達瑪烷苷元PPD和PPT是達瑪烷皂苷經過代謝後，去除側鏈糖基後的最終代謝產物，既往的研究已經表明，達瑪烷苷元比皂苷的活性增加5-10倍。

但是達瑪烷苷元是脂溶性的，難溶於水，因此，其口服的吸收率較低。中國醫科院江蘇分院研究發現：由於其難溶性和腸道吸收後的肝臟首過代謝效應，普通PPD 口服的生物利用度較低。因此，需要一種新型的製劑來增加達瑪烷苷元PPD的吸收率。

滴丸採用了固相分散和共溶技術，能夠大大提高難溶性物質的溶解度。在滴丸中，達瑪烷苷元PPD能夠以微小分子的形式均勻分散在製劑中（固相分散技術）。當滴丸的水溶性基質在消化道溶解時，PPD也以分子形式快速釋放，並在水溶性基質的幫助下，溶解在消化液中，從而被口腔粘膜或消化道上皮快速吸收。如果在舌下口服，它能規避了肝臟的首過代謝效應，大大提高滴丸的吸收率。

相關研究發表於2013年第3期的《藥理學報》，其摘要如下：

在這項研究對20（ S） – 原人參二醇（PPD）生物製藥性能進行了研究。首先，採用平衡溶解度和PPD的表觀油/水分配係數來預測PPD在體內的吸收。與此同時，利用Caco-2細胞模型和單通腸灌流模型來研究細胞膜對PPD的通透性和吸收窗口。此外，研究PPD在體內的生物利用度和代謝性質。

結果表明，PPD是難溶於水的，在水中的平衡溶解度僅為35.24毫克x長（-1） 。油水分配係數為46.21 （ logP值= 1.66 ） 。通過Caco-2細胞模型，結果表明吸收後的PPD也能夠流出細胞。空腸-迴腸-結腸原位腸灌注模型的結果顯示， PPD在腸道的吸收好，有效滲透係數分別為十二指腸>空腸>迴腸>結腸。但是，PPD的口服生物利用度僅為29.39 ％ 。

代謝研究表明PPD在體內被廣泛代謝，PPD較低口服生物利用度的主要因素是溶解性差和首過效應。

[Polybasic research on the biopharmaceutical characteristics of 20 (S)-protopanaxadiol].
Yao Xue Xue Bao. 2013 Mar;48(3):411-6
Abstract
In this study, the biopharmaceutical properties of 20 (S)-protopanaxadiol (PPD) were studied. Firstly, the equilibrium solubility and apparent oil/water partition coefficient of PPD were used to predict the absorption in vivo. Meanwhile the membrane permeability and absorption window were studied by Caco-2 cell model and single-pass intestinal perfusion model. Furthermore , the bioavailability and metabolism were combined to study the absorption properties and metabolic properties in vivo. All of them were used to provide theoretical and practical foundation for designing PPD preparation. The results showed that PPD is poorly water-soluble, and the equilibrium solubility in water is only 35.24 mg x L(-1). The oil-water partition coefficient is 46.21 (logP = 1.66). By Caco-2 cell model, the results showed PPD uptake in general, and it also has efflux. By in situ intestinal perfusion model, the results showed that the absorption of PPD in the intestine is good, and the effective permeability coefficient were duodenum > jejunum > ileum > colon. The oral bioavailability of PPD was 29.39%. It was not well. Metabolic studies showed PPD in vivo presented a wide spread metabolism. So the main factors that restricted oral bioavailability of PPD were the poor solubility and first-pass effect.