Opioids are substances that act on opioid receptors to produce morphine-like effects.[2] Medically they are primarily used for pain relief, including anesthesia.[3] Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, reversing opioid overdose, and suppressing cough.[3] Extremely potent opioids such as carfentanil are approved only for veterinary use.[4][5][6] Opioids are also frequently used non-medically for their euphoric effects or to prevent withdrawal.[7] Opioids can cause death and have been used for executions in the United States.
Opioid
Drug class
Side effects of opioids may include itchiness, sedation, nausea, respiratory depression, constipation, and euphoria. Long-term use can cause tolerance, meaning that increased doses are required to achieve the same effect, and physical dependence, meaning that abruptly discontinuing the drug leads to unpleasant withdrawal symptoms.[8] The euphoria attracts recreational use, and frequent, escalating recreational use of opioids typically results in addiction. An overdose or concurrent use with other depressant drugs like benzodiazepines commonly results in death from respiratory depression.[9]
Opioids act by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract. These receptors mediate both the psychoactive and the somatic effects of opioids. Opioid drugs include partial agonists, like the anti-diarrhea drug loperamide and antagonists like naloxegol for opioid-induced constipation, which do not cross the blood-brain barrier, but can displace other opioids from binding to those receptors.
Because opioids are addictive and may result in fatal overdose, most are controlled substances. In 2013, between 28 and 38 million people used opioids illicitly (0.6% to 0.8% of the global population between the ages of 15 and 65).[10] In 2011, an estimated 4 million people in the United States used opioids recreationally or were dependent on them.[11] As of 2015, increased rates of recreational use and addiction are attributed to over-prescription of opioid medications and inexpensive illicit heroin.[12][13][14] Conversely, fears about overprescribing, exaggerated side effects, and addiction from opioids are similarly blamed for under-treatment of pain.[15][16]Opioids include opiates, an older term that refers to such drugs derived from opium, including morphine itself.[17] Other opioids are semi-synthetic and synthetic drugs such as hydrocodone, oxycodone and fentanyl; antagonist drugs such as naloxone; and endogenous peptides such as the endorphins.[18] The terms opiate and narcotic are sometimes encountered as synonyms for opioid. Opiate is properly limited to the natural alkaloids found in the resin of the opium poppy although some include semi-synthetic derivatives.[17][19] Narcotic, derived from words meaning 'numbness' or 'sleep', as an American legal term, refers to cocaine okay..
2. Analgesics
Analgesics, or pain killers, that bind to opioid receptors which are
found principally in the:
CNS
Gastrointestinal tract
Classification:
Natural opiates
Semi-synthetic Opiates
Fully synthetic opioids
Endogenous opioid peptides
5. Method of action
Receptor
type
Location Effects
μ Brain,
spinal
cord
Analgesia, respiratory
depression, euphoria,
addiction, ALL pain
messages blocked
κ Brain,
spinal
cord
Analgesia, sedation, all
non-thermal pain
messages blocked
δ Brain Analgesia,
antidepression,
dependence
• In general, opioids
act upon mu-, delta-,
and kappa-receptors
on CNS neurons
producing:
• Analgesia via
decreased neuronal
transmitter release
and decreased
nociceptive impulse
propagation
• Appears to work by
elevating the pain
threshold, thus
decreasing the
brain’s awareness of
pain
6. Metabolism
• The opioids are converted in large part to polar
metabolites.
• Morphine is metabolized to M3G and M6G.
• M3G, a compound with neuroexcitatory
properties and M6G, an active metabolite with
analgesic property.
• Esters (e.g, heroin, remifentanil) are rapidly
hydrolyzed by common tissue esterases.
• Heroin (diacetylmorphine) is hydrolyzed to
monoacetylmorphine and finally to morphine,
which is then conjugated with glucuronic acid.
7. Excretion
• Polar metabolites, including glucuronide
conjugates of opioid analgesics, are excreted
mainly in the urine.
• Small amounts of unchanged drug may also be
found in the urine.
• Glucuronide conjugates are found in the bile.
• Enterohepatic circulation represents only a small
portion of the excretory process.
8. Mechanism of Action
• Opioid drug bind to opioid receptor widely
distributed in CNS and other tissues.
• A part of family of G- protein complex receptors.
• Open K+ Channels.
• Prevent opening of Ca2+ channels.
• Inhibit the release of other neurotransmitters.
9.
10.
11.
12.
13.
14. Clinical Uses
• Analgesia
• Acute Pulmonary Edema
• Cough Suppression
• Diarrhea
• Severe cute shooting visceral pain.
• MI.
• Shivering
• Terminal stages of malignancy.
• Severe crush injuries.
• Postoperative pain.
• Applications in Anesthesia
15. Clinical Use
• Treatment of acute opioid overdose.
• Treatment of opioid addiction.
• Analgesic.
• Used to reverse the effects of narcotic drugs
used during surgery or to treat pain.
16. Brands available
Generic Name Brand Name
buprenorphine Buprenex
butorphanol Stadol
codeine Tylenol with codeine
fentanyl Duragesic
hydrocodone Vicodin
hydromorphine Dilaudid
methadone Dolophine
morphine Astramorph
oxycodone OxyContin
porpoxyphene Darvon
