Editorial: Gin tonic revisited

Abstract

keywords antimalarial therapy, quinine, Cinchona barkSunset in the tropics. On the verandah: lounging Europeanexpats, buzzing mosquitoes, peak biting time. Once settledand seeking comfort and consolation, dawdling the hoursaway with generous gin & tonics, talks and tales soon turnto malaria. One has to drink gin tonic in the diaspora. Itkeeps away malaria and, with a twist of lime, even preventsscurvy. It is good for health.Stay cool and hark back to the febrifugal qualities oftonic water. It is sugar bubble water, flavoured with fruitessences and a small addendum of quinine. Quinine is analkaloid isolated from the bark of cinchona trees andnumerous legends exist on South American Indians’ useof the bark prior to Francisco Pizzaro’s conquista. In1633, quinine’s benefits were recognized in Peru byAntonio de Calancha, an Augustinian monk. The barkwas given to the feverish Countess Anna de Chincho´n,the Peruvian Viceroy’s shivering and delirious wife andnow, although erroneously misspelled by CarolusLinnaeus, bears her reputable name. Cinchona provedinvaluable in treating malaria and the remedy was widelyused in Europe in the 17th and 18th centuries for itsalleviating properties in various aguish and otherconditions.The medicinal addition of tonic water to gin promptedthe question whether the amount of quinine might besufficient to exert inhibitory or toxic effects on the malaria-causing Plasmodium falciparum parasites and, thus, mightprevent or even cure malaria. Willing to contribute to talksand tales and to battle cranky alibi myths, we made this anissue.Five hundred to 1000 ml of tonic water, containing58.3 mg/l quinine, was downed within 15 min by sixhealthy (voluntary!) candidates. Protein-bound andunbound plasma quinine concentrations were determined,by liquid-chromatography mass spectrometry (Kratzschet al. 2003), after achieving the peak plasma concentra-tion that occurs after 2 h. In accordance with valuesobtained in an earlier study on potential quinine-inducedaudiometric and visual disturbances (Worden et al.1987), a mean plasma level of 0.62 mg/l (0.4–0.77 mg/l)was measured at 1 and 2 h after intake (experimentaldata available upon request.) 0.62 mg/l roughly corres-ponds to the minimum inhibitory quinine concentrationof 0.68–0.89 mg/l (Breckenridge & Winstanley 1997;Pukrittayakamee et al. 2003), equivalent to an unboundquinine concentration of approximately 0.2 mg/l. Thetherapeutic range is unusually broad, from 0.2 mg/l to2.0 mg/l, because of the varying drug susceptibility ofdifferent P. falciparum strains (Winstanley et al. 1993;Breckenridge & Winstanley 1997). As initial antimalarialtreatment with unbound quinine plasma concentrations£0.5 mg/l within the first 12 h exerts suboptimal para-sitocidal effects because of the short half-life of quinine,loading doses of quinine are part of the standardtreatment regimen.Considerable quantities of tonic water may, for ashort period of time, lead to quinine plasma levels at thelower limit of therapeutic efficacy and may, in fact,cause transitory suppression of parasites. However,continuous levels that are appropriate for malariaprophylaxis cannot be maintained with even largeamounts of tonic.Dusk, verandah, mosquitoes – expats, please heed andkeep well in mind: do not mistake loading quinine dosesfor loading doses of gin tonic. Stay cool and healthy.References