BMA Concise Guide to Medicine & Drugs

Quinine

Brand name None

Used in the following combined preparations None

QUICK REFERENCE

Drug group Antimalarial drug and muscle relaxant

Overdose danger rating High

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Quinine, obtained from the bark of the cinchona tree, is the earliest antimalarial drug. It often causes side effects, but is still given for cases of malaria that are resistant to safer treatments. Owing to the resistance of malaria parasites to chloroquine and some of the more modern antimalarials, quinine remains the mainstay of treatment, but it is not used as a preventative.

At the high doses used to treat malaria, quinine may cause ringing in the ears, headaches, nausea, hearing loss, and blurred vision: a group of symptoms known as cinchonism. In rare cases, it may cause bleeding problems.

Quinine is also occasionally used to treat night-time leg cramps, although its effectiveness is limited.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, injection, infusion.

Frequency and timing of doses Malaria Every 8 hours. Muscle cramps Once daily at bedtime.

Adult dosage range 1.8g daily (malaria); 200–300mg daily (cramps).

Onset of effect 1–2 days (malaria); up to 4 weeks (cramps).

Duration of action Up to 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children. Protect from light.

Missed dose Take as soon as you remember. If your next dose is due within 4 hours, skip the missed one and return to your normal dosing schedule thereafter.

Stopping the drug If prescribed for malaria, take the full course. Even if you feel better, the original infection may still be present and may recur if treatment is stopped too soon. If taken for muscle cramps, the drug can safely be stopped as soon as you no longer need it.

OVERDOSE ACTION

Seek immediate medical advice in all cases. Take emergency action if breathing problems, seizures, or loss of consciousness occur.

POSSIBLE ADVERSE EFFECTS

Adverse effects are rare with low doses but more common with higher, antimalarial doses. All adverse effects should be reported to your doctor. They include nausea, vomiting, diarrhoea, ringing in the ears, and giddiness. If a rash, itching, loss of hearing, blurred vision, unusual bruising, or excessive bleeding occur, you should stop taking the drug and consult your doctor immediately.

INTERACTIONS

Digoxin Quinine increases blood levels of digoxin; the dose of digoxin should be reduced. Discuss with your doctor.

Cimetidine This drug increases the blood levels of quinine.

SPECIAL PRECAUTIONS

Be sure to consult your doctor if:

· You have heart problems, especially rhythm disturbances.

· You have a long-term kidney problem.

· You have tinnitus (ringing in the ears).

· You have optic neuritis.

· You have myasthenia gravis.

· You have glucose-6-phosphate dehydrogenase (G6PD) deficiency.

· You have diabetes.

· You are taking other medicines.

Pregnancy Not usually prescribed. May cause defects in the unborn baby. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk, but at normal doses adverse effects on the baby are unlikely. Discuss with your doctor.

Infants and children Reduced dose necessary.

Over 60 No special problems.

Driving and hazardous work Avoid these activities until you know how quinine affects you because the drug’s side effects may distract you.

Alcohol No known problems.

PROLONGED USE

Prolonged use of quinine can cause blood disorders. When quinine is used for night cramps, treatment should be reviewed after 4 weeks and stopped if the drug is producing no improvement. If the drug is continued, treatment should be reviewed every 3 months.