[CG] Use of opiates in pregnancy - guideline for obstetric management

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Audience

This document is the existing guideline for and details current practice in Princess Royal Maternity, Glasgow. It does not describe practice in Clyde. Modification to additionally reflect practice in Clyde is planned to allow adoption as a GG&C Guideline.

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Opiates

  • Opiate use is common and takes many forms.
  • Street drugs (e.g. Heroin, Dihydrocodeine) are of uncertain potency. Prescribed opiate substitute medication is ideally methadone or buprenorphine but sometimes dihydrocodeine (not recommended in pregnancy).
  • In Clyde substitute medication is prescribed by the addiction services / GPs and is dispensed by community pharmacists, commonly with daily supervision (except weekends).
  • In pregnancy substitute medication is also prescribed by Glasgow SNIPS (previously WRHS) with community dispensing.
  • During pregnancy dispensing should always be on a daily supervised basis.
  • Opiate detoxification is “obstetrically safe” at any stage of pregnancy but is rarely successful and should not be attempted unless the timing is right and there is a good prospect of success.
  • Substitute medication dose may need to be increased / decreased according to the woman’s ability to cope: aim should be to maintain women at the lowest dose compatible with stability.
  • Opiate users may be admitted to hospital either because of problems related to their drug use (e.g. DVT, endocarditis, injection site abscess) or unrelated pathologies.
  • Pregnant women admitted to non-maternity wards should have their substitute medication continued and the relevant prescribing team should be notified of the admission

GG&C has a policy for the removal of illicit drugs from patients. Contact Pharmacy for details.

Substitute Medication:

The aim of substitution therapy is not to wean patients off opiate use but to supply a safe oral alternative to illicit opiates.

1. Choice of substitute medication:

The actual amount of illicit opiate taken on a daily basis will not be known with any degree of certainty. The severity of withdrawal symptoms varies but all pregnant women with significant addiction should be prescribed substitute medication. Methadone is always the drug of choice. It is a long acting opiate and once an appropriate dose has been established the whole daily requirement should be given as a single daily dose. Buprenorphine (Subutex ®) is an acceptable substitute. If women are already established on this treatment it is not necessary to change to methadone. Suboxone ® is contraindicated in pregnancy (the combination preparation containing buprenorphine and naloxone). Community addiction services routinely transfer pregnant women on Suboxone ® to Subutex ® but any pregnant woman found on booking / admission to be on the combined preparation should be immediately transferred to the same dose of Subutex ®. Dihydrocodeine is effective in treating withdrawal symptoms but should not be used in pregnancy. For initiating substitution therapy in pregnancy oral methadone is always the drug of choice.

2. Initiation of methadone substitution therapy:

Starting doses of methadone:

The starting dose of prescribed methadone should be 5 – 20mg methadone according to current level of use with subsequent escalation to the minimum dose that controls withdrawal symptoms. The appropriate initial and final doses can be predicted using the following conversion:
Methadone 10mg/£10 heroin
Methadone 10mg/60mg dihydrocodeine
Methadone 10mg/10mg street methadone.
It must be emphasised that due to possible impurity of street drugs the required final dose may be higher or lower than predicted but regardless of circumstances the starting dose should never be greater than 20mg methadone.

Subsequent dosage of methadone:
Day 1: A second dose of methadone 10mg can be prescribed on day 1 (>/=) 6 hours after the first dose if significant withdrawal symptoms persist.
Day 2: A morning dose equal to the total prescribed on day 1. A second dose of methadone 10mg can be given as on day 1 if necessary.
Thereafter: Give a morning dose of methadone equal to the total prescribed on the previous day with the option of a further 10mg as above until patient asymptomatic. Do not escalate above methadone 40mg without consulting medical staff responsible for substitute (maintenance) prescribing.

3. Ongoing outpatient prescribing of substitute medication, methadone or buprenorphine in Glasgow:

a) Outpatient prescribing:

SNIPS midwives can sanction 2 consecutive increments to the prescribed dose of 5mg each of methadone or 2mg each of buprenorphine without authorisation by SNIPS medical staff. Further dose escalations must be authorised by SNIPS medical staff.

SNIPS midwives can authorise reduction in methadone dose of 5mg or buprenorphine dose of 2mg without consulting SNIPS medical staff.

