Nonproprietary Names

USP:Attapulgite

Synonyms

Actapulgite; Attaclay; Attacote; Attagel; attapulgus; palygorscite; palygorskite; Pharmsorb Regular.

Chemical Name and CAS Registry Number

Attapulgite [12174-11-7]

Empirical Formula and Molecular Weight

Attapulgite is a purified native hydrated magnesium aluminum silicate consisting of the clay mineral palygorskite, with the empirical formula Mg(Al0.5–1Fe0–0.5)Si4O10(OH)4H2O.

Structural Formula

See Section 4.

Functional Category

Adsorbent.

Applications in Pharmaceutical Formulation or Technology

Technology Attapulgite is widely used as an adsorbent in solid dosage forms. Colloidal clays (such as attapulgite) absorb considerable amounts of water to form gels and in concentrations of 2–5% w/v usually form oil-in-water emulsions. Activated attapulgite, which is attapulgite that has been carefully heated to increase its absorptive capacity, is used therapeutically as an adjunct in the management of diarrhea.

Description

Attapulgite occurs as a light cream colored, very fine powder. Particle size ranges depend on the grade and manufacturer.

Pharmacopeial Specifications

See Table I. See also Section 17. Table I: Pharmacopeial specifications for attapulgite. Test BP 2009 Identification Characters Acidity or alkalinity (5% w/v aqueous suspension) þ þ 7.0–9.5 Adsorptive capacity 5–14% Arsenic 48 ppm Heavy metals 420 ppm Acid-insoluble matter 412.5% Water-soluble matter 40.5% Loss on drying 417.0% Loss on ignition 15.0–27.0%

Typical Properties

Acidity/alkalinity pH = 9.5 (5% w/v aqueous suspension) Angle of repose 37.2–45.28(1) Density 2.2g/cm3 Density (tapped) 0.33 g/cm3 (1) Flowability 20.9–29.6% (Carr compressibility index)(1) Particle size distribution <2mm in size for powder; 2–5mm in size for aggregate.(1)

Stability and Storage Conditions

Attapulgite can adsorb water. It should be stored in an airtight container in a cool, dry, location.

Incompatibilities

Attapulgite may decrease the bioavailability of some drugs such as loperamide(2) and riboflavin.(3) Oxidation of hydrocortisone is increased in the presence of attapulgite.(4)

Method of Manufacture

Attapulgite occurs naturally as the mineral palygorskite.

Safety

Attapulgite is widely used in pharmaceutical formulations and is generally regarded as an essentially nontoxic and nonirritant material. It is not absorbed following oral administration. In oral preparations, activated attapulgite up to 9 g is used in daily divided doses as an adjunct in the management of diarrhea.(5) LD50 (rat, IP): 0.34g/kg

Handling Precautions

Observe normal precautions appropriate to the circumstances and quantity of material handled. Eye protection, gloves, and a dust mask are recommended. Attapulgite should be handled in a wellventilated environment and dust generation should be minimized. When heated to decomposition, attapulgite emits acrid smoke and irritating fumes.

Regulatory Status

Included in nonparenteral medicines licensed in a number of countries worldwide including the UK and USA. 17 Related Substances Activated attapulgite; magnesium aluminum silicate. Activated attapulgite Comments Activated attapulgite is a processed native magnesium aluminum silicate that has been carefully heated to increase its adsorptive capacity. Monographs for activated attapulgite are included in the BP 2009, USP 32, and other pharmacopeias. The USP 32 also includes a monograph for colloidal activated attapulgite.

Comments

The EINECS number for attapulgite is 302-243-0. 19 Specific References 1 Viseras C, Lo´pez-Galindo A. Characteristics of pharmaceutical grade phyllosilicate powders. Pharm Dev Technol 2000; 5(1): 47–52. 2 Mboya SA, Bhargava HN. Adsorption and desorption of loperamide hydrochloride by activated attapulgites. Am J Health Syst Pharm 1995; 52: 2816–2818. 3 Khalil SAH et al. Effect of attapulgite on the bioavailability of a model low dose drug (riboflavine) in humans. Drug Dev Ind Pharm 1987; 13: 369–382. Attapulgite 4 Cornejo J et al. Oxidative degradation of hydrocortisone in the presence 21 Author of attapulgite. J Pharm Sci 1980; 69: 945–948. 5 Sweetman SC, ed. Martindale: The Complete Drug Reference, 36th A Palmieri. edn. London: Pharmaceutical Press, 2009; 1709.

General References

Anonymous. The silicates: attapulgite, kaolin, kieselguhr, magnesium trisilicate, pumice, talc. Int J Pharm Compound 1998; 2(2): 162–163.

Date of Revision

Viseras C et al. Characteristics of pharmaceutical grade phyllosilicate compacts. Pharm Dev Technol 2000; 5(1): 53–58. 10 February 2009.