โ Scribed by D. D. McCollister; F. Oyen; G. K. Greminger Jr.
No coin nor oath required. For personal study only.
Patents, published literature, and commercial usage have established the utility of the propylene glycol ether of methylcellulose (hydroxypropyl methylcellulose) as a food additive and as a formulation aid inadrug products. Aqueous solutions of this cellulose gum, like methylcellulose, will gel upon heating. Feeding studies on Methocel, Methocel GOHG, and Methocel 65HG have previously been published. The results of feeding Methocel 70HG and Methocel 90HG in the diet of rats at levels of 0.3, 1.0, 3.0, 10.0, and 20.0 per cent for periods of ninety and eightyfour days, respectively, confirm previous chronic oral toxicity studies that the propylene glycol ether of methylcellulose is extremely low in repeated oral toxicity and that it can be used safely in the drug, food, and pharmaceutical fields where Methocel and Methocel65HG have been found suitable.
UMSHAVE BEEN used in food and drug prepa-G rations since earliest times. The first products were of natural origin and were used in either the "as found" or isolated states. Advancing technology has required more rigid control of gum properties and, in addition, has created a demand for products of increased utility. Methylcellulosel and its modification, propylene glycol ether of methylcellulose (hydroxypropq'l methylcellulose) have provided combinations of gum properties which have greatly expanded the industrial use of synthetic gums.
The propylene glycol ether of methylcellulose is a water-soluble ether of cellulose containing both methyl and propylene glycol ether groups attached to the anhydroglucose ring of cellulose. The propylene glycol ether of methylcellulose may also be described as hydroxypropyl methylcellulose.
The polymeric backbone of the propylene glycol ether of methylcellulose is provided by cellulose. The repeating structural unit of the cellulose chain is the anhydroglucose unit:
1 This anhydroglucose unit contains one primary hydroxyl group in the 6-position and two secondary hydroxyl groups in the 2-and 3-positions. Thus, the propylene glycol ether of methylcellulose is fundamentally a carbohydrate
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