Table 3.

Potential physiologic changes after weight loss surgery with relevance for drug treatment.

	Physiological changes immediately after surgery114	Physiological changes long-term after surgery
Absorption	Alteration of gastric emptying time, gastric/gastrointestinal pH. Duodenal absorption surface reduced. Reduced intestinal first-pass metabolism (CYP3A4, CYP3A5). Decreased intestinal p-glycoprotein efflux. Decreased intestinal transit time. Dissociation of bile salt delivery.	No long-term adaption/normalization
Distribution	No immediate changes after surgery	Normalization of obesity induced alterations 60: ↓ fat free mass, ↓↓ fat mass, ↓ organ volume, ↓ ejection fraction, ↓ blood volume, altered protein binding, ↓ alpha-1-acid glycoprotein, ↓ plasma lipids,↓ free fatty acids
Metabolism	No immediate changes after surgery	↓ intestinal blood flow, ↑ CYP3A4, ↓ liver fat, ↓ cholestasis, ↓ periportal fibrosis, ↓ specific enzymes (uridine-diphosphate-Glucuronosyl-transferase, xanthinoxidase, N-acetyltransferase, CYP2E1), ↓ glucuronidation, sulfidation, ↓ biliary secretion/transporter activity, ↓ inflammation
Excretion	No immediate changes after surgery	Regeneration of renal insufficiency induced by obesity?

CYP, cytochrome P450.