Many drug molecules possess inadequate physical-chemical characteristics that prevent to surpass the viscous mucus layer present in the surface of mucosal tissues. Due to mucus protective role and its fast turnover, these drug molecules end up being removed from the body before being absorbed and, thus, before exerting any physiologic affect. Envisaging a better pharmacokinetics profile, chemical modifications, to render drug a more mucopenetrating character, have been introduced to drug molecules backbone towards more effective therapies. Mucus penetration increases when drug molecules are provided with net-neutral charge, when they are conjugated with mucolytic agents and through modifications that makes them resistant to enzymes present in mucus, with the overall increase of their hydrophilicity and the decrease of their molecular weight. All of these characteristics act as a whole and influence each other so they must be well thought when drug molecules are being designed for mucosal delivery.

许多药物分子具有不足的物理化学特征，阻止超过粘膜组织表面存在的粘性粘液层。由于粘液的保护作用及其快速更新，这些药物分子最终在被吸收之前，因此在发挥任何生理影响之前从体内被除去。考虑到更好的药代动力学特性，为了使药物具有更多的粘膜渗透特性，已经进行了化学修饰，已被引入到药物分子骨架中，以实现更有效的治疗。当药物分子带有净中性电荷时，当它们与粘液溶解剂结合并经过修饰使其对粘液中存在的酶具有抗性时，粘液渗透性会增加，亲水性总体增加，分子量降低。