Cinchonism is apathological condition caused by an overdose ofquinine or its natural source,cinchona bark. Quinine and its derivatives are used medically to treatmalaria andlupus erythematosus. In much smaller amounts, quinine is an ingredient oftonic drinks, acting as abittering agent. Cinchonism can occur from therapeutic doses of quinine, either from one or several large doses.Quinidine (a Class 1Aanti-arrhythmic) can also cause cinchonism symptoms to develop with as little as a single dose.
Large doses of quinine may lead to severe (but reversible) symptoms of cinchonism: skin rashes, deafness,somnolence, diminished visual acuity or blindness,anaphylactic shock, and disturbances inheart rhythm or conduction, and death from cardiotoxicity (damage to the heart). Quinine may also trigger a rare form of hypersensitivity reaction in malaria patients, termedblackwater fever, that results in massivehemolysis,hemoglobinemia,hemoglobinuria, andkidney failure.[citation needed] Most symptoms of cinchonism (except in severe cases) are reversible and disappear once quinine is withdrawn. Attempted suicide by intake of a large dose of quinine has caused irreversible tunnel vision and very severe visual impairment.[2]
Quinine, likechloroquine, inactivates enzymes in thelysosomes of cells and has an anti-inflammatory effect, hence its use in the treatment ofrheumatoid arthritis. However, inactivation of these enzymes can also cause abnormal accumulation of glycogen and phospholipids in lysosomes, causing toxicmyopathy. It is possible this action is the root cause of cinchonism.[citation needed]
