위장관 질환 관련 약리학 (PPI, Antacids, H.pylori)

@ 위산 조절
-Basal 상태: Ach, Histamine
-Stimulated 상태: Gastrin
-Prostaglandin은 오히려 위산 억제

@ Antacids
-중화, 약간의 mucosal defense
-Magnesium hydroxide, Aluminum hydroxide 등 hydroxide계열 많이 먹음

@ Proton-pump inhibitors
-omeprazole, rabeprazole
-irreversible proton pump inhibition
-short half-life, long duration

@ H, pylori infected ulcer à Triple therapy
-PPI + Clarithromycin + Amoxicillin (b.i.d. 2주)

(+)Quadruple therapy
PPI + Metronidazole + Tetracycline + Bismuth subsalicylate

 

@ Hepatic clearance 공식
CLh (Clearance)
Q (hepatic blood flow)
Ci (input)(concentration)
Co (output)

CLh = Q(Ci-Co)/Ci

(extraction ratio) ER = (Ci-Co)/Ci

(bioavailability) F = 1 – ER

 

@ ER에 따른 Hepatic clearance
-high ER은 hepatic blood flow(Q)에 dependent
-low ER은 intrinsic clearance와 protein binding에 dependent

@ Half-life = Vd*0.693/CL
--> albumin 같은 protein 떨어지면
--> high protein binding하는 약은 Vd 상승 à half-life 증가(CL도 떨어짐)