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Mental Health
OST Prescribing Issues


  • The Tauranga Opioid Substitution Treatment service (OST) is one of the services offered by Bay of Plenty Addiction Service (BOPAS) that is part of Mental Health and Addiction Services, Bay of Plenty District Health Board (BOPDHB).
  • This pathway contains information and guidelines for General Practitioners authorized by BOPAS OST to prescribe methadone or buprenorphine/naloxone to patients in the GP Shared Care Programme. BOPAS OST intends that this information will assist in the provision of a quality, safe, professionally delivered OST Service that meets the needs of patients, their family/whanau, and the wider community. GPs and their staff are encouraged to consult with the Addiction Liaison Clinician or the Lead Clinician at BOPAS OST working in a shared-care partnership model.
  • BOPAS OST provides services for the management of opioid dependency from a harm reduction philosophy, supporting people towards recovery, relative to each individual and his or her own circumstances.
  • The OST programme is in accordance with:
  • The BOPAS Service manages the admission, stabilisation and specialist maintenance phases of OST treatment. Patients may then be assessed as meeting criteria for the GP Shared Care Programme where their OST is integrated with their primary health care provider who is authorised by BOPAS on a three-monthly (6-monthly with permission from the MOH) basis to prescribe methadone or buprenorphine/naloxone.

Prescribing Issues

  1. What to do when GP on leave/absent

    • GPs are urged to appoint a locum or practice partner to prescribe methadone or buprenorphine/naloxone to their authorised patients in their absence and to ensure that BOPAS, locum/practice partner and other practice staff are informed of this.
    • The BOPAS OST, Addiction Liaison Clinician is also available to support the locum/practice partner.
    • Should the GP plan to be away for longer than three months he/she needs to contact the Addiction Liaison Clinician so that BOPAS OST service can arrange authorization(s) for the locum or a practice partner (as required by Medsafe) and provide training and extra support.
  2. Prescribing for holidays/travel

    • Public holidays (Please contact BOPAS for support as required):
      • The GP is responsible for identifying when a patient's dispensing day/s fall on a public holiday and should annotate the prescription accordingly, i.e., write instructions for any change in dispensing required due to closure of the pharmacy. If space is limited use an additional sheet and attach it to the prescription.  The Addiction Liaison Clinician can assist with a generic holiday schedule that can be adjusted to suit individual needs.
      • It is preferred that no more than three consecutive takeaway doses are approved at any one time, except in the case of public holidays where pharmacies are not providing a service or in exceptional circumstances. In such cases 1 (one) additional takeaway dose (i.e., a total of four takeaway doses) may be prescribed for a patient providing the Patient, the Addiction Liaison Clinician and the GP are confident that it is a safe arrangement.
    • Patient holidays (within New Zealand):
      • The GP, with Addiction Liaison Clinician support, is responsible for organising alternative dispensing arrangements for patients on holiday. See transfers between pharmacies.
      • Patients should provide the GP with adequate notice of holidays.
    • Travel overseas:
      • GPs are advised to contact the Addiction Liaison Clinician for information and assistance with arranging overseas travel as soon as they receive a request from a patient. It is preferred that arrangements be made for the patient to be dispensed methadone or buprenorphine/naloxone via a programme in the country of destination.
    • Note: If the patient needs to travel with methadone or buprenorphine/naloxone doses they will require an exportation letter (explains dose and form (usually tablets) prescribed and the dates the medication is prescribed for).
    • Adequate notice (usually several weeks) is required to make these arrangements. More time may be required when a patient is travelling to more than one destination or where other complexities exist. There are a number of countries where OST is not available and/or where importation of methadone or buprenorphine/naloxone is illegal. In an emergency situation overseas travel may be arranged more quickly but this does not apply to all countries of destination.
    • *See Section 5.7 Travelling Overseas with Opioid Substitution Medication page 40 of “New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"
  3. Take away arrangements