Any changes in dose should be implemented when the next prescription is routinely provided. Urgent earlier changes can be sanctioned by SNIPS medical staff (if available) during normal working hours.

b) Inpatient prescribing:

For women whose inpatient dose of substitute medication requires to be altered the above alterations can be authorised by SNIPS midwives on 2 occasions separated by a minimum of 24 hours.

NB. INPATIENTS SHOULD ONLY BE PRESCRIBED THE FULL CURRENT DOSE OF METHADONE OR BUPRENORPHINE IF DAILY SUPERVISED DISPENSING HAS BEEN IN PLACE UNTIL ADMISSION. FOR UNSUPERVISED PRESCRIBING SEE PARA 4b.

4. Dispensing arrangements:

a) Outpatient dispensing:

Prescribed substitute medication is dispensed by community pharmacies.
REGARDLESS OF PREVIOUS ARRANGEMENTS, DURING PREGNANCY DISPENSING SHOULD ALWAYS BE ON A DAILY SUPERVISED BASIS.

b) Inpatient dispensing:

Inpatients on a substitution programme admitted to hospital should have the dose of substitute medication continued in hospital. Details of the substitution programme and current dose should be obtained from the SNIPS (Glasgow) and/or addiction services (Glasgow & Clyde) and community pharmacist by telephone at the time of admission or first working day thereafter if admitted out-with pharmacy opening hours to avoid possible abuse of the system. Prior to prescribing in hospital it is essential to confirm details of the last dose dispensed and that this was supervised. Six day pharmacies dispense the Saturday and Sunday doses on the Saturday and 5 day pharmacies dispense the Saturday and Sunday doses on the Friday.

Women using a 6 day pharmacy admitted on a Sunday should already have been given the Sunday dose and should have taken it. If the woman says she has not yet taken the Sunday dose she should have brought it with her. If she has failed to do so she should be instructed to arrange for it to be brought to the hospital. If the methadone cannot be produced and she is adamant she has not already taken it she can be given a single dose of up to 20mg methadone according to the prescribed dose with the option of a further dose of 10mg methadone >/= 6 hours later if the usual prescribed dose is higher and significant withdrawal symptoms persist (see Section 2). The full dose should be prescribed from the Monday.

Women using a 5 day pharmacy admitted on Saturday should already have been given that Saturday and Sunday doses and should have taken the Saturday dose. If the woman says she has not yet taken the Saturday dose manage as above. If she is still an inpatient on the Sunday and is also unable to produce the Sunday dose she should be prescribed a further single dose of up to 40mg methadone (according to prescribed dose and/or total prescribed dose on previous day) with the full dose prescribed from the Monday.

The same rationale should apply to public holidays.

If methadone (or buprenorphine) is dispensed unsupervised it is not possible to confirm the actual dose taken. On admission to hospital women prescribed unsupervised methadone (or buprenorphine) should therefore have their urine screened to confirm presence of methadone or buprenorphine and if positive, they should be given an initial maximum dose of 20mg methadone (or 4mg buprenorphine) with subsequent escalation of the dose according to the SNIPS guideline (see Section 2).

Missed doses:

NB THE FOLLOWING ONLY APPLIES TO WOMEN ON DAILY SUPERVISED DISPENSING.

a) Methadone:

  • If attends any time on date prescription due to start give prescription.
  • If attends any time on next calendar day after prescription due to start give prescription only if pharmacist can be contacted and authorised to dispense full dose that day.
  • If attends 2 – 7 calendar days after prescription due to start cancel existing prescription and replace as follows:
    • Dose confirmed and prescribed dose </= 20mg methadone no need to modify dose
    • Dose confirmed and prescribed dose >20</=50mg methadone
      Day 1: prescribe 20mg methadone. Woman may have further dose of 10mg methadone or remainder of usual prescribed dose (whichever less) if willing to re-attend hospital to collect prescription.
      Day 2: prescribe up to 30mg methadone (if attended once on previous day) or 40mg (if attended twice on previous day).
      Day 3: prescribe full dose in every case.
    • Dose confirmed and prescribed dose >50mg methadone
      Day 1: prescribe 30mg methadone. Woman may have further dose of 20mg methadone if willing to re-attend hospital to collect prescription.
      Day 2: prescribe 50mg methadone (if attended once on previous day) or up to 70mg methadone (if attended twice on previous day).
      From Day 3: prescribe methadone with daily increments of up to 20mg Methadone until usual prescribed dose is reached or withdrawal symptoms controlled, whichever is less.
  • If attends >7 calendar days after prescription due to start cancel existing prescription and arrange addictions review with management as for treatment naïve patient.

