mercap, azathioprine

Question 1

azathioprine metabolised to

Answer 1

mercaptopurine

Question 2

reduce dose of azathioprine with allopurinol to how much and why?

Answer 2

to 25% (not BY, but TO 25%) due to risk of haemotological toxicity

Question 3

this common drug class that is used literally all the time interacts with azathioprine - monitor due to increased risk of anaemia and/or leucopenia

Answer 3

ACEi

Question 4

pre treatment screening

Answer 4

TPMP enzyme
this metabolises thiopurine drugs
if pt has reduced TMPT enzyme activity, or no activity, increased risk of meylosuppression
Can use with reduced TPMP under expert supervision, caution!

Question 5

what would low or reduced TMPT activity do

Answer 5

increase risk of myelosuppression

this enzyme normally metabolises the thiopurine drug therefore if less effective = myelosuppression

Question 6

monitoring for azathioprine

Answer 6

FBC weekly for first 4 weeks
then reduce to at least every 3 months

monitoring can be increased if necessary e.g. RI, higher doses

blood tests and monitoring for signs of myelosuppression essential in the long term

Question 7

patients and carers should report the following symptoms

Answer 7

Bone marrow suppression

Patients and their carers should be warned to report immediately any signs or symptoms of bone marrow suppression e.g. inexplicable bruising or bleeding, infection.

Question 8

patient who has had a transplant and received athiothioprine. she is now pregnant and azathioprine is teratogenic. what to do?

Answer 8

DO NOT DISCONTINUE - specialist supervision

Transplant patients immunosuppressed with azathioprine should not discontinue it on becoming pregnant. However, there have been reports of premature birth and low birth-weight following exposure to azathioprine, particularly in combination with corticosteroids. Spontaneous abortion has been reported following maternal or paternal exposure.

Question 9

what to do if hypersensitivity reactions

Answer 9

(including malaise, dizziness, vomiting, diarrhoea, fever, rigors, myalgia, arthralgia, rash, hypotension and renal dysfunction) call for immediate withdrawal.

Question 10

nausea with azathioprine

Answer 10

Nausea is common early in the course of treatment and usually resolves after a few weeks without an alteration in dose. Moderate nausea can be managed by using divided daily doses, taking doses after food, prescribing concurrent antiemetics or temporarily reducing the dose.

Question 11

reduce dose of mercaptopurine. if concurrent use of allopurinol to …

Answer 11

25% usual dose

Question 12

risk of myelosuppression increased if pt has absent or reduced

Answer 12

TPMT activity

this normally metabolises it

Question 13

do they cause bone marrow depression

Answer 13

yes, dose related

Question 14

azathioprine important SE

Answer 14

Hypersensitivity reactions
- including malaise, dizziness, vomiting, diarrhoea, fever, rigors, myalgia, arthralgia, rash, hypotension and renal dysfunction) call for immediate withdrawal.

Neutropenia and thrombocytopenia
- Neutropenia is dose-dependent.
- Management of neutropenia and thrombocytopenia requires careful monitoring and dose adjustment.

Nausea
- common early in the course of treatment and usually resolves after a few weeks without an alteration in dose.

Question 15

Patient on azathioprine feels very nauseous even after a few weeks. How would you manage this

Answer 15

Moderate nausea can be managed by using divided daily doses, taking doses after food, prescribing concurrent antiemetics or temporarily reducing the dose.