A gel is a solid jelly-like soft material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid, it is the crosslinking within the fluid that gives a gel its structure and contributes to the adhesive stick. In this way gels are a dispersion of molecules of a liquid within a solid in which liquid particles are dispersed in the solid medium; the word gel was coined by 19th-century Scottish chemist Thomas Graham by clipping from gelatine. Gels consist of a solid three-dimensional network that spans the volume of a liquid medium and ensnares it through surface tension effects; this internal network structure may result from physical bonds or chemical bonds, as well as crystallites or other junctions that remain intact within the extending fluid. Any fluid can be used as an extender including water and air.
Both by weight and volume, gels are fluid in composition and thus exhibit densities similar to those of their constituent liquids. Edible jelly is a common example of a hydrogel and has the density of water. Polyionic polymers are polymers with an ionic functional group; the ionic charges prevent the formation of coiled polymer chains. This allows them to contribute more to viscosity in their stretched state, because the stretched-out polymer takes up more space; this is the reason gel hardens. See polyelectrolyte for more information. A hydrogel is a network of polymer chains that are hydrophilic, sometimes found as a colloidal gel in which water is the dispersion medium. A three-dimensional solid results from the hydrophilic polymer chains being held together by cross-links; because of the inherent cross-links, the structural integrity of the hydrogel network does not dissolve from the high concentration of water. Hydrogels are absorbent natural or synthetic polymeric networks. Hydrogels possess a degree of flexibility similar to natural tissue, due to their significant water content.
As responsive "smart materials," hydrogels can encapsulate chemical systems which upon stimulation by external factors such as a change of pH may cause specific compounds such as glucose to be liberated to the environment, in most cases by a gel-sol transition to the liquid state. Chemomechanical polymers are also hydrogels, which upon stimulation change their volume and can serve as actuators or sensors; the first appearance of the term'hydrogel' in the literature was in 1894. Common uses for hydrogels include: Scaffolds in tissue engineering; when used as scaffolds, hydrogels may contain human cells to repair tissue. They mimic 3D microenvironment of cells. Hydrogel-coated wells have been used for cell culture Environmentally sensitive hydrogels; these hydrogels have the ability to sense changes of pH, temperature, or the concentration of metabolite and release their load as result of such a change. Sustained-release drug delivery systems Providing absorption and debriding of necrotic and fibrotic tissue Hydrogels that are responsive to specific molecules, such as glucose or antigens, can be used as biosensors, as well as in DDS.
Disposable diapers where they absorb urine, or in sanitary napkins Contact lenses EEG and ECG medical electrodes using hydrogels composed of cross-linked polymers Water gel explosives Rectal drug delivery and diagnosis Encapsulation of quantum dots Breast implants Glue Granules for holding soil moisture in arid areas Dressings for healing of burn or other hard-to-heal wounds. Wound gels are excellent for helping to maintain a moist environment. Reservoirs in topical drug delivery. Materials mimicking animal mucosal tissues to be used for testing mucoadhesive properties of drug delivery systemsCommon ingredients include polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with an abundance of hydrophilic groups. Natural hydrogel materials are being investigated for tissue engineering. Hydrogels show promise for use in agriculture, as they can release agrochemicals including pesticides and phosphate fertiliser increasing efficacy and reducing runoff, at the same time improve the water retention of drier soils such as sandy loams.
