Gums and mucilages/Asian Journal of Pharmaceutical Sciences 2009, 4 (5): 308-322
`
`Gums and mucilages: versatile excipients
`for pharmaceutical formulations
`Girish K Jania, Dhiren P Shahb, *, Vipul D Prajapatia, Vineet C Jainb
`aS S R College of Pharmacy, Silvassa, India
`bC K Pithawalla Institute of Pharmaceutical Science and Research, Surat, Gujarat, India
`Received 4 November 2008; Revised 9 January 2009; Accepted 24 September 2009
`_____________________________________________________________________________________________________________
`
`Abstract
`
`Nature has provided us a wide variety of materials to help improve and sustain the health of all living things either directly or indirectly.
`In recent years there have been important developments in different dosage forms for existing and newly designed drugs and natural
`products, and semi-synthetic as well as synthetic excipients often need to be used for a variety of purposes. Gums and mucilages are
`widely used natural materials for conventional and novel dosage forms. These natural materials have advantages over synthetic ones
`since they are chemically inert, nontoxic, less expensive, biodegradable and widely available. They can also be modified in different
`ways to obtain tailor-made materials for drug delivery systems and thus can compete with the available synthetic excipients. In this
`review, we describe the developments in natural gums and mucilages for use in the pharmaceutical sciences.
`
`Keywords: Natural polysaccharide; Natural gum; Pharmaceutical application
`_____________________________________________________________________________________________________________
`
`1. Introduction
`
`Robbins has stated, "in spite of the problems
`which have beset the gums market in recent years, the
`fact remains that in many cases the gums provide a
`valuable source of income for many poor smallholders
`or itinerant labourers, either in very poor countries
`or in the poorest regions rather than more developed
`countries as such they are important commodities
`..." [1]. This remains true today. Tens of thousands of
`people worldwide, living in regions ranging from semi-
`arid deserts to rainforests, depend on the collection of
`gums, resins and latexes in order to provide them with
`an income. Equally, many millions of people around the
`world make use of these products in their everyday life [1].
`Mother nature has gifted India with great variety of
`flora and fauna. For centuries man has made effective
`use of materials of natural origin in the medical and
`
`__________
`*Corresponding author. Address: Dhiren P Shah, C K Pithawalla
`Institute of Pharmaceutical Science and Research, Via Magdalla
`Port, Nr. Malvan Mandir, Dumas Road, Gavior Gam, Surat. PIN
`–395007, Gujarat, India.
` Tel.: +91-261-6587286; Fax: +91-261-2723999
` E-mail: dhirenpshah1@gmail.com
`
`
`pharmaceutical field. Today, the whole world is increas-
`ingly interested in natural drugs and excipients. Natural
`materials have advantages over synthetic materials
`because they are non toxic, less expensive and freely
`available. Furthermore, they can be modified to
`obtain tailor made materials for drug delivery systems
`allowing them to compete with the synthetic products
`that are commercially available. Many kinds of natural
`gums are used in the food industry and are regarded as
`safe for human consumption. It should be noted that
`many ‘old’ materials are still popular today after almost
`a century of efforts to replace them. It is usual to strike
`a balance between economics and performance in the
`face of commercial realities [2-5].
`
`2. What are gums and mucilages?
`
`Gums are considered to be pathological products
`formed following injury to the plant or owing to unfavor-
`able conditions, such as drought, by a breakdown of
`cell walls (extra cellular formation; gummosis) while,
`mucilages are generally normal products of metabolism,
`formed within the cell (intracellular formation) and/or
`are produced without injury to the plant.
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`Gums readily dissolve in water, whereas, mucilage
`form slimy masses.
`Gums are pathological products, whereas mucilages
`are physiological products [6]. Acacia, tragacanth, and
`guar gum are examples of gums while mucilages are
`often found in different parts of plants. For example, in
`the epidermal cells of leaves (senna), in seed coats (linseed,
`psyllium), roots (marshmallow), barks (slippery elm)
`and middle lamella (aloe) [7].