    • Methadone or buprenorphine/naloxone Takeaway Arrangements:
      • A takeaway dose of methadone or buprenorphine/naloxone is any dose that is not consumed under observation at the dispensing pharmacy.
      • Takeaway arrangements in the GP Programme continue to be based on clinical safety and within the National Practice Guidelines.
      • Note: The National Practice Guidelines recommend that methadone or buprenorphine/naloxone should be observed to be consumed at the pharmacy or other dispensary on at least three non-consecutive days per week.
      • Variance: Where the authorised GP and the patient assess that less frequent dispensing is appropriate, this is notified to Addiction Liaison Clinician for BOPAS OST team review. Once the OST service supports the requested change, a new authorisation would need to be prepared to reflect these changes.  A copy will be sent to the GP, the pharmacy and the Ministry of Health.
      • Following the review any variance from the above policy needs to be documented and referenced in relation to the indicators of stability and instability.  Evidence such as proof of employment might be required to support requests for less frequent observation.
      • Note:
        • Every client in New Zealand must consume observed at least once weekly.
        • GPs are advised to refrain from making any changes to takeaway arrangements during the first 3 to 6 months in the GP programme to enable time to fully assess the patient and their safety with further takeaways.
      • *See Section 5.1 Takeaway Doses page 36 of "New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"
  4. Requests for replacement doses     

    • Replacement Doses: BOPAS OST policy is not to replace doses under any circumstances e.g., lost, stolen, spilt, damaged, retched.
    • If in exceptional circumstances that can be verified (i.e., by a police report, eyewitness by professional), the GP may (after discussion with the BOPAS OST service) offer to assess the patient 48 hours or more after their last dose was consumed and if there are signs of opioid withdrawal then part of subsequent doses may be replaced. When requests are made for replacement doses the GP should review the person's takeaway arrangements and notify the case manager and or Addiction Liaison Clinician.
    • BOPAS policy is to replace 50% of a vomited methadone dose when the patient vomits within approximately 30 minutes of consuming the dose, the vomiting was witnessed by a professional and the replacement is clinically appropriate. (e.g., pregnancy)
    • As buprenorphine/naloxone is absorbed sublingually, there is no need to replace doses after vomiting.
    • If a second replacement dose for vomiting is requested within a short time, or there are regular requests for replacement doses, no further replacement doses should be authorized until the patient has been assessed by the GP and any underlying cause for the vomiting assessed and treated.
    • All replacement doses must be prescribed on a new H572M prescription and must be consumed in the pharmacy.
    • Note: repeatedly seeking replacement dose is likely instability indicator.
    • *See Section 5.3; 5.3.1; 5.3.2 Replacement Doses page 38 of “New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"
  5. Agents acting on behalf

    • Agents Collecting on Behalf of a Patient: A GP can authorise an agent to collect OST on behalf of a patient in extraordinary circumstances where the patient is unable to attend the pharmacy e.g., when they are house-bound due to illness. Circumstances necessitating the authorization of an agent must be verified with the patient and the agent.
    • Authorization of an agent is limited to a maximum of 3 doses of methadone or buprenorphine/naloxone dispensing.
    • Authorization must be made in writing and faxed to the appropriate pharmacy and include:
      • Name and address of the agent.
      • Type of identification provided by agent.
      • Number of doses the agent is authorised to collect.
      • Signature of the authorising GP
    • The authorised agent must provide suitable identification.
    • Note: The GP must feel confident that the authorised agents can responsibly manage and administer the methadone/ buprenorphine/naloxone.
    • Discussion about safety of takeaways is essential e.g., storage away from children, no replacement of lost or stolen doses.
  6. How to write a prescription

    • Writing a methadone H572 controlled drug prescription
      • The use of H572M controlled drug prescription forms is restricted to prescribing methadone for patients under the authority conferred by Section 24(2) (d) Misuse of Drugs Act 1975 (i.e., where BOPAS has authorised a prescriber for a specific patient). The form is not used for prescribing of methadone to other patients in other circumstances (e.g., pain relief for a non-BOPAS client); in these cases, the general H572 controlled drug prescription is used.
    • OST Prescription Example


