Intestinal transit rate

RL Oberle, GL Amidon. The influence of variable gastric emptying and intestinal transit rates on the plasma level curve of cimetidine An explanation for the double peak phenomenon. J Pharmacok Biopharm 15 529-544, 1987. 

GI absorption of many poorly soluble drugs depends on small intestinal transit, as demonstrated for ketoprofen, nifedipine, haloperidol, miconazole, and others. Small intestinal transit rate and transit time become important factors in drug absorption, particularly when the ratio of dose to solubility is high and dissolution rate is very slow or when the drug is... 

Intestinal transit rate is highly dependent on the motility state of the GI tract either fasted or fed partly due to the higher viscosity of chyme in the fed state. Blair and co-workers conducted a study in 20 men (energy intake 1272-5342 kcal/day) and found that higher calorific intake was associated with faster tran-sit. Exercise in moderation appears to have no effect on transit. 

Increases small intestinal mucosal growth and retards intestinal transit rate... 

Hydrodynamics of the upper GI tract are characterized by 1) the kinetics of gastric emptying, and 2) the small intestinal transit and the flow rate of intestinal fluid (chyme). Gastric... 

Transit Rates and Flow Rates in the Human Small Intestine... 

Due to the paucity of data for humans, it might be helpful to look at the canine model. In general, mean intestinal transit and flow rates of the dog correspond well to analogous data from humans. Flow rates in the canine jejunum after administration of 200-600 mL of various liquid meals ranged between 1 and 4mL/min and sometimes up to 7 mL/min (72-76). Further, intestinal flow rates are highest in phase II/III of the MMC, followed by post-prandial flow rates. Flow rates in the canine duodenum and the proximal jejunum after administration of various liquids range between 2 and 13 mL/ min (30,43,77). For instance, median duodeno-jejunal flow... 

Another compartmental transit and absorption model, the GITA model, has been described by Sawamoto et al. [44] and reviewed by Kimura and Higaki [30], In this model the GI tract is divided into eight different well-stirred compartments and similarly to the CAT model presented by Yu et al. ([60], [63]), the transit of drug is described by a first-order transit rate constant (Ki for the intestine and Ks for the stomach). The absorption in each segment is assumed to be a first-order process described by an absorption rate constant (Ka). The amounts of compound in the different compartments are described by Eq. 18 for the stomach (Xs) and Eq. 19 for the intestinal compartments (Xi + i) [44],... 

Kaus, L. C., Gillespie, W. R., Hussain, A. S., and Amidon, G. A. The effect of in vivo dissolution, gastric emptying rate, and intestinal transit time on the peak concentration and area-under-the-curve of drugs with different gastrointestinal permeabilities. Pharm. Res. 16 272-280, 1999. 

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