Mannitol laxatives

Osmotic laxative effects are also produced by the polyhydric alcohols, mannitol and sorbitol, which unlike glucose cannot be transported through the intestinal mucosa, as well as by the non-hydrolyzable disaccharide, lactubse. Fermentation of lactulose by colon bacteria results in acidification of bowel contents and microfloral damage. Lactulose is used in hepatic failure in order to prevent bacterial production of ammonia and its subsequent absorption (absorbable NH3 nonabsorbable NH4+), so as to forestall hepatic coma. 

Saline laxatives like MgS04, Mg(OH)2, Mg2 Citrate and Na+ Phosphates act via their osmotic pressure to retain water in the colon. Other osmotic laxatives are carbohydrates such as lactulose, glycerin, sorbitol, and mannitol. They are not absorbed and are resistant to digestion in the small intestine. Most agents are orally administered. It should be noted however that glycerin, sodium phosphates and sorbitol are formulated for rectal use. From lactulose lactic and acetic acids are formed by intestinal bacteria and apart from its osmotic effects it thus acidifies the content of the colon. The reduction of the pH stimulates motility and secretion. 

Osmotic laxative effects are also produced by the polyhydric alcohols mannitol and sorbitol, which unlike glucose cannot be transported through the intestinal mucosa. 

Saline laxatives (magnesium citrate, magnesium sulfate, sodium sulfate, and disodium phosphate) or saccharide laxatives (sorbitol, mannitol, lactulose) are also used in poisoned patients. Common adverse effects are abdominal cramps, excessive diarrhea, and abdominal distension. Dehydration and electroljde imbalance in children, and hjrpermagnesemia and magnesium toxicity (with magnesium-based cathartics) have also been reported. 

Mannitol is an osmotic diuretic that has been used in acute oliguric renal insufficiency, acute cerebral edema, and the short-term management of glaucoma, especially to reduce intraocular pressure before ophthalmic surgery. Other indications include promotion of the excretion of toxic substances by forced diuresis, bladder irrigation during transurethral resection of the prostate, and oral administration as an osmotic laxative for bowel preparation. Mannitol is used as a diluent and excipient in pharmaceutical formulations and as a bulk sweetener. 

Polyhydric alcohols include xylitol, mannitol, sorbitol, maltitol, lactitol and isomalt. Although these products generally have a lower sweetening power than sucrose, they also have fewer calories, only 2.4 kilocalories per gram of dry matter. They also do not cause tooth decay, and for this reason are mainly used in anti-cariogenic chewing gum and confectionaries. However, polyhydric alcohols also have an undesirable laxative effect that becomes apparent with excess consumption and as a function of individual constitution. Eor this reason, the European Union does not allow the beverage industry to use polyhydric alcohols as a sweetener. 

For patients in whom diarrhea is the primary complaint, avoidance of certain food products may be necessary. Caffeine, alcohol, and artificial sweeteners (sorbitol, fructose, and mannitol) are known to irritate the gut and produce a laxative effect. Lactose... 

The drug Manna with 50-60% Mannitol is used as a mild laxative. Mannitol is not absorbed from the intestine and gives increased intestinal bulk because of the absorption of water. 

The production of nitromannitol is fairly easy because the starting material for its manufacture, mannitol, is fairly easily available at moderate prices from headshops. It may be labelled as baby laxative, but it is stocked as cut for cocaine and other white powders. The person behind the counter is likely to give you a knowing wink while making- the transaction, but have no idea of its usefulness in explosive manufacture. If there are no head shops in your area, a check of the classified section in High Times may turn up a supplier or two. 

Manna The sweetish exudata of the European flowering ash Ftaxlnus ornus and of several related species, obtained In the form of flakes, fragments or as a viscid mass. Its chief constituent is mannitol. Manna is used medicinally as a gentle laxative, demulcent, and expectorant ... 

Besides the use as filling agents and laxatives the hexoles are used as humectants (e.g. sorbitol in creams), for taste correction (e.g. sorbitol in oral liquids), to get iso-osmotic solutions (e.g., mannitol in eyewashes, see Sect. 10.6.2), as diuretics in parenterals and as a cake stabilising agent in freeze drying. 

Sugar alcohols, such as sorbitol, mannitol, and xyhtol are also used as sweeteners. They are derivatives of sugars that occur naturally in some fruits, and are manufactured by chemical reduction of the parent sugars. Sugar alcohols have a lower calorie yield than the sugars from which they are derived, and are commonly used in file preparation of jams and sweets used by diabetics. They are considered safe and can he used in foods in any required amount however, an intake greater than about 20 to 50 g day may cause gastrointestinal discomfort and have a laxative effect. 

Because mannitol and sorbitol are both moderately sweet and relatively inexpensive, they have been considered as special dietary constituents 63). The content of sorbitol in diabetic foods should be counted as available carbohydrate, and the label of foods containing sorbitol should indicate the amount present. Probably owing to the slow intestinal absorption of sorbitol, doses greater than 50 g. are laxative in humans, but smaller doses are well tolerated. Care needs to be exercised in determining more fully the possible harmful effect of ingesting considerable amounts of sugar alcohols, before their general use as food additives is accepted. 

Mannitol is a major component of the exudates ( manna ) of a range of trees including Fraxinus ornus (Oleaceae), Olea europaea (Oleaceae), Alhagi camelo-rum (Leguminosae), Myoporum platycarpum (Myoporaceae) (8, 12, 38). Mannitol was formerly used as a mild laxative. The manna that sustained the migration of the Israelites to Palestine in biblical times is reputed to have been composed of raffinose. 

Mannitol Diffusion Ptirtially utilized by liver Low Slightly cariogenic and laxative... 

The D-glucitol contents in some common fruits and vegetables are given in Table. 4.8. For example, rowan berries, together with the main hexitol D-glucitol, also contain D-mannitol and D-iditol. Prunes have a higher amount of glucitol, and for this reason they are used in various laxative preparations. 

The most important hexitols are o-glucitol and D-mannitol. The most important pentitol is xyhtol. The relative sweetness of both hexitols (in 10% solutions) and xyhtol, compared with saccharose, is about 60 and 100%, respectively. AU three polyols have very Kttle effect on blood glucose level and are therefore used as sweeteners for diabetics. However, their content must be included in the total energy intake. They exhibit mild laxative effects (such as prunes, which contain higher amounts ofglucitol than other fruits). 

The hygroscopic nature of polyols makes them effective osmotic laxatives since they retain water in the bowel thus softening faeces. Hie polyol, lactitol (Fig. 5.7), is even more effective for this purpose since it is not absorbed by the intestine and passes straight through to the bowel. Mannitol is used in infusions in order to treat cerebral oedema by drawing water away from brain tissue, e.g. due to the effects of high altitude. 

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