Meanwhile, because of the risk of retinal toxicity with hydroxychloroquine, there’s been a shift in recent years from dosing up to 6.5 mg/kg per day of ideal body weight to a ceiling of 5 mg/kg per day of actual body weight (JAMA Ophthalmol. 2014 Dec;132[12]:1453-60), and a ceiling of 2.3 mg/kg per day actual body weight for chloroquine.
The idea was to prevent overdosing in people who are under their ideal body weight, but there have been concerns about the efficacy of the new dosing regimen in other patients. Dr. Fernandez has not seen evidence of this. “We do adhere to the new dosing recommendations” at the Cleveland Clinic, and “personally, I think we are seeing similar efficacy,” he said.
The most important risk factor for retinal toxicity is cumulative dose. The risk seems to be extremely low in the first 5 years, but increases afterwards. Most patients who develop retinal toxicity have taken a cumulative hydroxychloroquine dose of 1,000 g, equal to about 400 mg/d for 7 years. “The longer you are on the medicine, the higher your risk of developing retinal toxicity,” he noted.
Regardless of weight, it’s recommended to limit hydroxychloroquine to 400 mg daily and chloroquine to 250 mg daily, with a baseline ocular exam, and – barring any intervening problems – annual screening after 5 years.