Artemether-mefloquine combination in multidrug resistant falciparum malaria

TRANSACTIONSOFTHE ROYAL Socmy

Artemether-mefloquine

213

OFTROPICAL MEDICINE AND HYGIENE (1995) 89,213-215

combination

in multidrug

resistant

falciparum

malaria

Danai Bunnagl, Tozo Kanda2, Juntra Karbwang3, Krongthong Thimasam4, Swangjai Pungpak’ and Tram&chit Harinasuta3 ‘Parasitology and Tropical Medicine Association of Thailand; *Japan Association for Tropical Medicine; 3Clinical Pharmacology Unit, Department of Clinical Tropical Medicine and Hospital for Tropical Diseases, Bangkok, Thailand; 4Malaria Division, Ministry of Public Health, Bangkok, Thailand

Abstract Plasmodium falciparum in Thailand is highly resistant to chloroquine and sulfadoxine/pyrimethamine and

there is increasing resistance to the alternative antimalarials, quinine and mefloquine. In eastern Thailand, the cure rates of mefloquine at 750 and 1250mg were 30% and 55%, respectively. The use of drug combinations may be necessaryin areaswhere drug-resistant parasites exist. 159 male Thai patients in Chantaburi, eastern Thailand, were allocated at random to receive either oral artemether at a single dose of 300 mg on the first day followed by mefloquine 750 mg at 24 h and 500 mg at 30 h (group A), or oral artemether at a single dose of 300 mg on the first day, mefloquine 750 mg at 24 h and placebo at 30 h (group B). The followup was on days 1, 2, 7, 14, 21, 28, 35 and 42. Most patients in both groups had a rapid initial response to treatment, parasitaemia being cleared within 24 h and fever cleared within 48 h in both groups. The cure rates were 97% and 90%, respectively, for groups A and B. No serious adverse effect was seen in either group; mild and transient nausea, vomiting and loss of appetite were noted. The adverseeffects did not differ between the 2 groups. The results suggestedthat a single oral doseof artemether (300 mg) can markedly improve the cure rate of mefloquine at a doseof 750 or 1250mg in multiple drug-resistant falciparum malaria. Keywords: malaria,multidrug resistance,artemetherplus mefloquine,Thailand

Introduction Plasmodium falciparum in Thailand is highly resistant

to chloroquine and sulfadoxine/pyrimethamine and there is increasing resistance to the alternative antimalarial drugs quinine and even mefloquine (BOUDREAUet al., 1982; HARINASUTAet al., 1990; KARBWANG& HARINASUTA, 1992; KARBWANG et al., 1992). Artemether is a promising drug currently used to cope with this situation but the course of treatment is long, which limits patients’ compliance (T. Harinasuta & K. Thimasarn, unpublished observations). The cure rate with artemether alone given for 5 d ranged from 88% to 97%. When the course of treatment was shortened to less than 3 d, the recrudescencerate was 100% (BUNNAGet al., 1991). An effective short treatment course of this drug was possible when it was used in combination with mefloquine, with a cure rate of 94% (KARBWANGet aE., in mess). Using mefloquine as a single dose in combination with a single dose of artemether may not be sufficient to treat mefloquineresistant parasites. In areas where mefloquine resistant strains of P. falciparum exist (KARBWANGet al., 1993), the cure rate was improved when the dose of mefloquine was increased to 1250 or 1500 mg (KARBWANGel al., 1991; BUNNAG et al., 1993; NA-BANGCHANGet al., 1993). We therefore carried out a ‘double blind’ comparative trial of 2 different regimens of an artemethermefloquine combination in patrents with acute uncomplicated falciparum malaria. Materials and Methods One hundred and fifty-nine male patients with acute uncomplicated falciparum malaria (asexual parasitaemia <5%), with no history of liver or kidney disease,who attended the malaria clinic in Makarm district, Chantaburi province, eastern Thailand during 1992-1994 were recruited into the study. They were aged between 15 and 65 years and weighed over 40 kg. Written informed consent for participation in the study was obtained from all patients. The study was approved by the ethics committee of the Ministry of Public Health, Bangkok, Thailand. The patients were randomly allocated to the following therapeutic regimens. Group A (80 patients): artemether 300 mg as a single oral dose followed by mefloquine (Lariam@, Hoffman La Roche, Basel, Switzerland) 750 mg at 24 h and 500 mg at 30 h. Group B (79 patients): artemether 300 mg as a single oral dose followed by mefloAddressfor correspondence: ProfessorJuntra Karbwang,Clinical PharmacologyUnit, Faculty of Tropical Medicine, Mahidol tJJy, 42016Rajvithi Road,Pyathai,Bangkok10400,Thai-

