Published: March 2012

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Antithrombotic Medicines - Still Causing Bleeding

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Prescriber Update 33(1): 1
March 2012

Anticoagulants and antiplatelet agents (antithrombotics) are widely used to treat a number of conditions, with recent guidance on their use being issued by the Best Practice Advocacy Centre (BPAC)¹.

Bleeding is the major risk associated with all antithrombotics. The Centre for Adverse Reaction Monitoring (CARM) continues to receive reports of serious bleeds experienced by patients taking these medicines.

An overview of 12 months of reporting to CARM is shown in Table 1. The main sites of serious bleeding were most often gastrointestinal or intracranial in origin.

Only a small fraction of suspected adverse reactions are reported to CARM, nevertheless these reports show that serious bleeds do occur with antithrombotics and that some bleeds may have been preventable. For example, although combination therapy is recommended for some conditions, adverse reaction data continues to indicate a major risk factor for bleeding is the concomitant use of more than one antithrombotic medicine.

Early treatment of bleeds is desirable and patients and/or carers should be advised to monitor for early signs of bleeding.

Table 1: Antithrombotic CARM reports associated with bleeding from 1 Oct 2010 to 30 Sept 2011.

Medicine	Total number of reports	Number of reports of bleeding (%)	Number of cases reported to be exposed to another anticoagulant or antiplatelet agent (%)	Number of bleeding cases reported to also be exposed to a NSAID or SSRI (%)
Aspirin	28	68	53	42
Clopidogrel	9	67	100	16
Dabigatran*	212	42	59	3
Dipyridamole	3	67	100	50
Enoxaparin	14	50	57	0
Rivaroxaban	3	0	N/A	N/A
Warfarin	32	56	50	11

* Dabigatran has been recently introduced with rapid uptake

References

1. A New Zealand Consensus Forum. 2011. The use of antithrombotic medicines in general practice: a consensus statement. Best Practice Journal, 39: 10-21