Quinine

How it works

It is a blood schizonticide that interferes with the parasite's ability to detoxify haem within its digestive vacuole, leading to accumulation of toxic haem and parasite death.

Prescribing in practice

• It has a narrow therapeutic index, and overdose or accumulation causes cinchonism and potentially fatal cardiotoxicity, hypoglycaemia and dose-related visual and auditory toxicity, so dosing and monitoring must be careful.
• It prolongs the QT interval and can cause hypoglycaemia, particularly with intravenous use, which should be given by slow infusion with cardiac and glucose monitoring.
• It can cause immune-mediated thrombocytopenia and, rarely, haemolysis, so it should be stopped if these occur.

Monitoring

During parenteral treatment monitor ECG, blood glucose and, in severe or prolonged therapy, plasma concentrations, alongside clinical parasitological response.

Counselling the patient

• Ringing in the ears, headache or blurred vision can indicate the dose is too high; report these.
• Report symptoms of low blood sugar such as sweating, shakiness or confusion.
• Take the course exactly as prescribed and do not exceed the stated amount.

Evidence & guidelines

Quinine remains an established option for malaria treatment, although intravenous artesunate is now preferred first-line for severe falciparum malaria in UK and WHO guidance.