`Gums and mucilages have certain similarities—both
`are plant hydrocolloids. They are also translucent amor-
`phous substances and polymers of a monosaccharide or
`mixed monosaccharides and many of them are combined
`with uronic acids. Gums and mucilages have similar
`constituents and on hydrolysis yield a mixture of
`sugars and uronic acids. Gums and mucilages contain
`hydrophilic molecules, which can combine with water
`to form viscous solutions or gels. The nature of the
`compounds involved influences the properties of differ-
`ent gums. Linear polysaccharides occupy more space
`and are more viscous than highly branched compounds
`of the same molecular weight. The branched compounds
`form gels more easily and are more stable because
`extensive interaction along the chains is not possible.
`
`3. Disadvantages of synthetic polymers in pharma-
`ceutical sciences
`
`The synthetic polymers have certain disadvantages
`such as high cost, toxicity, environmental pollution
`during synthesis, non-renewable sources, side effects,
`and poor patient compliance.
`Acute and chronic adverse effects (skin and eye
`irritation) have been observed in workers handling
`the related substances methyl methacrylate and poly-
`(methyl methacrylate) (PMMA) [8].
`Reports of adverse reactions to povidone primarily
`concern the formation of subcutaneous granulomas
`at the injection site produced by povidone. There is
`also evidence that povidone may accumulate in organs
`following intramuscular injections [9].
`Acute oral toxicity studies in animals have indicated
`that carbomer-934P has a low oral toxicity at a dose
`of up to 8 g/kg. Carbomer dust is irritating to the eyes,
`
`mucous membranes and respiratory tract. So, gloves,
`eye protection and dust respirator are recommended
`during handling [10].
`Studies in rats have shown that 5% polyvinyl alcohol
`aqueous solution injected subcutaneously can cause
`anemia and can infiltrate various organs and tissues [11].
`Some disadvantages of biodegradable polymers used
`in tissue engineering applications are their poor biocom-
`patibility, release of acidic degradation products, poor
`processing ability and rapid loss of mechanical properties
`during degradation. It has been shown that poly glyco-
`lides, polylactides and their co-polymers have an
`acceptable biocompatibility but exhibit systemic or local
`reactions due to acidic degradation products. An initial
`mild inflammatory response has been reported when
`using poly-(propylene fumarate) in rat implant studies [12].
`
`4. Advantages of natural gums and mucilages in
`pharmaceutical sciences
`
`The following are a number of the advantages of
`natural plant–based materials.
`Biodegradable—Naturally available biodegradable
`polymers are produced by all living organisms. They
`represent truly renewable source and they have no
`adverse impact on humans or environmental health (e.g.,
`skin and eye irritation).
`Biocompatible and non-toxic—Chemically, nearly
`all of these plant materials are carbohydrates composed
`of repeating sugar (monosaccharides) units. Hence, they
`are non- toxic.
`Low cost—it is always cheaper to use natural sources.
`The production cost is also much lower compared with
`that for synthetic material. India and many developing
`countries are dependent on agriculture.
`Environmental-friendly processing—Gums and
`mucilages from different sources are easily collected in
`different seasons in large quantities due to the simple
`production processes involved.
`Local availability (especially in developing countries)
`—In developing countries, governments promote
`the production of plant like guar gum and tragacanth
`because of the wide applications in a variety of
`industries.
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`Better patient tolerance as well as public acceptance—
`There is less chance of side and adverse effects with
`natural materials compared with synthetic one. For
`example, PMMA, povidone.
`Edible sources—Most gums and mucilages are
`obtained from edible sources.
`
`6.1. According to the charge
`
`
`Non-ionic seed gums: guar, locust bean, tamarind,
`xanthan, amylose, arabinans, cellulose, galactomannans.
`Anionic gums: arabic, karaya, tragacant, gellan, agar,
`algin, carrageenans, pectic acid.
`
`5. Disadvantages of natural gums and mucilages
`[13-14]
`
`6.2. According to the source
`
`Microbial contamination—The equilibrium moisture
`content present in the gums and mucilages is normally
`10% or more and, structurally, they are carbohydrates
`and, during production, they are exposed to the external
`environment and, so there is a chance of microbial con-
`tamination. However, this can be prevented by proper
`handling and the use of preservatives.
`Batch to batch variation—Synthetic manufacturing
`is a controlled procedure with fixed quantities of ingre-
`dients, while the production of gums and mucilages is
`dependent on environmental and seasonal factors.
`Uncontrolled rate of hydration—Due to differences
`in the collection of natural materials at different times,
`as well as differences in region, species, and climate
`conditions the percentage of chemical constituents
`present in a given material may vary. There is a need
`to develop suitable monographs on available gums and
`mucilages.
