Sustained-release dosage forms are prepared to achieve a desirable and predictable phamacodynamic response within appropriate pharmacokinetic parameters, improve patient compliance, reduce side effects, and maximize drug efficacy (1). Creating drug-embedded matrix tablets using direct compression of a blend of drug, retardant material, and additives is one of the simplest approaches for a formulation. One of the most commonly used methods of modulating drug release is including polymeric material within a matrix system. Matrix systems are important because of their simplicity, low cost, the small influence of physiological variables on their release behavior, and their suitability for manufacture on modern high-speed equipment. (2)
Drug-release retarding polymers are the key performers in matrix systems. Various polymers have been investigated as drug retarding agents, each presenting a different approach to the matrix system. Based on the features of the retarding polymer, matrix systems are usually classified into three main groups: hydrophilic, hydrophobic, and plastic. Hydrophilic polymers are the most suitable for retarding drug release, and there is growing interest in using these polymers in sustained drug delivery (3–5).
In India, natural gums and mucilage are well known for their medicinal use. They are widely used in the pharmaceutical industry as thickeners, water-retention agents, emulsion stabilizers, gelling agents, suspending agents, binders, film formers, and sustained-release agents. They also are used in cosmetics, textiles, paints, and paper-making. Demand for these substances is increasing, and new sources are being developed. India, because of its geographical and environmental position, has traditionally been a good source for such products among the Asian countries. Still, large quantities are imported from Europe to meet increasing demand. Natural gums and mucilage are preferred to semisynthetic and synthetic excipients because of their lack of toxicity, low cost, availability, soothing action, and nonirritant nature. (6–9).Mucilages are normal plant-cell constituents that exist in specialized histological formations such as cells or canals that are common in the external tegument of seeds. Many plants contain mucilage, which provides high concentration of complex polysaccharides. Mucilages are hydrophilic polymers (10).
The mucilage from Aloe barbadensis Miller (A. barbadensis), also known as curacao aloes (liliaceae), is obtained from the dried juice of the leaves. It is commonly known as aloe, musabbar, and kumari (gujarati). The principal active component is aloin, which is a mixture of barbaloin, isobarbaloin, aloe emodin, and resins. It also contains aloetic acid, galactouronic acid, glucosamine, monosaccharides, and polysaccharides. It is used as a purgative and is also used to heal wounds, burns, and to treat eczema and disturbed menstruation. In cosmetics, it is used to manufacture shampoos and conditioners. (11, 12).
Diclofenac sodium is a potent nonsteroidal anti-inflammatory drug that has anti-inflammatory, analgesic, and antipyretic properties. It is used to treat degenerative joint diseases such as rheumatoid arthritis, osteoarthritis, and ankylosing spondilitis. Diclofenac sodium is rapidly dissolved in intestinal fluid and reaches its maximum blood concentration (C max ) within 30 min. It is metabolized mainly by hepatic hydroxylation and subsequent conjugation (13). In healthy human volunteers, mean plasma clearance of diclofenac sodium was 16 L/h, and the mean elimination half-life of the terminal phase was 1.2–1.8 h (14). To diminish diclofenac sodium gastrointestinal irritation, which is a common problem with all nonsteroidal anti-inflammatory agents, effective enteric-coated dosage forms are used. Food, however, effectively delays the absorption of the drug, which causes a nonreproducible pharmacokinetic profile, and the drug has no immediate therapeutic effect (15).
A. barbadensis is available locally in India in large quantities and has not been explored as a pharmaceutical excipient. The goal of this research was to extract mucilage from the leaves of A. barbadensis and to study the various pharmaceutical properties of the mucilage to assess its functionality as an excipient in pharmaceutical sustained-release formulations.
Materials. Diclofenac sodium was obtained as a gift sample from Beacon Pharmaceuticals (Ahmedabad, India). The leaves of A. barbadensis were taken from the medicinal garden of C.K. Pithawala Institute of Pharmaceutical Science and Research in Surat, India. The plant was authenticated at the Bioscience Department of Veer Narmad South Gujarat University in Surat, India. Guar gum, isapgulla husk, Aerosil (colloidal silica), lactose IP, and sodium carboxymethylcellulose (sodium CMC) were procured from CDH (Mumbai, India). All other chemicals used were analytical-reagent grade.