The pharmacokinetic properties of intramuscular quinine in Gambian children with severe falciparum malaria

Clinical pharmacokinetics of quinine and its relationship with treatment outcomes in children, pregnant women, and elderly patients, with uncomplicated and complicated malaria: a systematic review

Background

Standard dosage regimens of quinine formulated for adult patients with uncomplicated and complicated malaria have been applied for clinical uses in children, pregnant women, and elderly. Since these populations have anatomical and physiological differences from adults, dosage regimens formulated for adults may not be appropriate. The study aimed to (i) review existing information on the pharmacokinetics of quinine in children, pregnant women, and elderly populations, (ii) identify factors that influence quinine pharmacokinetics, and (iii) analyse the relationship between the pharmacokinetics and treatment outcomes (therapeutic and safety) of various dosage regimens of quinine.

Methods

Web of Sciences, Cochrane Library, Scopus, and PubMed were the databases applied in this systematic search for relevant research articles published up to October 2020 using the predefined search terms. The retrieved articles were initially screened by titles and abstracts to exclude any irrelevant articles and were further evaluated based on full-texts, applying the predefined eligibility criteria. Excel spreadsheet (Microsoft, WA, USA) was used for data collection and management. Qualitative data are presented as numbers and percentages, and where appropriate, mean + SD or median (range) or range values.

Results

Twenty-eight articles fulfilled the eligibility criteria, 19 in children, 7 in pregnant women, and 2 in elderly (14 and 7 articles in complicated and uncomplicated malaria, respectively). Severity of infection, routes of administration, and nutritional status were shown to be the key factors impacting quinine pharmacokinetics in these vulnerable groups.

Conclusions

The recommended dosages for both uncomplicated and complicated malaria are, in general, adequate for elderly and children with uncomplicated malaria. Dose adjustment may be required in pregnant women with both uncomplicated and complicated malaria, and in children with complicated malaria. Pharmacokinetics studies relevant to clinical efficacy in these vulnerable groups of patients with large sample size and reassessment of MIC (minimum inhibitory concentration) should be considered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04065-1.

Population pharmacokinetic and pharmacodynamic properties of intramuscular quinine in Tanzanian children with severe Falciparum malaria

Although artesunate is clearly superior, parenteral quinine is still used widely for the treatment of severe malaria. A loading-dose regimen has been recommended for 30 years but is still often not used. A population pharmacokinetic study was conducted with 75 Tanzanian children aged 4 months to 8 years with severe malaria who received quinine intramuscularly; 69 patients received a loading dose of 20 mg quinine dihydrochloride (salt)/kg of body weight. Twenty-one patients had plasma quinine concentrations detectable at baseline. A zero-order absorption model with one-compartment disposition pharmacokinetics described the data adequately. Body weight was the only significant covariate and was implemented as an allometric function on clearance and volume parameters. Population pharmacokinetic parameter estimates (and percent relative standard errors [%RSE]) of elimination clearance, central volume of distribution, and duration of zero-order absorption were 0.977 liters/h (6.50%), 16.7 liters (6.39%), and 1.42 h (21.5%), respectively, for a typical patient weighing 11 kg. Quinine exposure was reduced at lower body weights after standard weight-based dosing; there was 18% less exposure over 24 h in patients weighing 5 kg than in those weighing 25 kg. Maximum plasma concentrations after the loading dose were unaffected by body weight. There was no evidence of dose-related drug toxicity with the loading dosing regimen. Intramuscular quinine is rapidly and reliably absorbed in children with severe falciparum malaria. Based on these pharmacokinetic data, a loading dose of 20 mg salt/kg is recommended, provided that no loading dose was administered within 24 h and no routine dose was administered within 12 h of admission. (This study has been registered with Current Controlled Trials under registration number ISRCTN 50258054.).

Treatment of African children with severe malaria - towards evidence-informed clinical practice using GRADE

Background

Severe malaria is a major contributor of deaths in African children up to five years of age. One valuable tool to support health workers in the management of diseases is clinical practice guidelines (CPGs) developed using robust methods. A critical assessment of the World Health Organization (WHO) and Kenyan paediatric malaria treatment guidelines with quinine was undertaken, with a focus on the quality of the evidence and transparency of the shift from evidence to recommendations.

