Singapore Drugs Database

Indication

For the suppressive treatment and treatment of acute attacks of malaria due to Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum. It is also indicated for the treatment of discoid and systemic lupus erythematosus, and rheumatoid arthritis.

Mechanism of Action

Although the exact mechanism of action is unknown, it may be based on ability of hydroxychloroquine to bind to and alter DNA. Hydroxychloroquine has also has been found to be taken up into the acidic food vacuoles of the parasite in the erythrocyte. This increases the pH of the acid vesicles, interfering with vesicle functions and possibly inhibiting phospholipid metabolism. In suppressive treatment, hydroxychloroquine inhibits the erythrocytic stage of development of plasmodia. In acute attacks of malaria, it interrupts erythrocytic schizogony of the parasite. Its ability to concentrate in parasitized erythrocytes may account for their selective toxicity against the erythrocytic stages of plasmodial infection. As an antirheumatic, hydroxychloroquine is thought to act as a mild immunosuppressant, inhibiting the production of rheumatoid factor and acute phase reactants. It also accumulates in white blood cells, stabilizing lysosomal membranes and inhibiting the activity of many enzymes, including collagenase and the proteases that cause cartilage breakdown.

Pharmacokinetics

Absorption

Very rapidly and completely absorbed following oral administration.

Distribution

Metabolism

Partially hepatic, to active de-ethylated metabolites.

Elimination

Toxicity

Symptoms of overdose include headache, drowsiness, visual disturbances, cardiovascular collapse, and convulsions, followed by sudden and early respiratory and cardiac arrest. The electrocardiogram may reveal atrial standstill, nodal rhythm, prolonged intraventricular conduction time, and progressive bradycardia leading to ventricular fibrillation and/or arrest.

Active Ingredient/Synonyms

(+-)-Hydroxychloroquine | (±)-hydroxychloroquine | 2-((4-((7-chloro-4-Quinolyl)amino)pentyl)ethylamino)ethanol | 2-(N-(4-(7-Chlor-4-chinolylamino)-4-methylbutyl)ethylamino)ethanol | 7-chloro-4-(4-(Ethyl(2-hydroxyethyl)amino)-1-methylbutylamino)quinoline | 7-chloro-4-(4-(N-Ethyl-N-beta-hydroxyethylamino)-1-methylbutylamino)quinoline | 7-chloro-4-[4-(N-Ethyl-N-beta-hydroxyethylamino)-1-methylbutylamino]quinoline | 7-chloro-4-[5-(N-Ethyl-N-2-hydroxyethylamino)-2-pentyl]aminoquinoline | Hidroxicloroquina | Hydroxychloroquinum | NSC4375 | Oxichlorochine | Oxichloroquine | Polirreumin | Hydroxychloroquine |