Hydroxychloroquine (hydroxychloroquine sulfate) (hye-drox-ee-klor’oh-kwin) is a 4-amino-quinoline antimalarial and a disease-modifying anti-rheumatic drug (DMARD) drug used to treat systemic lupus erythematosus (SLE), rheumatoid arthritis, juvenile inflammatory arthritis and other related inflammatory conditions. It is used to treat the salivary gland swelling and extraglandular features in Sjögren’s syndrome. It is also used to treat malaria in areas where malaria continues to be sensitive to the chloroquines which is only currently in parts of Central America and the Caribbean. Hydroxychloroquine achieved some notoriety in 2020 when USA President Donald Trump called it a ‘game changer’ for treating COVID-19 (it wasn’t).

Dose is 200–400mg daily.

Most commonly used brand name is Plaquenil®.

Hydroxychloroquine is a hydroxylated version of chloroquine which has a similar mechanism of action. Hydroxychloroquine has a safer profile than chloroquine.

Mechanism of action:
Hydroxychloroquine increases lysosomal pH in antigen-presenting cells so inhibits processing of peptide antigens and their assembly into MHC complexes by macrophages.

Rapidly absorbed with 50% protein-bound in the plasma. They extensively bound to tissues, especially in melanin containing tissues such as the eyes.
Deaminated in the liver and the blood elimination half-lives are of up to 45 days.

Common side affects:
Vomiting, headache, changes in vision, stomach cramps, muscle weakness

Serious side affects:
Retinopathy (seen as decreased visual acuity or pigmentation changes in the retina), heart failure, angioedema, bronchospasm, mental health affects (mood changes, suicidal thoughts)

Visual acuity should be monitored regularly.

A hypersensitivity to hydroxychloroquine or 4-aminoquinoline
Those taking tamoxifen (increases the risk of retinopathy)
Severe renal impairment (can be used at a lower dose)
Use caution if have retinopathy (makes monitoring more difficult)

Chemical formula: C18H26ClN3O
Don’t confuse with: hydroxyzine

Related Pages:
COVID-19 Controversy

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