Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to Plasmodium falciparum that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg cramps, quinine is a cinchona alkaloid with molecular formula C20H24N2O2 and a molecular weight of about 324.4 g/mol; it contains a quinoline chromophore and a quinuclidine-type bicyclic amine. Its antimalarial activity is attributed to inhibition of heme polymerization inside the parasite digestive vacuole, leading to accumulation of toxic heme derivatives. Quinine is supplied as oral sulfate tablets and as parenteral salts for severe infection, is substantially protein bound, is primarily metabolized by hepatic CYP isoforms including CYP3A4 to 3-hydroxyquinine and other metabolites, and has an elimination half-life in adults on the order of 8 to 12 hours. Clinically relevant adverse effects and toxicities include cinchonism characterized by tinnitus, headache, and nausea, as well as hypersensitivity reactions, hematologic abnormalities such as thrombocytopenia, and cardiovascular effects including QT interval prolongation; these properties guide monitoring during therapy.
Parent: Quinine Sulphate / Quinine
Parent: Quinine/ Quinine Sulfate Dihydrate
For pharmaceutical active ingredient manufacture and release, quinine API specifications typically control related substances and degradation products; common related compounds include other cinchona alkaloids such as quinidine, cinchonine, and cinchonidine, process-related impurities such as dehydroquinine and 3-hydroxyquinine, and trace residual solvents or inorganic salts from processing. Typical quality specifications set limits on individual unspecified impurities at or below about 0.5 percent of the API, and on total impurities in the range of about 1.0 to 2.0 percent, with tighter limits applied to known genotoxic degradants if present; final product limits must also meet pharmacopeial criteria and ICH Q3A/Q3B/Q3C guidance for impurities and residual solvents.
Quinine is used to treat malaria and babesiosis; it is an option for P. falciparum malaria when chloroquine resistance is present and intravenous artesunate is not available, and it is also indicated for babesiosis in specified clinical settings.
Quinine is added to tonic water at low concentrations for its bitter flavor; the amounts present in commercially available beverages are far below therapeutic doses and are intended for taste rather than medical effect.
People with known hypersensitivity to quinine or other cinchona alkaloids, individuals with a history of quinine-induced thrombocytopenia, patients with certain cardiac conduction abnormalities or long QT syndrome, and those taking interacting medications that prolong QT interval or inhibit CYP3A4 should avoid quinine unless supervised by a clinician; pregnant women generally should avoid quinine for noncritical uses and consult a clinician for pregnancy treatment decisions.
Quinine is primarily metabolized hepatically and cleared by multiple routes, but kidney function impacts elimination of metabolites and coadministered salts; quinine can cause adverse systemic effects and dose adjustments or increased monitoring may be required in renal impairment, so safety in patients with kidney disease should be assessed by a clinician and dosing guided by clinical status and product labeling.