`Reduced viscosity on storage—Normally, when gums
`and mucilages come into contact with water there is an
`increase in the viscosity of the formulations. Due to the
`complex nature of gums and mucilages (monosaccharides
`to polysaccharides and their derivatives), it has been
`found that after storage there is reduced in viscosity.
`
`6. Classification of gums and mucilages [15-20]
`
`Gums and mucilages are present in high quantities
`in a varities of plants, animals, seaweeds, fungi and
`other microbial sources, where they perform a number
`of structural and metabolic functions; plant sources
`provide the largest amounts. The different available
`gums and mucilages can be classified as follows.
`
`Marine origin/algal (seaweed) gums: agar, carra-
`geenans, alginic acid, laminarin.
`Plant origin: (1) shrubs/tree exudates—gum arabica,
`gum ghatti, gum karaya, gum tragacanth, khaya and
`albizia gums; (2) seed gums—guar gum, locust bean
`gum, starch, amylose, cellulose; (3) extracts—pectin,
`larch gum; (4) tuber and roots—potato starch.
`Animal origin: chitin and chitosan, chondroitin sulfate,
`hyaluronic acid.
`Microbial origin (bacterial and fungal): xanthan,
`dextran, curdian, pullulan, zanflo, emulsan, Baker’s
`yeast glycan, schizophyllan, lentinan, krestin,
`scleroglucan.
`
`6.3. Semi-synthetic
`
`Starch derivatives—hetastarch, starch acetate, starch
`phosphates.
`Cellulose derivatives—carboxy methyl cellulose
`(CMC), hydroxy ethylcellulose, hydroxypropyl methyl-
`cellulose (HPMC), methylcellulose (MC), microcrystal-
`line cellulose (MCC).
`
`6.4. According to shape
`
`Linear: algins, amylose, cellulose, pectins.
`Branched: (1) short branches—xanthan, xylan,
`galactomanan; (2) branch-on-branch—amylopectin, gum
`arabic, tragacanth.
`
`6.5. According to manomeric units in chemical structure
`
`Homoglycans—amylose, arabinanas, cellulose; di-
`heteroglycans—algins, carragennans, galactomannans;
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`tri-heteroglycans—arabinoxylans, gellan, xanthan;
`tetra-heteroglycans—gum arabic, psyllium seed gum;
`penta-heteroglycans—ghatti gum, tragacanth.
`
`7. Applications of gums and mucilages
`
`Gums and mucilages of different sources and their
`derivatives represent a group of polymers widely used
`in pharmaceutical dosage forms. Various kinds of gums
`are used in the food industry and are regarded as safe
`for human consumption.
`However, there is growing concern about the safety of
`pharmaceutical excipients derived from natural sources.
`Plant gums and exudates are now screened for their use
`as pharmaceutical adjuvants. Mucilages of different
`origins are also used in conventional dosage forms of
`various drugs for their binding, thickening, stabilizing
`and humidifying properties in medicine. Newer uses of
`different gums and mucilages in cosmetics and textiles
`has increased the demand and screening of gums has
`become an important pharmaceutical area. However,
`different gums and mucilages used as pharmaceutical
`adjuvants have stringent specifications, which few
`natural agents can fulfill. Gums and mucilages have the
`following applications.
`
`7.1. Applications in the food industry
`
`Gums and mucilages have a variety of applications
`in the food industry [21]. Different gums have different
`uses like water retention and stabilizztion (guar and
`locust bean gum), stabilizers for ice-cream, meat
`products and instant pudding (carrageenanas), dairy,
`confectionary and meat products (agar), confectionary,
`beverages, backed product, and sauces (gum arabic,
`tragacanth, pectins, alginates and xanthan gum).
`
`7.2. Pharmaceutical applications
`
`Gums and mucilages have a variety of applications
`in pharmacy. They are used in medicine for their
`demulcent properties for cough supression. They are
`ingredients of dental and other adhesives and can be
`used as bulk laxatives. These hydrophilic polymers
`
`are useful as tablet binders, disintegrants, emulsifiers,
`suspending agents, gelling agents, stabilizing agents,
`thickening agents, film forming agents in transdermal
`and periodontal films, buccal tablets as well as
`sustaining agents in matrix tablets and coating agents in
`microcapsules including those used for protein delivery.
