Antiepileptic properties of quinine: A systematic review.

Abstract

EXECUTIVE SUMMARY Background: Quinine has been found to have anti-epileptic properties in animals. However, in humans this has not been systematically investigated. If quinine has antiepileptic properties in humans, it may reduce the neurological sequelae associated with acute seizures in severe malaria and promote its choice over other antimalarial drugs in treating severe falciparum malaria. OBJECTIVE The review objective was to examine available research evidence on the effects of quinine on seizures in adults or children who present with seizures or who develop seizures in the course of treatment. INCLUSION CRITERIA Participants: This review considered adult and child patients who were prescribed using quinine for malaria, arthritis, nocturnal leg cramps, arrhythmia and systemic lupus erythematosus. INTERVENTION This review evaluated the use of quinine in comparison to other drugs used for malaria, arthritis, nocturnal leg cramps, arrhythmia and systemic lupus erythematosus. OUTCOMES The primary outcome of interest for this review was the proportion of participants who had seizures after the administration of quinine, compared with those who were not given quinine.Types of Studies: This review considered randomised controlled trials. SEARCH STRATEGY We searched online databases for published and unpublished studies written in English and identified articles using predefined criteria.Methodological Quality: Papers selected for retrieval were assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument. DATA EXTRACTION/SYNTHESIS The data extracted included specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives. A standardized data extraction tool was used. A random effects model was used to statistically pool data in meta-analysis, in order to determine the effect of quinine on prevalence of seizures in comparison to other drugs. RESULTS We identified six randomized controlled trials on severe malaria. Quinine was compared to the artemisinin derivatives in all trials. A total of 8,244 patients were included. In the meta-analysis, there was no significant effect of quinine on the prevalence of seizures (Odds ratio=0.90 95% Confidence Interval=0.63-1.30). There was significant heterogeneity (Chi-squared=17.44, p=0.008). DISCUSSION This is the first review on the antiepileptic effect of quinine in humans. However, this effect is not demonstrated in patients with malaria. A dose-response effect may be responsible for the absence of antiepileptic properties of quinine in humans. The results of the review are confounded by the fact that all the studies reviewed were conducted in patients with malaria, and quinine was only compared against artemisinin compounds which may have neurological effects. Further, incidence of seizures could not be assessed in this review. CONCLUSIONS There is not sufficient evidence to conclude that quinine has any antiepileptic properties. A dose-response effect may be responsible for the absence of antiepileptic properties of quinine in humans with severe malaria. IMPLICATIONS FOR PRACTICE This review provides data that may influence choice of antimalarial drugs in resource poor settings. IMPLICATIONS FOR RESEARCH This review identifies the need for further studies on the antiepileptic properties of quinine with sufficient power, designed to capture seizure prevalence and incidence as outcomes, that have the ability to control for confounders appropriately and that can explore the dose-response effect of quinine on seizures.