Opioid abuse


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

Stimulation of opiate receptors

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

Agonists

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

Antagonists

 * naloxone, naltrexone, nalorphine, levalorphan, ….

Agonists/Antagonists

 * buprenorphine, pentazocine, …

Opiate Peripheral Effects

 * reduced mobility in the gastrointestinal tract (constipation)
 * vascular hypotonia (hypotension)
 * bladder hypertonia (urinary retention)

Chronic abuse

 * 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

Therapy

 * "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.

Opium

 * dried juice from unripe poppies "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

 * 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

 * 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

 * respiratory depression
 * aspiration of vomit
 * pulmonary edema
 * rarely anaphylactic shock (hypersensitivity)
 * heroin leukoencephalopathy (inflammation of the white matter of the brain)

Related Articles

 * Drug addiction and illegal production and possession of narcotic substances
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 * Cannabinoid use disorders • Opioid use disorders