Medically reviewed by Drugs.com. Last updated on April 22, 2021.
Scientific Name(s): Hydrated aluminum silicate., Kaolin.
Common Name(s): Argilla, Bolus alba, China clay, Heavy or light kaolin, Porcelain clay, White bole
Drug class: Antidiarrheals
Kaolin has traditionally been used internally to control diarrhea. Kaolin has also been used topically as an emollient and drying agent. Specifically, it has been used to dry oozing and weeping poison ivy, poison oak, and poison sumac lesions. It has also been used as a protectant for the temporary relief of anorectal itching and diaper rash.
Diarrhea: 12 years of age and older: 26.2 g after each loose stool every 6 hours until firm stool; do not exceed more than 262 g per 24 hours; do not use longer than 2 days. Younger than 12 years of age: seek advice from physician. Diaper rash: 4% to 20% kaolin-containing products applied topically. Radiation- and chemotherapy-induced mucositis: 15 mL of kaolin/pectin and diphenhydramine in a 50:50 mixture; hold in mouth for 3 minutes.
Contraindications have not yet been identified.
FDA Pregnancy: Category C. Kaolin does not cross the placenta. There are no data regarding kaolin in breast-feeding.
Kaolin pectin may decrease the absorption of drugs that chelate with aluminum salts (eg, digoxin, clindamycin, lincomycin). Until more information is available, avoid taking kaolin with drugs that chelate with aluminum. It may also decrease the absorption of trimethoprim and quinidine.
Inhalation of kaolin through occupational exposure may cause pneumoconiosis.
Inhalation may predispose miners to pulmonary diseases.
Kaolin is a hydrated aluminum silicate. It occurs naturally as a clay that is prepared for pharmaceutical purposes by washing with water to remove sand and other impurities.(1)
Kaolin has been used commercially and medicinally for hundreds of years. It is currently used in the manufacture of pottery, bricks, cement, ceramics, paints, plastering material, color lakes (insoluble dyes), and insulators. As a raw material, it is commonly found in paper, plastics, cosmetics, and pharmaceuticals2 and it is also used in pharmaceutical preparations as a filtering agent to clarify liquids. Evidence also suggests that kaolin may be useful in the decolorization of dye wastewater via the electrocoagulation method.3 When applied topically, it serves as an emollient and drying agent. When ingested, it acts as an adsorbent to bind GI toxins and control diarrhea.
Kaolin has been added to dusting powders and is used as a tablet excipient.
Kaolin has the approximate chemical formula of H2Al 2Si2O8 (H2O) and is a white or yellow-white powder that has a slightly oily feel. It is an environmentally benign aluminosilicate mineral4 that is insoluble in water.1 Light kaolin is the preferred material for use in pharmaceutical preparations. The finely divided particles yield a very large surface area that adsorbs a wide variety of compounds.
Uses and Pharmacology
Antidiarrheal preparations containing kaolin have been used in the treatment of enteritis, cholera, and dysentery. Kaolin preparations, however, have no intrinsic antibacterial activity and should not be used as the sole treatment in infectious diarrheas. When given orally, kaolin, especially light kaolin, adsorbs substances from the GI tract and increases the bulk of feces. Kaolin improves stool consistency within 24 to 48 hours; however, it does not decrease the number of stools passed or reduce the amount of fluids lost.7, 8 Data regarding the effects of kaolin on travelers' diarrhea are lacking.9
Kaolin has been recognized as a coagulation activator and has been incorporated into various laboratory testing to measure activated clotting time (ACT)10, used to guide heparin anticoagulation to prevent thrombosis, and reduce inflammation.11
Venezuelan kaolin was tested in the presence of hydrochloric acid and pepsin in order to determine its neutralization capacity. Achievement of normal gastric pH occurred with 250 mg of the modified kaolin clay compared with 400 mg of original clay, leading to the conclusion that modified kaolin clay might be useful as a cheap and effective antacid.15
Kaolin has been used in the serodiagnosis of tuberculosis using the kaolin agglutination test (KAT).19 Kaolin has also been used experimentally to induce hydrocephalus in animal models in order to assess the effects of the condition on sensorimotor development.20 Additionally, kaolin has been studied for its effects when testing horse serum for seroconversion against equine influenza virus, which causes a major respiratory disease among horses.21
One small study suggested that the addition of kaolin to oil field wastewater can result in removal of chemical oxygen demand, removal of scaling ions, such as iron, calcium, and magnesium, improvement in membrane filter index, bacteriocidal effects, and inhibition of corrosion.22
12 years of age and older
26.2 g after each loose stool every 6 hours until firm stool; do not exceed more than 262 g per 24 hours; do not use longer than 2 days.23
Younger than 12 years of age
Seek advice from physician.23
4% to 20% kaolin-containing products can be applied topically.5
Radiation- and Chemotherapy-Induced Mucositis
15 mL of kaolin/pectin and diphenhydramine in a 50:50 mixture; hold in mouth for 3 minutes.24
Pregnancy / Lactation
Because kaolin-containing preparations are not systemically absorbed and do not cross the placenta, kaolin is listed as Pregnancy Category C. However, there is a possible association between kaolin ingestion and the development of iron deficiency anemia and hypokalemia, especially during pregnancy.25, 26
In a small study of female rats, hemoglobin, hematocrit, and red blood cell levels were reduced in the groups of rats that ingested a kaolin-containing diet. Additionally, the pups born to these rats exhibited low birth weights.27
There are no human data regarding breast-feeding and kaolin usage.25
Most drug interaction studies of kaolin have involved administration of kaolin pectin. Kaolin pectin can form insoluble complexes with a number of drugs and should be avoided in patients receiving drugs that may chelate with aluminum salts (eg, digoxin28, 29, 30 clindamycin31 lincomycin32 and penicillamine33. Until more information is available, interactions that occur with kaolin pectin should be considered to occur with kaolin alone. Additionally, concomitant administration of kaolin pectin and trimethoprim resulted in a reduced area under the curve for trimethoprim and decreased the average blood concentration of trimethoprim by 29.42%.34 An in vitro study suggests that quinidine absorption may be reduced with concomitant administration of kaolin-pectin preparations.35 To avoid potential drug interactions, kaolin should be used at least 3 hours before or after any other medications.36 When used topically for anorectal itching, petrolaturm or greasy ointments should be removed before applying kaolin-containing products in order to allow for proper adherence to the skin. Additionally, cocoa butter, cod liver oil, hard fat, lanolin, mineral oil, shark liver oil, petrolaturm, or white petrolaturm cannot be combined with kaolin because of limited skin adherence.7
Kaolin is highly insoluble and is not absorbed systemically. Therefore, it is not generally associated with severe toxicity. The toxicology of clays including kaolin used in food packaging has been reviewed, with no clear evidence of systemic toxicity reported.39
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