|Click on "►" to expand:|
Hydroxychloroquine (Brand name Plaquenil, among others) works by reducing inflammation in people with autoimmune diseases (this is where the body’s immune system attacks itself by mistake). It is considered a disease-modifying anti-rheumatic drug (DMARD) because it can decrease the pain and swelling of arthritis, and it may prevent joint damage and reduce the risk of long-term disability.
Hydroxychloroquine was first used to prevent and treat malaria. Today it is also used to treat rheumatoid arthritis, discoid and systemic lupus erythematosus, and other autoimmune diseases.
 BRAND NAMES
- International: Plaquenil
- Plaquinol (Portugal, Peru, Brazil, Chile, Colombia, Ecuador)
 MECHANISM OF ACTION
Hydroxychloroquine is primarily an anti-malarial agent with anti-inflammatory potentials. Hydroxychloroquine increases pH within intracellular vacuoles, and causes inhibition of lysosomal acidic proteases causing a diminished proteolysis effect. Higher pH within lysosomes causes decreased intracellular processing, glycosylation, and secretion of proteins with many immunologic and nonimmunologic consequences. These effects are believed to be the cause of a decreased immune cell functioning such as chemotaxis, phagocytosis and superoxide production by neutrophils.
Hydroxychloroquine is almost completely absorbed with wide tissue distribution, and is eliminated in urine.
Hydroxychloroquine is recommended for treatment of:
- Rheumatoid arthritis
- Discoid and systemic lupus erythematosus
- Photoprotective for photodermatosis and porphyria.
- Treatment and prophylaxis of malaria.
- Treatment of Sjögren's syndrome; Hydroxychloroquine has been shown to slow the immune system's attack on the tear and saliva glands and is helpful for some manifestations of Sjögren's syndrome, particularly fatigue, muscle, and joint pains.
Take with food or milk
- Rheumatoid Arthritis: Hydroxychloroquine tablet are used only as disease modifying agent in rheumatoid arthritis, discoid and systemic lupus with delayed onset of action (more than 6 weeks). If a patient shows no response after 5-6 months that this should be considered a drug failure.
- ADULT: Initially 400 mg are administered orally to adult and elderly in divided doses to be reduced to 200mg at maintenance; Maintenance should be achieved with the minimum effective dose that should not exceed 6.5mg /kg/day.
- ADULT: Prophylaxis: A dose of 400mg every 7 days is used for prophylaxis starting 2 weeks before exposure and continued for 4 weeks after departure from area. Acute treatment: an initial dose of 800 mg is used for treatment followed after 6-8hours by 400mg and further 400mg on each of the two following days.
- CHILDREN: Prophylaxis with weekly doses of 6.5mg/kg starting 2 weeks before exposure and continued for 4 weeks after departure from area. Acute treatment: Treatment should includes a loading dose of 13mg/kg followed by 6.5mg /kg 6hours later. For the two following days; a similar daily dose given.
- Systemic Lupus Erythematosus: ADULT, 400 mg once or twice daily; maintenance: 200-400 mg daily
- Porphyria Cutanea Tarda (photodermatitis): ADULT, Hydroxychloroquine 100-200 mg is given twice weekly.
- Sjögren's syndrome: 200-400 mg daily
- Hydroxychloroquine should not be used in patient with preexisting maculopathy.
- Should not be used during pregnancy
 WARNINGS AND PRECAUTIONS
- Patients should have an initial ophthalmologic examination to be repeated every 6 months.Treatment should be discontinued at the event of pigmentary abnormality or visual field defects. The occurrence of retinopathy is uncommon if recommended dose is not exceeded. Altered visual accommodation has been recorded at start of therapy.
- Periodic blood counts are advised when treatment is prolonged
- Hydroxychloroquine may increase plasma digoxin level.
- Cimetidine inhibits the metablism of Hydroxychloroquine, resulting in increase of its plasma levels .
- The use of antacids reduces its absorption and four–hours interval spacing should be considered when antacid are used.
- By virtue of its immunomodulatory action, Hydroxychloroquine reduces the antibody response to primary immunization with intradermal human diploid cell Rabies vaccine.
 PREGNANCY AND LACTATION
- PREGNANCY: Usage of this drug during pregnancy should be avoided except in the suppression or treatment of malaria when in the judgment of the physician the benefit outweighs the possible hazard. It should be noted that radioactively-tagged chloroquine administered intravenously to pregnant, pigmented CBA mice passed rapidly across the placenta. It accumulated selectively in the melanin structures of the fetal eyes and was retained in the ocular tissues for five months after the drug had been eliminated from the rest of the body.
 SIDE EFFECTS
- Retinopathy – visual field defects: Occurs rarely with the recommended daily dose. it is reversible on discontinuation when detected early (if left to developed there may be a risk of progression even after during withdrawal). Baseline ophthalmologic examination and a follow-up examination every 12 months are recommended during the period of treatment.
- Corneal opacities
- Skin rashes and pigmentary changes
- Other adverse effects include gastrointestinal disturbance (nausea, stomach cramps, vomiting) which resolve upon dose reduction, less frequently muscle weakness, vertigo, nervousness and headache .Rarely there have been reports of bone marrow depression.