Chloroquine

Products

Chloroquine was commercially available in tablet form (Nivaquine). It was approved in many countries since 1953. Its distribution was discontinued in 2019. It was first synthesized in 1934 by Hans Andersag at Bayer in Elberfeld (I.G. Farbenindustrie). Currently, medicines containing chloroquine are no longer available in many countries. Magisterial formulations can be made in pharmacies or tablets can be imported from abroad. Hydroxychloroquine (Plaquenil) is closely related to chloroquine and is commercially available.

Structure and properties

Chloroquine (C18H26ClN3, Mr = 319.9 g/mol) is a chlorinated 4-aminoquinoline derivative and a racemate related to quinine. It exists as chloroquine phosphate or as chloroquine sulfate, a white crystalline powder with a bitter taste that is readily soluble in water. It is structurally closely related to hydroxychloroquine. Chloroquine should be stored away from light because it discolors when exposed to light.

Effects

Chloroquine (ATC P01BA01) has antiparasitic, blood schizontocidal, anti-inflammatory, immunomodulatory (immunosuppressive), and antiviral properties. It has a long half-life of 10 to 30 days. Chloroquine has shown antiviral properties in several studies, including against coronaviruses.

Indications

Off-label use:

  • Chloroquine was studied and used in 2020 for the treatment of the viral disease Covid-19. It is antiviral and has additional immunomodulatory properties (see above).

Dosage

According to the professional information. The tablets should be taken after meals. The dosing interval depends on the indication.

Contraindications

  • Hypersensitivity
  • Glucose-6-phosphate dehydrogenase deficiency
  • Diseases of the hematopoietic organs
  • Central nervous diseases
  • Retinopathy, retinal or visual field changes.
  • Myasthenia gravis

Full details of precautions and interactions can be found in the drug label.

Interactions

Chloroquine has a high potential for interaction with several agents.

Adverse effects

The most common possible adverse effects include gastrointestinal discomfort, headache, itching, visual disturbances, and insomnia. Chloroquine can rarely cause serious side effects. These include retinopathy, severe skin reactions, blood count disorders, central disorders, convulsions, and cardiac arrhythmias. The active ingredient prolongs the QT interval. Chloroquine is toxic in high doses. An overdose can have a fatal outcome.