Opioids (narcotic analgesics)

What are opioids (narcotic analgesics)?

Opioids (narcotic analgesics) are a class of medicines that are used to provide relief from moderate-to-severe acute or chronic pain. They may also be called opiates, opioid analgesics, or narcotics. Analgesic is another name for a medicine that relieves pain. An opioid analgesic is an opioid that can be prescribed by a doctor to relieve pain.

Opioid analgesics are one of the most widely used analgesics for pain relief; however, they have been overused, overprescribed, and misused which has resulted in more than two million people in the U.S. alone having a substance misuse disorder involving prescription opioid analgesics.

Opioids work by binding to opioid receptors, which are part of the messenger system in our body that controls pain, and pleasurable and addictive behaviors. Opioid receptors are more abundant in the brain and spinal cord but are also located elsewhere in the body such as the stomach and the lungs. The main opioid receptor that opioids bind to is the mu receptor.

What are opioid analgesics used for?

In the past, opioid analgesics have been used for all types of pain, which may explain why there are so many people addicted to them today.

The most appropriate use of opioid analgesics is for the relief of short-term, intense pain, such as that occurring immediately after surgery or due to a medical condition.

Opioid analgesics may also be used to relieve pain due to cancer, or for palliative or end-of life care. They should only be used to treat other types of chronic pain under strict conditions and with close monitoring.

What are the differences between opioid analgesics?

Opioid analgesics differ in their structure, potency, and the way they are absorbed, distributed, metabolized and excreted within the body.

Some, like morphine and codeine were originally derived from plants. Others, such as heroin, hydrocodone, hydromorphone, oxycodone, and oxymorphone are made by modifying morphine and are called semi-synthetic. There are three main classes of opioids – those that are structurally like morphine (the phenanthrenes), those that resemble fentanyl (the phenylpiperidines), and those that resemble methadone (the phenylheptylamines).

Different opioid analgesics have different potencies, based on how strongly they bind to the opioid receptor (for example, fentanyl is 80 to 100 times stronger than morphine). This means that the dosages for one opioid may be significantly different from another. Although conversion charts exist (these tell you what dose of an opioid compares to the equivalent analgesic dose of morphine); these are only at best a guide because other variables, such as an individual’s genetics, play a part in how a person responds to a opioid.

If an opioid analgesic is deemed appropriate; codeine or tramadol should be tried first if the pain is mild-to-moderate. If the pain is unresponsive to these analgesics, or for more severe pain, then hydromorphone, morphine, or oxycodone should be considered. Fentanyl and methadone should only be used for severe pain that is unresponsive to other opioid analgesics.

Common opioid analgesics available in the U.S. include:

Name Route Onset of effect Duration of effect
alfentanil Intravenous (IV) 90 seconds 45-60 mins
codeine Oral 15-60 mins 3-4 hours
fentanyl IV Immediate 0.5-1h
Intramuscular (IM) 7-8 mins 1-2 hours
Buccal (through the gums) Sublingual (SL) 5-15mins 4-6 hours
Transdermal patch (via the skin) 6h 72-96 hours
hydrocodone Oral 10-20 minutes 4-8 hours
hydromorphone Oral 15-30 mins 3-4 hours
IV 5 mins 3-4 hours
methadone Subcutaneous (SC) (under the skin) 15 mins 3-4 hours
morphine Oral 30-60 mins 3-6 hours (immediate-release) 8-24 hours (extended-release)
IV/SC 5-10 mins 4 hours
oxycodone Oral 10-15 mins 3-6 hours
oxymorphone Oral 30-60 mins (immediate-release) 1-2 hours (extended-release) 4-6 hours (immediate-release) 12 hours (extended-release)
IM/IV/SC 5-10 mins 3-6 hours
tramadol Oral 30-60 mins (immediate-release) 1-2 hours (extended-release) 4-6 hours (immediate-release) 24 hours (extended-release)

Are opioid analgesics safe?

There are serious risks associated with opioid analgesics including respiratory depression (unusually slow and shallow breathing), opioid-use disorder, and potentially fatal overdose.

Opioid-use disorder is defined as the repeated occurrence of at least two out of 11 specific opioid-associated problems, including using opioids in increased amounts or for longer than intended; continued use despite interference with daily activities; or still using while in hazardous situations. Severe opioid-use disorder is defined as a cluster of 6 or more problems and it can affect people from all educational and socioeconomic backgrounds.

Opioid analgesics are potentially addictive and the risk of becoming emotionally and physically dependent on them increases the more you take and the longer you take them for. When prescribed by a doctor and used for short periods of time, such as for less than five days for pain relief after surgery, the risk of becoming addicted to opioid analgesics is relatively low. The number of fatal overdoses from opioids continues to rise. 

When taken exactly as prescribed by a doctor, for short periods of time, for the relief of severe pain, and under strict monitoring, opioid analgesics are considered acceptable to use. However, they may still be associated with some severe side effects, despite proper use.

