374 TRANSACTIONS
OFTHE ROYALSOCIETY OF TROPICAL MEDICINE
AND
HYGIENE (1992)86, 374375
Chronotherapy* of malaria: improved efficacy of timed chloroquine of patients with Plasmodium falciparum infections
treatment
I. Landau’, J.-P. Lepers2, P. Ringwald2, P. Rabariso&, H. Ginsburg3 and A. Chabaudl ‘Laborutoire de Zoologie (Vers) associe au CNRS, Must%m National d’Histoire Naturelle, Paris, France; 21nstitut Pasteur de Madagascar; 3Department of Biological Chemistry, The Hebrew University ofJerusalem,Jerusalem, Israel Abstract The effect of routine treatment with chloroquine (10 mg/kg on days 1 and 2 and 5 mgikg on day 3) on parasitaemia and uarasitaemic urofile of oatients infected with Plasmodium falciaarum was studied. As with P. vinckei petteri; the mid-term trophozoites of I’. falciparum were the most susceptible stages to chloroquine treatment. It is suggested that, in order to diminish the frequency of drug administration and to lower the risks of chemoresistance developing, treatment should be diversified, using the drug which is most effective on the parasite stages present in-theperipheral blood. Introduction In cultures, Plasmodium falciparum displays stage-dependent sensitivity to various drugs (YANON et al., 1983; GEARY et al., 1989; KRUGLIAK & GINSBURG, 1992), suggesting that the organisms may be more susceptible, or that the affected process(es) may be more critical to parasite viability, at this particular stage. Other developmental stages may be less sensitive or altogether unresponsive to the drug. In viva, parasite clearance was slower when pyrimethamine-sulfadoxine was administered when young ring forms predominated (RIECKMAN et al., 1987). Chinese clinicians prefer to treat malaria patients with qinghaosu and its analogues when tiny ring forms predominate, to get a better therapeutic outcome (JIANG et al, 1982). Hence, the proper timing of treatment may not only yield better results? but possibly also succeed in curing drug-resistant strains at permissible dosage levels. Recent investigations (CAMBIE et al., 1991; LANDAU et al., 1990) have established that in murine malaria the stage most susceptible to chloroquine was the mid-term trophozoite. These results were obtained with P. vinckei petteri, which is remarkably synchronous and hence amenable to controlled experimentation, and it was therefore deemed worthwhile to ascertain whether these findings could be extrapolated to I’. falciparum infections in man. Methods Endemic I’. falciparum malaria has been studied for several years at Ankazobe at 90 km north-west of Tananarive in Malagasy by the Institut Pasteur de Madagascar (LEPERS et al., 1990). Patients attending the clinic for consultation are routinely given orally 10 mgikg of chloroquine immediately after positive diagnosis (day 0), then a second dose of 10 mgikg on day 1 and 5 mgikg on day 2. Blood films are examined on day 0 before treatment, prior to medication, and then on days 1, 2,7 and 14. Examination of the stained slides permits determination of the parasitaemic profile (the distribution of parasite stages) as well as the total parasitaemia (percentage of infected erythrocytes). These data suffice to establish a putative correlation between the parasitaemic profile and the efficacy of treatment, and thus to identify the stage that is most susceptible to the drug. For the sake of comparison between P. falciparum and P. vinckei petter-i, 2 factors must be considered. (i) The schizogonic cycle of the murine parasite lasts 24 h, while that of I’. falciparum lasts 48 h. The relevant parasite stage appears 12 h after schizogony in I’. vinckei petter-i and 24 h in I’. falciparum. (ii) The midterm trophozoite of P. vinckei petteri has been defined as being 113 to 2/3 of the host cell size, with a vacuole smaller than that of the young trophozoite and traces of pigment in its cytoplasm. The equivalent stage of P. *Chronotherapy is the timing of drug treatment to achieve maximum therapeutic effect.
falciparum is defined as a ‘trophozoite’ compared to the previous ring stage and the subsequent older trophozoite stages, and is characterized by the first appearance of Maurer’s clefts (LANDAU et al., 1991). Since these clefts may sometimes appear later in the cycle or be absent altogether, we define as trophozoites those parasites that reach l/5 to l/4 of the host cell’s size. Most importantly, under the influence of chloroquine treatment, trophozoites are small and have an enlarged nucleus and thicker cytoplasm compared to the true ring stage. Obviously, these parasites are classified as trophozoites. For evaluation of the efficacy of drug treatment, we use the equation Y = 100 (A-B)/A where A is the parasitaemia on day 0 and B is that observed on day 1. The higher the value of Y, the greater the efficacy. Results Data were collected from 31 patients and the efficacy of treatment plotted against the percentage of trophozoites observed before the first treatment (Figure). The
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PERCENTAGE Of TROPHOZOITES Figure. Effect of proportion of trophozoites in the blood on efficacy of chloroquine treatment of falciparum malaria. Parasitaemia was determined by microscopical examination of blood films on admission of patients to the clinic before drug treatment (A) and on the following day (B). The efficacy of drug treatment was computed using the formula Y= 100 (A-B)/A and plotted against the percentage of trophozoites present upon admission.
