Phenelzine- withdrawing or switching

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Phenelzine is a monoamine oxidase inhibitor (MAOI) antidepressant.

Due to numerous interactions with drugs and foodstuffs, its use is reserved mainly for patients who have failed to respond to other antidepressants. 

There is a small but important group of patients who historically have responded well to treatment and who have been treated with phenelzine for many years (decades in some cases).

The UK licensed version of phenelzine (Nardil) has been unavailable since August 2019.

Clinicians were asked to review all affected patients and where possible withdraw treatment or switch to an alternative antidepressant. However, the availability of imported foreign licensed phenelzine tablets has allowed patients to be maintained on treatment.

The Covid-19 pandemic has severely disrupted the supply of non-UK phenelzine and supply of the drug is very unreliable. Consequently GPs and psychiatrists were asked to urgently review all remaining patients prescribed phenelzine  as continued treatment cannot not be guaranteed. 

Issues to consider during review

Any patient prescribed phenelzine is likely to have been taking it for many years. Most likely at the point of prescribing they will have had unsuccessful treatment with a number of antidepressants. They will require a clear explanation of why this review is happening and what their options may be. They are likely to be very anxious about this given the long history of successful treatment and have fears about any proposed change.

Consider the following points:

  • Provide a clear explanation of the need for review
  • Discuss the potential options
  • Offer on-going support.
Managing withdrawal & discontinuation

For some patients it may be possible to completely withdraw treatment and not prescribe a replacement antidepressant.

Each patient’s experience of treatment and withdrawal will differ and an individualised approach will be required.

However availability of supply may curtail the withdrawal period. Please contact Leverndale Pharmacy for advice if issues arise.

Factors to consider for a successful withdrawal:

  • How long has the patient been on treatment and at what dose? The longer the treatment and the higher the dose the longer the withdrawal process may take.
  • Ideally withdraw over at least 4 weeks with dose reductions of no more than 15mg per week.
  • Agree the proposed rate of withdrawal with the patient and provide a mechanism for them to seek support and reassurance during the withdrawal period should they need it.
  • Once treatment has been withdrawn offer follow up in case symptoms re-emerge.
Introduction of alternative antidepressant

This is likely to be the more common scenario for most patients. As it takes 2 weeks for monoamine oxidase enzyme activity to recover there will be a mandatory wash out period after phenelzine has been discontinued before any new treatment can be initiated safely.

Factors to consider for a successful change of treatment:

  • Withdraw phenelzine gradually over 2 - 4 weeks.
  • Agree the proposed rate of withdrawal with the patient and provide a clear explanation of the need for a washout period before any new antidepressant can start. Offer them a mechanism to obtain support during this period.
  • Review their antidepressant history prior to phenelzine to identify potential treatment options. The mental health pharmacy service can offer advice on options but does not have the capacity to undertake a detailed medication review for all affected patients.
  • After the washout period is complete, consider prescribing with any antidepressant the patient has not been previously treated with.
  • Review those options with the patient and agree a treatment plan going forward. Provide the patient with information on those options via the Choice and Medication website.
  • Review the patient frequently as treatment is established and offer support as necessary.
  • If the first option is partially or unsuccessful consider switching to an alternative antidepressant or consider an augmentation strategy e.g. antidepressant combination, adding lithium or adding quetiapine.
Patients unable to withdraw

PMG(MH) expects the majority of patients to be managed via one of the options above however there may be some for whom it may to be too distressing to have treatment changed or for whom alternative treatment fails. In those instances consider the following:

  • Contact the patient’s community pharmacy to identify what if any form of phenelzine they can source.
  • If they can source phenelzine ask the patient’s GP to prescribe that form to continue treatment.
  • If alternative treatments fail and you wish to re-establish phenelzine treatment, observe any necessary switching process and washout. Then contact their community pharmacy and GP as above.
Editorial Information

Last reviewed: 24 July 2020

Next review: 01 August 2021

Author(s): PMG-MH

Version: 1

Approved By: PMG-MH

Reviewer Name(s): Andrew Walker, Suzanne Burke