A REVIEW REPORT ON: COATING OF SOFT GELATIN CAPSULES
KAPIL V BIYANI1, DR.P.S. KAWTIKWAR2, N. M. MAHAJAN3
1. M.Pharm, IBSS COLLEGE OF PHARMACY,
BULDHANA ROAD, MALKAPUR (M.S)
2. HOD, SNIOP, PUSAD
3. HOD, IBSS COLLEGE OF PHARMACY,
BULDHANA ROAD, MALKAPUR (M.S)
Introduction1, 2, 3, 4, 5, 6, 7, 8
Capsule is the most versatile of all dosage forms. Capsules are solid dosage forms in which one or more medicinal and inert ingredients are enclosed in a small shell or container usually made of gelatin. There are two types of capsules, “hard”and“soft”. The hard capsule is also called “two pieces” as it consists of two pieces in the form of small cylinders closed at one end, the shorter piece is called the “cap” which fits over the open end of the longer piece, called the “body”. The soft gelatin capsule is also called as “one piece”. Capsules are available in many sizes to provide dosing flexibility. Unpleasant drug tastes and odors can be masked by the tasteless gelatin shell. The administration of liquid and solid drugs enclosed in hard gelatin capsules is one of the most frequently utilized dosage forms.
Reference Id: PHARMATUTOR-ART-1220
Advantages of Capsules:
•Capsules mask the taste and odor of unpleasant drugs and can be easily administered.
• They are attractive in appearance
• They are slippery when moist and, hence, easy to swallow with a draught of water.
• As compared to tablets; fewer adjuncts are required.
• The shells are physiologically inert and easily and quickly digested in the gastrointestinal tract.
• They are economical
• They are easy to handle and carry.
• The shells can be opacified (with titanium dioxide) or colored, to give protection from light.
Disadvantages of Capsules
• The drugs which are hygroscopic absorb water from the capsule shell making it brittle and hence are not suitable for filling into capsules.
• The concentrated solutions which require previous dilution are unsuitable for capsules because if administered as such lead to irritation of stomach.
Soft gels – a brief review 9, 10, and 11
Soft gel (a soft gelatin capsule) is a solid capsule (outer shell) surrounding a liquid or semi-solid center (inner fill) active ingredient can be incorporated into the outer shell, the inner fill, or both. The formulation of drugs into soft gelatin capsules has gained popularity throughout the past decade due to the many advantages of this dosage form. The bioavailability of hydrophobic drugs can be significantly increased when formulated into soft gelatin capsules. Many problems associated with tableting, including poor compaction and lack of content or weight uniformity, can be eliminated when a drug is incorporated into this dosage form. Improved stability of drugs that are highly susceptible to oxidation can be achieved when formulated into a soft gelatin capsule.
Gelatin soft capsules are made from gelatin and water but with the addition of a polyhydic alcohol, such as glycerol or sorbitol, to make them flexible. Sorbitol is less hygroscopic than glycerol. They usually contain a preservative, such as beta-naphthol. They are available in variety of shapes and sizes.
• Spherical – 0.05 -5 ml
• Ovoid – 0.05 - 7 ml
• Cylindrical – 0.15- 25 ml
• Tubes – 0.5 - 0 ml
• Pear shaped – 0.3 - 5ml
They are most suitable for liquids and semisolids and are widely used, in spherical and ovoid forms for vitamin preparations such as cod liver oil, vitamins A and D and multiple vitamins.
Solid dosage forms containing drugs that are susceptible to degradation in the stomach due to the acidic environment or gastric enzymes have been stabilized with an enteric film coating. A decrease in gastric irritation caused by drugs, such as aspirin, can also be achieved by enterically coating the solid dosage form In addition, enteric coatings can be used to target drug release in the small intestine.6 Enteric coating of soft gelatin capsules combines the advantages of the delivery system with the protective properties of the film coating. However, the physicochemical properties of the gelatin and capsule shell present significant challenges to the pharmaceutical scientist when film coating soft gelatin capsules with enteric polymers.
Soft capsules are a single-unit solid dosage form, consisting of a liquid or semi-solid fill enveloped by a one-piece sealed elastic outer shell. The amount of drug or extract together with adjuvant is enclosed within a globular, oval or other shape of a soft shell. Soft gelatin capsules (softgel) offer the possibility of delivering a liquid in a solid oral dosage form. The softgel can contain the active ingredient in solution, suspension or emulsion, which will inherently lead to better absorption of the active ingredient as compared with delivery in a tablet or as a powder.
Highly developed soft capsules are currently being applied widely in the pharmaceutical, chemical, food and cosmetic industry. This is attributed to the features of softgels like desirable aesthetic properties and ‘swallowability’, safety enclosure, precise contents, and pleasing appearance. This has enabled their use as an effective delivery system for hydrophobic drugs, low melting-point drugs, easy-oxidized drugs, and a variety of health care oil. Since the introduction of Soft Capsule Making Machine in the 1970s, formulations have continually become more popular with rapid developments in recent years. This could be illustrated by emergency of a more than 560 sets of Soft Capsule Making Machine with transfer mode having a production rate of up to 60 billion pills/year (i.e.more than 3600 kinds of drugs) in the world. Up to now, there are more than 30 manufacturers producing more than 40 kinds of soft capsules by using over 60 sets of advanced machines. Softgels’ ability to enhance bioavailability not only makes them the preferred dosage form for new chemical entities with poor oral bioavailability, they can also be used for reformulation of existing drugs, with the purpose of life-cycle extension.