What are the side effects of opioid analgesics?

Opioid analgesics have many side effects, although people with cancer or terminal illness taking opioids for long periods of time may become tolerant to some of these side effects.

Drowsiness, sleepiness, or dizziness is common with most opioid analgesics. This can affect driving or a person's ability to operate machinery and perform other hazardous tasks. Alcohol may potentiate these effects.

Other commonly reported side effects include:

  • Constipation
  • Breathing difficulty
  • Itching or a skin rash
  • Loss of appetite
  • Low blood pressure
  • Miosis (constriction of the pupil of the eye)
  • Nausea and vomiting
  • Problems with urination
  • Shakiness or a tremor
  • Slow heartbeat.

Withdrawal symptoms may occur when people who have been taking opioid analgesics abruptly stop taking them. Symptoms are like having the flu, and may include body aches, chills, depression, diarrhea, goose-bumps, headaches, high blood pressure, insomnia, irritability, a runny nose and sweats. Withdrawal symptoms usually last about a week.

References

  • Drewes AM, Jensen RD, Nielsen LM, et al. Differences between opioids: pharmacological, experimental, clinical and economical perspectives. British Journal of Clinical Pharmacology. 2013;75(1):60-78. doi:10.1111/j.1365-2125.2012.04317.x.
  • Busse, J. W., Craigie, S., Juurlink, D. N., Buckley, D. N., Wang, L., Couban, R. J., Agoritsas, T., Akl, E. A., Carrasco-Labra, A., Cooper, L., Cull, C., da Costa, B. R., Frank, J. W., Grant, G., Iorio, A., Persaud, N., Stern, S., Tugwell, P., Vandvik, P. O., & Guyatt, G. H. (2017). Guideline for opioid therapy and chronic noncancer pain. CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 189(18), E659–E666. https://doi.org/10.1503/cmaj.170363
  • Drug Overdose Death Rates. National Institute on Drug Abuse. 2023. https://nida.nih.gov/research-topics/trends-statistics/overdose-death-rates
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    List drug with Opioids (narcotic analgesics)

