Published: 1 March 2018

Publications

Drug-Induced Immune Thrombocytopenia

This article is more than five years old. Some content may no longer be current.

Prescriber Update 39(1): 14
March 2018

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 thrombocytopaenia^1,2

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).