Methods

Systematic reviews of the literature were conducted using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool to appraise included studies. The findings were used to evaluate the WHO and Kenyan recommendations for the management of severe childhood malaria.

Results

The WHO 2010 malaria guidance on severe malaria in children, which informed the Kenyan guidelines, only evaluated the evidence on one topic on paediatric care using the GRADE tool. Using the GRADE tool, this work explicitly demonstrated that despite the established use of quinine in the management of paediatric cases of severe malaria for decades, low or very low quality evidence of important outcomes, but not critical outcomes such as mortality, have informed national and international guidance on the paediatric quinine dosing, route of administration and adverse effects.

Conclusions

Despite the foreseeable shift to artesunate as the primary drug for treatment of severe childhood malaria, the findings reported here reflect that the particulars of quinine therapeutics for the management of severe malaria in African children have historically been a neglected research priority. This work supports the application of the GRADE tool to make transparent recommendations and to inform advocacy efforts for a greater research focus in priority areas in paediatric care in Africa and other low-income settings.

Pathogenesis, clinical features, and neurological outcome of cerebral malaria

Cerebral malaria is the most severe neurological complication of Plasmodium falciparum malaria. Even though this type of malaria is most common in children living in sub-Saharan Africa, it should be considered in anybody with impaired consciousness that has recently travelled in a malaria-endemic area. Cerebral malaria has few specific features, but there are differences in clinical presentation between African children and non-immune adults. Subsequent neurological impairments are also most common and severe in children. Sequestration of infected erythrocytes within cerebral blood vessels seems to be an essential component of the pathogenesis. However, other factors such as convulsions, acidosis, or hypoglycaemia can impair consciousness. In this review, we describe the clinical features and epidemiology of cerebral malaria. We highlight recent insights provided by ex-vivo work on sequestration and examination of pathological specimens. We also summarise recent studies of persisting neurocognitive impairments in children who survive cerebral malaria and suggest areas for further research.

Management of severe malaria

Prompt diagnosis and early institution of therapy is an important determinant of outcome in severe falciparum malaria. Thick smears are the gold standard for diagnosis; in situations where reliable microscopy is not available, tests based on HRP-2 antigen/parasite LDH are useful. As there is widespread resistance to chloroquine in P falciparum in India, the choice for specific antimalarial therapy is between quinine and artermisinin derivatives. Randomized controlled trials have not revealed any significant benefit of the artemisinin derivatives over quinine in quinine sensitive areas. Also, if quinine is administered in the recommended way, the side effects are no greater than artemisinins. However, as the artemisinin derivatives are easier to administer, their use in severe malaria in India is increasing. It is vital that we use these drugs in a rational and judicious manner to prevent development of drug resistance. Supportive care, early diagnosis and management of complications are as essential as antimalarial therapy. The role of exchange blood transfusion in the management of severe malaria is still controversial. It may be considered in the presence of high parasites counts (>10%) with multiorgan dysfunction if adequate quantities of safe blood are available.

High first dose quinine regimen for treating severe malaria

BACKGROUND

Quinine is used for treating severe malaria. There are arguments for giving an initial high dose. We examined the evidence for and against this policy.

OBJECTIVES

To assess the clinical outcomes and adverse events of a high first (loading) dose regimen of quinine compared with a uniform (no loading) dose regimen in people with severe malaria.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group's trials register (April 2004), CENTRAL (The Cochrane Library Issue 1, 2004), MEDLINE (1966 to April 2004), EMBASE (1974 to April 2004), LILACS (1982 to April 2004), and conference proceedings for relevant abstracts. We also contacted researchers working in the field and checked the reference lists of all studies.

SELECTION CRITERIA

Randomized controlled trials comparing a high first (loading) dose of intravenous quinine with a uniform (no loading) dose of intravenous quinine in people with severe malaria.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality of the trials and extracted data (including adverse event data). We used Review Manager 4.2 to analyse the data: relative risk (RR) for binary data and weighted mean difference (WMD) for continuous data with 95% confidence intervals (CI). We contacted study authors for additional information.

