Peristalsis, promotion,

Mechanism of Action A laxative prepared from the bean of the castor plant but the exact mechanism of acfion is unknown. Acts primarily in the small intestine. Maybe hydrolyzed to ricinoleicacid which reduces net absorption of fluid and electrolytes and stimulates peristalsis. Therapeutic Effect Increases peristalsis, promotes laxative effect. 

Laxatives promote and facilitate bowel evacuation by acting locally to stimulate intestinal peristalsis, to soften bowel contents, or both. 

These laxatives act by softening and increasing faecal mass thus promoting normal peristalsis. The outer layers of cereal grains, especially wheat, form an important source of natural fibre in the diet and by increasing faecal mass natural fibre has laxative effects. 

Mechanism of Action A GI stimulant that has a direct effect on colonic smooth musculature by stimulating the intramural nerve plexus. Therapeutic Effect Promotes fluid and ion accumulation in the colon, increasing peristalsis and producing a laxative effect. 

Mechanism of Action A lactose derivative that retains ammonia in colon and decreases serum ammonia concentration, producing osmotic effect. Therapeutic Effect Promotes increased peristalsis and bowel evacuation, which expels ammonia from the colon. 

Mechanism of Action A bulk-forming laxative that dissolves and swells in water providing increased bulk and moisture content in stool. Therapeutic Effect Promotes peristalsis and bowel motility. 

Bulk-forming laxatives are indigestible, hydrophilic colloids that absorb water, forming a bulky, emollient gel that distends the colon and promotes peristalsis. Common preparations include natural plant products (psyllium, methylcellulose) and synthetic fibers (polycarbophil). Bacterial digestion of plant fibers within the colon may lead to increased bloating and flatus. 

Laxatives Bulk formers Polycarbophil, psyllium, and methylcellulose preparations. Citrucel, Fibercon, Konsyl, Metamucil, Perdiem, The safest laxatives for chronic use include the bulk formers and stool softeners. Saline laxatives and stimulants may be used acutely but not chronically (see text). Bulk formers hold water and expand in stool, promoting peristalsis. 

Laxative An agent that promotes peristalsis and evacuation of the bowel in a relatively slow manner (as opposed to a cathartic). 

Laxatives in this group exert an irritant action on the enteric mucosa (A). Consequently, less fluid is absorbed than is secreted. The increased filling of the bowel promotes peristalsis excitation of sensory nerve endings elicits enteral hypermotility. According to the site of irritation, one distinguishes the small-bowel irritant castor oil from the large-bowel irritants anthraqui-none and diphenylmethane derivatives (for details see p.178). 

Carminatives—serve to promote normal bowel function by stimulating peristalsis and relaxing the gastrointestinal tract. 

Laxative Osmotic effect primarily in small intestine. Draws water into intestinal lumen, produces distention, promotes peristalsis, bowel evacuation... 

AVP is formed by neuronal cells of hypothalamic nuclei and stored in the neurohypophysis. In humans, it contains arginine at position 8. (In pigs, lysine is found at position 8.) AVP stimulates contraction of the muscles of capillaries and arterioles, raising blood pressure promotes contraction of the intestinal musculature, increasing peristalsis exerts contractile influence on the uterus and has a specific effect on the epithelial cells of renal collecting tubules, augmenting resorption of water independently of solutes to cause concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma. 

Osmotic laxatives are either inorganic salts or organic compounds which are poorly absorbed and create a hypertonic state in the intestine. To equalise osmotic pressure, water is drawn from the intestinal wall into the lumen, raising the intraluminal pressure by increasing the volume of the contents, thus stimulating peristalsis and promoting evacuation. 

Lactulose, another sahne laxative, is not absorbed and draws water into the intestines and promotes water and electrolyte retention. Lactulose decreases the semm ammonia level and is useful in liver diseases such as cirrhosis. Glycerin acts like lactulose by increasing water in the feces in the large intestine. The bulk that results from the increased water in the feces stimulates peristalsis and defecation. Patients who have diabetes melMtus should avoid lactulose because it contains glucose and fmctose. 

Bulk-forming laxatives are natural fibrous substances that promote large, soft stools by absorbing water into the intestines and increasing fecal bulk and peristalsis. Bulk-forming laxatives are non-absorbable. Defecation usually occurs within 8 to 24 hours but can take up to 3 days after the start of therapy for the stool to become soft and formed. 

The mechanism of action of -limonene has not been fully elucidated in this regard, but it is thought that it may coat the mucosal lining and offer protection against gastric acid and/or promote healthy peristalsis. 

Gastrointestinal constipation and nausea are common. Nausea may be treated with antiemetics, and frequently improves with ongoing therapy. Virtually all patients taking opioids become constipated and do not become tolerant to this side effect. Activation of mu receptors in the gastrointestinal tract slows peristalsis, which promotes further absorption of water and electrolytes in the colon. Patients should be treated prophylactically with stool softeners and/ or laxatives. There is an oral oxycodone/naloxone prolonged-release tablet in clinical trials to counteract opioid-induced constipation, which is often debilitating. 

The autonomic system is responsible for the moment-to-moment modification of practically all functions of the body. Although there are intrinsic plexi that promote normal activity, the sympathetic and parasympathetic systems enhance or retard function. Auerbach s and Meissner s plexi become activated by intraluminal distension and initiate peristalsis in an anterograde fashion. Increased parasympathetic activity, primarily from the vagus nerve in the cranial axis, increases gastrointestinal motility. The same can occur from microbial and chemical irritation of the inner walls. The effects are decreased transit time and decreased water absorption, among other effects. The person may also have other symptoms including discomfort, nausea, oating, and irritation. 

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