The standard form of methadone used in NHS Lothian is methadone 1mg/ml oral solution. Do not use higher concentrations or oral tablets.
Methadone has a long half-life (range from 14 to 72 hours) with mean of approximately 24 hours. It is frequently lethal in overdose or when given to opioid naive patients, or in those who have lost their tolerance to opioids.
Extra caution should be exercised when re-introducing methadone after a period of abstinence e.g. post intubation following an ITU admission.
Please consult with Drug Liaison Nurses or the PrePare Team if the patient is pregnant. See Useful phone numbers and contacts during working hours.
Cautions
Exercise extra caution when prescribing methadone in patients with:
- Respiratory disease
- Head injury – the Glasgow Coma Scale is not sensitive enough to assess opioid intoxication
- Renal Impairment
- Liver disease/hepatitis
- Co-existent alcohol dependence
- Overdose/decreased tolerance
- If receiving opioid analgesia or other sedating medications
- Interactions with other prescribed drug e.g. rifampicin used in the treatment of tuberculosis reduces methadone plasma concentration by 30-65%
- Pregnancy; unless indicated for emergency treatment of seizure activity please contact PrePare Team for advice. See Useful phone numbers and contacts during working hours.
If a methadone dose has been missed for more than three days, refer to section Missed doses and contact the Drug Liaison Nurses for dosing advice. If out of hours, refer to the Inpatient substance misuse pathway