Opioid abuse

From WikiLectures

  • Opiate receptors - located in the CNS, in peripheral tissues
  • Endogenous agonists (ligands): endorphins, enkephalins, dynorphin (peptides)[1]

Opiate CNS Effects[edit | edit source]

Stimulation of opiate receptors[edit | edit source]

  • μ – respiratory depression, supraspinal analgesia, physical dependence
  • κ – spinal analgesia, miosis
  • δ – spinal analgesia, euphoria, sometimes dysphoria
  • ε – supraspinal analgesia
  • σ – mydriasis, dysphoria

Agonists[edit | edit source]

  • morphine, codeine, heroin,...
  • methadone, pethidine, der. fentanyl, …

Antagonists[edit | edit source]

  • naloxone, naltrexone, nalorphine, levalorphan, ….

Agonists/Antagonists[edit | edit source]

  • buprenorphine, pentazocine, …

Opiate Peripheral Effects[edit | edit source]

  • reduced mobility in the gastrointestinal tract (constipation)
  • vascular hypotonia (hypotension)
  • bladder hypertonia (urinary retention)[1]

Chronic abuse[edit | edit source]

  • Development of tolerance - adaptation of receptor density (?)
  • Reduced tolerance to respiratory depression
  • In a state of drug withdrawal:
– hypersensitivity of adapted neurons
– unpleasant peripheral vegetative effects[1]

Therapy[edit | edit source]

  • "Harm reduction" programs: exchange of syringes and needles
  • "Substitution programs" - the ultimate goal should be abstinence
  • Replacement of heroin addiction with another drug (methadone, buprenorphine),
  • Suppression of withdrawal symptoms, reduction of euphoric feelings by administration p.o.[1]

Opioid Agents[edit | edit source]

Opium[edit | edit source]

  • dried juice from unripe poppies "Papaver somniferum"
Papaver somniferum
  • is contained in:
- morphine 4-30%
- codeine 0.3-3%
- noscapine, narcotine 4–10%
- papaverine 1-1.5%
- thebaine 0.2-1%

Heroin[edit | edit source]

  • diacetylmorphine – "pro-drug" of morphine
– morphine transporter to the brain
– easier to penetrate membranes
– labile, deacetylates easily
  • 6-monoacetylmorphine' and morphine 6-glucosiduronate are active metabolites

Abuse[edit | edit source]

  • Usual doses of heroin: 10-15 mg/day
  • With tolerance up to 2 g/day
  • Symptoms: euphoria, lethargy, miosis, respiratory depression, bradycardia, hypotension, depression to coma, possible death
  • Addicts report 4 stages after a heroin high (i.v. injection):
  1. High – kick
  2. well-being, happiness,
  3. composure,
  4. "abstract".

Causes of Death[edit | edit source]


Links[edit | edit source]

Related Articles[edit | edit source]

References[edit | edit source]

  1. a b c d e BALÍKOVÁ, Mary. Abuse and intoxication [online]. [cit. 2012-03-09]. <https://el.lf1.cuni.cz/p56355604/>.