Acids pH-pK。=log A→) HA BH Acids ionized some in Bases ionized some in stomach and almost fully in stomach but almost none in intestine or in blood; may be intestine or blood; absorbed absorbed from stomach and mainly from intestine trapped in blood entity cid diaz phenylbutazone c warfar一 aminopyrine phenobarbital 8 Acids ionized almost none 9-procainamide Bases ionized almost in stomach, a little in intestine ful lly in stomach and some and more in blood; absorbed in intestine and blood from stomach 10--amphetamine absorbed mainly from intestine; also secreted into stomach and trapped l1 mecamylamine th ere
When pH Is less than pK When pH is greater than pKa the protonated forms the deprotonated forms A and BH+ predomInate. A and B predominate HA=A·and BH◆〓B PH s pKa pH> PK 10 lpH<pKa: HA and BH*are predominant pH>pKa: A and B are predominant
pH < pKa: HA and BH+ are predominant pH > pKa: A－ and B are predominant
Part a Pharmacokinetic processes 口 Implications I Absorption 0 Distribution 0 Excretion
Implications Absorption Distribution Excretion Part A Pharmacokinetic Processes
[1000 1001 HA仝A+H+ Total [HA]+[A] Plasma pH=7.4 Lipid Mucosal Barrier Gastric Juice pH= 1.4 [0.001] 1.001 HA A,+H+ Weak Acid HA A +H pKa=4.4 nonionized ionized Figure 1-2. Infiuence of pH on the distribution of a weak acid between plasma and gastric juice, separated by a lipid barrier
Part a Pharmacokinetic processes 0 2.2 Free and bound forms D Plasma protein binding D Tissue /organ affinity
2.2 Free and Bound Forms Plasma protein binding Tissue / organ affinity Part A Pharmacokinetic Processes