Opioids (general) Flashcards
MoA
Acts on opioid receptors in the brain, spinal cord and other nervous tissue to relieve pain
Weak opioids
- Codeine (CD5, injections = CD2)
- Dihydrocodeine (CD5)
- Meptazinol (POM)
Moderate opioids
Tramadol
- CD3
- Exempt from safe custody requirements
Strong opioids
- Morphine
- Oxycodone
- Diamorphine
- Buprenorphine (S/L or 3/4/7 day pacthes)
- Fentanyl (72 hr patch or injection)
- Methadone
- Hydromorphone
All CD2, except buprenorphine which is CD3
Others
Pethidine
- Used in labour
- If accumulates = convulsions
Tapentadol
- Less nausea, vomiting and constipation than other strong opioids.
Breakthrough pain
- 1/10th or 1/6th of daily dose every 2-4 hours PRN
- Must be IR preparations
Opioid overdose
Symptoms = pinpoint pupils, coma, respiratory depression
Antidote = naloxone
Naloxone
Opioid receptor antagonists
Reverses respiratory depression
- Effects of buprenorphine are only partially reversed.
Can be supplied without a prescription by drug treatment services for the purpose of saving a life in an emergency e.g. heroin
Opioids - side effects
NERDSCeverything
(nerds see everything)
- N + V
- Euphoria, hallucinations
- Reduced concentration + confusion
- Dry mouth
- Sedation
- Constipation
N + V
Frequently with morphien
Give an antiemetic at start of treatment
- Prokinetic drug e.g. metoclopramide
Euphoria
Common with morphine
Sedation
Alcohol enhances this effect.
Driving may be impaired.
Constipation
Faecal softener + peristaltic stimulant
e.g. Senna + Lactulose
Larger doses - side effects
Respiratory depression
Hypotension
Pupil constriction
Muscle rigidity
Long term use - side effects
Hypogonadism
- Reduced fertility
- Amenorrhoea
- ED
Adrenal insufficiency
Hyperalgesia
- Reduce dose or switch
Respiratory depression
Major concentration
Treatment:
- Artificial ventilation
- Naloxone
Dependence
Becomes apparent on withdrawal
Avoid abrupt withdrawal after long-term treatment
Tolerance
Larger doses needed to achieve same level of analgesia
Contraindications
- Comatose patients
- Risk of paralytic ileus (reduced GI motility)
- Respiratory depression (avoid in asthma attacks/COPD)
- Head injury or raised intraocular pressure (interact with pupillary responses vital for neurological assessment)
Interactions - increased sedation
- Antidepressants
- Antihistamines
- Antipsychotics
- Antiepileptics
- Alcohol
- Benzodiazepines (also cause respiratory depression)
- Z drugs
Interactions - CNS excitation or depression
Hypertension
Hypotension
MAOIs
Cautionary labels
Warning: this medicine may make you sleepy. If this happens do not drive or use tools or machines. Do not drink alcohol
Side effects - SUMMARY
“MORPHINE”
- Miosis (pinpoint pupils), muscle rigidity
- Out of it (sedation)
- Respiratory depression
- Postural hypotension
- Hyperalgesia, hallucinations
- Infrequency (constipation + urinary retention)
- N + V
- Euphoria
Methadone
Used in opioid dependence
OD
More sedating
Long half life
- Accumulates = toxicity
Side effects
- QT prolongation
When would methadone be given?
Long history of opioid misuse
Increased anxiety during withdrawal
Abuses sedative drugs/alcohol
Buprenorphine - opioid dependency
OD
Less sedating
Safer
- can be used with other sedatig drugs
- less interactions
Milder withdrawal reaction
Lower risk of overdose
Buprenorphine - when to take (opioid dependency)
Take first dose on withdrawal signs
Take first dose 6-12 afters hour after OR 24-48 hours after methadone.