b) Buprenophrine:

  • If attends any time on date prescription due to start give prescription.
  • If attends any time on next calendar day after prescription due to start give prescription only if pharmacist can be contacted and authorised to dispense full dose that day.
  • If attends 2 – 7 calendar days after prescription due to start cancel existing prescription and replace as follows:
    • Dose confirmed and prescribed dose </=4mg buprenorphine
      No need to modify dose
    • Dose confirmed and prescribed dose >4</=10mg buprenorphine
      Day 1: prescribe 4mg buprenorphine. Woman may have further dose of buprenorphine 2mg or remainder of usual prescribed dose (whichever is less) if willing to re-attend hospital to collect prescription.
      Day 2: prescribe up to 6mg buprenorphine (if only attended once on previous day) or 8mg (if attended twice on previous day).
      Day 3: prescribe full dose in every case.
    • Dose confirmed and prescribed dose >10mg buprenorphine
      Day 1: prescribe 6mg buprenorphine. Woman may have further dose of 4mg buprenorphine if willing to re-attend hospital to collect prescription.
      Day 2: prescribe 10mg buprenorphine (if attended once on previous day) or up to 14mg buprenorphine until usual prescribed dose reached or withdrawal symptoms controlled whichever is less.
  • If attends >7 calendar days after prescription due to start cancel existing prescription and arrange addictions review with management as for treatment naïve patient. Commencement of substitution therapy using buprenorphine is not currently an option in Glasgow SNIPS. Nevertheless, women who have been in receipt of prescribed buprenorphine from the service and have used illicit buprenorphine since last prescribed buprenorphine can be recommenced on prescribed buprenorphine with an initial dose of maximum 4mg buprenorphine (with option of second dose of up to 2mg buprenorphine on day 1 if willing to attend twice and symptoms merit) and escalation to previous dose (or till no withdrawal symptoms) by 2mg buprenorphine increments daily.

Women who have used other opiates since last use of prescribed buprenorphine should only be offered re-stabilisation on methadone.

For women on large doses of methadone or buprenorphine in-patient re-stabilisation may be the best option.

For women on large doses of methadone in-patient re-stabilisation may be the best option.

Additional Obstetric Care

  1. Record use of drugs (problem alcohol and / or drug use) (illicit and / or prescribed) on yellow alert sheet (maternal and neonatal sections) in maternal case notes.
  2. Women on regular benzodiazepines prescribed or illicit should be informed of the increased risk of cleft lip and/or palate at the time of the routine FAS scan is offered.
  3. Any woman with problem drug use (including women on prescribed opiate substitutes) should have AC measurements carried out at 28 – 30 and 32 – 34 weeks gestation at least 2 weeks apart.
  4. Opiates and / or benzodiazepines can cause reduced variability on CTG. Other explanations must be considered and excluded before assuming a causal link in this group of patients. Particular attention should be given to any CTG with more than one abnormal parameter.

Important notes

  1. Uncontrolled use of illicit opiates constitutes an obstetric emergency. Women reporting such use should be admitted immediately for stabilisation on prescribed methadone. Prescription of substitute methadone can be initiated by mainstream staff in accordance with the SNIPS guideline.
  2. Transfer to SNIPS of existing maintenance methadone prescription must be authorized by a member of SNIPS staff. This must be arranged during normal working hours and with a minimum of one week’s notice.
  3. Uncontrolled use of benzodiazepines is a significant obstetric problem but does not invariably warrant emergency admission. Inpatient detoxification (see above) is advisable but management cannot be agreed if the woman is intoxicated in which case she should be invited to return the following day for review.
  4. SNIPS staff should be notified as soon as possible with regard to ongoing management.

Last reviewed: 01 April 2016

Next review: 22 June 2021

Author(s): Dr E Ellis, Associate Specialist Obstetrician PRM; Mrs J Grant, Lead Clinical Pharmacist, W&C, O&G, GGC

Co-Author(s): Others professionals consulted: Dr H Mactier, Consultant Paediatrician, PRM; GG& C Obstetric Guideline Group

Approved By: Dr C Bain, Clinical Director, Obstetrics, GGC