Opiate Overdose

Question 1

Define opiate overdose.

Answer 1

Opioids are used in the treatment of pain but are often sold illicitly and abused for their euphoric effects.

An overdose occurs when larger quantities than physically tolerated are taken, resulting in central nervous system and respiratory depression, miosis, and apnoea, which can be fatal if not treated rapidly.

Question 2

What is the antidote to opioid overdose?

Answer 2

Naloxone

Question 3

List some common opoiods. (5)

Answer 3

Opiates (natural)

• Morphine
• Codeine
• Thebaine

Other opiods (synthetic and natural)

• Fentanyl
• Heroin (diacetylmorphine)
• Hydromorphone
• Meperedine
• Methadone (high bioavailability and half life)
• Oxymorphone

Question 4

What is the difference between an opiod and an opiate?

Answer 4

An opioid is any synthetic or natural agent that stimulates opioid receptors and produces opium-like effects.

Opiates are opioids naturally derived from the opium poppy, Papaver somniferum, and include morphine and codeine.

Question 5

How common is opioid abuse?

Answer 5

In 2016, opioid overdose deaths exceeded those from heroin overdose.

Recent abstinance, resulting in loss of tolerance, increases risk of overdose - most common cause of death for former inmates after prison release is overdose.

Question 6

What are the causes of opioid overdose?

Answer 6

1. Substance abuse complication
2. Unintentional overdose on prescription
3. Self-harm
4. Iatrogenic overdose by practitioner

Question 7

What is the pathophysiology of opioid overdose?

Answer 7

Reduce pain perception by inhibiting neurotransmission in PNS and CNS by binding opioid receptors:

• mu - mediate analgesia, sedation, resp depression, euphoria, GI dysmotility and physical dependance
• kappa - mediate analgesia, miosis, diuresis, dysphoria
• delta - mediate analgesia, DA release inhibition, cough suppression

In overdose, patients usually succumb to respiratory failure (decrease medullary hypercarbia response and decrease respiratory response to hypoxia resulting in no stimulus to breathe and apnoea)

Question 8

What are the signs and symptoms of opioid overdose?

Answer 8

• miosis - pin
• bradypnoea
• altered mental status - drowsiness/sleepiness
• needle marks/old track marks
• drug paraphernalia e.g. syringes, smoking equipment
• decreased GI motility
• dramatic response to NALOXONE

Other: pulmonary rales (=ARDS), frothy pink sputum, seizures (w/ overdose of meperidine, propoxyphene, and tramadol), dysrhythmias

Question 9

What investigations would you do for opioid overdose?

Answer 9

• Trial of naloxone - check for reversal
• ECG - check for myocardial ischaemia, QRS prolongation in propoxyphene overdose
• CXR - non-cardiogenic pulmonary oedema, ARDS (perihilar, basilar, or diffuse alveolar infiltrates)
• AXR - in “body packers” may show packets throughout GI tract
• Urinalysis - toxicology screen for opioids but can be positive even if opioid was taken several days prior
• Gas chromatography/mass spectrometry - most sensitive and specific to test for opioids in serum

Question 10

How do you manage opiate overdose? (not on Sofia)

Answer 10

• Ventilation - maintain sats at 94-98%
• Naloxone - 0.4-2mg IV/IM/SC every 2-3mins until breathing is adequate (duration of effect is 30-90mins so repeat as necessary as short half life).
• Patients with retained drug packages - whole bowel irrigation; polyethylene glycol electrolyte solution given NG until rectal effluent is clear

Question 11

What are the side effects of naloxone?

Answer 11

• Naloxone precipitates features of opiate withdrawal - diarrhoea and cramps
• These respond to diphenoxylate and atropine (e.g. co-phenotrope)
• Sedate as needed

Question 12

What might you give to combat withdrawal in high-dose opiate misusers?

Answer 12

Methadone (10-30mg/24hr PO)

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