quine (Lariam@‘,Hoffman La Roche, Basel, Switzerland) 750 mg at 24 h and placebo at 30 h. This study was a field trial and hospital admission of patients was impossible due to limited facilities in the clinic. Patients were asked to return to the clinic for fol:2.v-up examination on days 1, 2, 7, 14, 21, 28, 35 and -Patients who failed to respond to the treatment were retreated with auinine sulnhate 600 me 3 times dailv and tetracycline 256 mg 4 times daily foi 7 d. Patients in whose peripheral blood P. vivax was seenduring the follow-up period were treated with chloroquine 300 mg (base) to suppress the symptoms; a full course of treatment was given on day 42 (i.e., chloroquine 1500 mg over 2 d followed by primaquine 15 mg daily for 14 d). Parasite counts (per 1000 red blo&d cells or per’200 white cells) were nerformed on davs 0. 1. 2. 7. 14. 21. 28, 35 and42, u&g thin and thick blood films s&ted with Giemsa’sstain. The patients were asked about any abnormal signs or symptoms after drug administration at each follow-up, and the date, duration and frequency were recorded, Patients were included in the final assessmentonly if their follow-up examination had been completed to day 42. Efficacy was evaluated in terms of parasite clearance time (the time taken for the parasite count to fall below the level of microscopical detection-i.e., <2O/yL), fever clearance time (the time taken for the temperature to return to normal, i.e. below 37.3”C), cure rate, and the occurrence of adverse reactions. Statistical analysis was by Fisher’s exact test for proportions and the Mann-Whitney U test for other variables. Results All patients presented with symptoms of acute malaria. The levels of admission parasitaemia and other characTable 1. Admission clinical and laboratory data of patients with falciparum malaria

Mefloquine” 1250mg 750 mg 80 79

No. of oatients Age (ye&s)b 26 (15-57) 30 (15-63) Weight (kg)b 55 (45-78) 54 (43-68) Temperature(“C)b 38.3 (36*0-40~0) 38.0 (36*0-41*0) Parasitaemia(per pL)c 1740(60-30600) 3000(120-53700) “Total doseof mefloquine (seetext for dosagedetails) given -together with artemether(300 mg single dose). bMeclian(range in parentheses). ‘Geometricmean (range in parentheses).

214 teristics were not significantly different between the 2 treatment groups (Table 1). Sixteen uatients did not comnlete the 42 d follow-un period (10’in group A and 6 in’ group B); only 143 patients therefore qualified for efficacy assessment. No patient showed RI1 or RI11 resistance. Parasitaemia reappeared in 2 patients in group A and 7 in group B, between days 14 and 28. The cure rates in the 2 groups (Table 2) were not statistically significantly different (P=O.17, relative risk= l-07, 95% confidence interval 0.9sl.17). Fever and parasitaemia clearance times were also similar in the 2 groups (Table 2). The 8 patients who were still parasitaemic at 48 h had neither fever nor parasitaemia on day 7. Table 2. Therapeutic responses of patients with falciparum malaria

Mefloquine” 750 mg 1250 mg No. of patients Fever clearance Within 24 h Within 48 h Not.clearedat 48 h PEE” :arbance

80

Within 48 h Not clearedat 48 h Cure rate No. of patients with S response S/RI resoonse

66 6

RI response

P. vivax

“Total dose of mefloquine (seetext for dosagedetails) given together with artemether(300 mg single dose). b95%confidenceinterval. Transient mild nausea, vomiting and loss of appetite were found in a few patients in each grou (Table 3). No neuropsychiatric side-effect was observe8. m any patient during the 42 d follow-up period. Five patients (2 in group A and 3 in group B) developed P. &ax parasitaemia between days 7 and 42. Table 3. Adverse effects in patients with falciparum malaria Mefloquine” 1250 mg 750 mg ;z.

