Heparin/low dose aspirin prevent recurrences in obstetric APS, but up to 20% of pregnancies are refractory to this therapy.
Additional therapies on top of the standard treatment may increase the positive pregnancy outcome.
Anecdotal reports showed that hydroxychloroquine is beneficial in refractory obstetric APS.
Experimental models suggest that hydroxychloroquine prevents pathogenic effect of anti-phospholipid antibodies.