An organogel is a non-crystalline, non-glassy thermoreversible solid material composed of a liquid organic phase entrapped in a three-dimensionally cross-linked network. The liquid can be, for an organic solvent, mineral oil, or vegetable oil; the solubility and particle dimensions of the structurant are important characteristics for the elastic properties and firmness of the organogel. These systems are based on self-assembly of the structurant molecules. Organogels have potential for use in a number of applications, such as in pharmaceuticals, art conservation, food. A xerogel is a solid formed from a gel by drying with unhindered shrinkage. Xerogels retain high porosity and enormous surface area, along with small pore size; when solvent removal occurs under supercritical conditions, the network doe
Modified-release dosage is a mechanism that delivers a drug with a delay after its administration or for a prolonged period of time or to a specific target in the body. Sustained-release dosage forms are dosage forms designed to release a drug at a predetermined rate in order to maintain a constant drug concentration for a specific period of time with minimum side effects; this can be achieved through a variety of formulations, including liposomes and drug-polymer conjugates. Sustained release's definition is more akin to a "controlled release" rather than "sustained". Extended-release dosage consists of sustained-release and controlled-release dosage. SR maintains drug release over a sustained period but not at a constant rate. CR maintains drug release over a sustained period at a nearly constant rate. Sometimes these and other terms are treated as synonyms, but the United States Food and Drug Administration has in fact defined most of these as different concepts. Sometimes the term "depot tablet" is used by non-native speakers, but this is not found in any English dictionaries and is a literal translation of the term used in Swedish and some other languages.
Modified-release dosage and its variants are mechanisms used in tablets and capsules to dissolve a drug over time in order to be released slower and steadier into the bloodstream while having the advantage of being taken at less frequent intervals than immediate-release formulations of the same drug. For example, extended-release morphine enables people with chronic pain to only take one or two tablets per day. Most it refers to time dependent release in oral dose formulations. Timed release has several distinct variants such as sustained release where prolonged release is intended, pulse release, delayed release etc. A distinction of controlled release is that not only it prolongs action but it attempts to maintain drug levels within the therapeutic window to avoid hazardous peaks in drug concentration following ingestion or injection and to maximize therapeutic efficiency. In addition to pills and injectable drug carriers, forms of controlled release medicines include gels and devices and transdermal patches.
Examples of cosmetics, personal care and food science applications centre on odour or flavour release. The release technology scientific and industrial community is represented by the Controlled Release Society; the CRS is the worldwide society for delivery science and technologies. CRS serves more than 1,600 members from more than 50 countries. Two-thirds of CRS membership is represented by industry and one-third represents academia and government. CRS is affiliated with the Journal of Controlled Release and Drug Delivery and Translational Research scientific journals; the earliest SR drugs are associated with a patent in 1938 by Israel Lipowski, who coated pellets which led to coating particles. The science of controlled release developed further with more oral sustained-release products in the late 1940s and early 1950s, the development of controlled release of marine anti-foulants in the 1950s and controlled release fertilizer in the 1970s where sustained and controlled delivery of nutrients following a single application to the soil.
Delivery is effected by dissolution, degradation or disintegration of an excipient in which the active compound is formulated. Enteric coating and other encapsulation technologies can further modify release profiles. There is no industry standard for these abbreviations, confusion and misreading have sometimes caused prescribing errors. Clear handwriting is necessary. For some drugs with multiple formulations, putting the meaning in parentheses is advisable. A few other abbreviations refer to dose rather than release rate, they include ES and XS. Today, most time-release drugs are formulated so that the active ingredient is embedded in a matrix of insoluble substance such that the dissolving drug must find its way out through the holes. In some SR formulations, the drug dissolves into the matrix, the matrix physically swells to form a gel, allowing the drug to exit through the gel's outer surface. Micro-encapsulation is regarded as a more complete technology to produce complex dissolution profiles.
Through coating an active pharmaceutical ingredient around an inert core, layering it with insoluble substances to form a microsphere one can obtain more consistent and replicable dissolution rates in a convenient format that can be mixed and matched with other instant release pharmaceutical ingredients in to any two piece gelatin capsule. There are certain considerations for the formation of sustained-release formulation: If the pharmacological activity of the active compound is not related to its blood levels, time releasing has no purpose except in some cases, such as bupropion, to reduce possible side effects. If the absorption of the active compound involves an active transport, the development of a time-release product may be problematic; the half-life of the drug refers to the drug's elimination from the bloodstream which can be caused by metabolism and other forms of excretion. If the active compound has a long half-life, it is sustained on its own. If the active compound has a short half-life, it would require a large amount to maintain a prolonged effective dose.
