Thus , drug penetration may be attributed mostly to the un - ionized form 因此,药物穿透主要是由非解离型来完成的。
The un - ionized form is usually lipid soluble and diffuses readily across cell membranes 非解离型部分通常为脂溶性,很容易透过细胞膜扩散。
Most drugs are weak organic acids or bases , existing in un - ionized and ionized forms in an aqueous environment 多数药物是弱有机酸或弱有机碱药物,他们以非解离或解离型态存在于水性环境中。
When the weak acid is given orally , the concentration gradient for un - ionized drug between stomach and plasma tends to be large , favoring diffusion through the gastric mucosa 当这种弱酸性药物经口服给药时,胃与血浆之间的非解离型药物浓度梯度很大,从而有利于透过胃粘膜扩散。
The ionized form cannot penetrate the cell membrane easily because of its low lipid solubility and high electrical resistance , resulting from its charge and the charged groups on the cell membrane surface 解离型则由于其脂溶性低,及其电荷和细胞膜表面带电荷基团所产生的高电阻,而不易透过细胞膜。