      1. Date prescription written to be no more than 7 days from prescription starting date (point 5).
      2. Name and current residential address of patient. It is not acceptable to use the pharmacy address as the patient address.
      3. Patient's NHI number.
      4. Written dose, in numeric and word form e.g., 80 (eighty) mg.  Note, if a patient is undertaking any type of withdrawal from methadone, then the new prescription should state the current dose as the starting dose.  The script should then be annotated "adjust for reduction" to allow pharmacist to adjust the starting dose. Annotate with formulation of methadone to be used - BOPAS authorises 5mg/ml (consider using a stamp to pre-populate scripts). (2mg/ml can be used in doses under 20mg).
      5. Start date (actual date pharmacist is to begin dispensing).  Check that the commencement date is a consumption day.
      6. Total period of supply up to a maximum of 30 days, however a 28-day cycle is routine to ensure ease of keeping to a regular cycle.
      7. Maximum rate of any withdrawal regimen (if any) is specified. e.g., Reduce 1mg/week at request.
      8. Days for which takeaways are authorised.  For example, 'Tuesday, Wednesday, Friday, Saturday and Sunday' for a patient on twice weekly dispensing who collects and consumes doses on Mondays and Thursdays.
      9. Name of pharmacy.
      10. Prescriber's signature.
      11. Prescriber's stamp or print NZMC Reg. No., doctor name and address.  Each copy must be stamped.
      12. Top three copies to pharmacy (via patient or post). Note: Bottom copy (blue) to be kept on patient file; please do not send to the pharmacy.
    • Ordering
      • These CD pads are requested 3-6 monthly by GPs based on their current number of authorised patients.
      • Orders are faxed to the Ministry of Health using the approved order form (refer to Forms section).  On receipt of the pads, sign the enclosed verification of delivery form and fax to the Ministry of Health as soon as possible.
    • Ministry of Health contacts
      • MedSafe Office - ph. 09 441-3670
    • Storage
      • These CD pads must be stored in a secure place as for other CD prescription pads.  You are advised to keep the receipt for the pads as a record of the prescription pad numbers.
    • Theft of prescription forms
      • If the prescription numbers are known, inform the Ministry of Health MedSafe office.  If the prescription numbers are unknown, inform the Ministry of Health and request the prescription numbers of the pads recently sent to the practice.  Inform the MOH MedSafe office of the numbers.
    • Ceasing to prescribe
      • Notify the Ministry of Health that you no longer require these pads.
    • Receipt of excess pads
      • Notify the Ministry of Health that you no longer require these pads. Destroy or return any unused pads to the Ministry of Health
  7. Split Methadone or Buprenorphine/Naloxone dosing

    • For the vast majority of patients adequate stability can be achieved on a once daily dose of methadone or buprenorphine/naloxone.
    • Patients in GP shared care are unlikely to require a change to split dosing, unless in exceptional circumstances.
    • Partial splitting of the dose may also be considered for stable pregnant patients in the latter half of pregnancy in order to avoid the necessity for increase in the dose, especially for those on doses below 60mg. A single daily dose should be reinstituted following delivery--See

      There are several health problems during pregnancy that should be discussed including:

      • General nutrition.
      • Risks of anaemia.
      • Alcohol and nicotine consumption.
      • Oral hygiene and dental health.
      • Complications from chronic infection related to injection practice.
      • Antenatal and postnatal mental health problems.

      Advice should be given regarding potential complications of pregnancy associated with drug use:

      • Premature delivery.
      • Low birth weight.
      • Placental abruption.
      • Neonatal abstinence syndrome.

      Opioid Detoxification in pregnant women:

      • Should be undertaken with caution; and
      • In the second trimester with small frequent reductions − however, expert opinion suggests that a patient should be free to choose to initiate detoxification at any stage of pregnancy, provided her circumstances and her ability to cope are taken into consideration.

      Partial splitting of the dose may also be considered for stable pregnant patients in the latter half of pregnancy in order to avoid the necessity for increase in the dose, especially for those on doses below 60mg. A single daily dose should be reinstituted following delivery.


      A small number of women become fast metabolizers of methadone or buprenorphine/naloxone in pregnancy. Where this is suspected, obtain trough and peak serum methadone levels and discuss with the BOPAS before instituting split dosing. These women are at greater risk of destabilization in pregnancy and timely assessment and management can prevent this.


