Research Articles

In vitro and in vivo reversal of chloroquine resistance in Plasmodium falciparum with promethazine

The effect of combining promethazine with chloroquine was examined against Plasmodium falciparum in vitro in the Aotus-P. falciparum model and in bioassays from volunteers given promethazine. The combination of chloroquine plus promethazine (1 x 10(-6) M) reversed chloroquine resistance in standard P. falciparum clones and patient parasite isolates from Nigeria. The combination reduced the 50% inhibitory concentrations (IC50s) for chloroquine against resistant parasites by 32-92%. Coadministration of promethazine with chloroquine also demonstrated a dose-dependent effect in Aotus monkeys infected with chloroquine-resistant P. falciparum. Monkeys were given a chloroquine dose (20 mg/kg of body weight for seven days), which normally has no effect on parasitemia, plus 10, 20, 40, or 80 mg of promethazine/kg of body weight. In one monkey, parasitemia was suppressed at the lowest promethazine dose, but re-treatment with 20 mg/kg resulted in clearance of parasitemia. Initial treatment with chloroquine and 20 or 40 mg/kg of promethazine cleared parasitemia in some animals followed by recrudescence. Re-treatment at higher doses cured one monkey and resulted in initial clearance and delayed recrudescence 28 or 63 days after treatment in two monkeys. Recrudescent parasitemia in the two monkeys was low (10 parasites/microl of blood) and subsequently cleared without re-treatment. An in vitro bioassay model was developed to examine the effects of clinically achievable doses of promethazine on parasites susceptibilities in vitro. Plasma samples taken at hourly intervals from patients given a single oral dose of 25 mg of promethazine decreased the IC50 values for chloroquine by 20-58% with the most significant reductions occurring in plasma obtained from volunteers 3-4 hr after ingestion. Plasma obtained from two volunteers 6 hr after ingestion of the drug demonstrated no effect on chloroquine susceptibility, suggesting that study of the pharmacokinetic disposition and potential interaction is warranted to optimize the dose regimen in patients for antimalarial efficacy. Historic use of this drug combination for treatment or prevention of chloroquine-associated pruritus or as an antiemetic suggest that the combination is safe and effective when used at standard dosages. The results from this study demonstrate that promethazine is a potent modulator of chloroquine resistance. Clinical evaluation of therapeutic regimens is required to validate clinical efficacy of this promising combination for treatment of uncomplicated chloroquine-resistant malaria.

This article has been cited by other articles:

				N. Obaldia III, W. Milhous, and D. Kyle Adaptation of a Thai Multidrug-Resistant C2A Clone of Plasmodium falciparum to Aotus Monkeys and Its Preliminary in vivo Antimalarial Drug Efficacy-Resistance Profile Am J Trop Med Hyg, October 1, 2009; 81(4): 587 - 594. [Abstract] [Full Text] [PDF]

				J. X. Kelly, M. J. Smilkstein, R. A. Cooper, K. D. Lane, R. A. Johnson, A. Janowsky, R. A. Dodean, D. J. Hinrichs, R. Winter, and M. Riscoe Design, Synthesis, and Evaluation of 10-N-Substituted Acridones as Novel Chemosensitizers in Plasmodium falciparum Antimicrob. Agents Chemother., November 1, 2007; 51(11): 4133 - 4140. [Abstract] [Full Text] [PDF]

				J. Millet, S. Alibert, M. Torrentino-Madamet, C. Rogier, C. Santelli-Rouvier, P. Bigot, J. Mosnier, E. Baret, J. Barbe, D. Parzy, et al. Polymorphism in Plasmodium falciparum Drug Transporter Proteins and Reversal of In Vitro Chloroquine Resistance by a 9,10-Dihydroethanoanthracene Derivative Antimicrob. Agents Chemother., December 1, 2004; 48(12): 4869 - 4872. [Abstract] [Full Text] [PDF]

				J. Millet, M. Torrentino-Madamet, S. Alibert, C. Rogier, C. Santelli-Rouvier, J. Mosnier, E. Baret, J. Barbe, D. Parzy, and B. Pradines Dihydroethanoanthracene Derivatives as In Vitro Malarial Chloroquine Resistance Reversal Agents Antimicrob. Agents Chemother., July 1, 2004; 48(7): 2753 - 2756. [Abstract] [Full Text] [PDF]

				M. Ciach, K. Zong, K. C. Kain, and I. Crandall Reversal of Mefloquine and Quinine Resistance in Plasmodium falciparum with NP30 Antimicrob. Agents Chemother., August 1, 2003; 47(8): 2393 - 2396. [Abstract] [Full Text] [PDF]

				B. Pradines, S. Alibert, C. Houdoin, C. Santelli-Rouvier, J. Mosnier, T. Fusai, C. Rogier, J. Barbe, and D. Parzy In Vitro Increase in Chloroquine Accumulation Induced by Dihydroethano- and Ethenoanthracene Derivatives in Plasmodium falciparum-Parasitized Erythrocytes Antimicrob. Agents Chemother., July 1, 2002; 46(7): 2061 - 2068. [Abstract] [Full Text] [PDF]

				D. A. van Schalkwyk, J. C. Walden, and P. J. Smith Reversal of Chloroquine Resistance in Plasmodium falciparum Using Combinations of Chemosensitizers Antimicrob. Agents Chemother., November 1, 2001; 45(11): 3171 - 3174. [Abstract] [Full Text] [PDF]

				D. Taylor, J. C. Walden, A. H. Robins, and P. J. Smith Role of the Neurotransmitter Reuptake-Blocking Activity of Antidepressants in Reversing Chloroquine Resistance In Vitro in Plasmodium falciparum Antimicrob. Agents Chemother., October 1, 2000; 44(10): 2689 - 2692. [Abstract] [Full Text]

				I. Crandall, J. Charuk, and K. C. Kain Nonylphenolethoxylates as Malarial Chloroquine Resistance Reversal Agents Antimicrob. Agents Chemother., September 1, 2000; 44(9): 2431 - 2434. [Abstract] [Full Text]

				J. L. Vennerstrom, E. O. Nuzum, R. E. Miller, A. Dorn, L. Gerena, P. A. Dande, W. Y. Ellis, R. G. Ridley, and W. K. Milhous 8-Aminoquinolines Active against Blood Stage Plasmodium falciparum In Vitro Inhibit Hematin Polymerization Antimicrob. Agents Chemother., March 1, 1999; 43(3): 598 - 602. [Abstract] [Full Text]