MAIN RESULTS

Four trials (n = 144) met the inclusion criteria. Loading dose was associated with fewer deaths, but this was not statistically significant (RR 0.62, CI 0.19 to 2.04, 3 trials). Loading dose was associated with faster clearance of parasites (WMD -7.44 hours, CI -13.24 to -1.64 hours, 2 trials), resolution of fever (WMD -11.11 hours, CI -20.04 to -2.18 hours, 2 trials). No statistically significant difference was detected for recovery of consciousness, neurological sequelae, or convulsions, but the numbers were small.

REVIEWERS' CONCLUSIONS

Quinine loading dose reduced fever clearance time and parasite clearance time. Data are insufficient to directly demonstrate an impact of loading dose on risk of death.

High first dose quinine regimen for treating severe malaria

BACKGROUND

Quinine is used for treating severe malaria. There are arguments for giving an initial high dose. We examined the evidence for and against this policy.

OBJECTIVES

To assess clinical outcomes and adverse events of a high first (loading) dose regimen of quinine with a uniform (no loading) dose regimen in people with severe malaria.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group specialized trials register (May 2002), The Cochrane Controlled Trials Register (Issue 2, 2002), MEDLINE (1966 to April 2002), EMBASE (1988 to March 2002), LILACS (www.bireme.br; accessed February 2002), and conference proceedings for relevant abstracts. We also contacted researchers working in the field and checked the reference lists of all studies.

SELECTION CRITERIA

Randomized controlled trials.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality of the trials and extracted data. Review Manager (Version 4.1) was used to analyse the data: Relative Risk for binary data and weighted mean difference (WMD) for continuous data. Study authors were contacted for additional information.

MAIN RESULTS

Three small trials, with two contributing to a meta-analysis of 72 participants. Loading dose was associated with fewer deaths, but this was not statistically significant (RR 0.43; 95% confidence interval (CI) 0.09 to 2.15). Loading dose was associated with faster clearance of parasites (WMD 7.44; 95% CI 1.64 to 13.2 hours), resolution of fever (WMD 11.11; 95% CI 2.18 to 20.04 hours), and transient hearing loss (RR 3.14; 95% CI 1.05 to 9.38). No significant difference was detected for recovery of consciousness, neurological sequelae, or convulsions, but the numbers were small.

REVIEWER'S CONCLUSIONS

Quinine loading dose reduced fever clearance time and parasite clearance time. Data are insufficient to confirm or refute whether a loading dose reduced the risk of death or convulsions.

Population pharmacokinetics of intramuscular quinine in children with severe malaria

We present the first population pharmacokinetic analysis of quinine in patients with Plasmodium falciparum malaria. Ghanaian children (n = 120; aged 12 months to 10 years) with severe malaria received an intramuscular loading dose of quinine dihydrochloride (20 mg/kg of body weight). A two-compartment model with first-order absorption and elimination gave post hoc estimates for pharmacokinetic parameters that were consistent with those derived from non-population pharmacokinetic studies (clearance [CL] = 0.05 liter/h/kg of body weight; volume of distribution in the central compartment [V(1)] = 0.65 liter/kg; volume of distribution at steady state = 1.41 liter/kg; half-life at beta phase = 19.9 h). There were no covariates (including age, gender, acidemia, anemia, coma, parasitemia, or anticonvulsant use) that explained interpatient variability in weight-normalized CL and V(1). Intramuscular quinine was associated with minor, local toxicity in some patients (13 of 108; 12%), and 11 patients (10%) experienced one or more episodes of postadmission hypoglycemia. A loading dose of intramuscular quinine results in predictable population pharmacokinetic profiles in children with severe malaria and may be preferred to the intravenous route of administration in some circumstances.

An open randomized clinical study of intrarectal versus infused Quinimax for the treatment of childhood cerebral malaria in Niger

The intrarectal route has been shown to be an alternative to parenteral therapy for the treatment of acute uncomplicated malaria. We conducted an open randomized clinical study of intrarectal Quinimax (a Cinchona alkaloids association) (20 mg/kg, then 15 mg/kg every 8 h) vs. intravenous Quinimax (8 mg/ kg infused over 4 h every 8 h) for 2 d in 76 children (39 in the intrarectal and 37 in the infusion groups) with cerebral falciparum malaria in Niger. This treatment was followed by oral chloroquine (10 mg/kg/d for 3 d). The primary end points of the study were fatal outcome and coma recovery time. In the intrarectal group, 35 children were cured (90%) and 4 died. In the infused group, 28 were cured (76%) and 9 died; mean coma recovery times were 34.6 h (SD = 12.8) and 33.0 h (SD = 14.1) for the intrarectal and infused groups, respectively. None of the differences was significant. Both treatments were well tolerated and no anal irritation was observed with intrarectal Quinimax. These findings suggest that intrarectal Quinimax can be an alternative to intravenous administration for rapid onset childhood cerebral malaria in the rural tropics, where the safety of parenteral administration cannot be guaranteed.