results clearly demonstrate that the decline in parasitaemia was significantly increased as the percentage of trophozoites increased (P
OFTHE ROYALSOCIETY OF TROPICAL MEDICINE
AND
HYGIENE (1992)86, 374375
Chronotherapy* of malaria: improved efficacy of timed chloroquine of patients with Plasmodium falciparum infections
treatment
I. Landau’, J.-P. Lepers2, P. Ringwald2, P. Rabariso&, H. Ginsburg3 and A. Chabaudl ‘Laborutoire de Zoologie (Vers) associe au CNRS, Must%m National d’Histoire Naturelle, Paris, France; 21nstitut Pasteur de Madagascar; 3Department of Biological Chemistry, The Hebrew University ofJerusalem,Jerusalem, Israel Abstract The effect of routine treatment with chloroquine (10 mg/kg on days 1 and 2 and 5 mgikg on day 3) on parasitaemia and uarasitaemic urofile of oatients infected with Plasmodium falciaarum was studied. As with P. vinckei petteri; the mid-term trophozoites of I’. falciparum were the most susceptible stages to chloroquine treatment. It is suggested that, in order to diminish the frequency of drug administration and to lower the risks of chemoresistance developing, treatment should be diversified, using the drug which is most effective on the parasite stages present in-theperipheral blood. Introduction In cultures, Plasmodium falciparum displays stage-dependent sensitivity to various drugs (YANON et al., 1983; GEARY et al., 1989; KRUGLIAK & GINSBURG, 1992), suggesting that the organisms may be more susceptible, or that the affected process(es) may be more critical to parasite viability, at this particular stage. Other developmental stages may be less sensitive or altogether unresponsive to the drug. In viva, parasite clearance was slower when pyrimethamine-sulfadoxine was administered when young ring forms predominated (RIECKMAN et al., 1987). Chinese clinicians prefer to treat malaria patients with qinghaosu and its analogues when tiny ring forms predominate, to get a better therapeutic outcome (JIANG et al, 1982). Hence, the proper timing of treatment may not only yield better results? but possibly also succeed in curing drug-resistant strains at permissible dosage levels. Recent investigations (CAMBIE et al., 1991; LANDAU et al., 1990) have established that in murine malaria the stage most susceptible to chloroquine was the mid-term trophozoite. These results were obtained with P. vinckei petteri, which is remarkably synchronous and hence amenable to controlled experimentation, and it was therefore deemed worthwhile to ascertain whether these findings could be extrapolated to I’. falciparum infections in man. Methods Endemic I’. falciparum malaria has been studied for several years at Ankazobe at 90 km north-west of Tananarive in Malagasy by the Institut Pasteur de Madagascar (LEPERS et al., 1990). Patients attending the clinic for consultation are routinely given orally 10 mgikg of chloroquine immediately after positive diagnosis (day 0), then a second dose of 10 mgikg on day 1 and 5 mgikg on day 2. Blood films are examined on day 0 before treatment, prior to medication, and then on days 1, 2,7 and 14. Examination of the stained slides permits determination of the parasitaemic profile (the distribution of parasite stages) as well as the total parasitaemia (percentage of infected erythrocytes). These data suffice to establish a putative correlation between the parasitaemic profile and the efficacy of treatment, and thus to identify the stage that is most susceptible to the drug. For the sake of comparison between P. falciparum and P. vinckei petter-i, 2 factors must be considered. (i) The schizogonic cycle of the murine parasite lasts 24 h, while that of I’. falciparum lasts 48 h. The relevant parasite stage appears 12 h after schizogony in I’. vinckei petter-i and 24 h in I’. falciparum. (ii) The midterm trophozoite of P. vinckei petteri has been defined as being 113 to 2/3 of the host cell size, with a vacuole smaller than that of the young trophozoite and traces of pigment in its cytoplasm. The equivalent stage of P. *Chronotherapy is the timing of drug treatment to achieve maximum therapeutic effect.
falciparum is defined as a ‘trophozoite’ compared to the previous ring stage and the subsequent older trophozoite stages, and is characterized by the first appearance of Maurer’s clefts (LANDAU et al., 1991). Since these clefts may sometimes appear later in the cycle or be absent altogether, we define as trophozoites those parasites that reach l/5 to l/4 of the host cell’s size. Most importantly, under the influence of chloroquine treatment, trophozoites are small and have an enlarged nucleus and thicker cytoplasm compared to the true ring stage. Obviously, these parasites are classified as trophozoites. For evaluation of the efficacy of drug treatment, we use the equation Y = 100 (A-B)/A where A is the parasitaemia on day 0 and B is that observed on day 1. The higher the value of Y, the greater the efficacy. Results Data were collected from 31 patients and the efficacy of treatment plotted against the percentage of trophozoites observed before the first treatment (Figure). The
qo
q q
q
0
•I
q
q
0 0's. 0
I 20
I 40
8. 60
I 80
I 100
PERCENTAGE Of TROPHOZOITES Figure. Effect of proportion of trophozoites in the blood on efficacy of chloroquine treatment of falciparum malaria. Parasitaemia was determined by microscopical examination of blood films on admission of patients to the clinic before drug treatment (A) and on the following day (B). The efficacy of drug treatment was computed using the formula Y= 100 (A-B)/A and plotted against the percentage of trophozoites present upon admission.
results clearly demonstrate that the decline in parasitaemia was significantly increased as the percentage of trophozoites increased (P
