Levorphanol
Opioids and antagonists
Opioids and antagonistsHigh alert
An error with this medicine can cause serious harm: double checks and protocols are used.
A full μ-opioid agonist with a long half-life for severe pain. It builds up over the first days, so sedation and breathing are watched closely.
Quick facts
- Group
- Opioids and antagonists
- Target
- μ-opioid receptor
- Key effects
- Constipation · Nausea and vomiting
- Monitor
- Respiratory rate · Pain score
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows morphine in the μ receptor; levorphanol, a morphinan, occupies the same site.
Levorphanol is a full opioid agonist, relatively selective for the μ receptor, that binds other opioid receptors at higher doses. Its long half-life makes the drug and its inactive glucuronide accumulate with repeated doses.
- Activates μ-opioid receptors (others at high doses)
- Pain transmission and perception fall
- Long half-life: levels keep rising for about three days
Indications
- Pain severe enough to need an opioid when other treatments are not enough
Adverse effects
Common
- Constipation
- Nausea and vomiting
- Sleepiness and tiredness
- Headache and dizziness
Contraindications
- Significant respiratory depression
- Acute or severe asthma without monitoring or resuscitation equipment
- Known or suspected bowel obstruction, including paralytic ileus
Key interactions
- Benzodiazepines, alcohol and other CNS depressants
- Additive sedation and respiratory depression, with risk of death
- Serotonergic drugs (SSRIs, SNRIs, tricyclics, MAO inhibitors, tramadol)
- Serotonin syndrome
- Mixed agonist-antagonist or partial agonist opioids (such as buprenorphine)
- Less pain relief and possible withdrawal
What is monitored
- Respiratory rate, sedation level and oxygen saturation, above all at the start and after dose changes
- Pain score, bowel habit and signs of misuse
- Sedation over the first days, when levels are still rising
Administration and safety
- Controlled medicine (Schedule II in the United States): counted, stored locked and documented
- Oral tablets are swallowed whole; crushing or dissolving them for injection is dangerous
- Dose changes are spaced out because the drug accumulates
Pregnancy and breastfeeding
Prolonged use in pregnancy can cause neonatal opioid withdrawal syndrome; it is not recommended during labour.
Nursing care
- Check breathing rate and sedation before each dose and hold the drug if the patient is hard to wake
- Keep naloxone available and know the local overdose protocol
- Start a bowel regimen and watch for urinary retention
- Teach safe storage away from children, no alcohol and no driving while drowsy
Pharmacokinetics
- Metabolism
- In the liver to an inactive glucuronide, which accumulates with chronic use
- Elimination
- The glucuronide is excreted by the kidneys
- Half-life
- Long, about 11 to 16 hours
Test yourself
Think of the answer, then tap the question to see it.
Why is levorphanol watched closely over the first days?
Its long half-life makes it accumulate, so sedation and respiratory depression can appear late.
Is its glucuronide metabolite active?
No; it is inactive but accumulates and is excreted by the kidneys.
Which opioid shares this accumulation problem?
Methadone.
Connections
← Back to the class: Opioids and antagonists
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - LEVORPHANOL TARTRATE tablet (DailyMed (U.S. National Library of Medicine), 2026); Levorphanol: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026).
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Representative model, for educational purposes only.