of&ients

80

Nausea Vomiting Loss of appetite

16 (20%) 8 (10%) 14 (18%)

79

*Total dose of mefloquine (see text for dosage details) given together with artemether (300 mg single dose). Discussion Artemether is a rapidly acting blood schizontocidal drug, effective against chloroquine-sensitive and chloroquine-resistant falciparum malaria. It has been used extensively in China, Viet Nam and Thailand, but the best dosage regimen, giving a cure rate of lOO%, has not yet been established. As a consequence, development of resistance to this drug may be enhanced. The efficacy of oral artemether has been shown previously in multidrug resistant falciparum malaria, with rapid clearance of parasitaemia and fever and a cure rate of 97% (KARBWANG et al., 1992). However, the drug has to be administered for at least 5 d. Treatment for less than 5 d has been associated with a high recrudescence rate, particularly in severemalaria (BUNNAG et al., 1992). Under field conditions, it is unlikely that patients would take the full 5 d course of treatment.

A combination of one of the artemisinin group of compounds with mefloquine has been extengively studied and found to be effective (NAING et al., 1988; SHWE et al., 1988, 1989; LOOAREESUWAN et al., 1992). Multi le doses of artemisinin or its derivatives were used, Pol-

lowed by one (750 mg) or 2 dosesof mefloquine (750 mg and 500 ma. 6 h aoart). The duration of treatment was 3-6 d. Ho& treatment is unlikely to be successful with regimens lasting longer than 2 or 3 d (T. Harinasuta & K. Thimasarn, unpublished observation). In the present study! using a single dose of artemether, the maximum duration of treatment was only 30 h, which should encouragecompliance. The combination regimens reduced the recrudescence rate far more than expected. In 1991-1992, cure rates with mefloquine 750 mg and 1250mg were only 30% and 55% (BUNNAG et aE., 1991; KARBWANG et al., 1992; KETRANGSEEet al., 1992). The present study confirmed the

effectiveness of a single dose of artemether combined with a single dose of mefloquine observed in a previous hospital-based study (KARBWANG et al., in press). Psychosis is one of the more serious adverse effects of mefloquine and has been estimated to occur in 1% of patients with acute uncomplicated falciparum malaria given mefloquine (HARINASUTA et al., 1983). It usually occurs in the second week after treatment and resolves completely during the following 2 weeks without any specific treatment. In our study, none of the patients developed psychosis but the small size of the group precludes the drawing of any firm conclusion from this. The appearanceof P. vivux in a few patients of both groups suggests that neither artemether nor mefloquine is effective against hypnozoites of this species. Acknowledgements

The stud wassupportedmainly by the JapaneseMinistry of Postsand J elecommunications,Japan.We are grateful to the staff of MakarmMalaria Clinic, ChantaburiProvince,for their excellentassistance. References

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Bunnag, D., Viravan, C., Looareesuwan,S., Karbwang, J. & Harinasuta,T. (1991).Clinical trial of artesunateand artemetheron multidrug resistantfalciparum malaria.Southeast AsznJournal

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Karbwang, J., Na Bangchang, K., Thanavibul, A., Bunnag, D., Chongsuphajaisiddhi, T. & Harinasuta, T. (1992). Comparison of oral artemether and meflo uine m acute uncomphcated falciparum malaria. Southeast 8, ssan 3ournal of Troprcal Medicine and Public Health, 23,1245-1248.

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Naing, U. T., Win, U. H., Nwe, D. Y. Y., Myint, U. P. T. & Shwe. U. T. (1988). The combined use of artemether. sulfadoxini and p$me&amine in the treatment of uncom$icated falciparum malaria. Transactions of the Royal Sociery of Tropical Medicine and Hygiene, 82,530-531.