      In general, it is safe to breastfeed while a mother is taking methadone as long as there are no other factors that would make breastfeeding unsafe, such as using illegal drugs or using certain prescription medications. Methadone is found in breast milk, but only a small amount gets passed along to the baby.

      There are many benefits to breastfeeding for both the mother and her baby.

      • Breast milk has important nutrients that will help baby grow and may help prevent infection
      • Babies who are breastfed are generally more healthy and don't have to visit the doctor as often as babies who are fed formula
      • Breastfeeding helps the mother and her baby bond
      • Breastfeeding may help baby cope with withdrawal symptoms

      Although there is no official statement saying that mothers cannot breastfeed if they are taking methadone, it would be wise to discuss this with the specialist service to learn more about it.

      *See Section 6.7 Management of Pregnant and Breastfeeding Women page 52-56 of " New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"

    • Note: A small number of women become fast metabolizers of methadone or buprenorphine/naloxone in pregnancy. Where this is suspected, obtain trough and peak serum levels and discuss with the BOPAS before instituting split dosing. These women are at greater risk of destabilization in pregnancy and timely assessment and management can prevent this.
    • Split dosing may also be considered for stable patients in the latter part of a planned withdrawal from methadone or buprenorphine/naloxone (usually at doses of 30mg or less) in order to reduce pre-dose withdrawal symptoms and to increase the likelihood of successful completion of withdrawal from methadone or buprenorphine/naloxone.  This needs discussion with and authorisation by the OST service.
    • Split dosing may be in exceptional circumstances considered for stable patients to better manage physical pain symptoms.
    • Split dosing(including the proportions of each dose) requires the approval of the BOPAS
    • *See Section 5.6 Split Methadone Doses page 40 of "New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"
  8. Transfers between Pharmacies

    • The Case Manager and or Addiction Liaison Clinician may assist you with this.
    • Otherwise:
      • Establish with the patient which dispensing pharmacy in the area is suitable and confirm with the pharmacy that they are able to dispense to the patient.
      • Cancel the script at their existing pharmacy.
      • Write a new script for the new pharmacy and fax it to them if necessary.
      • Contact the Addiction Liaison Clinician to request that an 'Introduction to Pharmacy' letter with a photo ID is sent to the new pharmacy.
      • The patient will be required to provide photo-ID at the new pharmacy.
  9. Transfer to another OST Programme

    • Contact the BOPAS OST with details about the proposed new location of the patient and request assistance with the transfer.
    • Note: Waiting times for transfer to other OST programmes vary considerably throughout the country.
    • Where a patient is stable the treatment service at the new location may agree to the transfer of the patient directly to a GP authorised by that service and the transfer may be achieved more quickly. Alternatively, out of area prescribing may be arranged until such time as the local OST service is able to take them onto their programme. However, during this interim period the patient should return to be seen at least 3 monthly by their prescribing doctor. The Specialist OST service will not be able to authorise an out of area GP.
    • *See Section 7.1 Transferring between Specialist Services page 57 of "New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"
  10. Managing missed doses

    • The pharmacy should notify you if the patient misses any doses. Three or more consecutive missed doses as under National protocols the patient must be reassessed by the BOPAS OST service, before dispensing can resume. They need to be seen and assessed as to whether it is safe for them to resume dispensing the usual dose or whether they require a dose decrease due to reduced tolerance. Opioid tolerance rapidly changes, so several days without opioids can significantly alter tolerance to prescribed OST.


Disclaimer: These pathways, for the care and management of patients within Bay of Plenty, have been developed jointly by primary and secondary care clinicians. They provide guidance for General Practice teams to diagnose and manage patients suffering from a number of different conditions, and contain patient information resources. The pathways are maps of publicly-funded services accessed by referral from the community, and are strongly evidence based, but are not full clinical guidelines. As the pathways are suggested guidance only, while using them you must exercise your own clinical judgement and pertinent clinical data when treating your patient. This site is intended to be flexible and frequently updated. While every effort has been made to ensure accuracy, all information should be verified.