Prescribe quinine with caution in patients at risk of QT prolongation, MHRA advises

New advice highlights that quinine can have effects on the QT interval even at therapeutic doses in patients with risk factors for QT prolongation.

Quinine has been used in the UK for the treatment of nocturnal leg cramps for many years. | iStock/Jay_Zynism
Quinine has been used in the UK for the treatment of nocturnal leg cramps for many years. | iStock/Jay_Zynism

GPs prescribing quinine to treat nocturnal leg cramps should exercise particular care in patients with conditions that predispose to QT prolongation, the MHRA has advised following a routine EU review.

Such patients include those with pre-existing cardiac disease or electrolyte disturbances, as well as those receiving other medications known to prolong the QT interval.

Owing to the potential of quinine to aggravate conduction deficits, GPs are also advised to use caution when prescribing the drug in patients with atrioventricular block.

Anticonvulsant toxicity

In addition to highlighting the cardiac risks of quinine, the European review identified a pharmacokinetic study which reported that serum levels of phenobarbital or carbamazepine could become raised with the concomitant use of quinine.

Although the data on this interaction appear to be limited to this study, it is advisable to monitor patients closely for evidence of anticonvulsant toxicity if the use of quinine with these drugs is necessary.

The MHRA has previously warned that quinine should only be used to treat nocturnal leg cramps that regularly disrupt sleep, and should not be considered a routine treatment for nocturnal leg cramps.

Want news like this straight to your inbox?
Sign up for our bulletins

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Register
Already registered?
Sign in

MIMS Product Slides

Product overviews prepared by the MIMS team, in a handy slide format.

Click here

Slides are initiated, funded & reviewed by the companies specified.

Register or Subscribe to MIMS

GPs can get MIMS print & online and GPonline for free when they register online – take 2 minutes, and make sure you get your free MIMS access! If you're not a GP, you can subscribe to MIMS for full access.

Register or subscribe

MIMS Dermatology

Read the latest issue online exclusively on MIMS Learning.

Read MIMS Dermatology

MIMS Adviser

Especially created for prescribing influencers.

Request free copy

Mobile apps

MIMS: access the full drug database and quick-reference tables on the go

MIMS Diagnosis and Management: concise information on signs and symptoms, investigations and diseases