Sila-On Warisada, Vardhanabhuti Nontima, Ongpipattanakul Boonsri, Kulvanich Poj
Chulalongkorn University, Department of Manufacturing Pharmacy, Faculty of Pharmaceutical Sciences, Bangkok, Thailand.
PDA J Pharm Sci Technol. 2006 May-Jun;60(3):172-81.
Phospholipids--stabilized submicron emulsions require the addition of preservatives to destroy or inhibit the growth of microorganisms when these preparations are non-sterile products or when packed in multi-dose containers. This study examined the distribution of four paraben esters--methylparaben, ethylparaben, propylparaben, and butylparaben--that were added into submicron emulsions by de novo emulsification. The distribution of preservative compounds among different phases was determined after separation of submicron emulsions by ultracentrifugation. The compounds with higher lipophilicity were concentrated in the oil phase and phospholipids-rich phase, leading to an increase in oil droplet size. However, the effect of the paraben distribution on zeta potential and pH of emulsion fluctuated depending on the type of phospholipid used. The lower lipophilic compounds were mostly found in the aqueous phase and mesophase. These results signify the possibility that the chemical structures and lipophilicity of preservative compounds affected their distribution in phospholipid-stabilized submicron emulsions. We conclude that the higher concentration of preservatives or their combination may be required for efficient preservation of submicron emulsion products.
磷脂稳定的亚微米乳液，当这些制剂为非无菌产品或包装在多剂量容器中时，需要添加防腐剂来杀灭或抑制微生物的生长。本研究考察了通过从头乳化法添加到亚微米乳液中的四种对羟基苯甲酸酯——对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯和对羟基苯甲酸丁酯的分布情况。通过超速离心分离亚微米乳液后，测定了防腐剂化合物在不同相之间的分布。亲脂性较高的化合物集中在油相和富含磷脂的相中，导致油滴尺寸增大。然而，对羟基苯甲酸酯分布对乳液ζ电位和pH值的影响因所用磷脂类型而异。亲脂性较低的化合物大多存在于水相和中间相中。这些结果表明，防腐剂化合物的化学结构和亲脂性可能会影响它们在磷脂稳定的亚微米乳液中的分布。我们得出结论，对于亚微米乳液产品的有效保存，可能需要更高浓度的防腐剂或其组合。