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Ketrangsee, S., Vijayakadga, S., Yamokgul, I’., Jatapadma, S., Thimasarn, K. & Rooney, W. (1992). Comparative trial on the response of Plasmodium falciparum to halofantrine and meflo uine in Trat Province,, eastern Thailand. Southeast giany7 ournal of Tropical Me&me

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Looaieesuwan, S., Viravan, C., Vanijanonta, S., Wilairatana, P., Charoenlarp, P., Canfield, C. J. & Webster, K. (1992). Randomised trial of arfesunate and mefloquine alone and in sequence for acute uncomplicated falciparum malaria. Lancet, 339,821-824. Na Bangchang, K., Karbwang, J., Banmairuroi, V., Bunnag, D. & Harinasuta, T. (1993). Mefloquine monitoring in acute

Shwe, T., Myint, P. T., Htut, Y., Myint, W. & See,.L. (1988). The effect of mefloquine-artemether compared wnh quinine on patients with complicated falciparum malaria. Transactions o&b Royal Society of Tropical Medicine and Hygiene, 82,665Shwe, T., Myint, P. T., Myint, W., Htut, Yl., Soe, L. & Thwe! M. (1989). Clinical studies on treatment of cerebral malaria with artemether and mefloquine. Transactions of the Royal Societyof Tropical Medicine and Hygiene, 83,489. Received 6 May 1994; revised 30 June 1994; accepted for publication 23 August 1994

TRANSACTIONSOFTHE ROYAL SOCIETYOF TROPICAL MEDICINE AND HYGIENE (1995) 89,215-216

[Short] Inhibition of tumour necrosis factor (TNF) production by antimalarial drugs used in cerebral malaria Dominic Kwiatkowski and Clive Bate Department Paediatrics, UK

John Radcliffe

Hospital,

Oxford,

of OX3 9DU,

Keywords: malaria, Plasmodwn fahparum, turnout- necrosis factor, inhibition in vitro, chloroquine, quinine, artemether, artesunate

Introduction New therapeutic strategies are needed for cerebral malaria, which has a hospital fatality rate of around 15% (WARRELL et al., 1990). Quinine is the first line of treatment in most of the world. Artemisinin (qinghaosu) derivatives are increasingly being used because of their prompt antiparasitic action (HIEN & WHITE, 1993). Resistance to chloroquine is so widespread that it is now rarely used when life-threatening complications occur. A consideration in defining the optimal therapy for cerebral malaria is the inherent ability of certain antimalarial drugs to inhibit the production of tumour necrosis factor (TNF). TNF mediates malaria fever (K~‘IAIxo~‘SKI et al., 1993) and high TNF levels are associated with a fatal outcome in cerebral malaria (GKI\K et al., 198y; KLUATKCNXKI et al., 1990). Independently of their antlparasitic properties, chloroquine and quinine inhibit TNF production by human monocytes (P~c:(yr er al., 1991. 1993’1.As the artemisinin derivatives are beeinnine to replace iuinine and chloroquine in the treatGent oyf severe malaria, it is of interest to know whether they too have TNF-suppressive properties.

Methods We tested artemether, artesunate, quinine and chloroquine for their ability to inhibit TNF production by human periuheral blood mononuclear cells (PBMNC! when stlmuiated by lysed erythrocytic forms of Plasm01 dium falciparum in vitro. Artemether was a gift from Dr Barry Elford and artesunate was supplied by Guilin No. 2 Pharmaceutical Factory, Guangxi, China. Chloroquine

L 0

-4 log10

‘r’

I

-5

-6

-7

-8

concentration of antimalarial (mol/L)

Figure. 1nhlbltu.m by different antunalarial drugs of turnour necrosis factor production bv human mononuclear cells stimulated with lvsed erythrowtic forms of I’. /ulc~~urum. iMean oi 7 exoeriments: bars &resent \tandard error. )

diphosphate and quinine were purchased from Sigma. Parasitized erythrocytes were obtained from cultures in vitro of P. fafciparum. Preparations containing predominantly schizonts were harvested from synchronized cultures at approximately 5% parasitaemia, incubated for 16 h at 37°C at 2.5~ lo8 erythrocytes/mL in MEM medium, and then centrifuged at 10 000 g for 10 min. The pellet was lysed with 4 volumes of pyrogen-free water and stored at -20°C. PBMNC were obtained from European donors, separated by density gradient separation on LvmDhooren”. resusoended in MEM olus 1% heattrkated fiukan AB+s’erum, and dispensed into sterile microtitre plates at 2 X lo5 cells per well. Parasite lysates were added to PBMNC at final concentrations between 1:20 and 1:200, together with‘Ihe antimalarial drugs to be tested. Artemether was dissolved in a small amount of dimethyl sulphoxide and artesunate was dissolved in 5% sodium bicarbonate immediately before diluting with