Overview
Opioid Misuse & Dependence
1. Clinical Overview
Summary
Opioid use disorder involves problematic use of opioids (heroin, morphine, prescription opioids) leading to clinically significant impairment. Physical dependence develops rapidly, and withdrawal, though rarely fatal, is extremely unpleasant. Overdose causes fatal respiratory depression.
Key Facts
| Aspect | Detail |
|---|---|
| Most Dangerous Risk | Respiratory depression (overdose → death) |
| Classic Triad (Overdose) | Pinpoint pupils, respiratory depression, decreased consciousness |
| Antidote | Naloxone (opioid antagonist) |
| Withdrawal | Flu-like, NOT fatal (unlike alcohol/benzodiazepines) |
| Treatment | Opioid substitution therapy (OST) |
Clinical Pearls
- Pinpoint pupils: Pathognomonic - always consider opioid toxicity
- Naloxone saves lives: Community naloxone programmes reduce deaths
- Methadone/Buprenorphine: Evidence-based treatment, reduces mortality
- BBV risk: IV users - screen for Hep B, C, HIV
2. Epidemiology
UK Statistics
| Metric | Data |
|---|---|
| Opioid-related deaths (England & Wales) | ~3,000/year |
| People in treatment for opioids | ~130,000 |
| Age group | Most deaths in 40-49 year olds |
Risk Factors
| Risk Factor | Association |
|---|---|
| Previous overdose | Highest risk for future |
| Loss of tolerance | Post-prison, post-detox |
| Polydrug use | Benzodiazepines, alcohol |
| Injecting drug use | Higher risk than other routes |
| Mental health comorbidity | Depression, trauma |
| Homelessness | Access barriers |
3. Pathophysiology
Opioid Receptor Effects
Mu (μ) Receptor Activation
↓
┌────┴────┐
↓ ↓
Analgesia Euphoria Respiratory Depression
↓
DEATH (Overdose)
Tolerance and Dependence
| Process | Mechanism |
|---|---|
| Tolerance | Receptor downregulation - need more for same effect |
| Dependence | Homeostatic adaptations - withdrawal if stopped |
| Addiction | Compulsive use despite harm |
Withdrawal Mechanism
- Removal of opioid → rebound sympathetic activation
- Noradrenaline surge causes symptoms
4. Clinical Presentation
Intoxication
| Feature | Description |
|---|---|
| Pupils | Pinpoint (miosis) |
| CNS | Drowsiness → unconsciousness |
| Respiratory | Depression (slow, shallow) - FATAL |
| GI | Constipation, nausea |
| Skin | Warm, flushed |
Overdose
| Sign | Severity |
|---|---|
| RR <8/min | Severe |
| O2 sats <90% | Severe |
| GCS <8 | Requires airway protection |
| Cyanosis | Severe hypoxia |
Withdrawal
| Feature | Description |
|---|---|
| Flu-like | Myalgias, rhinorrhoea, lacrimation |
| Pupils | Dilated (mydriasis) |
| GI | Diarrhoea, vomiting, abdominal cramps |
| Autonomic | Sweating, piloerection ("cold turkey") |
| Psychological | Agitation, insomnia, cravings |
| Timing | Starts 6-12 hrs (heroin), peaks 36-72 hrs |
| Danger | Very unpleasant but rarely fatal |
5. Clinical Examination
Intoxication/Overdose
| Finding | Notes |
|---|---|
| Pinpoint pupils | Pathognomonic |
| Respiratory rate | <12/min concerning, <8/min severe |
| Track marks | Evidence of IV use |
| GCS | Assess level of consciousness |
Withdrawal
| Finding | Notes |
|---|---|
| Dilated pupils | Opposite to intoxication |
| Rhinorrhoea | "Runny nose" |
| Piloerection | "Goosebumps" |
| Restlessness | Agitation |
Evidence of Chronic Use
- Track marks / injection sites
- Abscesses, cellulitis
- Dental decay
- Poor nutritional state
6. Investigations
Overdose
| Test | Purpose |
|---|---|
| ABG | Hypoxia, hypercapnia |
| Blood glucose | Exclude hypoglycaemia |
