As doctors, you will frequently see patients with opiate dependence. It isn’t uncommon for these patients to be admitted due to withdrawal or due to consequences of their drug use such as a groin abscess or overdose. It is difficult to differentiate symptoms of withdrawal from other conditions & the symptoms can be horrible leading to agitated patients that might attempt to self-discharge.
Opiate dependence is due to the body adapting to repeated exposure; this leads to it only functioning “normally” in the presence of opiates which can occur fairly quickly within days of continual use. Removing the drug can lead to withdrawal and typically can begin in 6-12 hours or longer (up to 30h) if a long-acting opiate is used. The withdrawal can last several days to weeks depending: on the short end for morphine and the longer end for opiates with a longer half-life such as methadone. Opioid withdrawal can be precipitated by opioid antagonists (such as naloxone) or partial agonists (such as buprenorphine). Precipitated withdrawal tends to be more severe & acute therefore avoid this.
Signs and symptoms of opiate withdrawal
- Gastrointestinal symptoms: diarrhoea, nausea, vomiting, abdominal cramps
- Flu-like symptoms: runny eyes/nose, sweating & shivering
- Autonomic: tachycardia, hypertension, dilated pupils, anxiety/irritability, insomnia and rarely pyrexia, tremor
- CNS: seizures, reduced GCS
- And others: yawning, anorexia, joint & muscle aches
Take a history
- Drug use (route, quantity/frequency, time of the last dose, reasons for taking/stopping) & use of other drugs
- Past medical history (e.g. liver dysfunction that might alter treatment)
- Psychiatric and substance misuse team history & contact with services
- Harm due to use including physical & mental (e.g. blood-borne viruses)
- Social history, support & possibility of pregnancy/children and whether they are known to social services & any domestic abuse or vulnerable adults
- FBC, U&Es, LFTs, Bloodborne viruses. Consider urine toxicology
- ECG for QTc
Withdrawal scoring and opiate substitution
All NHS trusts should have local guidelines on how to quantify & manage opiate withdrawal with substance misuse team that supports this. Clinical Opiate Withdrawal Scale (COWS) is typically used because it is easy to use, standardised & sensitive (see it here). Most charts will offer guidance on opiate substitution and treatment of withdrawal symptoms based on the patients’ usual opiate dose and their current presentation. The most common medications used for opiate substitution are methadone and buprenorphine. Benzodiazepines are sometimes used for symptom relief however should be avoided where possible. It is important to be aware that many patients may not provide an accurate substance history and be mindful of this when prescribing. As a rule, you can always increase doses if more is required!
Opiate conversion is extremely difficult, particularly with regards to methadone dosing and therefore it is important to check trust guidance and seek advice from pharmacy or alcohol and drugs services when calculating opiate substitution doses. The BNF provides good guidance on safe methadone dosing and titration of doses should these services not be available.
When prescribing methadone to a patient already on a methadone programme it is usually possible to gain additional information regarding their dose from the patient’s community pharmacy and the local alcohol and drugs service. Ensure these teams have verified the dose before prescribing it & don’t use what the patient says alone – this could lead to a life-threatening overdose. It is also imperative that you involve senior clinicians early in any patient with withdrawal symptoms.
Additionally, antiemetics (promethazine, metoclopramide) and anti-diarrhoeals (loperamide) may be used for symptomatic management. Note that metoclopramide, ondansetron, loperamide all prolong the QTc.
It is important to consider a concurrent prescription of naloxone in all patients with an active COWS or with strong opiates prescribed. This should be prescribed as a stat dose to be used in case of opiate toxicity precipitating respiratory depression or reduced GCS.
Both buprenorphine and methadone are metabolised largely by the liver. This requires caution when titrating doses in patients with liver dysfunction and those at risk of hepatotoxicity.
It is important to be mindful that buprenorphine can precipitate withdrawal in someone who has used heroin in the previous 8 hours or methadone within the past 24 hours so seek expert advice early in these patients.
Further Reading & References
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