Quinine Sulphate Microparticles as Treatment for Leishmaniasis

Abstract

Background: Leishmaniasis is a neglected tropical disease caused by the Leishmania parasite and transmitted by the female phlebotomine sandfly. The disease can affect the skin (least fatal) or internal organs (most fatal). Current treatment options for leishmaniasis have a number of adverse effects, and there appears to be resistance by the protozoan parasite (Leishmania spp.). Reports suggest that quinine sulphate, not indicated for leishmaniasis, is effective in killing the Leishmania parasite. Indeed, the efficacy of any drug is dependent on the concentration at the target site, which is also almost dependent on drug formulation. The current study assessed the pharmacokinetic profile of the microparticulate formulation of quinine sulphate and its in vitro and in vivo efficacy against Leishmania donovani.

Methods: Quinine sulphate was encapsulated in bovine serum albumin by the spray-drying method. Quinine sulphate microparticles were evaluated for size, zeta potential, drug content, encapsulation efficiency, and in vitro release properties. Afterwards, the pharmacokinetic characteristics of quinine sulphate microparticles were estimated and in vivo efficacy studies were also conducted.

Results: The size range of the quinine sulphate microparticles was between 2.0 and 5.0 µm. Microparticles had an average zeta potential of -35.2 mV and an encapsulation efficiency of 94.5%. Also, C _max, t _1/2, and AUC were all significantly desirable for quinine sulphate microparticles compared to the drug powder. Quinine sulphate microparticles significantly reduced parasite load in rat organs than amphotericin B.

Conclusion: Overall, quinine sulphate microparticles had better pharmacokinetic profile and showed higher efficacy against Leishmania donovani parasites in vivo. Thus, quinine sulphate microparticles have the potential, especially, in treating visceral leishmaniasis.

Figure 1

Scanning electron microscope (SEM) images of quinine sulphate microparticles. Scanning electron micrograph of quinine sulphate-BSA microparticles observed at 5 kV. The image shows particles that are irregular and porous.

Figure 2

In vitro cumulative percent release of quinine sulphate formulations. The microparticle formulation (QS MP) showed extended release profile (91% over 24 hours) compared with the drug powder (QS powder) (98% over 8 hours), n = 3. Release of quinine sulphate from the albumin matrix was biphasal. A burst release of about 40% was observed in the first hour.

Figure 3

Comparative studies on parasite load reduction in rat peritoneal macrophages using various drug formulations. AMB, amphotericin B; QS powder, quinine sulphate powder; QS MP, quinine sulphate microparticles; Control: untreated group (n = 5). Quinine sulphate significantly reduced parasite load in the macrophage cells used. Formulated QS MP were much more effective than the pure quinine sulphate powder. Effect of formulated quinine sulphate microparticles was comparable to the standard drug amphotericin B, the positive control (^∗p < 0.05 and ^∗∗p < 0.01).

Figure 4

The mean plasma drug concentration-time profile of the quinine sulphate formulations. Sharp spike in serum concentration was observed with the microparticulate formulation (QS MP). Area under the curve (AUC) was significantly higher in the microparticulate formulation group than in the powder group (p ≪ 0.01 in Table 2).

Figure 5

Comparative studies on percent parasite reduction in blood and tissues. In all the tissues studied, treatment with quinine sulphate microparticles resulted in more than 60% reduction in parasite load (n = 5). The reduction observed was about 15–18 percentage points better than the standard drug “amphotericin B.” Difference observed was significant (^∗p < 0.05). AMB, amphotericin B; QS MP, quinine sulphate microparticles; QS powder, quinine sulphate powder; Blank MP, blank microparticles; Control, untreated group. (a) Blood. (b) Liver. (c) Spleen.