`Various gums and mucilages with their common names,
`biological sources, family and applications are listed in
`Table 1. Table 2 lists the different applications of gums
`and mucilages in novel drug delivery systems.
`
`7.3. Industrial uses
`
`Gums used in cosmetics (acacia, tragacanth and karaya
`gum), textiles (starch, dextrin, cellulose, pectins, and
`tamarind gum), adhesives (acacia gum, and tragacanth),
`lithography (gum arabic, tragacanth, and locust bean
`gum), paints (pectins, hemicellulose, and resins) and
`paper manufacturer (tamarind, and cellulose).
`
`8. Isolation and purification of gums/mucilages
`
`
`Plant material is dried in sunlight (preferably) or in
`an oven at 105˚C to retain its properties unchanged.
`Generally, chlorophyll or pigments are present in the
`plant which should be removed before isolating the
`mucilage. Plant material must be treated with petroleum
`ether and chloroform (to remove pigments and
`chlorophyll) and then with distilled water. Care should
`be taken when drying the final isolated/extracted
`mucilage. It must be dried at a very low temperature (not
`more than 50˚C) or in a vacuum. The dried material
`is stored carefully in desiccators to prevent further
`moisture uptake or degradation. The general isolation
`and purification processes for gums and mucilages are
`shown in Fig. 1.
`Baveja et al., [22] and Wahi et al., [23] reported
`the following method for the isolation of mucilage.
`The fresh plant materials were collected washed with
`water to remove dirt and debris, and dried. Then, the
`powdered material was soaked in water for 5–6 h,
`boiled for 30 min, and allows standing 1 h so that all the
`mucilage was released into the water. The material was
`then squeezed from an eight muslin bag to remove the
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`Table 1
`Pharmaceutical applications or uses of natural gums and mucilages.
`Common name
`Botanical name
`Family
`Abelmoschus
`Abelmoschus
`esculentus
`mucilage
`
`Malvaceae
`
`Pharmaceutical Applications
`
`Binder in tablets, Sustained release
`
`Reference
`
`34, 35
`
`Agar
`
`Gelidium amansii
`
`Gelidaceae
`
`Suspending agent, emulsifying agent, gelling agent in
`suppositories, surgical lubricant, tablet disintegrants,
`medium for bacterial culture, laxative
`
`Albizia gum
`Aloe mucilage
`
`Albizia zygia
`Aloe species
`
`Leguminoseae
`Liliaceae
`
`Asario mucilage
`
`Lepidum sativum
`
`Cruciferae
`
`Tablet binder
`Gelling agent, sustained release agent
`
`Suspending agent, emulsifying agent,
`controlled release tablet
`
`Bavchi mucilage
`
`Ocimum canum
`
`Labiatae
`
`Suspending agent, emulsifying agent
`
`Carrageenan
`
`Chondrus cryspus
`
`Gigarginaceae
`
`Gelling agent, stabilizer in emulsions and
`suspensions, in toothpaste, demulcent and laxative
`
`Cashew gum
`
`Cassia tora
`
`Fenugreek mucilage
`
`Guar gum
`
`Anacardium
`occidentale
`Cassia tora Linn
`Trigonella foenum
`graecum
`Cyamompsis
`tetraganolobus
`
`Anacardiaceae
`
`Leguminosae
`
`Leguminoseae
`
`Leguminoseae
`
`Gum acacia
`
`Acacia arabica
`
`Leguminoseae
`
`Gum ghatti
`
`Anogeissus latifolia Combretaceae
`
`Gum tragacanth
`
`Astragalus gummifer Leguminoseae
`
`Suspending agent
`
`Binding agent
`Gelling agent, tablet binder, sustaining agent,
`emollient and demulcent
`Binder, disintegrant, thickening agent, emulsifier,
`laxative, sustained release agent
`Suspending agent, emulsifying agent, binder in tablets,
`demulcent and emollient in cosmetics
`Binder, emulsifier, suspending agent
`
`Suspending agent, emulsifying agent, demulcent,
`emollient in cosmetics and sustained release agent
`
`36
`
`37
`38
`
`39, 40
`
`39
`
`41, 42, 43
