Merieux Anti-Thymocyte globulin (ATG)
Indication
With the introduction of Tacrolimus and MMF, rejection resistant to steroids or these agents is uncommon.
Contra-indications
- known allergy to rabbit proteins
- acute viral illness
- full anaphylactic response to the test done.
Dosage and administration
ATG is usually given over a 10 day period with an absolute T-cell count determining the administration schedule (ATG only given if absolute T-Cell count >0.05).
Test dose
- A test dose is needed to identify those patients who will develop severe reactions including anaphylaxis.
- Signs of anaphylaxis are tingling in the extremities and around the mouth, swelling of the lips and larynx, bronchospasm, tenesmus, hypotension.
- Any reaction will normally respond to hydrocortisone 100 mg IV and chlorphenaramine 10 mg IV although 0.5 ml adrenaline 1:1000 IM may be necessary.
Administration of test dose
Pre-dose administration of 1g paracetamol and 10mg chlorpheniramine iv is recommended.
Preparation of test dose
Reconstitute vial contents with accompanying diluent (5 ml water for injections), giving a solution of 5 mg ATG per ml.
Take 1 ml of solution and add to 100 ml NaCl 0.9%.
Observations during / after test dose
Monitor BP, pulse and temperature according to the following schedule:
| Time after dose |
Frequency of observations |
| 0 - 2 hrs | 15 mins |
| 2 - 4 hrs | 30 mins |
| thereafter | hourly |
• First full dose
Administration
Preparation
Add contents of reconstituted vials to 0.9% NaCl, allowing 50 ml per vial (250 ml bag usually appropriate).
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Observations Side effects
• Further doses
Further doses given when absolute T cell count >0.05. if <0.05, ATG not given. It is unlikely that ATG will need to be given daily: more usually only 3 doses are needed over the 10 day period.
To allow calculation of T cell count, need:
DAILY FACS - convert result to decimal to plug into equation, e.g. 30% = 0.3
DAILY LYMPHOCYTE COUNT
T cell count is determined as follows:
No. lymphocytes x FACS result = T cell count
e.g. 0.2 x 0.3 = 0.06.
Other hypersensitivity reactions include rigors (1%), fever (4%), arthralgia (1%), erythema (1%) and pruritic skin eruptions (0.5%). Symptoms are most commonly seen after the first injection and decrease during the course of treatment.
Other side effects include thrombocytopenia (approx. 5%), neutropenia, serum sickness (3%) and lymphoma.
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Monitoring
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Also:
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Daily differential WCC for lymphocytes } for T cell count determination FBC } during 10 day course and for 2 weeks after U & E's Interrupt treatment if platelet count <50000 / mm3 Consider interrupting treatment if <2000 leukocytes / mm3
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Interactions
|
DRUG |
DAY |
||||||||||||
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11-30 | 31+ | |
| ATG | Full | * | * | * | * | * | * | * | * | * | * | ||
| Tacrolimus/ Ciclosporin |
Y | N | N | N | N | N | N | Y2 | Y2 | Y2 | Y2 | Y2 | Y2 |
| Prednisolone | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| Azathioprine/ Mycophenolate mofetil |
Y | N | N | N | N | N | N | N | Y | Y | Y | Y | Y |
| PCP prophylaxis1 | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
*Depending on T cell count
- For PCP prophylaxis use cotrimoxazole 480 mg daily, if patient allergic to co-trimoxale then the cotrimoxazole de-sensitisation protocol should be used (see page 39.) Continue if need to complete 3 month course.
CMV and HSV prophylaxis using Valganciclovir for 6 months should also be used (see page33).
- Tacrolimus reinstated at dose of 0.05 mg / kg twice daily. Ciclosporin reinstated at dose 3 mg / kg twice daily.
Storage
Ordering
Out of hours: contact resident pharmacist, bleep 2268
small stock held in pharmacy.
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