Hydroxychloroquine
2-[{4-[(7-chloroquinolin-4-yl)amino]pentyl}(ethyl)amino]ethanol

Absorption：Hydroxychloroquine is readily absorbed from the GI tract. T max is 1 to 3 h.

Distribution：Hydroxychloroquine concentrates in the liver, spleen, kidney, heart, lungs, and brain.

Metabolism：It is partially hepatic to active de-ethylated metabolites.

Elimination：Approximately 50% of the unchanged drug is excreted in urine. Elimination in urine is very slow and may persist for months or years after discontinuation. Renal excretion is increased by acidification and decreased by alkalinization of the urine. The plasma t ½ is approximately 32 days.

Beta-blockers (eg, metoprolol)
Plasma levels and CV effects of certain beta-blockers may be increased.

Cimetidine
Pharmacologic effect of hydroxychloroquine may be increased.

Cyclosporine
Serum levels may be increased by hydroxychloroquine, increasing the risk of nephrotoxicity.

Digoxin
May increase serum digoxin levels.

Hepatotoxic drugs
May increase potential for hepatotoxicity.

Magnesium sulfate
Absorption of hydroxychloroquine may be reduced, decreasing the pharmacologic effect; antacid activity of magnesium sulfate may be decreased.

Mefloquine
Coadministration may increase risk of seizures.