`
`44, 45
`
`46
`
`22, 47, 48
`
`49, 50,
`51, 52
`
`53
`
`54
`
`55
`
`Hibiscus mucilage Hibiscus esculentus
`Linn
`Hibiscus mucilage Hibiscus rosasinensis
`Linn
`Plantago psyllium,
`Plantago ovata
`
`Ispagol mucilage
`
`Malvaceae
`
`Emulsifying agent, sustained release agent,
`suspending agent
`
`56, 57
`
`Malvaceae
`
`Suspending agent, Sustained release agent
`
`58, 59, 60
`
`Plantaginaceae
`
`Cathartic, lubricant, demulcent, laxative, sustaining
`agent, binder, emulsifying and suspending agent
`
`61, 62, 63,
`64, 65
`
`Karaya gum
`
`Sterculia urens
`
`Sterculiaceae
`
`Meliaceae
`
`Suspending agent, emulsifying agent, dental adhesive,
`sustaining agent in tablets, bulk laxative
`Binding agent
`Emulsifying agent, suspending agent, binder in tablets,
`disintegrating agent in tablets
`
`Khaya gum
`
`Leucaena seed gum
`
`Ocimum seed
`mucilage
`Pectin
`
`Khaya grandifolia
`Leucaena
`leucocephata
`Ocimum gratissimum
`Linn
`Citrus aurantium
`
`Labiatae
`
`Suspending agent, binding agent
`
`Rutaceae
`
`Thickening agent, suspending agent, protective agent
`
`Sodium alginate
`
`Macrocytis pyrifera
`
`Lessoniaceae
`
`Suspending agent, gelation for dental films,
`stabilizer, sustained release agent, tablet coating
`
`Satavari mucilage Asparagus racemosus Aapocynaceae
`
`Binding agent and sustaining agent in tablets
`
`3121
`
`11
`
`66, 67
`
`68
`69, 70, 71,
`72, 73
`
`74, 75
`
`76, 77
`79, 80, 81,
`82, 83
`78
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`Table 1
`Pharmaceutical applications or uses of natural gums and mucilages (Continued).
`
`Common name
`Tamarind seed
`polysaccharide
`
`Botanical name
`
`Family
`
`Tamarindus indica
`
`Leguminoseae
`
`Xanthan gum
`
`Gellan gum
`
`Xanthomonas
`lempestris
`Pseudomonas elodea
`
`---
`
`---
`
`Pharmaceutical applications
`Binding agent, emulsifier,
`suspending agent, sustaining agent
`Suspending agent, emulsifier, stabilizer in toothpaste
`and ointments, sustained release agent
`Disintegrating agent,
`
`Reference
`
`84
`
`66, 85
`
`86
`
`Table 2
`Applications of gums and mucilages in NDDS.
`
`Common name
`Acacia
`Bhara gum
`
`Botanical name
`Acacia Senegal
`Terminalia bellerica roxb
`
`Family
`Leguminosae
`Combretaceae
`
`Pharmaceutical applications
`Osmotic drug delivery
`Microencapsulation
`
`Chitosan
`
`—
`
`—
`
`Cordia gum
`
`Cordia obliqua willed
`
`Boraginaecae
`
`Colonspecific drug delivery, microspheres,
`carrier for protein as nanoparticles
`
`Novel oral sustainedrelease matrix
`forming agent in tablets
`
`Cactus mucilage
`
`Opuntia ficus-indica
`
`—
`
`Gelling agent in sustained drug delivery
`
`Guar gum
`
`Cyamompsis
`tetraganolobus
`
`Leguminoseae
`
`Colontargeted drug delivery,
`cross-linked microspheres
`
`Reference
`87, 88
`89
`
`90, 91
`
`92
`
`93
`
`94, 95, 96
`
`Gellan gum
`
`Pseudomonas elodea
`
`Hakea
`
`Hakea gibbosa
`
`—
`
`—
`
`Ophthalmic drug delivery, sustaining agent,
`beads, hydrogels, floating in-situ gelling,
`controlledrelease beads
`
`97, 98, 99, 100,
`101, 102
`
`Sustainedrelease and peptide mucoadhesive
`for buccal delivery
`
`103, 104
`
`105, 106,
`107, 108
`
`109
`110
`111
`
`112
`
`113, 114, 115,
`116, 117, 118,
`119, 120
`
`121
`
`Ispagol
`
`Karaya gum
`Locust bean gum
`Mucuna gum
`
`Plantago psyllium,
`Plantago ovata
`
`Sterculia urens
`Ceratania siliqua
`Mucuna flagillepes
`
`Plantaginaceae
`
`Sterculiaceae
`Leguminoseae
`Papillionaceae
`
`Hydrogels, colon drug delivery,
`gastroretentive drug delivery
`
`Mucoadhesive and buccoadhesive
`Controlledrelease agent
`Microspheres
`
`Okra
`
`Hibiscus esculentus
`
`Malvaceae
`
`Pectin
`
`Citrus aurantium
`
`Rutaceae
`
`Sodium alginate
`
`Macrocytis pyrifera
`
