Intestinal motility activity

Intestinal motility activity. Rat intestinal epithelia mounted in an Ussing chamber attached with voltage/current clamp were used for measuring changes of the short-circuit current across the epithelia. The intestinal epithelia were activated with current raised by serosal administration of forskolin 5 pM. Ethanol extracts of cannabis augmented the current additively when each was added after forskolin. In subsequent experiments, ouabain, and bumetanide... 

Biologica.1 Activities a.ndAna.logues, The many pharmacological actions of neurotensin include hypotension, increased vascular permeabihty, hyperglycemia, increased intestinal motility, and inhibition of gastric acid secretion (120). In the brain, it produces analgesia at remarkably low doses (121). 

Cannabimimetics reduce the intestinal motility by a CB1-mediated inhibitory activity on acetylcholine release from autonomic fibers. An endo-cannabinoid, 2-AG, was isolated from dog intestine however, its role there remains unknown (Mechoulam, 1995a). 

A summary of how physiological factors affect the dissolution rate is given in Table 21.2. The effective surface area will be affected by the wetting properties of the bile acids and other surface-active agents in the gastrointestinal tract. The dif-fusivity of a drug molecule in the intestinal juice will be altered by changes in viscosity that are induced, for instance, by meal components. An increased dissolution rate could be obtained at more intense intestinal motility patterns or increased... 

The motility of the small bowel has been studied in great detail in experimental, physiological and clinical research [21, 71, 106, 107,109], and the patterns are well defined in man [21, 23, 110], Although a standard test of intestinal motor activity with regard to the efficiency of mechanical luminal clearance is not yet established for clinical use, means to evaluate this function have been proposed. 

Castor oil is metabolized in the GI tract to an active compound, ricinoleic acid, which stimulates secretory processes, decreases glucose absorption, and promotes intestinal motility, primarily in the small intestine. Castor oil usually results in a bowel movement within 1 to 3 hours of administration. Because the agent has such a strong purgative action, it should not be used for the routine treatment of constipation. 

Loperamide is an opioid analogue that binds to the opiate gut receptors, thereby decreasing intestinal motility and increasing transit time. Loperamide is contraindicated in patients with active ulcerative colitis and children under 4 years. It is used in the treatment of diarrhoea. 

Decreasing intestinal motility will favor the intestinal absorption of water. For this purpose the activity of opioids can be employed. Also combinations of opioid agonists with muscarinic receptor antagonists are used for this purpose. 

Inhibition of intestinal peristalsis rates among one of the more common effects of morphine that are not directly related to its analgesic activity. The finding that meperidine (21-4) shares this effect led to the development of a highly substituted derivative, diphenoxilate (22-3), that also inhibits intestinal motility and thus acts as an antidiarrheal agent. The side chain in (22-3) is prepared by alkylation of the anion from diphenylacetonitrile with 1,2-dibromoethane to give the bromoethyl... 

HT 4 agonists Tegaserod activates enteric 5-HT4 receptors and increases intestinal motility... 

Slows intestinal motility Dose Adults. Initial 4 mg PO, then 2 mg after each loose stool, up to 16 mg/d Peds. 2-5 y, 13-20 kg 1 mg PO tid 6-8 y, 20-30 kg 2 mg PO bid 8-12 y, >30 kg 2 mg PO tid Caution [B, +] Not for acute D caused by Salmonella sp, Shigella sp, or C. difficile Contra Pseudomembranous colitis, bloody D Disp Caps, tabs, Liq SE Constipation, sedation, dizziness Interactions T Effects W/ antihistamines, CNS depressants, phenothiazines, TCAs, EtOH EMS Use caution w/ narcotics, may T risk of constipation related to opioids OD May cause constipation and CNS depression activated charcoal may be effective, naloxone (Narcan) may be effective... 

In spite of the well documented inhibitory effects mediated by H3 receptors in electrically-stimulated preparations of the guinea pig intestine, the activation of this receptor subtype does not influence the reflex-evoked peristaltic motility of the guinea pig ileum (Poli et al., 1997 Poli and Pozzoli 1997). Since this experimental model reproduces peristalsis in quasi-physiologic conditions (Holzer, 1989), H3 receptors apparently play a minor role when compared to that of the other prejunctional receptors, such as a2-adrenoceptors and adenosine Ai-receptors, in the control of the physiologic motility of the gut (Figure 8). 

If an organ is innervated by both the sympathetic and parasympathetic divisions, a physiologic antagonism typically exists between these divisions. That is, if both divisions innervate the tissue, one division usually increases function, whereas the other decreases activity. For instance, the sympathetics increase heart rate and stimulate cardiac output, whereas the parasympathetics cause bradycardia. However, it is incorrect to state that the sympathetics are always excitatory in nature and that the parasympathetics are always inhibitory. In tissues such as the gastrointestinal tract, the parasympathetics tend to increase intestinal motility and secretion, whereas the sympathetics slow down intestinal motility. The effect of each division on any tissue must be considered according to the particular organ or gland. 

The charcoal passage test can be used for evaluation of laxative activity as well as for inhibition of intestinal motility. 

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