The softgel delivery system is a unitary package, formed with gelatin outer layers, which contain between them the active ingredients in solution, suspension or paste form. Hydrophobic drugs do not dissolve readily in water, gastric or intestinal fluid. When they are compounded in solid dosage forms, their dissolution rate is usually low and absorption varies resulting in poor bioavailability. Bioavailability of these drugs can be improved in the presence of fatty acids e.g. mono or diglycerides. Fatty acids do solubilize hydrophobic drugs in the gut and enable more rapid absorption. The softgel delivers drugs in solution and yet offers solid dosage form. These hydrophobic drugs are dissolved in a hydrophilic solvent, which, when crushed or chewed, releases the drug immediately to produce a solution of the drug in gastric juice ready for absorption from the gastrointestinal tract into the blood stream. This results in rapid onset of desired therapeutic effects6. For example, Ibuprofen soft gel gives rise to a shorter time to peak plasma concentration and greater peak plasma concentration compared to a marketed tablet formulation. Cyclosporine does give therapeutic blood levels which are not achievable from tablet form. Similarly oral hypoglycemic glipizide in softgel is also known to have better bioavailability results compared with tablet form. Softgel delivery systems can also incorporate phospholipids or polymers or natural gums to entrap the drug active in the gelatin layer with an outer coating to give desired delayed/control release effects.
The designs for a specific soft gelatin capsule formulation involve appropriate selection of the shell and fill composition. This is followed by optimization of the two to allow for efficient production of a chemically and physically stable product with the desired biopharmaceutical properties. The shell of a soft gelatin capsule is composed of gelatin, a plasticizer or a combination of plasticizers and water. In addition, it may contain preservatives, coloring and opacifying agents, flavorings and sweeteners, possibly sugars to impart chewable characteristics to the shell, gastroresistant substances and in special cases even active compounds8.The formulation of the fill is individually developed to fulfill the requirements for optimum therapeutic action.This entails optimizing the chemical stability of the active compound to improve bioavailability. Emphasis is also put on efficient and safe filling process in order to achieve a physically stable capsule product.
Improved drug absorption is the primary reason for selection of soft gel as a dosage form. Nevertheless as a drug delivery system for oral administration of therapeutic agent several advantages as well as disadvantages have been reported with soft gelatin capsules.
Advantages of soft gel capsules:
1. Ease of use - easy to swallow, no taste, unit dose delivery, temper proof.
i. Accommodates a wide variety of compounds filled as a semisolid, liquid, gel or paste.
ii. Wide variety of colors, shapes and sizes
iii. Immediate or delayed drug delivery-can be used to improve bioavailability by delivering drug in solution or other absorption enhancing media.
Disadvantages of soft gel capsules:
1. Requires special manufacturing equipment
2. Stability concerns with highly water soluble compounds, and compounds susceptible to hydrolysis
3. Limited choices of excipients/carriers compatible with the gelatin
Content of a softgel capsule is a liquid, or a combination of miscible liquids, a solution of a solid(s) in a liquid(s) or a suspension of a solid(s) in a liquid(s).
Liquids are an essential part of the capsule content. Only those liquids that are both water miscible and volatile cannot be included as major constituents of the capsule content since they can migrate into the hydrophilic gelatin shell and volatilize from its surface. Water, ethyl alcohol and emulsions fall into this category.The softgel dosage form has been around from many years. The earliest soft gels date back to the 19th century. Since then, many improvements have been made with respect to the production of these soft capsules. Softgel manufacturing still requires special skills and equipment that less than a handful of companies can offer to pharmaceutical clients. Notwithstanding the progress that has been made in softgel manufacturing, the softgel as a dosage form has remained largely unchanged over the years. As a result, patent protection on the technology was lost, which is a disadvantage in the era of pharmaceutical life-cycle management. For that reason, Banner has developed new softgel variants that not only offer specific benefits over the standard softgel, but also provide additional patent protection to the compounds they deliver. Soft gelatin capsules (soft gels) offer the possibility of delivering a liquid in a solid oral dosage form. The softgel can therefore contain the active ingredient in solution, suspension or emulsion, which will inherently lead to better absorption of the active ingredient as compared with delivery in a tablet or as a powder. Soft gels are therefore the ideal solution –and sometimes the only solution – for delivery of compounds with poor oral bioavailability. Other properties that make soft gels a useful and frequently applied dosage form include their aesthetic properties and ‘swallowability’, their tamper-resistance, their protection of the active ingredient from light and oxidation, their taste- masking of ingredients and their masking of unpleasant odours of ingredients
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