Metabolism of quinine in children with global malnutrition

Malnutrition and malaria are two important public health problems in Africa. Quinine is one of the major treatments of chloroquine-resistant malaria. Although some authors have shown that quinine clearance is decreased in kwashiorkor, this type of malnutrition is caused by protein deficiency that differs from global protein-energy malnutrition. In rats, hepatic metabolism of many drugs is decreased in protein deficiency and increased in global food restriction. Several studies have found that human hepatic metabolism of many drugs is decreased in kwashiorkor, but, as yet, no study has focused on human global energy-protein malnutrition. Thus, as quinine is a drug with a narrow therapeutic index, we compared the pharmacokinetics of quinine in two groups. One group included children with global malnutrition and the other was a control group of children with normal nutrition. Volume of distribution and plasma concentrations of unbound quinine did not differ between children with global malnutrition and children with normal nutritional status. Clearance was significantly faster, half-life shorter, and concentrations, 12 h after the beginning of treatment, lower in malnourished children compared with control subjects. The ratio between area under the curve of hydroxyquinine (metabolite of quinine in man) and area under the curve of quinine was significantly increased in malnourished children and correlated with mid-arm/ head circumference ratio (marker of malnutrition in children). Thus, as metabolism of quinine is increased in children with global malnutrition, we suggest that the administration interval should be reduced in these children to obtain the same plasma concentrations of quinine found in normally nourished children. A safe and effective dosing strategy is postulated.

A controlled trial of artemether or quinine in Vietnamese adults with severe falciparum malaria

BACKGROUND

Artemisinin (qinghaosu) and its derivatives are rapidly effective antimalarial drugs derived from a Chinese plant. Preliminary studies suggest that these drugs may be more effective than quinine in the treatment of severe malaria. We studied artemether in Vietnam, where Plasmodium falciparum has reduced sensitivity to quinine.

METHODS

We conducted a randomized, double-blind trial in 560 adults with severe falciparum malaria. Two hundred seventy-six received intramuscular quinine dihydrochloride (20 mg per kilogram of body weight followed by 10 mg per kilogram every eight hours), and 284 received intramuscular artemether (4 mg per kilogram followed by 2 mg per kilogram every eight hours). Both drugs were given for a minimum of 72 hours.

RESULTS

There were 36 deaths in the artemether group (13 percent) and 47 in the quinine group (17 percent; P = 0.16; relative risk of death in the patients given artemether, 0.74; 95 percent confidence interval, 0.5 to 1.11). The parasites were cleared more quickly from the blood in the artemether group (mean, 72 vs. 90 hours; P < 0.001); however, in this group fever resolved more slowly (127 vs. 90 hours, P < 0.001), the time to recovery from coma was longer (66 vs. 48 hours, P = 0.003), and the hospitalization was longer (288 vs. 240 hours, P = 0.005). Quinine treatment was associated with a higher risk of hypoglycemia (relative risk, 2.7; 95 percent confidence interval, 1.7 to 4.4; P < 0.001), but there were no other serious side effects in either group.

CONCLUSIONS

Artemether is a satisfactory alternative to quinine for the treatment of severe malaria in adults.

A trial of artemether or quinine in children with cerebral malaria

BACKGROUND

Cerebral malaria has a mortality rate of 10 to 30 percent despite treatment with parenteral quinine, a situation that may worsen with the spread of quinine resistance. Artemether is a new antimalarial agent that clears parasites from the circulation more rapidly than quinine, but its effect on mortality is unclear.

METHODS

We conducted a randomized, unblinded comparison of intramuscular artemether and intramuscular quinine in 576 Gambian children with cerebral malaria. The primary end points of the study were mortality and residual neurologic sequelae.

