A 7-day in vivo test system was applied to assess the parasitological response to chloroquine treatment in patients with falciparum malaria in the Central Province and National Capital District of Papua New Guinea. 30 patients were investigated but only 23 took a full course of chloroquine and were completely followed up. Of the 23 patients, 13 (57%) were negative for malaria parasites on day 2, 4 (17%) had significantly reduced parasitaemia by day 2 and cleared parasites by day 7, and 1 (4%) showed a partial response (R2). In 5 (22%) of the patients resistance at the R3 level was observed. The indication from this study is that chloroquine should continue to be the first-line drug for the treatment of uncomplicated falciparum malaria. However, judicious use of chloroquine in uncomplicated falciparum malaria is required to halt the spread of chloroquine-resistant strains of Plasmodium falciparum.
Antimalarials - therapeutic use ; Chloroquine - therapeutic use ; Drug Resistance ; Malaria, Falciparum - drug therapy ; Malaria, Falciparum - parasitology

No Abstract
Animals ; Hospitals, General ; Humans ; Malaria - epidemiology ; Malaria &ndash ; parasitology ; Papua New Guinea - epidemiology ; Plasmodium - isolation & ; purification

The susceptibility of Plasmodium falciparum to chloroquine, quinine, mefloquine and halofantrine was investigated in the Central Province of Papua New Guinea between March 1995 and September 1996, when chloroquine resistance was widely present in the country. The standard World Health Organization in vitro microtest methodology was used in the study. Of the 30 isolates tested for chloroquine susceptibility all were resistant to chloroquine with median IC50 of 1.15 mumol/l (range 0.54 to 4.24), indicating a high prevalence and degree of resistance. Three isolates each for quinine (3/31) and halofantrine (3/28) showed resistance at concentrations of 51.2 mumol/l and 10 nM respectively, while all 31 isolates tested for mefloquine were fully susceptible. The comparative analysis of median IC50 values between isolates resistant and susceptible to chloroquine showed chloroquine-resistant isolates to be less susceptible to quinine and halofantrine while fully susceptible to mefloquine. It seems that the evolution of chloroquine resistance together with increased use of quinine treatment of P. falciparum malaria may increase the risk of emergence of quinine resistance and possibly of halofantrine resistance as well. The development of mefloquine resistance, however, is independent of chloroquine resistance.
Antimalarials - pharmacology ; Chloroquine - pharmacology ; Drug Resistance, Microbial ; Mefloquine - pharmacology ; Microbial Sensitivity Tests ; Papua New Guinea

Halofantrine is a newer antimalarial drug which has not been approved for clinical use in Papua New Guinea. We assessed 21 Central Province isolates of Plasmodium falciparum for their in vitro susceptibility to halofantrine. The concentration required to inhibit 50% of parasite growth (IC50) ranged from 0.05 to 7.0 nM with a mean of 1.90 nM and a median of 1.50 nM. The minimum inhibitory concentration (MIC) values ranged from 2.5 to 50 nM with a median of 5.0 nM. All but one isolate had an MIC of 10 nM or less. These results indicate that halofantrine would be a suitable alternative for the treatment of P. falciparum malaria in the region in the future, if and when the need arises, provided that its use was carefully monitored. PIP: Halofantrine is a newer antimalarial drug which has not been approved for clinical use in Papua New Guinea. The authors assessed 21 Central Province isolates of Plasmodium falciparum for their in vitro susceptibility to halofantrine. The concentration required to inhibit 50% of parasite growth (IC50) ranged from 0.05 to 7.0 nmol with a mean of 1.90 nmol and a median of 1.50 nmol. The minimum inhibitory concentration (MIC) values ranged from 2.5 to 50 nmol with a median of 5.0 nmol. All but one isolate had an MIC of 10 nmol or less. These results indicate that halofantrine would be a suitable alternative for the treatment of P. falciparum malaria in the region in the future, if and when the need arises, provided that its use was carefully monitored.
Antimalarials - pharmacology ; In Vitro Techniques ; Microbial Sensitivity Tests ; Papua New Guinea ; Phenanthrenes - pharmacology

We evaluated the efficacy and safety of halofantrine in 19 patients with acute uncomplicated falciparum malaria. Each patient received oral halofantrine hydrochloride 500 mg every 6 hours for 3 doses (total 1.5 g). In almost all the patients clinical symptoms of malaria and parasitaemia disappeared within 2 and 3 days, respectively, of starting treatment. We observed no recurrence of parasitaemia during 14 days of follow-up. Tolerance to halofantrine was good except for minor and self-limiting gastrointestinal side-effects. Haematological and biochemical indices were not seriously affected. Halofantrine-induced prolongation of Q-T/Q-Tc intervals was the consistent cardiac manifestation in 84% of patients. The Q-T/Q-Tc interval prolongation increased with each dose; it reached a maximum between 18 and 24 hours and thereafter returned to baseline. These preliminary data indicate that, apart from the cardiac side-effects, halofantrine is an effective and safe drug, well tolerated by most of the patients in the study. PIP: The authors evaluated the efficacy and safety of halofantrine in 19 patients with acute uncomplicated falciparum malaria. Each patient received oral halofantrine hydrochloride 500 mg every 6 hours, for a total of 3 doses (total 1.5 g). In almost all the patients clinical symptoms of malaria and parasitemia disappeared within 2 and 3 days, respectively, of starting treatment. They observed no recurrence of parasitemia during 14 days of follow-up. Tolerance to halofantrine was good except for minor and self-limiting gastrointestinal side effects. Hematological and biochemical indices were not seriously affected. Halofantrine-induced prolongation of Q-T/Q-Tc intervals was the consistent cardiac manifestation in 84% of patients. The Q-T/Q-Tc interval prolongation increased with each dose; it reached a maximum between 18 and 24 hours and thereafter returned to baseline. These preliminary data indicate that, apart from the cardiac side effects, halofantrine is an effective and safe drug, well tolerated by most of the patients in the study.
Antimalarials - administration & ; dosage ; Antimalarials - therapeutic use ; Electrocardiography ; Malaria, Falciparum - blood