What Is the Difference Between Hydroxychloroquine and Chloroquine?

Hydroxychloroquine is a 4-aminoquinoline derivative antimalarial drug. Its action and mechanism are similar to chloroquine, but its toxicity is only half that of chloroquine. This product also has anti-inflammatory, immune regulation, anti-infection, light filtering, anticoagulation and other effects.

Basic Information

Chinese name

Hydroxychloroquine

Foreign name

Plaquenil

Pharmacological action

Action and mechanism similar to chloroquine

Use

Controlling clinical symptoms of malaria

Hydroxychloroquine indication

Suitable for malaria, allergic and autoimmune diseases.

Clinical application of hydroxychloroquine

The tablets are administered orally. Adults (including the elderly) take the first dose of 400 mg daily in divided doses. When the efficacy does not improve further, the dose can be reduced to 200 mg to maintain. If the response to treatment weakens, the maintenance dose should be increased to 400 mg daily. The minimum effective dose should be used, which should not exceed 6.5 mg / kg / day (calculated from the ideal weight rather than the actual weight) or 400 mg / day or even less. Children should use the minimum effective dose, which should not exceed 6.5 mg / kg / day (based on the ideal weight) or 400 mg / day or even less. Children younger than 6 years old are contraindicated and 200mg tablets are not suitable for children weighing less than 35kg. Eat or drink milk at the same time with each dose.

Hydroxychloroquine has a cumulative effect and takes several weeks to exert its beneficial effects, while minor adverse reactions may occur relatively early. If rheumatic disease does not improve after 6 months of treatment, treatment should be discontinued. In the case of light-sensitive diseases, treatment should only be given to the maximum exposure to sunlight.

Hydroxychloroquine adverse reactions

Retinal changes

Changes in retinal pigmentation and visual field defects can occur, but they are rare. These lesions are reversible after early discontinuation of this product. If further development, even after stopping this product, there is still a danger of increasing. Patients with retinopathy may be asymptomatic in the early stages, or may be accompanied by dark spots in the center, circular defects around the center, temporal defects and abnormal color vision.

2. Changes in the cornea

Reports of corneal changes include corneal edema and opacities, which can be unconscious symptoms or can cause halos, blurred vision, or photophobia. These symptoms may be temporary or reversed after withdrawal. Blurred vision due to abnormal regulatory function is dose-dependent and may be reversible.

Hydroxychloroquine precautions

1. Before starting treatment with this product, all patients should undergo an ophthalmological examination. Examinations include visual acuity, ophthalmic microscopy, central visual field, and color vision. Thereafter, it should be checked at least once a year.

2. There is a great correlation between retinopathy and drug dose, and the risk of retinal damage is low when the maximum daily dose does not exceed 6.5mg / kg body weight. But exceeding the recommended daily dose will greatly increase the risk of retinal toxicity. The frequency of eye examinations should be increased in patients with:

(1) The daily dose exceeds the ideal body weight of 6.5mg / kg. Abdominal patients will be overdose based on absolute weight as a guide for dosing.

(2) Renal insufficiency;

(3) Cumulative drug usage exceeds 200g;

(4) the elderly;

(5) Impaired visual acuity; if visual impairment (visual acuity, color vision, etc.) occurs, the drug should be discontinued immediately and the progress of the abnormal condition of the patient closely monitored. Retinopathy (and visual impairment) may develop even after stopping treatment, and patients who are taking medications that may cause eye or skin adverse reactions should use this product with caution. This product should also be used with caution in patients with liver or kidney disease, or those who are taking medications known to affect these organs, as well as patients with severe gastrointestinal, neurological, and hematological disorders. Patients with severely impaired liver and kidney function should be assessed for plasma chlorochloroquine levels in order to adjust the dose used.

Although the risk of myelosuppression is low, anaemia, aplastic anemia, granulocytopenia, leukopenia, and thrombocytopenia have been reported. Regular blood counts are recommended, and this product should be discontinued if abnormalities occur. Patients who are sensitive to quinine, those who are deficient in glucose-6-phosphate dehydrogenase, those who take hydroxychloroquine can exacerbate late-onset skin porphyria, and psoriasis patients seem to increase the risk of skin adverse reactions due to this product , This product should also be used with caution. Patients with rare genetic disorders of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption should not take this product.

Children are particularly sensitive to the toxic effects of 4-aminoquinoline; patients are therefore warned to keep this product out of reach of children. All patients undergoing long-term treatment should be checked regularly for skeletal muscle function and tendon reflexes. If there is a decrease in skeletal muscle function and tendon reflexes, the drug should be discontinued.

Impaired vision regulation has been reported shortly after starting treatment. The persons involved in driving and operating the machine should be reminded. If symptoms cannot be self-limited, the dose should be reduced or treatment discontinued. Malaria: Plasmodium falciparum, which is resistant to chloroquine, is ineffective in treatment with hydroxychloroquine, and it is also ineffective against Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae outside the red blood cells, so it cannot prevent its infection and prevent recurrence.

(Note: The above content is only for introduction, the drug use must be carried out by a regular hospital under the guidance of a doctor.)