Hydroxychloroquine Sulfate is a prescription medication used to treat malaria, rheumatoid arthritis, and systemic lupus erythematosus. . It belongs to a class of medications known as disease-modifying antirheumatic drugs (DMARDs) and can reduce skin problems in lupus and prevent swelling/pain in arthritis.  It is also used to prevent malaria in areas or regions where other medicines may not work, such as in Africa, South America, and Southern Asia. .
Hydroxychloroquine Sulfate is available under the brand name Plaquenil and comes in the form of a tablet with a dose of 200mg. The inactive ingredients include dibasic calcium phosphate USP, hypromellose USP, and magnesium stearate. . The molecular weight of hydroxychloroquine sulfate is 433.95 and its molecular formula is C18H26ClN3OHSO4.
The pharmacokinetics of hydroxychloroquine sulfate were studied in healthy males, and following a single 200mg oral dose, the mean peak blood concentration was 129.6 ng/mL reached in 3.26 hours with a half-life of 537 hours (22.4 days). The plasma peak concentration was 50.3 ng/mL reached in 3.74 hours with a half-life of 2963 hours (123.5 days). . The FDA recommends that the use of hydroxychloroquine sulfate should not exceed 6.5mg/kg (5mg/kg base) of actual body weight and durations of use should not be greater than five years. .
In certain hospitalized patients, hydroxychloroquine may also be used to treat coronavirus (COVID-19). . Taking hydroxychloroquine to prevent COVID-19 may increase the risk of diarrhea, nausea, abdominal pain, drowsiness, and headache. .