Opioid Agonist Therapy (OAT)
Methadone
- Methadone is a long-acting synthetic opioid agonist that prevents withdrawal symptoms and reduces cravings without producing euphoria when used therapeutically.
- Administered daily in specialized Opioid Treatment Programs (OTPs) with strict federal regulations and monitoring requirements.
- Peak plasma levels occur 2-4 hours after oral administration, with elimination half-life of 8-59 hours requiring careful dose titration.
Critical Alert: QT prolongation risk - monitor ECG before initiation and periodically during treatment, especially with doses >100mg/day.
Key Points
- Take-home privileges earned through compliance and stability
- Drug interactions with benzodiazepines increase respiratory depression risk
- Pregnancy: Not contraindicated; used for OUD in pregnancy under close monitoring; benefits may outweigh risks
Buprenorphine
- Buprenorphine is a partial opioid agonist with a "ceiling effect" for respiratory depression, making it safer than full agonists.
- Available as sublingual tablets/films (Suboxone contains naloxone to prevent injection abuse) and monthly injectable (Sublocade).
- Can be prescribed by qualified physicians in office-based settings, providing greater treatment accessibility than methadone.
Memory Aid: "BUPE = Better Under Physician's Eye" - can be prescribed in office settings unlike methadone
Key Points
- Precipitated withdrawal risk if given too soon after last opioid use
- Sublingual absorption - avoid eating/drinking 15 minutes before and after
- High binding affinity may block effects of other opioids
Opioid Antagonist Therapy
Naltrexone
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- Naltrexone is a pure opioid antagonist that blocks euphoric effects of opioids, requiring complete detoxification before initiation.
- Available as daily oral tablets (ReVia) or monthly intramuscular injection (Vivitrol) to improve medication adherence.
- Most effective for highly motivated patients with strong psychosocial support systems and extended periods of abstinence.
Critical Alert: Must be opioid-free for 7-14 days before starting to prevent severe precipitated withdrawal syndrome.
- Confirm opioid-free status with urine drug screen
- Consider naloxone challenge test if uncertain about last use
- Start with lower dose and monitor for withdrawal symptoms
- Provide emergency medical identification card
Commonly Confused Concepts
| Medication |
Mechanism |
Setting |
Key Risk |
| Methadone |
Full agonist |
OTP only |
QT prolongation |
| Buprenorphine |
Partial agonist |
Office-based |
Precipitated withdrawal |
| Naltrexone |
Antagonist |
Any setting |
Overdose risk if relapse |
Clinical Scenario
A patient on naltrexone for 6 months relapses and uses heroin. Due to blocked opioid receptors, they may use larger amounts to overcome the blockade, significantly increasing overdose risk due to using larger amounts to overcome blockade, causing respiratory depression.
Nursing Considerations
Assessment and Monitoring
- Monitor for signs of withdrawal, intoxication, and medication adherence through regular urine drug screening and clinical assessment.
- Assess for concurrent mental health disorders, as dual diagnosis is common and requires integrated treatment approaches.
- Evaluate social support systems, housing stability, and employment status as these factors significantly impact treatment success.
Key Points
- Document baseline vital signs and pain levels
- Screen for hepatitis B, C, and HIV due to high prevalence
- Monitor for drug interactions, especially with CNS depressants
Memory Aid: "SOAR" - Support systems, Opioid-free period, Adherence monitoring, Risk assessment
Study Tips
- Remember the "3 A's": Agonist (methadone), Partial agonist (buprenorphine), Antagonist (naltrexone)
- Focus on safety concerns: respiratory depression with agonists, precipitated withdrawal with partial agonists/antagonists
- Understand regulatory differences: methadone requires specialized clinics, buprenorphine allows office-based treatment
Quick Check
- ☐ Can identify mechanism of action for each medication class
- ☐ Understand when to use each medication type
- ☐ Know major safety concerns and contraindications
- ☐ Recognize signs of withdrawal vs. intoxication
Common Pitfalls: Don't confuse naltrexone (oral/injectable addiction treatment) with naloxone (emergency overdose reversal). Remember buprenorphine can cause precipitated withdrawal if given too soon after last opioid use.