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opioid_dependence

opiate and opioid dependence

History in Australia:

  • heroin injecting commenced in Australia in the late 1960's
  • by 1997, it was estimated there was ~70,000 heroin-dependent persons with a rapid increase over the past few years associated with cheaper heroin
  • deaths from heroin overdose has increased from 6 in 1964 to 600 in 1997 and 737 in 1998
  • HIV / AIDS remains under good control amongst heroin injectors but ~11,000 cases of hep C in 1997 were attributed to sharing of injection equipment
  • heroin dependency is a poorly understood, chronic relapsing condition
  • mortality is 1-2% per year which is ~15 times that for similar age & sex population
  • a UK study in 2005 showed that of those that took heroin “regularly” at less than 3x per week, on average it took 9 months for them to become physically dependent and use it daily. The actual time for physical dependence depended on a complex interaction of social factors (eg. living with a dependent person accelerated dependence), personality and context in which people use the drug. None became instantly addicted, some took as little as 5-6 months, while others took 5 years before becoming physically dependent.

Benefits of treatment of heroin dependence:

health:

  • reduction in deaths
  • reduction in morbidity - hep C, hep B, HIV, bacterial infections (abcesses, SBE), non-fatal overdoses
  • improvement in mental health

social:

  • improved relationships & parenting
  • reduction in crime
  • increased employment
  • improved residential status (ie. less homelessness)
  • increased education & training
  • reduction in all sorts of drug usage

 *reduction in heroin use

economic:

  • earning income legally, or social security
  • less debt
  • benefits outweigh costs to individuals & society

Drug Treatment of Opioid Dependence:

initial detoxification:

  • most is provided in residential care but outpatient detox. is increasing, though not all are suitable or willing for this approach.
  • relapse is common and should not be cause for despair, but should be Rx by further detox. or other Rx forms ASAP.
  • usual detoxification is a combination Rx of (this can also be used for inadvertent naltrexone usage causing withdrawal):
    • IV fluids
    • anti-emetic:
      • helps ameliorate some of the more distressing symptoms of heroin withdrawal
      • dose: 75-150 mcg orally when vomiting controlled, or up to 300mcg i.v. titrated to effect (monitor BP)
      • if cease clonidine abruptly may get rebound hypertension
      • lofexidine is similar but with less CVS adverse effects but not available in Aust. yet.
      • for bone pain
    • diphenoxylate or lomotil:
      • for diarrhoea
      • for abdominal cramps
      • dose: 20mg slow i.v. titrated to effect
      • for short term Rx of insomnia
      • eg. midazolam 5mg i.v. boluses titrated to effect or oral diazepam as symptoms settle
    • if uncontrollable delirium, then consider:
      • rapid sequence induction anaesthesia, usually using propofol infusions

accelerated detoxification:

  • Ultra Rapid Opiate Detoxification (UROD)
  • Rapid Opiate Detoxification (ROD)
  • both currently experimental and require general anaesthesia or heavy sedation.

maintenance:

    • an opioid agonist which is well absorbed orally with a long half-life allowing once daily dosing
    • introduced in Australia for Rx of heroin dependence in 1964
    • pts attend a clinic or pharmacy each day to be given a supervised dose
    • detoxification is not required for pts starting methadone
    • psychosocial interventions are an important adjunct
    • as many as 85% will stay on methadone for 12mths & most require Rx for at least 2 yrs
    • pts retained in Rx on a larger dose & for a longer duration generally achieve better results
    • optimal dose is 60-100mg/day
    • important Rx factors include optimal dosing & the morale of clinic staff
    • programs are not available in the NT
    • a long acting opioid antagonist which is well absorbed orally
    • a severe withdrawal reaction may be precipitated if the pt has recently taken heroin or another opioid
    • thus should not be started until 7-10days after last opioid dose
    • dose: usually 50mg per day
    • best results are obtained with “motivated” pts (eg. white-collar professionals, persons on parole, probation or in jail)
    • if it is taken intermittently & then heroin is taken in the intervening periods, the risk of death from overdose may be INCREASED due to the reduced opioid tolerance.
    • has also been found useful to decrease craving in chronic alcoholics undergoing withdrawal treatment
    • a partial mu agonist and weak kappa antagonist taken sublingually as it has a high 1st pass metabolism
    • half-life 4-5hrs
    • ceiling effect:
      • because it is a partial agonist, its effects plateau at higher doses & then begins to behave more like an antagonist which limits its maximal analgesic & resp. depression effects
      • this confers a high safety profile clinically (better than methadone) although deaths have occurred from overdoses
    • the high affinity blockade significantly limits the effect of subsequently administered opioid agonists or antagonists
    • results are comparable to methadone
    • can be taken on alternate days
    • more expensive than methadone but may become Rx of choice
    • pts on large doses of heroin may experience some withdrawal symptoms
    • dose regimen:
      • 8-12mg sublingually daily for 5-7 days then maintenance dose 4-32mg/d will suppress symptoms of withdrawal & reduce illicit opioid use. Dosing can be extended to every 2-3 days.
    • acute overdose:
      • naloxone may be helpful in improving resp. depression although improvement in mental state may be less. Doses of 5-10mg may be needed.
  • leva-alpha-acetylmethadol (LAAM):
    • a methadone derivative with longer half-life allowing alternate day dosing
    • maybe available in Australia soon
  • sustained release oral morphine (SROM):
    • few studies; a trial has commenced in Australia in 2000;
  • prescription heroin:
    • has been available in UK since 1926 but has not been well studied.
    • results might be comparable to methadone & a Swiss study in late 1990's showed impressive results
    • may have a place in users refractory to other Rx
  • non-pharmacologic Rx:
    • examples:
      • drug-free outpatient counselling
      • residential rehabilitation
      • self-help groups (eg. Narcotics Anonymous)
    • retention is often poor& good evidence of benefit is hard to find
opioid_dependence.txt · Last modified: 2014/05/05 04:55 by gary1