Hydroxychloroquine (Plaquenil) :- Uses, Mechanism Of Action, Adverse Effects & Contraindications

hydroxychloroquine commercially known as plaquenyl is a medication used in the treatment and prevention of malaria in areas where malaria remains sensitive to chloroquine in addition it is used in the treatment of rheumatoid arthritis systemic lupus arithmatisis and porphyria cutanea tarta hydroxychloroquine has different mechanisms of action depending on the disease being treated by the drug in case of malaria it is indicated for prophylaxis in geographic areas where chloroquine resistance is not reported additionally it is used in the treatment of uncomplicated malaria caused by plasmodium vivax plasmodium malaria plasmodium ovale and plasmodium falciprum here hydroxychloroquine accumulates within the lysosomes of malaria parasite raising the ph within this causes inability to proteolyze human hemoglobin and consequently impaired growth and replication of the parasite in the treatment of rheumatoid arthritis hydroxychloroquine acts as a disease-modifying anti-rheumatic drug though the mechanism of action is not well understood here it reduces the inflammation pain and swelling associated with rheumatoid arthritis it also reduces joint damage and helps prevent disability in the long term hydroxychloroquine is the first line drug in the treatment of systemic lupus arithmatisis regardless of the disease severity here it acts as an immunomodulator and reduces flare-ups and improves survival of the patient hydroxychloroquine is well absorbed from the gastrointestinal tract and it is concentrated in many tissues including erythrocytes heart liver kidney spleen cornea and retina the drug is slowly released from these tissues and it has a longer plasma half-life of 50 days the drug is eliminated from the kidneys hydroxychloroquine has some important drug interactions to bear in mind first its absorption is reduced in the gut by antacids therefore hydroxychloroquine and antacids should not be taken together it also increases the plasma concentration of digoxin and cyclosporine leading to their toxic effects finally hydroxychloroquine should not be used with amiodarone or antipsychotic drugs as it can lead to severe arrhythmias hydroxychloroquine has a narrow therapeutic index meaning that the difference between toxic dose and therapeutic dose is minimal common adverse effects of hydroxychloroquine include the following gastrointestinal symptoms such as nausea abdominal cramps and diarrhea itching headache muscle weakness allergic reactions and visual disturbances hydroxychloroquine is contraindicated in patients with known hypersensitivity in patients who develop visual disturbances and in patients with heart disease and it is safer to use during pregnancy and breastfeeding you