Publications

Published: 1 March 2018

Drug-Induced Immune Thrombocytopenia

Prescriber Update 39(1): 14
March 2018

Key Messages

  • Drug-induced immune thrombocytopenia is a relatively uncommon adverse reaction caused by drug-dependent antibodies.
  • Always consider medicines as a possible cause of immune thrombocytopenia purpura.
  • Discontinuation of the offending medicine usually resolves the condition.

Background

Drug-induced Immune Thrombocytopaenia (DITP) is characterised by a low platelet count (typically less than 50x109/L). Presentations vary from petechia, bruising and bleeding from mucosal membranes (eg, epistaxis), to potentially life-threatening intracranial haemorrhage.

DITP is caused by drug-dependent antibodies that react with platelet membrane glycoproteins when the offending drug is present, resulting in platelet destruction1. This mechanism differs from thrombocytopaenia induced by some cytotoxic drugs that affect the bone marrow2.

The typical time to presentation of DITP is within one to two weeks of starting the medicine. Previously sensitised patients can experience rapid drops in platelet counts within one to two hours on repeat exposure2. Platelet count usually returns to normal within one week of stopping the offending medicine. Patients with severe thrombocytopaenia or haemorrhage may require platelet transfusion1.

Glycoprotein IIb/IIIa inhibitors (tirofiban, abciximab, and eptifibatide) have been associated with rapid onset DITP3. This can occur within minutes after exposure to the medicine.

Heparin induced thrombocytopenia (HIT) is a similar condition. Further information on HIT be found in the Prescriber Update article ‘Don’t get HIT: Heparin-induced Thrombocytopenia’4.

Medicines Known to Cause DITP

Over 100 medicines have been associated with DITP1. Examples of medicines associated with DITP are shown in Table 1 (the list is not exhaustive).

Table 1: Examples of medicines associated with drug-induced immune thrombocytopaenia1,2

Medicine Classification Examples of Implicated Medicines
Antibiotics Cephalosporins, linezolid, penicillins, sulphonamides, trimethoprim, vancomycin
Antimalarials Quinine
Antimycobacterials Ethambutol, rifampicin
Antiepileptics Carbamazepine, phenytoin, sodium valproate
NSAIDs Ibuprofen, naproxen
Cardiovascular drugs Abciximab, amiodarone, eptifibatide furosemide, quinidine, thiazides, tirofiban
Vaccines Diphtheria, Tetanus, Pertussis (DTaP), Haemophilus influenzae type B, Influenza, MMR, pneumococcal, varicella zoster
Others Haloperidol, paracetamol, irinotecan, mirtazapine, oxaliplatin

New Zealand Cases

To date, a total of 25 cases of DITP have been reported to the Centre for Adverse Reaction Monitoring (CARM). In 20 of these reports a vaccine was the suspected medicine. The reported vaccines included Measles/Mumps/Rubella (6 reports), Meningococcal B (5), Diphtheria/Tetanus/Pertussis (4), Pneumococcal conjugate (2), Hepatitis B (2), Influenza trivalent (1), ADT Booster (1), and Haemophilus influenzae type B (1). Other suspected medicines were salmeterol (2 reports), tacrolimus (1), ciprofloxacin (1), and acyclovir (1).

References
  1. Curtis BR. 2014. Drug-induced immune thrombocytopenia: incidence, clinical features, laboratory testing, and pathogenic mechanisms. Immunohematology 30(2): 55–65.
  2. Aster RH, Curtis BR, McFarland JG, et al. 2009. Drug‐induced immune thrombocytopenia: pathogenesis, diagnosis, and management. Journal of Thrombosis and Haemostasis 7(6): 911–8.
  3. Visentin GP, Liu CY. 2007. Drug-induced thrombocytopenia. Hematology/oncology clinics of North America 21(4): 685–96.
  4. Medsafe. 2016. Don't get HIT: Heparin-induced Thrombocytopenia. Prescriber Update 37(4): 59–60. URL: www.medsafe.govt.nz/profs/PUArticles/December 2016/HeparinInducedThrombocytopenia.htm (accessed 7 February 2018).