圈>f线一Gastric mtying-inthe absence offd ©i生Physio factors-Gastric emptying In the absence of food,the empty stomach and the intestinal tract undergo a sequence of repetitious events referred to as the interdigestive migrating The factors affecting stomach emptying notor complex(消化间期移行性复合运动)which is Food composed of four stages at a period of 2 hours. 国Drug Stage 1:minimal activity,about Ih. Stage 2:irregular contractions that gradually increase in ©Sickness strength,30-45 min. ©Others Stage 3:intense peristaltic waves that result in the emptying ·Body position of gastric contents,5-15 min.(housekeeper waves) ·Viscosity Stage 4:a transition of decreasing activity,leading to the beginning of the next cycle. .Emotional state...... 国ft线Gastric emptying--in the absenceoffood 国生 Gastric emptying The gastric residence time of a solid dosage form will An increased gastric-emptying rate will vary from perhaps 5 to 15 minutes if ingested at the probably increase the rate of absorption for beginning of the housekeeper to about 2 hours or longer if drugs absorbed by passive diffusion. ingested at the end of the housekeeper. An increased gastric-emptying rate will The foregoing considerations will not apply to liquid probably decrease the extent of absorption for dosage forms which are generally able to empty during all phases of the migrating motor complex. drugs absorbed by active transport. ©上t线_Gastric emptying-ithe presenceof food 国秋生 Physiological factors Components and properties of GI fluids. In the presence of food,gastric emptying is ©Gastric emptying controlled by a complex variety of mechanical, ©Intestinal transit hormonal,and neural mechanisms. ©Blood flow 88 Shanghai Jiao Tong University Gastric emptying-in the absence of food In the absence of food, the empty stomach and the intestinal tract undergo a sequence of repetitious events referred to as the interdigestive migrating motor complex(消化间期移行性复合运动) which is composed of four stages at a period of 2 hours. • Stage 1: minimal activity, about 1h. • Stage 2: irregular contractions that gradually increase in strength, 30-45 min. • Stage 3: intense peristaltic waves that result in the emptying of gastric contents, 5-15 min. (housekeeper waves) • Stage 4: a transition of decreasing activity, leading to the beginning of the next cycle. Shanghai Jiao Tong University Gastric emptying-in the absence of food The gastric residence time of a solid dosage form will vary from perhaps 5 to 15 minutes if ingested at the beginning of the housekeeper to about 2 hours or longer if ingested at the end of the housekeeper. The foregoing considerations will not apply to liquid dosage forms which are generally able to empty during all phases of the migrating motor complex. Shanghai Jiao Tong University Gastric emptying-in the presence of food In the presence of food, gastric emptying is controlled by a complex variety of mechanical, hormonal, and neural mechanisms. Shanghai Jiao Tong University Physiological factors-Gastric emptying The factors affecting stomach emptying Food Drug Sickness Others • Body position • Viscosity • Emotional state…… Shanghai Jiao Tong University Gastric emptying An increased gastric-emptying rate will probably increase the rate of absorption for drugs absorbed by passive diffusion. An increased gastric-emptying rate will probably decrease the extent of absorption for drugs absorbed by active transport. Shanghai Jiao Tong University Physiological factors Components and properties of GI fluids. Gastric emptying Intestinal transit Blood flow