| ECG | QTc if methadone toxicity |
| Drug screen | Confirm opioids (often not helpful acutely) |
General Assessment
| Test | Purpose |
|---|---|
| BBV screen | Hep B, Hep C, HIV |
| LFTs | Hepatitis |
| FBC | Anaemia, infection |
| ECG | QTc before methadone |
7. Management
Overdose
| Step | Action |
|---|---|
| A | Airway (head tilt, chin lift, recovery position) |
| B | Breathing support |
| Naloxone | 400mcg IM/IV, repeat every 2-3 min PRN |
| Monitor | Naloxone wears off before opioids - may need repeat/infusion |
Naloxone Dosing
| Route | Dose | Repeat |
|---|---|---|
| IM/SC | 400mcg initial | Repeat 2-3 min |
| IV | 100-200mcg | Titrate carefully |
| Intranasal | 2mg (community) | Single dose |
Withdrawal Management
| Approach | Options |
|---|---|
| Symptomatic | Lofexidine (alpha-2 agonist), anti-diarrhoeals, antiemetics |
| Substitute | Buprenorphine taper, methadone taper |
Opioid Substitution Therapy (OST)
| Drug | Properties | Notes |
|---|---|---|
| Methadone | Full agonist, long half-life | QTc monitoring, supervised consumption |
| Buprenorphine | Partial agonist | Precipitates withdrawal if given too early |
| Buprenorphine/naloxone | Combined formulation | Deters injection |
OST Principles
- Daily supervised consumption initially
- Aim stable dose, then flexibility
- Reduces mortality by 50%
- Harm reduction: needle exchange, naloxone supply
Psychosocial Support
- Key-working
- Group therapy
- Contingency management
- Treatment of comorbid mental illness
8. Complications
| Complication | Notes |
|---|---|
| Death (overdose) | Main cause of death |
| Infective endocarditis | Right-sided (tricuspid), IV drug use |
| Hepatitis B/C | IV sharing |
| HIV | IV sharing |
| Cellulitis/abscesses | Injection sites |
| Deep vein thrombosis | IV damage |
| Overdose on release | Loss of tolerance post-prison/hospital |
9. Prognosis & Outcomes
| Factor | Outcome |
|---|---|
| OST retention | Reduces mortality 50% |
| Untreated | High mortality, ongoing harm |
| Hepatitis C treatment | Now curable (DAAs) |
| Recovery | Possible with support |
10. Evidence & Guidelines
| Organisation | Key Points |
|---|---|
| NICE NG52 | OST, harm reduction, naloxone |
| NICE CG51 | Drug Misuse Management |
| Orange Guidelines | Clinical management of drug dependence |
11. Patient / Layperson Explanation
What is opioid dependence? It's when your body becomes reliant on opioids (like heroin or prescription painkillers) and you feel unwell if you stop taking them. It's a medical condition, not a moral failing.
What happens in overdose? Opioids slow your breathing. Too much can stop your breathing completely. Warning signs are pinpoint pupils, drowsiness, slow breathing. This is a medical emergency - call 999.
What is naloxone? It's a medication that reverses opioid overdose. It's available in community programmes and can save lives. If you use opioids or know someone who does, carry it.
What is treatment?
- Methadone or buprenorphine: Prescribed opioid substitutes that stop cravings and withdrawal
- Harm reduction: Clean needles, naloxone, safer use advice
- Support: Counselling, groups, help with housing and mental health
- Recovery is possible with the right support
12. References
- NICE NG52. Drug Misuse in Over 16s: Opioid Detoxification. 2007.
- NICE CG51. Drug Misuse: Psychosocial Interventions. 2007.
- PHE. Clinical Guidelines on Drug Misuse (Orange Book). 2017.
- Degenhardt L, et al. Global burden of disease attributable to illicit drug use. Lancet. 2013.