Products
Hydroxychloroquine is commercially available in the form of film-coated tablets (Plaquenil, auto-generic: Hydroxychloroquine Zentiva). It has been approved in many countries since 1998. Unlike the closely related chloroquine, it is currently on sale. Generic drugs are registered.
Structure and properties
Hydroxychloroquine (C18H26ClN3O, Mr = 335.9 g/mol) is an aminoquinoline derivative. It is present in drugs as hydroxychloroquine sulfate, a white crystalline powder that is very soluble in water. Hydroxychloroquine is structurally closely related to chloroquine. It is a hydroxylated chloroquine (hydroxychloroquine).
Effects
Hydroxychloroquine (ATC P01BA02) has anti-inflammatory, immunomodulatory (immunosuppressive), antiparasitic, and antiviral properties. It is photoprotective, meaning it reduces the skin‘s sensitivity to UV radiation. Hydroxychloroquine has a long half-life.
Indications
- Chronic polyarthritis
- Lupus erythematosus
- Photodermatoses
- Prevention and treatment of malaria
Off-label use:
- In 2020, chloroquine and hydroxychloroquine were studied and used for the treatment of covid-19, infection with the new coronavirus.
Dosage
According to the professional information. The tablets are usually taken two to three times daily with meals and sufficient liquid. The dosing interval and therapeutic regimen also depend on the indication.
Contraindications
- Hypersensitivity to 4-aminoquinolines.
- Porphyria
- Hemolytic anemia
- Glucose-6-phosphate dehydrogenase deficiency
- Discontinue treatment if blood count abnormalities occur.
- Pre-existing retinopathy or visual field impairment.
- Myastenia gravis
- Psoriasis (psoriasis)
- Infants and children under 6 years
Full precautions can be found in the drug label.
Interactions
Hydroxychloroquine has a high potential for interaction with several drugs. These include, for example, liver toxic drugs, glucocorticoids, methotrexate, digoxin, and antibiotics (selection).
Adverse effects
The most common possible adverse effects include nausea and abdominal pain. Other common adverse effects include:
- Loss of appetite, vomiting, diarrhea.
- Mental disorders
- Headache
- Visual disturbances such as accommodation disorders and blurred vision.
- Itching, skin rash
Hydroxychloroquine prolongs the QT interval. It can rarely cause serious adverse effects such as severe skin reactions, retinopathy, blood count abnormalities, convulsions, cardiomyopathies, and cardiac arrhythmias.