Hydroxychloroquine (Plaquenil) is primarily used in combination with other drugs, including methotrexate and/or sulfasalazine for moderate to severe Rheumatoid Arthritis. It is only prescribed alone in patients with very mild symptoms, who are RF negative and have non-erosive disease. It is slow acting, and usually takes 2-6 months for any benefits to be felt.
How does it work?
From Australian Prescriber – “Hydroxychloroquine interferes with antigen presentation and the activation of the immune response by increasing the pH within macrophage phagolysosomes.”
In plain English, this means the drug interferes with communication of the cells in the immune system, thereby reducing inflammation.
Patients usually start by taking 400mg daily. Once a response is achieved, the dose may be lowered to 200mg daily.
Hydroxychloroquine side effects
Hydroxychloroquine, as one of the milder DMARDs is generally very well tolerated and serious side effects are rare. The most common side effects are gastric – nausea and diarrhoea. This usually improves over time, and it should be taken with food to minimise these effects.
Rashes are quite common, and some hair thinning. Patients may also develop hyper pigmentation when exposed to the sun, and patients should always wear sunscreen. The most serious potential side effect is retinal toxicity with macular damage. When starting hydroxychloroquinine patients should have an eye exam, and repeat this every two years, of if they notice any visual changes.
For a complete list of side effects, click here.
Patients taking hydroxychloroquine should have a baseline ophthalmologic exam, especially if they have pre-existing eye disease or diabetes, and then every two years. No specific laboratory monitoring is required.
Patients with pre-existing maculopathy should not take hydroxychloroquine.
Advice in pregnancy/breastfeeding
Hydroxychloroquine is not safe to take in pregnancy. Low concentrations are found in breast milk, therefore caution is recommended if the patient is breastfeeding.