`Lessoniaceae
`
`Hydrophilic matrix for controlled
`release drug delivery
`Beads, floating beads, colon drug delivery,
`pelletization by extrusion/spheronization,
`microparticulate delivery, transdermal delivery,
`Iontophoresis, hydrogels
`Bioadhvesive microspheres,
`nanoparticles, microencapsulation
`
`Tamarind
`
`Tamarindus indica
`
`Leguminoseae
`
`Hydrogels, mucoadhesive drug delivery for
`ocular purposes, spheroids, nasal drug delivery
`
`122, 123
`
`Xanthan gum Xanthomonas lempestris
`
`—
`
`Pellets, controlled drug delivery system
`
`124, 125
`
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`marc from the solution. Following this, three volumes
`of acetone was added to the filtrate to precipitate the
`mucilage. The mucilage was separated, dried in an oven
`at a temperature less than 50˚C, and the dried powder
`was passed through a No. 80 sieve and stored in a
`
`Selection of part of plant for isolating gum/mucilage
`
`Steps for plant identification, characters
`and chemical tests are taken
`
`Take plant part in which gum/mucilage are
`present for drying, grinding and sieving.
`
`Dried gum/mucilage is stirred in distilled water and
`heated initially for complete dispersion in
`distilled water and keep for 6–8 h at room temperature.
`
`The supernatant is obtained by centrifugation.
`The residue is washed with water and the
`washings are added to the separated supernatant.
`The procedure is repeated four times.
`
`Selection of solvents for moistening and precipitation.
`
`desiccator until required. The isolated mucilage from
`the plant was subjected to some preliminary confirma-
`tive testing. Table 3 shows the preliminary confirmative
`test for dried mucilage [6, 15, 16].
`Extraction is one of the most crucial procedures to
`achieve complete recovery of target compounds from
`plants. Recently, microwave energy has started to
`be used for the extraction of phytoconstituents from
`plants [24]. It is a simple, fast, clean, eco-friendly and
`efficient method and saves energy, fuel and electricity.
`Microwave extraction follows the same principle as
`maceration or percolation, but the speed of breaking up
`of the plant cells and tissues is much higher. Microwave
`assisted extraction methods require a shorter time
`and less solvent, and provide a higher extraction rate
`and better products at a lower cost. Plant material is
`powdered in a mechanical blender for 5 m and then
`soaked in distilled water for 24 h in a 1000 ml beaker.
`It is kept in a microwave oven along with a glass tube
`to prevent bumping when subjected to microwave
`irradiation. The beaker is removed from the oven and
`allowed to stand for 2 h to allow the mucilage to be
`released into the water. It is then processed in a similar
`way to the conventional procedure, weighed and stored.
`
`Finally, the supernatant is mixed with twice
`the volume of acetone by continuous stirring.
`
`9. Characterization / Standardization of gums and
`mucilages
`
`The precipitated material is washed with distilled water
`and dried at 50–60˚C under vacuum.
`Fig. 1. General isolation/extraction procedure for mucilages.
`
`Table 3
`Preliminary confirmative tests for dried mucilage powder.
`
`Test
`Molisch’s test: (100 mg dried mucilage powder + Molisch’s
`reagent + conc. H2SO4 on the side of a test tube)
`Ruthenium test: Take a small quantity of dried mucilage
`powder, mount it on a slide with ruthenium red solution, and
`observe it under microscope.
`Iodine test: 10 0mg dried mucilage powder +
`1 ml 0.2 N iodine solution.
`
`Enzyme test: dissolve 100 mg dried mucilage powder in
`20 ml-distilled water; add 0.5 ml of benzidine in alcohol (90%).
