Polycarbophil

Polycarbophils are polymers of acrylic acid crosslinked with divinyl glycol. The molecular weight of these polymers is theoretically estimated to range from 700 000 to 3-4 billion. However, there are no methods currently available to measure the actual molecular weight of a crosslinked (i.e. three-dimensional) polymer of this type. 

Adsorbent bioadhesive controlled-release tablet binder emulsifying agent thickening agent suspending agent. 

Polycarbophil occurs as fluffy, white to off-white, mildly acidic polymer powder with slightly acetic odor. 

Conventionally, polycarbophil is used as a thickening agent at very low concentrations (less than 1 %) to produce a wide range of viscosities and flow properties in topical lotions, creams, and gels, in oral suspensions, and in transdermal gel reservoirs. It is also used as an emulsifying agent in topical oil-in-water systems. 

Dissociation constant pK = 6.0 0.5 Equilibrium moisture content 8-10% (at 50% relative humidity) 

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Polycarbophil binds free water and, therefore, increases the fluidity of stools. It is most active in the slightly acid or alkaline medium of the small... 

Attapulgite adsorbs excess fluid in the stool with few adverse effects. Calcium polycarbophil is a hydrophilic polyacrylic resin that also works as an adsorbent, binding about 60 times its weight in water and leading to the formation of a gel that enhances stool formation. Neither attapulgite nor polycarbophil is systemically absorbed. Both products are effective in reducing fluid in the stool but can also adsorb nutrients and other medications. Their administration should be separated from other oral medications by 2 to 3 hours. Psyllium and methylcellulose products may also be used to reduce fluid in the stool and relieve chronic diarrhea. 

Calcium polycarbophil Adults 1000 mg 4 times daily or after each loose stool, not to exceed 12 tablets per day Children ages 6-12 500 mg 3 times daily Children ages 3-6 500 mg twice daily ... 

Polycarbophil 2 tabs one to four times daily First-line agent... 

Figure 5. Release of insulin from lightly crosslinked (Polycarbophil) and 5 mol% crosslinked poly(acrylic acid).

CM Lehr, YH Lee, VHL Lee. (1994). Improved ocular penetration of gentamicin by mucoadhesive polymer polycarbophil in the pigmented rabbit. Invest Ophthalmol Vis Sci 35 2809-2814. 

Polycarbophil 500 mj/tablet Chew 2 tablets four times daily or after each loose stool do not exceed 12 tablets/day... 

Leitner VM, Guggi D, Bernkop-Schnurch A (2004) Thiomers in noninvasive polypeptide delivery in vitro and in vivo characterization of a polycarbophil-cysteine/glutathione gel formulation for human growth hormone. J Pharm Sci 93 1682-1691. 

Lehr et al. [61] investigated two gentamiein formulations of polycarbophil (neutralized vs. nonneutralized) to pigmented rabbit eye. Both polymeric formulations doubled the uptake of gentamiein by the bulbar conjimctiva. 

Conventional vaginal delivery systems include tablets, foams gels, suspensions, and pessaries. Mucoadhesive gel formulations based on polycarbophil have been reported to remain 3 to 4 days at the vaginal tissue, providing an excellent vehicle for the delivery of progesterone and nonoxynol-9 [66]. 

Mussel adhesive protein (MAP) is a 130-kDa protein produced by the blue mussel Mytilus edulis), which provides strong adhesion to submerged surfaces. MAP films were prepared by drying and stored under nitrogen atmosphere. These films showed twice the adhesion strength of polycarbophil when tested on porcine duodenum in vitro [95]. 

LueBen, H.L., Verhoef, J.C., Borchard, G., Lehr, C.-M., De Boer, A.G., and Junginger, H.E., Mucoadhesive polymers in peroral peptide drug delivery. II. Carbomer and polycarbophil are potent inhibitors of the intestinal proteolytic enzyme trypsin, Pharm. Res., 12 1293-1298 (1995). 

In vivo methods, which are few, measure the residence time of bioadhesives at the application site [47]. Techniques like y-scintigraphy, the perfused intestinal loop and radiolabeled transit studies using Cr-labeled bioadhesive polymer [48] and Tc-labeled polycarbophil [49] have been employed for this purpose. 

A novel concept of using bioadhesive polymers as enzyme inhibitors has been developed [97]. Included are derivatives of poly acrylic acid, polycarbophil, and car-bomer to protect therapeutically important proteins and peptides from proteolytic activity of enzymes, endopeptidases (trypsin and a-chymotrypsin), exopeptidases (carboxypeptidases A and B), and microsomal and cytosolic leucine aminopeptidase. However, cysteine protease (pyroglutamyl aminopeptidase) is not inhibited by polycarbophil and carbomer [97]. 

Psyllium Useful in patients with irritable bowel syndrome and diverticular disease. Polycarbophil For constipation or diarrhea associated with conditions such as irritable bowel syndrome and diverticulosis acute nonspecific diarrhea. 

Hydrophilic substances such as calcium polycarbophil (FiberCon, Equalactin), methylceUulose (Citrucel), and various psyllium seed derivatives (Metamucil) are natural or synthetic fiber supplements that bind water and bile salts and may be useful in controlling diarrhea associated with the passing of excessively watery stools. 

The bulk-forming laxative group includes the hydrophilic substances described previously calcium polycarbophil FiberCon, Equalactin), methylcellulose Citrucel), and various psyllium seed derivatives Metamucil). All act by increasing the bulk of the feces, part of this action being due to their capacity to attract water and form a hydrogel. The increased volume of feces stretches the walls of the GI tract and stimulates peristalsis. Their action may not be evident for 2 to 3 days after starting treatment. Because their use results... 

Porter, and J. S. Fordtran. Effect of psyllium, calcium polycarbophil, and wheat bran on secretory diarrhea induced by phenolphthalein. Gastroenterology 1993 104(4) 1007-1012. Colliopoulos, J. Psyllium-based laxative compositions. Patent-US-5,232, 699 1993 6 p. 

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. 

Polycarbophil. Polycarbophil [73038-24-1] (copolymer of acrylic acid and divinyl glycol (l,5-hexadiene-3,4-diol [1069-23-4])) consists of white-to-creamy white granules having a slight ester-like odor. It swells to contain a maximum of 1.5% water, but is insoluble in water and most organic solvents. It is prepared by copolymerization of acrylic acid and divinyl glycerol in a hot salt slurry using azobisisobutyronitrile as the initiator. 

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