Hydroxychloroquine (brand name, Plaquenil) and chloroquine (brand name, Aralen) are medications that are typically used to treat malaria, a mosquito-borne infectious disease. They can also be used to manage certain symptoms of sarcoidosis.

How anti-malarial treatments work

Sarcoidosis is an inflammatory condition where the immune system remains in an unusually active state. It is characterized by clumps of immune cells, called granulomas, that accumulate in different tissues and organs. They are most commonly found in the lungs, skin, lymph nodes, and eyes. The kidneys, liver, heart, nervous system, bones, and muscles may also be affected. Granulomas can lead to organ damage if the condition is left untreated.

Anti-malarials work by suppressing the immune response by preventing the release of chemicals that normally promote inflammation. They also stop the activation of immune cells called T-cells, which play an important role in the formation of granulomas.

Anti-malaria treatments may be used to treat several types of sarcoidosis, including cutaneous sarcoidosis, pulmonary sarcoidosis, and neurosarcoidosis, as well as arthritis.

Anti-malarials in clinical trials for sarcoidosis

A randomized controlled trial found that six months of oral chloroquine (initially 750 mg per day, reduced to 250 mg per day at the end of the six months) was able to improve lung function and ease disease symptoms in patients with pulmonary sarcoidosis. Further maintenance treatment (250 mg per day of chloroquine for an average of one year) resulted in a slower decline in lung function and fewer sarcoidosis relapses in treated patients, compared to those who did not receive maintenance treatment.

Published results of a retrospective study reported that either 250 mg of chloroquine or 200 mg of hydroxychloroquine (both taken twice a day for between six and 21 months) was effective in treating 10 of 12 patients with neurosarcoidosis. Two did not respond to these treatments. None of the participants developed vision problems (ocular toxicity).

Hydroxychloroquine at 2-3 mg per kilogram per day was also seen to be effective in treating cutaneous sarcoidosis. Skin symptoms improved within one to three months after starting hydroxychloroquine in 12 of the 17 patients treated, allowing them to stop other medications. Three patients responded partially, and two did not respond. None of the patients experienced vision problems.

Two patients who were intolerant to high doses of corticosteroids (a common treatment for sarcoidosis) and in need lowering the calcium levels in their urine were able to achieve reductions after adding a six- or ten-month course of 500 g of chloroquine daily to their treatment regimen.

Further details

Patients receiving anti-malarial treatment (especially chloroquine) should have regular eye checkups every six months to a year, as these medications are known to cause vision problems and ocular toxicity.

Other side effects that may occur while taking anti-malaria treatments are nausea, dizziness, ringing in the ears (tinnitus) or diminished hearing, hair loss, skin changes (rashes, itching, darkened skin), heart or liver problems, muscle weakness, nerve damage, headaches, and seizures.

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