`Shake and allow to stand for few minutes
`
`A suitable strategy is required to save money and
`time. Over-characterization is not desirable, because
`excessive use of time and resources could actually delay
`
`Observation
`Violet green color observed at the
`junction of the two layers
`
`Inferences
`
`Carbohydrate present
`
`Pink color develops
`
`Mucilage present
`
`No color observed in solution
`
`No blue color produced
`
`Polysaccharides present
`(starch is absent)
`
`Enzyme absent (Distinction
`between dried mucilage and
`acacia)
`
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`Gums and mucilages/Asian Journal of Pharmaceutical Sciences 2009, 4 (5): 308-322
`
`the launch of innovative excipients. The characterization
`of gums and mucilages is initially achieved by only a
`multiple-technique approach [25]. For excipient analysis,
`analytical techniques can be classified according to the
`type of information generated.
`Structural—Gums and mucilages are polysaccharides
`and contain sugars. So, confirmation of the different
`sugars is carried out by chromatography and structure
`elucidation can be carried out by NMR and mass
`spectroscopy.
`Purity—To determine the purity of the selected gum
`and mucilage, tests for alkaloids, glycosides, carbo-
`hydrates, flavanoids, steroids, amino acids, terpenes,
`saponins, oils and fats, and tannins and phenols are
`carried out.
`Impurity profile—Testing for impurities must be
`carried out using suitable analytical techniques.
`Physico-chemical properties—Color, odor, shape,
`taste, touch, texture, solubility, pH, swelling index,
`loss on drying, hygroscopic nature, angle of repose,
`bulk and true densities, porosity and surface tension.
`Different ash values are also estimated. The microbial
`load and presence of specific pathogens are also
`determined. In vitro cytotoxicity is also determined.
`Gums and mucilages are highly viscous in nature. So,
`the rheological properties of excipients are important
`criteria for deciding their commercial use. The flow
`behavior of the samples is determined.
`Toxicity—The acute toxicity of gums and mucilages
`are determined by the followings fixed-dose method
`as per OECD guideline No. 425. A sub-acute toxicity
`study, determination of the LD50 etc., is carried out in
`rats and guinepigs of both sexes.
`Once analysis is complete, determination of the
`structure, composition and impurity profile enables
`a scientific dossier to be prepared describing the
`excipient. This information is of value for the regulatory
`dossier of the final pharmaceutical product that would
`contain the given excipient.
`Finally, gums and mucialges are added to pharma-
`ceutical formulations. So a compatibility study is
`important. The compatibility studies of gum/mucilage/
`drugs are performed using spectrophotometry/FTIR/
`DSC.
`
`10. Pharmacopoeial standard specifications of gums
`and mucilages
`
`Different pharmacopoeias, like USP, PhEur, and JP
`give pharmacopoeial standards for specific gums [26].
`These are shown in Table 4.
`
`11. Reasons for developing new excipients
`
`For a number of reasons there has been an increase in
`interest in the development of new excipients/diluents.
`Some drugs show incompatibilities with many of
`the current range of excipients. For example, atenolol-
`PVP, atenolol-mg-stearate [27]. One of the more
`common drug-excipient incompatibilities is the reaction
`between aldehydic sugars, such as lactose and primary
`and secondary amines, leading to the formation of
`Schiff bases. These complex series of reactions lead
`to browning and discoloration of the dosage form.
`Despite being a carrier of choice for dry powder aerosol
`formulations, lactose may need to be replaced with a
`different carrier, such as mannitol or sucrose, when
`formulating primary and secondary amines.
`Mg-stearate is incompatible with aspirin, some
`vitamins and most alkaloidal salts [28].
`There is a need for excipients that will allow faster
`manufacturing of formulations. For example, at the
`present time, in tablet dosage forms, new excipients
`having better compressibility at very high compression
`speeds are needed. Today, it is not unheard of to have
`tableting equipment compressing 8000 to 10000 tablets
`per min. It is critical under these conditions to have
`an exceptionally efficient flowing granulation/powder
`blend. Many sugar-based excipients, such as maltose,
`mannitol, and sorbitol are not compressible in their
`natural state and need to be modified for use in direct
`compression tableting.
`Some future developments may require new delivery
`systems. For example, new drug delivery systems for
`oral administration of biotechnology products need
`new excipients which will avoid the inconvenience of
`multiple daily injections. Progress in the development
`of peptides as therapeutic drugs has been impeded in
`part by their rapid excretion, resulting in short
`
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