RESULTS

Fifty-nine of the 288 children treated with artemether died in the hospital (20.5 percent), as compared with 62 of the 288 treated with quinine (21.5 percent). Among the 418 children analyzed at approximately five months for neurologic disease, residual neurologic sequelae were detected in 7 of 209 survivors treated with artemether (3.3 percent) and 11 of 209 survivors treated with quinine (5.3 percent, P = 0.5). After adjustment for potential confounders, the odds ratio for death was 0.84 (95 percent confidence interval, 0.53 to 1.32) in the artemether group, and for residual neurologic sequelae, 0.51 (95 percent confidence interval, 0.17 to 1.47). There were fewer local reactions at the injection site with artemether than with quinine (0.7 percent vs. 5.9 percent, P = 0.001).

CONCLUSIONS

Artemether is as effective as quinine in the treatment of cerebral malaria in children.

Intrarectal Quinimax (an association of Cinchona alkaloids) for the treatment of Plasmodium falciparum malaria in children in Niger: efficacy and pharmacokinetics

In an attempt to avoid the complications associated with intramuscular quinine administration, we assessed the intrarectal route. Sixty-six children aged from 2 to 10 years with Plasmodium falciparum malaria were included in the study, which took place in Niamey, Niger. Fifty-five children were given 20 mg/kg of the diluted injectable form of Quinimax (a quinine, quinidine, cinchonine, cinchonidine association) intrarectally. A further 11 children with malaria were treated with 12.5 mg/kg of the same Quinimax solution by the intramuscular route. All the children were treated twice a day for 3 d. Blood samples were drawn from 20 children (15 treated intrarectally and 5 intramuscularly) for a kinetic study. Both modes of administration were well tolerated. Mean fever clearance times (+/- standard errors) were 48.6 +/- 2.7 h and 35.9 +/- 2.2 h in the intrarectal and intramuscular groups, respectively (P = 0.05). Mean parasite clearance times (+/- standard errors) and mean times to achieve 50% reduction in parasitaemia (+/- standard errors) were similar after intrarectal (46.5 +/- 5.7 h and 7.8 +/- 0.9 h respectively) and intramuscular administration (27.4 +/- 3.6 h and 8.7 +/- 1.7 h, respectively). Tmax. after intrarectal administration (2.7 +/- 0.4 h) did not differ significantly from the value after intramuscular administration (1.1 +/- 0.6 h), but Cmax. and the area under the concentration-time curve from 0 to 48 h were lower (4.9 +/- 0.6 mg/L and 230.0 +/- 9.6 mg/L.h, respectively) than after intramuscular administration (9.1 +/- 1.2 mg/L and 356.0 +/- 4.2 mg/L.h, respectively) (P < 0.001). Compared to the intramuscular route, intrarectal Quinimax bioavailability was 40%.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of intramuscular and intravenous quinine for the treatment of severe and complicated malaria in children

To compare the efficacy and side effects of intramuscular (i.m.) and intravenous (i.v.) quinine, children in Mozambique with severe and complicated malaria between 6 months and 7 years were randomized to treatment with i.m. or i.v. quinine, both in a dosage of quinine dihydrochloride 20 mg/kg followed by 10 mg/kg every 8 h. Of 57 children treated with i.m. quinine, 4 died, 3 had neurological sequelae and 2 had sterile intramuscular abscesses. Of 47 children treated with i.v. quinine, 6 died and 1 had neurological sequelae. The mean parasite clearance time was 58.6 h in the i.m. group and 59.3 h in the i.v. group. Mean temperature clearance times were 56.1 and 51.8 h, and mean coma clearance times 40.4 and 38.7 h, respectively. None of these differences was statistically significant. Mean trough and peak concentrations of quinine were almost identical in the 2 groups, ranging from 10.5 to 12.6 mg/L, which is in the therapeutic non-toxic range. It is concluded that i.m. quinine is as effective as quinine by i.v. infusion in children with severe and complicated malaria; that minor local side effects can probably be avoided by using diluted quinine for i.m. injection; and that the optimal dose regimen for children with severe and complicated malaria in Africa at present is probably quinine salt 20 mg/kg followed by 10 mg/kg every 12 h.

