Hydroxychloroquine

Pharmaceuticals -> Used in Switzerland

Pharmaceuticals

Breast Feeding; Lactation; Milk, Human; Anti-infective Agents; Antiparasitic Agents; Antimalarials; Antirheumatic Agents; Antiprotozoal Agents

Antimalarial medicines > Medicines for chemoprevention

89-91

90 °C

169.89 Ų [M+H-H2O]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

180.2 Ų [M+H]+ [CCS Type: TW; Method: Major Mix IMS/Tof Calibration Kit (Waters)]

Warning

H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]

P264, P270, P301+P317, P330, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 40 reports by companies from 2 notifications to the ECHA C&L Inventory.

Hydroxychloroquine has not been associated with significant serum enzyme elevations during therapy of rheumatologic diseases. Furthermore, clinically apparent liver injury from hydroxychloroquine is rare. A single case series (two cases) of acute liver failure attributed to hydroxychloroquine was published twenty years ago, but case reports of clinically apparent liver injury have not appeared subsequently. Thus, acute liver injury with jaundice due to hydroxychloroquine must be very rare, if it occurs at all. In clinical trials of hydroxychloroquine for COVID-19 prevention and treatment, there were no reports of hepatotoxicity and rates of serum enzyme elevations during hydroxychloroquine treatment were low and similar to those in patients receiving placebo or comparator agents.

Although the exact mechanism of action is unknown, it may be based on ability of hydroxychloroquine to bind to and alter DNA. Hydroxychloroquine has also has been found to be taken up into the acidic food vacuoles of the parasite in the erythrocyte. This increases the pH of the acid vesicles, interfering with vesicle functions and possibly inhibiting phospholipid metabolism. In suppressive treatment, hydroxychloroquine inhibits the erythrocytic stage of development of plasmodia. In acute attacks of malaria, it interrupts erythrocytic schizogony of the parasite. Its ability to concentrate in parasitized erythrocytes may account for their selective toxicity against the erythrocytic stages of plasmodial infection. As an antirheumatic, hydroxychloroquine is thought to act as a mild immunosuppressant, inhibiting the production of rheumatoid factor and acute phase reactants. It also accumulates in white blood cells, stabilizing lysosomal membranes and inhibiting the activity of many enzymes, including collagenase and the proteases that cause cartilage breakdown.

P01BA02

P - Antiparasitic products, insecticides and repellents

P01BA02

The S enantiomer of hydroxychloroquine is 64% protein bound in plasma. It is 50% bound to serum albumin and 29% bound to alpha-1-acid glycoprotein. The R enantiomer is 37% protein bound in plasma. It is 29% bound to serum albumin and 41% bound to alpha-1-acid glycoprotein. In total, hydroxychloroquine is 50% protein bound in plasma.

Hydroxychloroquine affects the function of lysosomes in humans as well as plasmodia. Altering the pH of the lysosomes reduces low-affinity self-antigen presentation in autoimmune diseases and interferes with the ability of plasmodia to proteolyze hemoglobin for their energy requirements. Hydroxychloroquine has a long duration of action as it may be taken on a weekly basis for some indications. Hydroxychloroquine may lead to severe hypoglycemia and so diabetic patients are advised to monitor their blood glucose levels. Hydroxychloroquine is active against the erythrocytic forms of chloroquine-sensitive strains of P. falciparum, P. malariae, P. vivax, and P. ovale. Hydroxychloroquine is not active against the gametocytes and exoerythrocytic forms including the hypnozoite liver stage forms of P. vivax and P. ovale. Hydroxychloroquine is not effective against malaria in areas where chloroquine resistance has been reported.

The exact mechanisms of hydroxychloroquine are unknown. It has been shown that hydroxychloroquine accumulates in the lysosomes of the malaria parasite, raising the pH of the vacuole. This activity interferes with the parasite's ability to proteolyse hemoglobin, preventing the normal growth and replication of the parasite. Hydroxychloroquine can also interfere with the action of parasitic heme polymerase, an enzyme that uses ferriprotoporphyrin IX (FP) released from hemoglobin as a substrate to form beta-hematin. By reducing the activity of heme polymerase without inhibiting the release of FP, hydroxychloroquine leads to the accumulation of FP in a toxic form. Hydroxychloroquine accumulation in human organelles also raise their pH, which inhibits antigen processing, prevents the alpha and beta chains of the major histocompatibility complex (MHC) class II from dimerizing, inhibits antigen presentation of the cell, and reduces the inflammatory response. Elevated pH in the vesicles may alter the recycling of MHC complexes so that only the high affinity complexes are presented on the cell surface. Self peptides bind to MHC complexes with low affinity and so they will be less likely to be presented to autoimmune T cells. Hydroxychloroquine also reduces the release of cytokines like interleukin-1 and tumor necrosis factor, possibly through inhibition of Toll-like receptors. The raised pH in endosomes, prevent virus particles (such as SARS-CoV and SARS-CoV-2) from utilizing their activity for fusion and entry into the cell. Hydroxychloroquine inhibits terminal glycosylation of ACE2, the receptor that SARS-CoV and SARS-CoV-2 target for cell entry. ACE2 that is not in the glycosylated state may less efficiently interact with the SARS-CoV-2 spike protein, further inhibiting viral entry.