Quinine

Endpoint summary

Description of key information

Quinine has an absorption rate of 76 %. About 70 %  of the plasma quinine is bound to proteins. Quinine is metabolized in the liver by hydroxylation and metabolic products are excreted in urine. The half-life of quinine in plasma is about 4 to 10 hours.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

76

Additional information

In the study published by Paintaud, 1993 the pharmacokinetic of quinine was determined after oral and intravenous administration. Quinine had an absorption rate of 76 %. The AUC of quinine after oral administration was about 248 µmol/L *h and the peak plasma concentration was about 15.2 µmol/L. The half-life of quinine in plasma is about 10 hours. The AUC of quinine after intravenous infusion was about 321 µmol/L *h and the half-life in plasma is about 11.3 hours. It could be conclude that the oral absorption of quinine is extensive and fast in healthy subjects. According to the peer-reviewed database, HSDB, quinine is readily absorbed when given orally or intramuscularly. It is almost completely absorbed from the gastrointestinal tract (over 90 %). Absorption of quinine occurs mainly from the upper small intestine. Following administration of a single oral dose, peak serum concentration of quinine occur within 1-3 h. A large fraction (approx. 70 %) of plasma quinine is bound to proteins in healthy adults. Plasma protein binding is increased in patients with cerebral malaria. Quinine is widely distributed to body tissues. It is present in cerebrospinal fluid where its concentration is 1-5% of the plasma concentration. Small amounts of the drug are distributed into bile and saliva. The half-life in plasma is 4-6 hours. The plasma elimination half-life of quinine reportedly averages 8-21 h in adults with malaria and 7-13 h in healthy or convalescing adults. However, in overdose patients, its elimination half-life is 25-26 hours. Quinine is metabolized in the liver by hydroxylation. In humans, quinine is metabolized by oxidation of quinuclidine and quinoline rings to yield 2-hydroxyquinine, the major metabolite. After consumption of quinine-containing beverages, quinine-N-oxide was identified in urine by MS. Less than 5% of admin dose of quinine is excreted unaltered in urine. Quinine is excreted mainly in urine as metabolic products, but small amount also appear in feces, gastric juice, bile and saliva. Because quinine is reabsorbed when the urine is alkaline, renal excretion of the drug is twice as rapid when the urine is acidic than when it is alkaline.