Towards optimal regimens of parenteral quinine for young African children with cerebral malaria: the importance of unbound quinine concentration

Young African children with severe malaria are given quinine using a regimen designed for Thai adults. We measured quinine in the blood, plasma and plasma water of young children in Kenya after rapid intravenous and intramuscular dosing, and calculated the therapeutic range of unbound quinine. The peak plasma quinine concentration after rapid intravenous dosing was 12.3 +/- 3.7 mg/L (mean +/- SD), 43% higher than in adults given the same regimen previously; this was due to a smaller apparent volume of distribution in the children. The therapeutic range of unbound quinine was calculated as 0.2-2.0 mg/L. Simulations of unbound quinine were made for the standard quinine regimen: unbound drug concentrations rose above the therapeutic range after each dose. The possible risks of quinine-induced visual impairment are discussed. Alternative, lower dose regimens for young African children with severe malaria are described.

Diagnosis, treatment, and prevention of malaria

Optimal treatment of malaria requires rapid case identification, initiation of specific and supportive therapy based on parasitologic and clinical classification of the patient, and recognition of inadequate response to therapy. Health care providers advising travelers should assess the risk of malaria based on itinerary and clinical condition, and counsel to reduce contact with mosquitoes; prescribe appropriate chemoprophylaxis; and counsel regarding potential side effects and requirement for diagnosis and treatment if fever develops.

Disposition of quinine in rats with induced renal failure

Aetiologically different models of experimental acute renal failure were induced in rats by the administration of glycerol, mercuric chloride and gentamicin, respectively, to different groups. Quinine levels in plasma and urine of the rats with induced renal failure were determined and pharmacokinetic parameters (elimination t1/2, CLp, V, CLR AUC0-infinity) of the drug were derived and compared with values obtained from control rats following intraperitoneal administration of a 10 mg/kg body-weight dose of quinine. Results showed that each of the three compounds caused an up to 25-fold increase in the plasma levels of the drug and a marked decrease in the levels of the metabolite 3-hydroxyquinine. All the pharmacokinetic parameters determined for the rats with renal impairment were markedly different when compared to control. The high plasma quinine levels observed in the rats with renal failure could be largely due to the marked decrease in V and reduced metabolism. Also, in the rats with renal impairment, no correlation was observed between the increased plasma urea levels and plasma quinine levels or disposition of the drug. The results of the study suggest that quinine should be used with caution in patients with renal impairment. The plasma urea levels, as a measure of renal function, might not provide a suitable index for determining quinine dosage.

Absorption of intramuscular phenobarbitone in children with severe falciparum malaria

The absorption of intramuscular phenobarbitone 7 mg.kg-1 was studied in 11 Karen children aged between 1.7 and 11 y with severe falciparum malaria. Eight of the children were comatose. Clinical findings were compared with those in 9 further children with severe malaria of similar age range (four of whom were unconscious), who received an identical placebo. One child, who had received placebo, had repeated convulsions and died 1 h after admission to hospital. The remainder made an uncomplicated recovery. There were no convulsions subsequent to treatment, although the study was too small to assess anticonvulsant efficacy. There was no observable toxicity, but phenobarbitone recipients had a significant tendency to deepen in their level of coma or to become sleepy within the 4 h after drug administration. Phenobarbitone was rapidly absorbed, reaching a mean (range) peak concentration of 34.2 [29.3-42.6] mumol.l-1 in a median (range) of 4 (2.5-12) h. These values are comparable to those previously reported in healthy children and in children with febrile convulsions. Intramuscular phenobarbitone is well absorbed in children with severe malaria; the optimum prophylactic anticonvulsant dose remains to be determined.

Cerebral malaria in children

Cerebral malaria is a rapidly progressive encephalopathy with up to 50% mortality. A cardinal feature is the massing of red cells containing mature Plasmodium falciparum within the cerebral capillaries. Adhesion of these parasitised red cells to endothelium, an event which may initiate cerebral malaria, is being studied at the molecular level. However, the relevance of these studies to the pathophysiology and treatment of human cerebral malaria is uncertain. Although chloroquine is still widely used to treat falciparum malaria, resistance has spread to most of the endemic zone. Quinine is emerging as the only effective treatment for cerebral malaria, though resistance to this drug threatens to become a problem. Alternative drugs are urgently needed.