71.依據pH分配假說，若細胞膜兩側pH值不同時，下列敘述何者錯誤？
(A)膜兩側的總藥品濃度不相等
(B)藥品在膜兩側解離程度不同
(C)弱酸性藥品在胃中快速被吸收
(D)藥品在較低解離一側含有較大的藥物總濃度

答案：登入後查看
統計： A(320), B(53), C(620), D(1958), E(0) #442711

詳解 (共 10 筆)

#1432778
不相等喔
在低解離度的藥品以分子態過細胞膜
到了高解離度再解離
所以高解離度那側濃度會較高
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#1615081

弱酸藥物在胃中不解離→分子態→易吸收

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#1014778
(D)藥品在較高解離一側含有較大的藥物總...
(共 24 字，隱藏中）
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#3078262
兩側各自總濃度不相等 但解離藥加不解離藥...
(共 29 字，隱藏中）
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#1014787

Table 13.2 Relative Concentrations of Salicylic Acid as Affected by pH


Drug Gastric Juice (pH 1.2) Plasma (pH 7.4)
RCOOH 1.0000 1
RCOO–
 		 0.0158 25100
Total drug concentration 1.0158 25101

Thus, the pH affects distribution of salicylic acid (RCOOH) and its salt (RCOO–) across cell membranes. It is assumed that the acid, RCOOH, is freely permeable and the salt, RCOO–, is not permeable across the cell membrane. In this example the total concentration of salicylic acid at equilibrium is approximately 25,000 times greater in the plasma than in the stomach (). These calculations can also be applied to weak bases, using Equation 13.5.

According to the pH–partition hypothesis, if the pH on one side of a cell membrane differs from the pH on the other side of the membrane, then 

(1) the drug (weak acid or base) will ionize to different degrees on respective sides of the membrane; 

(2) the total drug concentrations (ionized plus nonionized drug) on either side of the membrane will be unequal; and 

(3) the compartment in which the drug is more highly ionized will contain the greater total drug concentration. For these reasons, a weak acid (such as salicylic acid) will be rapidly absorbed from the stomach (pH 1.2), 

whereas a weak base (such as quinidine) will be poorly absorbed from the stomach.

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#1232475
兩側總藥品濃度到底相等否???????黃的祥解寫相等
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#4150196


(共 1 字，隱藏中）
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8
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#2795685

請問A選項是正確的嗎？

依據pH分配假說，在膜兩端的總藥物濃度是相等的。

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#4494869

藥物總濃度= 未解離 + 解離 【要考慮未解離啊！！

藥品在較高解離一側含有較大的藥物總濃度

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#1612278

為什麼Ｃ對

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