Pharmacopoeias. In Europe. Also in USNF.
European Pharmacopoeia, 6th ed. (Guar). Guar is obtained by grinding the endosperms of the seeds of Cyamopsis tetragonolobus. It consists mainly of guar galactomannan. Guar is a white or almost white powder, yielding a mucilage of variable viscosity when dissolved in water. Practically insoluble in alcohol.
European Pharmacopoeia, 6th ed. (Guar Galactomannan). A yellowish-white powder. It is soluble in cold and hot water practically insoluble in organic solvents. Its main components are polysaccharides composed of D-galactose and D-mannose at molecular ratios of 1:1.4 to 1:2. The molecules consist of a linear main chain of β-(1 —>4)-glycosidically linked mannopyranoses and single α-(1 —>6)-glycosidically linked galactopyranoses.
The United States Pharmacopeia 31, 2008, and Supplements 1 and 2 (Guar Gum). A gum obtained from the ground endosperms of Cyamopsis tetragonolobus (Leguminosae). It consists chiefly of a high-molecular-weight hydrocolloidal polysaccharide, a galactomannan, composed of galactan and mannan units combined through glycosidic linkages. It is a white to yellowish-white, practically odourless, powder. Dispersible in hot or cold water forming a colloidal solution.
Adverse Effects and Precautions
Guar gum can cause gastrointestinal disturbance with flatulence, diarrhoea, or nausea, particularly at the start of treatment.
Because guar gum swells on contact with liquid it should always be washed down carefully with water and should not be taken immediately before going to bed. It should not be used in patients with dysphagia, oesophageal disease, or intestinal obstruction.
Interactions
Guar gum may retard the absorption of other drugs where this is likely to pose a problem the other drug should be taken at least an hour before guar gum.
Uses and Administration
Guar gum is used in diabetes mellitus as an adjunct to treatment with diet, insulin, or oral antidiabetics since it results in some reduction in both postprandial and fasting blood-glucose concentrations. It is given with or immediately before meals in doses of 5 g usually 3 times daily. Adverse gastrointestinal effects may be reduced by using a lower initial dose of 5 g once daily before breakfast for 1 week, then increasing to 5 g twice daily, then 3 times daily, as required. Each dose of guar gum granules should be taken stirred in about 200 mL of a cold drink. Alternatively it can be sprinkled over or mixed with food which must be taken with about 200 mL of fluid.
Guar gum is also used to slow gastric emptying in some patients with the dumping syndrome. It is also used as an adjunct in the treatment of hyperlipidaemias.
Guar gum is also used as a thickening and suspending agent, and as a tablet binder. It has been incorporated into processed foods.
Guar gum is an example of a soluble fibre. On contact with water it forms a highly viscous gel, the viscosity of which varies with such factors as its plant source or the form in which it is given.
Fibres such as guar gum reduce postprandial and fasting blood-glucose concentrations as well as plasma-insulin concentrations in healthy subjects and diabetic patients. Such reductions in blood-glucose concentrations and in glycosylated haemoglobin have been demonstrated in both type 1 and type 2 diabetes, but they have generally been small. Possible mechanisms for these effects of guar gum include a delay in gastric emptying, decreased small-bowel motility, decreased glucose absorption resulting from increased viscosity of the contents of the gastrointestinal tract, or inhibition of gastrointestinal hormones.
Guar gum also lowers serum total cholesterol and low-density -lipoprotein (LDL) cholesterol concentrations high-density-lipoprotein (HDL) cholesterol and triglyceride concentrations appear to be unaffected. The most likely mechanism is binding of bile acids, reducing their enterohepatic circulation in a similar way to bile-acid sequestrants. When used alone in patients with hype rcholesterolaemia guar gum has generally produced a modest reduction in plasma-cholesterol and LDL-cholesterol concentrations although some studies have been unable to demonstrate an effect. A few studies have suggested that the cholesterol-lowering effect is attenuated after 8 to 12 weeks of treatment but a long-term study observed a 17% decrease in total serum cholesterol that was maintained for 24 months. Some studies have shown further reductions in cholesterol and LDL-cholesterol concentrations on addition of guar gum to therapy with other li-pid regulating drugs. The usual treatment of hyper lip idaemias is discussed.
There have been suggestions that guar gum reduces appetite by promoting a feeling of fullness, but a meta-analysis has indicated that it is not effective for reducing body-weight. Products containing guar gum have, however, been promoted as slimming aids. Their use cannot be advocated because of the risk of tablets swelling before reaching the stomach and causing oesophageal obstruction.
Preparations
Proprietary Preparations
Argentina: Regudigl
Australia: Benefiber †
Brazil: Benefiber † Biofiber †
Finland: Guarem
Germany: Figur-Verlan Guar Verlan
Hong Kong: Guarem
Ireland: Guarem †
Italy: Novafibra
New Zealand: Guarcol
Spain: Fibraguar Plantaguar
Switzerland: Leiguar
UK: Resource Benefiber
USA: Benefiber
Multi-ingredient
France: Carres Parapsyllium Moxydar Mucipulgite Mulkine Seroxydar
Italy: Cruscasohn Resource Gelificata
Switzerland: Mucipulgite