Shared Care Policy and Prescribing Information for General Practitioners for
Mercaptopurine [off-label use] (Adults only, non-renal, gastroenterology patients)
Publish public
Coordinator
Gastroenterology
Signature:
L Crighton
Applies to: NHS Grampian
Authorised for issue by
Medicines Guidelines
and Policies Group
Signature:
C Hind
Version 1
Document no:
NHSG/SCPa/Mer/MGPG353
Effective date: August 2009
Review Date: August 2011
Supersedes: n/a
Please keep this document in the patients notes
PATIENT NAME
UNIT NUMBER
CHI NUMBER

WARD
TELEPHONE NO
CONSULTANT (print name)
ADDRESS
DATE OF BIRTH

Insert patient sticker here
HOSPITAL

DATE
SIGNATURE
Therapeutic Indication for this patient: (to be completed by consultant)
Dosage/preparation/route/frequency of administration: (to be completed by consultant)
SAFE PRACTICE IS THAT THE CLINICIAN WHO ORDERS THE TEST MUST ACT ON THE RESULT
CARE WHICH IS THE RESPONSIBILITY OF
THE HOSPITAL CONSULTANT
CARE WHICH IS THE RESPONSIBILITY OF THE
GENERAL PRACTITIONER
1. Prescribing of medication under guidance of consultant.
Baseline:
2. Check before prescribing medication that the monitoring
1. Full Blood Count (FBC), urea, creatinine
is up to date and results are within the normal range.
and electrolytes (U&Es), liver function tests 3. GP should be aware that the drug can cause bone
(LFTs).
marrow suppression, leucopenia, increased risk of
malignancy – lymphomas and skin cancer.
† Optional Check - TPMT (thiopurine

Patients should be asked about the presence of sore
methyltransferase). Deficiencies of the
throat, abnormal bruising or bleeding at each visit.
enzyme TPMT may result in an increased
 Check for development of lymphomas and other
risk of toxicities and more frequent blood
malignancies particularly of the skin.
monitoring may be required.
When
the
patient has an intercurrent illness FBC, U&Es and
Consultant to advise GP if more frequent
LFTs should be done and any abnormal results including
monitoring required as a result of this test
those noted above should be reported to the consultant.
4. The General Practitioner has primary responsibility for
2. Copy of results to be sent to GP.
monitoring therapy according to the schedule below¥:
 FBC and LFTs (incl. ALT and Alk Phos) weekly for
3. Initiation of therapy and recommendations
the first month or until maintenance dose achieved.
for dose increments.
 FBC and LFTs monthly thereafter.
4. Decision on final dose required for patient.
When writing laboratory request forms always include
5. Monitoring clinical response to treatment.
details of the patient’s medication
6. Advise patients to immediately report
signs or symptoms of bone marrow
suppression, e.g. infection, inexplicable
bruising or bleeding.
¥
NOTE: in addition to absolute values for haematological
indices a rapid fall or a consistent downward trend in any
value should prompt caution and extra vigilance.
If something unexpected occurs Contact Consultant.
Notify the consultant if the drug is stopped.
Consultant to advise if more frequent monitoring required as a result of TPMT test.
UNCONTROLLED WHEN PRINTED
Review date: August 2011
NHSG/SCPa/Mer/MGPG353
SCP and Prescribing Information for General Practitioners for Mercaptopurine (off-label use) Adults only Gastroenterology – Version 1
-1-
Shared Care Policy and Prescribing Information for General Practitioners for
Mercaptopurine [off-label use] (Adults only, non-renal, gastroenterology patients)
MONITORING: - Action to be taken if:




WBC <4.0 x 109/L
Neutrophils <2 x 109/L
Platelets <150 x 109/L
>2-fold rise in ALT or Alk Phos (from upper limit of reference range)
withhold until discussed with consultant

MCV >105fl



Abnormal Bruising, sore throat, rash, oral ulceration
Unexplained fever
Malignancies
investigate and if B12 or folate low start
appropriate supplementation
withhold until discussed with consultant
withhold until discussed with consultant
withhold until discussed with consultant
FOR SPECIFIC PRODUCT INFORMATION PLEASE CONSULT THE CURRENT SUMMARY OF
PRODUCT CHARACTERISTICS (http://emc.medicines.org.uk/) AND THE BNF (http://www.bnf.org/bnf/)
Other information
 Live vaccines should be avoided in patients taking mercaptopurine.
 Single pneumococcal vaccination and annual influenza vaccine should be given.
 Varicella Zoster Immunoglobulin should be given to non-immune individuals if exposed to shingles or
chickenpox.
 There are a number of drug interactions that must be considered when a new drug is prescribed
please refer to Summary of Product Characteristics, BNF or contact Medicines Information
 If Allopurinol is co-prescribed the dose of mercaptopurine should be reduced by 75%.
 Inhibition of the anticoagulant effect of warfarin, when administered with mercaptopurine has been
reported.
 To minimise the risk of skin cancer, exposure to sunlight and ultraviolet light should be limited by wearing
protective clothing and using sunscreen with a high protection factor.
Pregnancy
Discuss with consultant. Mercaptopurine should not be given to patients who are pregnant or likely to
become pregnant without careful assessment of risk versus benefit.
Adequate contraceptive precautions should be advised if either partner is receiving mercaptopurine.
Breast-feeding
Discuss with Aberdeen Maternity Hospital or contact Medicines Information. Discontinue breast-feeding.
Responsibilities of GPs undertaking monitoring
A GP agreeing to monitor mercaptopurine should:
 Ensure that the relevant monitoring requirements are undertaken at the correct frequency,
 Ensure that the test results are checked for any abnormality as soon as the results are available,
 Ensure abnormal results are acted upon,
 Only continue to prescribe mercaptopurine if it is being satisfactorily monitored,
 Contact the consultant in the event of a drug reaction or monitoring abnormality or any other concerns,
 Be alert for any of the known adverse reactions.
The patient should be encouraged to ensure blood tests are taken at the correct intervals.
UNCONTROLLED WHEN PRINTED
Review date: August 2011
NHSG/SCPa/Mer/MGPG353
SCP and Prescribing Information for General Practitioners for Mercaptopurine (off-label use) Adults only Gastroenterology – Version 1
-2-