de Araújo Ivonete Batista, Damasceno Bolívar P G L, de Medeiros Tereza Maria Dantas, Soares Luiz Alberto Lira, do Egito E Sócrates Tabosa
Programa de Pós-graduação em Ciências da Saúde (PPGCSA), Universidade Federal do Rio Grande do Norte (UFRN), Departamento de Farmácia (DFAR)- Laboratório de Sistemas Dispersos (LASID) - Natal/RN, Brazil.
Curr Drug Deliv. 2005 Apr;2(2):199-205.
The aim of this work was to develop an in vitro experimental protocol for the evaluation of toxicity and efficacy of an amphotericin B (AmB) micelle system, Fungizone, which was previously diluted with a lipid based emulsion for parenteral use, named Lipofundin LCT/MCT-20%. Two cell models were used for the experiments: Red Blood Cells (RBC) from human donnors and Candida tropicalis (Ct). These models were used to perform the toxicity and activity of the Fungizone/ Lipofundin admixture (AmB-LP) and the Fungizone (AmB-M) alone. While potassium (K+) and hemoglobin leakage from RBC were the parameters used to evaluate the acute and chronic toxicity, respectively, the efficacy of AmB-LP and AmB-M were assessed by K+ leakage or cell survival rate (CSR) from Ct. The results show that the toxicity of AmB-LP to RBC was concentration dependent concerning the K+ leakage; while at high concentrations, 5 and 50 mg x mL(-1), the leakage was 50.91 +/- 2.09% and 95.71 +/- 0.64%, respectively, at a concentration of 0.5 mg x mL(-1) this value was 17.16 +/- 1.57% and the value tended to zero for the lowest concentration studied, 0.05 mg x mL(-1). Surprisingly, AmB-LP induced very low hemoglobin leakage for all concentrations studied. At the highest concentration, 50 mg x mL(-1), this value was around 3%. When the cell model was Ct, the results changed completely. Not only high concentrations of AmB-LP, but also lower ones were able to induce a K+ permeability of around 100%. The CSR parameter showed an inverse correlation with the concentration; high values, between 50 and 5 mg x mL(-1), resulted in a CSR of around 8%. On the other hand, for lower concentration values, 0.05 and 0.5 mg x mL(-1), this one was around 80%. The same profile of activity against Ct was found for AmB-M. Only a small variation was found for the K+ leakage at 0.05 mg x mL(-1) that presented a value of 96.99 +/- 2.53%. However, AmB-M seemed to be much more toxic than AmB-LP. Its induction of hemoglobin leakage started at 0.5 mg x mL(-1) and reached the 100% at 5 mg x mL(-1). K+ leakage results were worse. The intermediate concentrations of study, 0.5 and 5 mg x mL(-1), presented a significant increase compared to AmB-LP. All together these results reveal that the activity of AmB is not only concentration dependent, but also depends on the drug carrier in which this compound was inserted. The AmB-LP preparation showed the same efficacy as AmB-M, but with a low toxicity. Therefore, AmB-LP presented a higher therapeutic index that permits the administration of high concentration of AmB without revealing side effects. However, the simple mixture of two complex pharmaceutical entities, as micelles and emulsions, should be analyzed carefully to assure that physicochemical stability is not reduced and thereby cause a different biodistribution in vivo.
本研究的目的是开发一种体外实验方案，用于评估两性霉素B（AmB）胶束系统Fungizone的毒性和疗效。Fungizone先前用一种名为Lipofundin LCT/MCT - 20%的基于脂质的乳剂稀释用于肠胃外给药。实验使用了两种细胞模型：来自人类供体的红细胞（RBC）和热带假丝酵母（Ct）。这些模型用于检测Fungizone/Lipofundin混合物（AmB - LP）和单独的Fungizone（AmB - M）的毒性和活性。红细胞中钾离子（K +）泄漏和血红蛋白泄漏分别作为评估急性和慢性毒性的参数，而AmB - LP和AmB - M的疗效通过热带假丝酵母的钾离子泄漏或细胞存活率（CSR）来评估。结果表明，AmB - LP对红细胞的毒性与钾离子泄漏呈浓度依赖性；在高浓度（5和50 mg·mL⁻¹）时，泄漏率分别为50.91±2.09%和95.71±0.64%，在浓度为0.5 mg·mL⁻¹时，该值为17.16±1.57%，而在所研究的最低浓度0.05 mg·mL⁻¹时，该值趋于零。令人惊讶的是，对于所有研究浓度，AmB - LP诱导的血红蛋白泄漏都非常低。在最高浓度50 mg·mL⁻¹时，该值约为3%。当细胞模型为热带假丝酵母时，结果完全不同。不仅高浓度的AmB - LP，而且较低浓度的AmB - LP都能诱导约100%的钾离子通透性。细胞存活率参数与浓度呈负相关；在50至5 mg·mL⁻¹的高浓度下，细胞存活率约为8%。另一方面，对于较低浓度值0.05和0.5 mg·mL⁻¹，细胞存活率约为80%。AmB - M对热带假丝酵母的活性表现出相同的特征。仅在0.05 mg·mL⁻¹时钾离子泄漏有小的变化，其值为96.99±2.53%。然而，AmB - M似乎比AmB - LP毒性大得多。其诱导的血红蛋白泄漏从0.5 mg·mL⁻¹开始，在5 mg·mL⁻¹时达到100%。钾离子泄漏结果更糟。研究的中间浓度0.5和5 mg·mL⁻¹与AmB - LP相比有显著增加。所有这些结果表明，AmB的活性不仅取决于浓度，还取决于该化合物所嵌入的药物载体。AmB - LP制剂显示出与AmB - M相同的疗效，但毒性较低。因此，AmB - LP具有更高的治疗指数，允许在不产生副作用的情况下给予高浓度的AmB。然而，胶束和乳剂这两种复杂药物实体的简单混合应仔细分析，以确保其物理化学稳定性不会降低，从而在体内导致不同的生物分布。
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