hydroxychloroquine, Plaquenil

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GENERIC NAME: hydroxychloroquine

BRAND NAME: Plaquenil

DRUG CLASS AND MECHANISM: Hydroxychloroquine is classified as an anti-malarial drug. It is similar to chloroquine (Aralen) and is useful in treating several forms of malaria as well as lupus erythematosus and rheumatoid arthritis. Its mechanism of action is unknown. Malaria parasites invade human red blood cells. Hydroxychloroquine may prevent malaria parasites from breaking down (metabolizing) hemoglobin in human red blood cells. Hydroxychloroquine is effective against the malarial parasites Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum. Hydroxychloroquine prevents inflammation caused by lupus erythematosus and rheumatoid arthritis. The FDA approved hydroxychloroquine in April 1955.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablet: 200 mg.

STORAGE: Hydroxychloroquine should be stored at room temperature up to 30 C (86 F) in a sealed, light resistant container.

PRESCRIBED FOR: Hydroxychloroquine is used for the treatment of malaria due to Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum. It is also used for treating rheumatoid arthritis, and chronic discoid and systemic lupus erythematosus when other therapies have failed. It may prevent relapse and relieve skin inflammation, hair loss, mouth sores, fatigue, and joint pain caused by systemic lupus erythematosus.

DOSING: The usual adult dose for treating malaria is 800 mg initially, followed by 400 mg 6 hours later then 400 mg on days 2 and 3. The dose for malaria prevention is 400 mg every week starting 1 or 2 weeks before exposure and for 4 weeks after leaving the high risk area.

The recommended adult dose for rheumatoid arthritis is 400-600 mg daily for 4-12 weeks followed by 200-400 mg daily.

Systemic lupus erythematosus is treated with 400 mg once or twice daily for several weeks then 200-400 mg daily. Hydroxychloroquine should be taken with food or milk in order to reduce stomach upset.

DRUG INTERACTIONS: Administration of hydroxychloroquine with penicillamine (Cuprimine, Depen) may increase penicillamine levels, increasing the risk of penicillamine side effects. The mechanism is unknown. Combining telbivudine (Tyzeka) and hydroxychloroquine may increase the risk of unexplained muscle pain, tenderness, or weakness because both drugs cause such side effects.

PREGNANCY: Hydroxychloroquine should only be used in pregnant women for malaria prophylaxis or treatment.

NURSING MOTHERS: Hydroxychloroquine may be secreted in breast milk and may cause side effects in the infant.

SIDE EFFECTS: Side effects include irritability, headache, weakness, hair lightening or loss, stomach upset, nausea, dizziness, muscle pain, rash and itching. Rarely, hydroxychloroquine can affect the bone marrow leading to reduced white blood cells (leukopenia) or platelets (thrombocytopenia) and abnormal red blood cells (anemia). Rare but potentially serious eye toxicity can occur. This toxicity affects a part of the eye called the retina and can lead to color blindness and even loss of vision. An ophthalmologist (eye specialist) often can detect changes in the retina that suggest toxicity before serious damage occurs. Therefore, regular eye examinations, even when there are no symptoms, are mandatory. Patients who are genetically deficient in a certain enzyme, called G6PD, can develop a severe anemia resulting from the rupture of red blood cells. This enzyme deficiency is more common in persons of African descent and can be evaluated by blood testing. Hydroxychloroquine may worsen psoriasis.

Reference: FDA Prescribing Information


Last Editorial Review: 1/14/2009




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