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Hydroxychloroquine (Plaquenil) dosing calculator

Checks a hydroxychloroquine dose against the retinopathy-risk threshold of 5.0 mg/kg real body weight/day.

Hydroxychloroquine (Plaquenil) dosing calculator
Real (actual) body weight
Use actual body weight, not ideal or adjusted body weight — hydroxychloroquine distributes into lean tissue, and dosing by ideal weight underestimates risk in overweight or obese patients.
Prescribed or planned daily dose
mg
Complete the fields above to see the result.

When to use

  • Dosing hydroxychloroquine at treatment initiation, or reviewing an existing dose, to keep long-term use within the threshold associated with lowest retinopathy risk.
  • Deciding retinopathy-screening risk category alongside duration of therapy, renal function, tamoxifen use, and pre-existing retinal or macular disease.

Formula

Dose per kilogram = prescribed daily dose (mg) / real body weight (kg). Maximum recommended daily dose = 5.0 mg/kg x real body weight (kg). The AAO 2016 revised recommendations set the ceiling for long-term hydroxychloroquine use at 5.0 mg/kg real (actual) body weight per day.

Pearls and pitfalls

  • Round to the nearest available tablet size (100 mg or 200 mg), or alternate daily doses (e.g. 200 mg/400 mg on alternating days), to approach but not exceed the 5.0 mg/kg/day target.
  • Real body weight is used, not ideal or lean body weight; using ideal weight in overweight patients underestimates true retinopathy risk.
  • Daily dose >5.0 mg/kg/day and treatment duration beyond 5 years are the two strongest modifiable risk factors for hydroxychloroquine retinopathy; annual screening is recommended after 5 years of use at recommended doses.

References

  1. Marmor MF, Kellner U, Lai TY, Melles RB, Mieler WF; American Academy of Ophthalmology. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Ophthalmology. 2016;123(6):1386-1394.
  2. Melles RB, Marmor MF. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA Ophthalmol. 2014;132(12):1453-1460.