Module 2: Treatment options Flashcards
Why should medically supervised withdrawal (detox) alone be avoided when trying to achieve opioid abstinence?
- Alone, it rarely leads to abstinence (CRISM, 2018; CAMH, 2021).
- Individuals face higher risk of opioid poisoning due to tolerance reduction.
When to consider abstinence-based treatment?
- client prefers it
- younger
- brief history of OUD
- good social supports
- no major psychiatric co-morbidity
- not dependent on other substances
- good past response to abstinence-based treatment (i.e. ++months abstinent after first try)
What is the rate of relapse to opioid use following withdrawal management (detox)?
90% by six months (Tuten et al., 2012)
Define harm reduction
Approaches that reduce the risk of a behaviour without the expectation the behaviour will stop.
e.g. seat belts and helmets
What are some harms that substance use harm reduction focuses on?
- infectious diseases (HIV, Hep B/C)
- opioid poisoning
- injury from IV drug use
- death
Naltrexone mechanism of action
opioid receptor antagonist
Naltrexone forms
Oral (+ IM in the US only)
Patient factors suggesting trial of naltrexone for OUD
- have completed detox/withdrawal
- high motivation
- physically healthy
- better when combined with psychosocial therapy
Patient factors that are barrier to naltrexone use
- poor medication adherence history
(see https://www.porticonetwork.ca/web/opioid-toolkit/treatment/naltrexone)
1st-4th line treatments for OUD
- buprenorphine/naltrexone
- methadone
- SROM (off-label)
- iOAT (Injectable opioid agonist therapy) (diacetylmorphine or hydromorphone)
What are pros of bup/nlx for OUD?
- superior safety profile
- more flexible take-home dosing
OAT pros
bup/nlx and methadone:
- significant reduction all-case and opioid-related mortality
- improves social functioning and QOL
- reduction in use of other opioids
- reduction in high risk behaviour
- reduction in crime
- reduction in opioid poisoning
buprenorphine mechanism of action
- partial opioid receptor agonist (mu) + antagonist (kappa)
- attentuates withdrawal
- reduces cravings
- blocks other opioids (b/c high affinity)
bup/nlx pros over methadone
- safety: ceiling effect (b/c partial agonist) -> less likely to cause respiratory depression
- convenience: easier to allow take-home doses
- rapid: takes only days/weeks to titrate up to effective dose vs weeks/months for methadone
- less QTc prolonging
- lower risk with diversion
- easier to taper d/t long-half life and partial agonist
buprenorphine pharmacodynamics
receptor activity and the effects on the person
- mu partial agonist (high affinity)
- kappa antagonist
- mu agonism = analgesia, resp/LOC depression, pupillary constriction, decreased bowel motility
- kappa antagonism = anti-analgesia and anti-dysphoria
buprenorphine - why is activity at kappa receptor important?
anti-analgesia -> less opioid hyperalgesia
anti-dysphoria -> less dysphoria
Common Adverse effects of bup/nlx
differentiate persistent vs subside with time
persistent:
constipation
sweating
decreased libido
insomnia
subside with time:
reduced appetite
weight gain
nausea
drowsiness
nervousness
(shared with methadone)
Less common adverse effects of bup/nlx
flushing
vomiting
dizziness
dry mouth
swelling of ankles
heaviness in arms and legs
abdominal cramps
Mehanism of inducing withdrawal when using bup/nlx
- bup high affinity for mu -> displacing any full agonist
- since bup is only partial agonist, activity at receptors drop from high to lower activity -> withdrawal
Even at max dosing, bup/nlx may cause withdrawal for some individuals
Indications for methadone
(in general)
OUD and chronic pain
pharmacodynamics of methadone
mu full agonist
methadone benefits
supress withdrawal
reduces cravings
reduces euphoric effect of other opioids
long acting (vs say heroin)
tolerance develops slowly (years)
methadone – common adverse effects
persistent vs temporary
common/persistent:
sweating,
conspitation,
decreased libido,
insomnia
temporary
abdominal cramps
nausea
reduced appetite
drowsiness
nervousness
methadone – serious side effects
QTc prolongation
sedation / cognitive dulling
resp. depression
(dose-dependent, therefore suggest dose is too high)
Indications for SROM (slow-release oral morphine)
contraindications, intolerable side-effects, or inadequate reponse to bup/nlx or methadone
What must be done before SROM treatment is initiated (and why)?
Must have specialist consultation because it is off-label
High risk factors for methadone toxicity (overdose)
- older or teens with short period of use / no IVDU
- use benzos, EtOH or other sedatives
- COPD or resp illness
- low tolerance to opioids (use infrequently, small amounts)
When to use methadone over bup/nix
- failed bup/nlx (likely highly tolerant or bup/nlx by IV)
- prefers methadone and severely dependentd
methadone vs bup/nlx efficacy
Methadone only has advantage to bup/nlx when both are used at low doses
Therefore, start with bup/nlx and get to a good treatment dose
(Mattick et al., 215/2018)- Cochrane review of tx heroin use disorder