    Drug Name
    Abstral
    Generic name: Fentanyl (sublingual)
    Actiq
    Generic name: Fentanyl Citrate (oral Transmucosal)
    Alfentanil
    Generic name: Alfentanil
    Arymo ER
    Generic name: Morphine (MOR-feen)
    Astramorph PF
    Generic name: Morphine (MOR-feen)
    Avinza
    Generic name: Morphine
    ConZip
    Generic name: Tramadol
    Belbuca
    Generic name: Buprenorphine (oral/buccal)
    Buprenex
    Generic name: Buprenorphine Injection
    Buprenorphine
    Generic name: Buprenorphine
    Butorphanol injection
    Generic name: Butorphanol (injection)
    Butorphanol nasal
    Generic name: Butorphanol (nasal)
    Butrans
    Generic name: Buprenorphine Transdermal (skin Patch)
    Dazidox
    Generic name: Oxycodone
    Demerol
    Generic name: Meperidine
    Demerol (Meperidine Injection)
    Generic name: Meperidine
    Demerol (Meperidine Oral)
    Generic name: Meperidine
    Dilaudid
    Generic name: Hydromorphone (oral)
    Dilaudid (Hydromorphone Injection)
    Generic name: Hydromorphone
    Dilaudid (Hydromorphone Oral)
    Generic name: Hydromorphone
    Dilaudid injection
    Generic name: Hydromorphone (injection)
    Dilaudid rectal
    Generic name: Hydromorphone (rectal)
    Dilaudid-5
    Generic name: Hydromorphone
    Dilaudid-HP
    Generic name: Hydromorphone
    Diskets Dispersible
    Generic name: Methadone
    Dolophine
    Generic name: Methadone
    Dsuvia
    Generic name: Sufentanil
    Duragesic
    Generic name: Fentanyl Transdermal (skin Patch)
    Duragesic-100 skin patch
    Generic name: Fentanyl Transdermal (skin Patch)
    Duramorph
    Generic name: Morphine (MOR-feen)
    Duramorph PF injection
    Generic name: Morphine (injection)
    Eth-Oxydose
    Generic name: Oxycodone
    Exalgo
    Generic name: Hydromorphone (oral)
    Fentanyl
    Generic name: Fentanyl
    Fentanyl (Buccal mucosa, Oromucosal, Sublingual)
    Generic name: Fentanyl
    Fentanyl (Injection)
    Generic name: Fentanyl
    Fentanyl (Transdermal)
    Generic name: Fentanyl
    Fentanyl buccal/sublingual
    Generic name: Fentanyl (buccal/sublingual)
    Fentanyl citrate oral transmucosal
    Generic name: Fentanyl Citrate (oral Transmucosal)
    Fentanyl nasal
    Generic name: Fentanyl (nasal)
    Fentanyl transdermal skin patch
    Generic name: Fentanyl Transdermal (skin Patch)
    Fentora
    Generic name: Fentanyl (buccal/sublingual)
    FusePaq Synapryn
    Generic name: Tramadol
    Hydromorphone
    Generic name: Hydromorphone (oral)
    Hydromorphone (Oral)
    Generic name: Hydromorphone
    Hydromorphone injection
    Generic name: Hydromorphone (injection)
    Hydromorphone rectal
    Generic name: Hydromorphone (rectal)
    Hysingla ER
    Generic name: Hydrocodone (oral)
    Infumorph
    Generic name: Morphine (MOR-feen)
    Infumorph injection
    Generic name: Morphine (injection)
    Ionsys
    Generic name: Fentanyl Transdermal (device)
    Kadian
    Generic name: Morphine (oral)
    Kadian ER
    Generic name: Morphine (MOR-feen)
    Lazanda
    Generic name: Fentanyl (nasal)
    Levo-Dromoran
    Generic name: Levorphanol
    Levorphanol
    Generic name: Levorphanol (oral)
    Meperidine
    Generic name: Meperidine (oral/injection)
    Meperidine (Injection)
    Generic name: Meperidine
    Meperidine (Oral)
    Generic name: Meperidine
    Meperitab
    Generic name: Meperidine
    Methadone
    Generic name: Methadone (oral/injection)
    Methadone (Oral)
    Generic name: Methadone
    Methadose
    Generic name: Methadone
    Mitigo injection
    Generic name: Morphine (injection)
    Morphabond
    Generic name: Morphine (MOR-feen)
    Morphabond ER
    Generic name: Morphine (MOR-feen)
    Morphine
    Generic name: Morphine (oral)
    Morphine (Epidural)
    Generic name: Morphine
    Morphine (Oral)
    Generic name: Morphine (MOR-feen)
    Morphine injection
    Generic name: Morphine (injection)
    MS Contin
    Generic name: Morphine Sulfate (oral)
    Nalbuphine
    Generic name: Nalbuphine
    Nubain
    Generic name: Nalbuphine
    Nucynta
    Generic name: Tapentadol
    Nucynta ER
    Generic name: Tapentadol
    Numorphan
    Generic name: Oxymorphone
    Oliceridine
    Generic name: Oliceridine
    Olinvyk
    Generic name: Oliceridine
    Onsolis
    Generic name: Fentanyl (buccal)
    Opana
    Generic name: Oxymorphone
    Opana ER
    Generic name: Oxymorphone
    Opium
    Generic name: Opium
    Opium preparation
    Generic name: Opium Preparation
    Oramorph SR
    Generic name: Morphine (MOR-feen)
    Oxaydo
    Generic name: Oxycodone
    Oxecta
    Generic name: Oxycodone
    Oxycodone
    Generic name: Oxycodone
    Oxycontin
    Generic name: Oxycodone
    Oxycontin CR
    Generic name: Oxycodone
    Oxydose
    Generic name: Oxycodone
    Oxyfast
    Generic name: Oxycodone
    OxyIR
    Generic name: Oxycodone
    Oxymorphone
    Generic name: Oxymorphone
    Oxymorphone (Injection)
    Generic name: Oxymorphone
    Oxymorphone (Oral)
    Generic name: Oxymorphone
    Palladone
    Generic name: Hydromorphone
    Pentazocine
    Generic name: Pentazocine
    Propoxyphene
    Generic name: Propoxyphene
    Qdolo
    Generic name: Tramadol Hydrochloride
    Remifentanil
    Generic name: Remifentanil
    Roxanol
    Generic name: Morphine (MOR-feen)
    Roxanol-T
    Generic name: Morphine (MOR-feen)
    Roxicodone
    Generic name: Oxycodone
    Roxicodone Intensol
    Generic name: Oxycodone
    RoxyBond
    Generic name: Oxycodone
    Rybix ODT
    Generic name: Tramadol
    Ryzolt
    Generic name: Tramadol
    Stadol
    Generic name: Butorphanol
    Stadol NS
    Generic name: Butorphanol
    Sublimaze
    Generic name: Fentanyl
    Subsys
    Generic name: Fentanyl (buccal/sublingual)
    Sufenta
    Generic name: Sufentanil
    Sufentanil (Injection)
    Generic name: Sufentanil
    Sufentanil (Sublingual)
    Generic name: Sufentanil
    Talwin
    Generic name: Pentazocine
    Tapentadol
    Generic name: Tapentadol
    Tramadol
    Generic name: Tramadol
    TraMADol Hydrochloride ER (Eqv-Ryzolt)
    Generic name: Tramadol
    TraMADol Hydrochloride ER (Eqv-Ultram ER)
    Generic name: Tramadol
    Ultiva
    Generic name: Remifentanil
    Ultram
    Generic name: Tramadol
    Ultram ER
    Generic name: Tramadol
    Vantrela ER
    Generic name: Hydrocodone
    Xtampza ER
    Generic name: Oxycodone
    Zohydro ER
    Generic name: Hydrocodone (oral)

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