chloroquine as chemoprophylaxis for malaria

Last edited 02/2023 and last reviewed 06/2023

Chloroquine as chemoprophylaxis for malaria:

Mode of action

• chloroquine is concentrated in the malaria parasite lysosome and is thought to act by interfering with malaria pigment formation, causing generation of a ferriprotoporphyrin IX-chloroquine complex which is highly toxic to the parasite.

Efficacy

• chloroquine-resistant falciparum malaria is now reported from all WHO regions except Central America north of the Panama Canal and the Island of Hispaniola (Haiti & the Dominican Republic). It remains effective against most P. vivax, all P. ovale, P. knowlesi, and virtually all P. malariae

Prophylactic regimen

• adult dose 310 mg (2 tablets) weekly, starting 1 week before entering a malarious area, continuing throughout the time in the area and for 4 weeks after leaving the area.

Contraindications

• Allergy to chloroquine or to any other ingredients of the formulation (tablet or syrup). Concomitant use with amiodarone

Cautions

• Chloroquine should not be used in those with a history of epilepsy. The risk of epilepsy is higher in first degree relatives of those in whom this condition has been diagnosed so it should be considered as part of risk assessment. Epilepsy in a first-degree relative may not contraindicate the use of an antimalarial but may influence the choice of drug
  
  
• Chloroquine may exacerbate psoriasis and myasthenia gravis
  
  
• severe hypoglycaemia has occurred in diabetics and non-diabetics.

In long term use, eye examinations every 6-12 months should be considered after 6 years' prophylactic usage, though the risk of retinopathy developing on prophylactic dosage is considered to be very low.

Chloroquine is highly toxic in overdose and children are particularly susceptible

Interactions

• Drugs: Use with amiodarone is contraindicated (increased risk of ventricular arrhythmias)
  
  
• Other interactions include: ciclosporin (increased risk of ciclosporin toxicity); digoxin (possibly increases plasma concentration of digoxin); mefloquine (increased risk of convulsions); moxifloxacin (increased risk of ventricular arrhythmias)
  
  
• vaccines: Chloroquine may suppress the antibody response to pre-exposure intradermal human diploid cell rabies vaccine. This interaction is not seen when rabies vaccine is given intramuscularly (the currently recommended mode of vaccination in the UK).

Side-effects

• Frequently reported side effects are gastrointestinal disturbances and headache. Convulsions and severe skin reactions have been reported. Chloroquine may cause itching, especially in persons of African descent

Reference:

• Public Health England. Guidelines for malaria prevention in travellers from the UK 2022