Treating hives when antihistamines fail

2 minute read

Researchers put hydroxychloroquine and omalizumab to the test with promising results.

An anti-inflammatory drug used to treat malaria, arthritis and lupus should be considered as an add-on treatment for chronic hives, according to a comparison study of the DMARD hydroxychloroquine and the monoclonal antibody, omalizumab.  

Researchers compared the real-world effectiveness of hydroxychloroquine (Plaquenil) and omalizumab as therapies for refractory chronic spontaneous urticaria and found that while omalizumab was superior, hydroxychloroquine achieved a complete response in two-thirds of treated patients and presented a favourable safety profile. 

The authors wrote in JACI that the existing practice parameter “did not specify omalizumab as a preferred first-line add-on agent for antihistamine refractory [chronic spontaneous urticaria], recognising the potential of other add-on agents”. 

They said that hydroxychloroquine should be considered as an add-on treatment for refractory chronic spontaneous urticaria, given its functional role in controlling symptoms.  

To determine the efficacy of selected treatment regimes, the researchers conducted a review in 264 patients with refractory chronic spontaneous urticaria, uncontrolled with antihistamines, as well as those unresponsive to second-line therapies. 

Overall, omalizumab was significantly more likely to result in a complete response compared to hydroxychloroquine. After three months, a complete response was observed in over twice as many patients treated with omalizumab than those receiving hydroxychloroquine. 

Of the 45 patients with incomplete responses to first add-on interventions, the number achieving complete responses was similar between the two drugs (around two-thirds). 

Hydroxychloroquine (200mg) is administered orally twice daily, while omalizumab (300mg) is a monthly subcutaneous injection. This advantage of hydroxychloroquine may be particularly relevant if the drug is approved for use in children, for which it has shown to be safe and effective. 

To date, omalizumab is indicated for patients 12 years and older, but is not approved for younger children. 

Most adverse effects reported following treatment were transient, most commonly headache, fatigue and injection site pain.  

“Both omalizumab and hydroxychloroquine exhibited acceptable safety profiles in this study,” the authors wrote.  

They briefly mentioned rare anecdotal cases of cardiac events including arrhythmias, cardiac conduction abnormalities and cardiomyopathy which had previously been associated with hydroxychloroquine. The risk is minimal, although doctors are advised to be aware of potential cardiac effects, particularly in patients receiving additional medications that prolong the QTc interval. 

“Current evidence does not support a strong relationship between hydroxychloroquine and risk for cardiac side effects,” the authors wrote. 

JACI 2022, online 20 September 

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