms of opioid use disorder

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• Opioids bind to and activate opioid receptors in the brain
  • Mu opioid receptors primarily responsible for rewarding and analgesic effects (euphoria, pain relief)
• Repeated opioid use leads to neuroadaptations in the brain's reward system
  • Increased dopamine release in the nucleus accumbens reinforces drug-seeking behavior (positive reinforcement)
  • Decreased sensitivity of the reward system to natural reinforcers (food, social interaction)
• Chronic opioid use results in the development of tolerance
  • Higher doses required to achieve desired effects (analgesia, euphoria)
• Withdrawal symptoms occur when opioid use is abruptly discontinued or reduced
  • Dysregulation of the noradrenergic system contributes to withdrawal symptoms (increased norepinephrine release)

Signs of opioid use disorder

• Compulsive opioid use despite negative consequences (legal, financial, social)
• Increased tolerance to opioids over time (need for higher doses)
• Withdrawal symptoms when opioid use is reduced or stopped
  • Anxiety, restlessness, insomnia
  • Muscle aches, abdominal cramps, diarrhea
  • Nausea, vomiting, sweating
• Neglect of personal responsibilities and relationships (work, family)
• Continued opioid use despite physical or psychological problems (health issues, depression)

Causes and diagnosis of opioid addiction

• Risk factors for developing opioid use disorder
  • Genetic predisposition (family history of addiction)
  • Chronic pain conditions (back pain, fibromyalgia)
  • Mental health disorders (depression, anxiety, PTSD)
  • Early exposure to opioids (prescription pain medications)
• Diagnosis based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria
  • Presence of at least two symptoms within a 12-month period
  • Symptoms include tolerance, withdrawal, loss of control, social impairment
• Screening tools for opioid use disorder
  • Drug Abuse Screening Test (DAST) assesses problematic drug use
  • Current Opioid Misuse Measure (COMM) identifies aberrant medication-related behaviors

Neurobiology of opioid addiction

• Opioids interact with the brain's reward system by increasing dopamine release
• Endogenous opioids, such as endorphins, play a role in pain modulation and reward
• Chronic opioid use alters neurotransmitter systems, leading to dependence and addiction
• Repeated use can result in neuroplastic changes, affecting decision-making and impulse control

Treatment of Opioid Use Disorder

Medications for opioid addiction treatment

• Methadone
  • Full opioid agonist binds to and activates opioid receptors
  • Long-acting oral medication provides stable blood levels
  • Reduces withdrawal symptoms and cravings by preventing opioid withdrawal
  • Requires daily dosing at a specialized clinic (methadone maintenance treatment)
• Buprenorphine
  • Partial opioid agonist binds to opioid receptors with lower intrinsic activity than full agonists
  • Sublingual or buccal administration (Suboxone, Zubsolv)
  • Reduces withdrawal symptoms and cravings with a lower risk of respiratory depression (ceiling effect)
  • Can be prescribed by certified physicians in office-based settings (DATA 2000 waiver)
• Naltrexone
  • Opioid antagonist binds to opioid receptors and blocks their activation
  • Oral or long-acting injectable formulations (Vivitrol)
  • Blocks the effects of opioids and reduces cravings by preventing euphoria
  • Requires complete detoxification before initiation to avoid precipitated withdrawal

Effects of opioid addiction treatments

• Methadone
  • Effects: Reduces withdrawal symptoms and cravings, blocks the effects of other opioids
  • Side effects: Sedation, constipation, sweating, respiratory depression (in high doses)
  • Drug interactions: CYP450 inducers (rifampin) and inhibitors (fluconazole) can affect methadone levels
• Buprenorphine
  • Effects: Reduces withdrawal symptoms and cravings, partially blocks the effects of other opioids
  • Side effects: Nausea, headache, insomnia, constipation
  • Drug interactions: CYP3A4 inhibitors (ketoconazole) can increase buprenorphine levels
• Naltrexone
  • Effects: Blocks the effects of opioids, reduces cravings by preventing euphoria
  • Side effects: Nausea, headache, dizziness, insomnia
  • Drug interactions: Opioid-containing medications (codeine, oxycodone) should be avoided

Nursing care for opioid addiction patients

• Assessment
  1. Evaluate patient's history of opioid use and current withdrawal symptoms (COWS scale)
  2. Monitor vital signs (blood pressure, heart rate) and pain levels (numeric rating scale)
• Planning
  1. Collaborate with the healthcare team to develop an individualized treatment plan (medication, therapy)
  2. Set goals for medication adherence and participation in behavioral therapies (counseling, support groups)
• Implementation
  1. Administer medications as prescribed and monitor for side effects (constipation, sedation)
  2. Provide patient education on the medication, its effects, and potential side effects
  3. Encourage participation in behavioral therapies and support groups (Narcotics Anonymous)
• Evaluation
  1. Assess the patient's response to treatment and progress towards goals (urine drug screens, self-reported cravings)
  2. Modify the care plan as needed based on the patient's response and changing needs (dose adjustments, additional therapies)

Patient education on addiction treatments

• Explain the purpose and benefits of medication-assisted treatment (MAT)
  • Reduces withdrawal symptoms and cravings (methadone, buprenorphine)
  • Blocks the effects of opioids and prevents relapse (naltrexone)
• Describe how each medication works to reduce withdrawal symptoms and cravings
  • Methadone and buprenorphine activate opioid receptors to prevent withdrawal
  • Naltrexone blocks opioid receptors to prevent euphoria and relapse
• Discuss the importance of adherence to the prescribed medication regimen
  • Taking medications as directed ensures consistent blood levels and therapeutic effects
  • Skipping doses or taking extra doses can lead to withdrawal or overdose
• Emphasize the role of behavioral therapies and support groups in recovery
  • Counseling helps address underlying psychological and social factors contributing to addiction
  • Support groups provide a sense of community and accountability in recovery
• Provide information on potential side effects and when to contact a healthcare provider
  • Common side effects include constipation, nausea, and sedation
  • Severe side effects like respiratory depression require immediate medical attention
• Include resources for additional support and information, such as helplines and websites
  • Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline: 1-800-662-HELP (4357)
  • National Institute on Drug Abuse (NIDA) website: www.drugabuse.gov
• Discuss relapse prevention strategies and the importance of ongoing support
• Explain harm reduction approaches for patients who continue to use opioids