G Quinine

Indications

Quinine Dihydrochloride is the injectable form of quinine, an antimalarial medicine. It is used in hospital to treat severe or complicated malaria caused by Plasmodium falciparum, especially when Artesunate injection is not available or not suitable, and in people who cannot take medicine by mouth.

How It Works

Quinine kills the malaria parasites living inside red blood cells. It is thought to stop the parasite from safely getting rid of toxic waste (haem) produced when it digests haemoglobin, so the parasite poisons itself.

Dosage and Administration

Given only by a doctor or nurse in hospital, usually as a slow intravenous infusion diluted in glucose or saline over several hours, or sometimes as a deep intramuscular injection. The dose is calculated by body weight and may start with a loading dose, as prescribed. It must never be given as a rapid injection into a vein. When the patient can swallow, treatment is switched to tablets or another antimalarial to complete the course.

Interactions

• Mefloquine, Halofantrine and other medicines that prolong the QT interval (some antiarrhythmics, antipsychotics, Macrolide antibiotics, Fluoroquinolones): risk of dangerous heart rhythm problems and seizures.
• Digoxin: levels may rise.
• Warfarin: bleeding risk may increase.
• Diabetes medicines and insulin: higher risk of low blood sugar.
• Rifampicin: lowers quinine levels.
• Antacids containing Aluminium or Magnesium, and Cimetidine, may change levels of oral quinine.

Contraindications

• Allergy to quinine or quinidine.
• Past severe reaction to quinine, such as low platelets, haemolytic uraemic syndrome or blackwater fever.
• Optic neuritis or tinnitus (ringing in the ears) caused by quinine.
• Myasthenia gravis.
• Prolonged QT interval, unless the benefit clearly outweighs the risk.

Side Effects

Common effects (known as cinchonism) include ringing in the ears, mild hearing loss, headache, nausea, dizziness and blurred vision. Low blood sugar is common and can be serious, especially in pregnant women and children. Pain at the injection site may occur.

Doctors and nurses watch closely for, and urgent help is needed with: sweating, confusion or drowsiness from low blood sugar; irregular heartbeat or very low blood pressure; bleeding or bruising; dark urine; sudden vision loss; or signs of severe allergy.

Pregnancy and Lactation

Severe malaria is life-threatening for mother and baby, so quinine is used in pregnancy when needed, with careful blood sugar checks. Artesunate is often preferred where available. Quinine passes into breast milk in small amounts; breastfeeding can usually continue, but the doctor should be consulted, especially if the baby has G6PD deficiency.

Precautions and Warnings

Blood sugar, heart rhythm (ECG), blood pressure and kidney function are monitored during treatment. Doses are reduced in kidney or liver problems and if treatment lasts more than 48 hours. Use with care in people with heart disease, G6PD deficiency or atrial fibrillation.

Overdose

Overdose can cause severe ringing in the ears, blindness, seizures, dangerous heart rhythm problems, low blood pressure and coma. It is a medical emergency managed in hospital.

Therapeutic Class

Antimalarial (cinchona alkaloid).

Storage

Store as directed on the pack, below 30°C and protected from light. Hospital use only; keep out of the reach of children.