By Gary M. White, MD
Note: This is only a partial summary. Other resources should be consulted before prescribing hydroxychloroquine (HCQ).
One tablet is 200 mg.
Dose: 200 mg QD-BID (try to stay at or below 5 mg/kg/day--max 400 mg/day)
Periodic blood cell counts should be made if patients are given prolonged therapy.
Children are especially sensitive to the 4-aminoquinoline compounds. A number of fatalities have been reported following the accidental ingestion of chloroquine, sometimes in relatively small doses (0.75 g or 1 g in one 3-year-old child). Parents should be strongly warned to keep these drugs out of the reach of children.
The current recommendations are that all patients should receive a baseline screening before or within 1 year of initiation of hydroxychloroquine therapy. If the patient is at or below the recommended maximum daily dose and does not fall into a higher risk category, the screening interval is 5 years after the initial evaluation. The incidence of retinopathy is less than 1% at 5 years and only 2% at 10 years. The incidence increases to 20% at 20 years of treatment. Concomitant use of tamoxifen greatly increases the risk of retinal toxicity (odds ratio 4.59).
These are not uncommon side effects.
All patients on long-term therapy with this preparation should be questioned and examined periodically, including the testing of knee and ankle reflexes, to detect any evidence of muscular weakness. If weakness occurs, discontinue the drug.
The daily dosage of hydroxychloroquine should not exceed, if possible, 5.0 mg/kg actual body weight a day. Daily consumption of 5.0 mg/kg of real body weight or less for up to 10 years is associated with a low risk of ocular side effects. [JAMA Ophthalmol. 2014 Oct 2].
Expert opinion suggests that HCQ can be continued during both pregnancy and lactation in patients felt to be benefitting from it.
Smoking may decrease the benefit of HCQ.
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