In this case, a broad therape
A pastille is a type of candy or medicinal pill made of a thick liquid, solidified and is meant to be consumed by light chewing and allowing it to dissolve in the mouth. They are used to describe certain forms of incense. A pastille is known as a troche, a medicated lozenge that dissolves like candy. A pastille was a pill-shaped lump of compressed herbs, burnt to release its medicinal properties. Literary references to the burning of medicinal pastilles include the short story "The Birth-Mark" by Nathaniel Hawthorne, the poem "The Laboratory" by Robert Browning, the novel Jane Eyre by Charlotte Brontë, they are mentioned in the novel McTeague by Frank Norris, when the title character's wife burns them to mask an unpleasant odor in the couple's rooms. In Dashiell Hammett's The Maltese Falcon, "a half-filled package of violet pastilles" are among the items found in Joel Cairo's pockets, they were widely used during the eighteenth century in Western cultures to take herbal curatives and medicines, which were developed into candies.
Pastilles are made by pouring a thick liquid into a powdered, sugared, or waxed mold and allowing the liquid to set and dry. The substances contained in the dried liquid are released when chewed and allowed to dissolve in the mouth; the substances are absorbed by the mucous membranes of the oral cavity or in the lower gastro-intestinal tracts. Various substances, be they for flavour, can be put into pastille forms. Due to the oily nature of these active substances, pastilles are based on a mixtures of starch and gum arabic, which emulsifies the substance and binds them in a hydrocolloidal matrix; the starch and gum reduces the rate in which the pastille dissolves and moderates the amount of active substances delivered at a time. Gum arabic hardens the pastilles and makes them more sturdy in storage and transport. Well known pastille type candies include: Läkerol Violets Mason Dots Mentos Vocalzone Throat Pastilles, natural throat pastilles for voice overuse Jujube Rowntree's Fruit Pastilles, small round sweets Vichy Pastilles, octagonal candy pastilles Wine gum Grether's Pastilles Pastiglie Leone, Herbal digestives and candy pastilles Gum drops Throat lozenge
Decoction is a method of extraction by boiling herbal or plant material to dissolve the chemicals of the material, which may include stems, roots and rhizomes. Decoction involves first mashing the plant material to allow for maximum dissolution, boiling in water to extract oils, volatile organic compounds and other various chemical substances. Decoction can be used to make herbal teas, leaf teas, coffees and similar solutions. Decoctions and infusions may produce liquids with differing chemical properties as the temperature and/or preparation difference may result in more oil-soluble chemicals in decoctions versus infusions; the process can be applied to meats and vegetables to prepare bouillon or stock, though the term is only used to describe boiled plant extracts for medicinal or scientific purposes. Decoction is the name for the resulting liquid. Although this method of extraction differs from infusion and percolation, the resultant liquids can sometimes be similar in their effects, or general appearance and taste.
The term dates back to 1350–1400 from present participle stem of Latin decoquere, de "from" + coquere "to cook". In brewing, decoction mashing is the traditional method where a portion of the mash is removed to a separate vessel, boiled for a time and returned to the main mash, raising the mash to the next temperature step. In herbalism, decoctions are made to extract fluids from hard plant materials such as roots and bark. To achieve this, the plant material is boiled for 1–2 hours in 1-5 liters of water, it is strained. Ayurveda utilizes this method to create Kashayam type of herbal medicines. For teas, decoction involves boiling the same amount of the herb and water that would be used for an infusion for about five to ten minutes. Concoction Percolation Infusion Maceration Tincture Herbalism How To Make a Herbal Decoction from unexplainable.net
In the manufacture of pharmaceuticals, encapsulation refers to a range of dosage forms—techniques used to enclose medicines—in a stable shell known as a capsule, allowing them to, for example, be taken orally or be used as suppositories. The two main types of capsules are: Hard-shelled capsules, which contain dry, powdered ingredients or miniature pellets made by e.g. processes of extrusion or spheronization. These are made in two halves: a smaller-diameter “body”, filled and sealed using a larger-diameter “cap”. Soft-shelled capsules used for oils and for active ingredients that are dissolved or suspended in oil. Both of these classes of capsules are made from aqueous solutions of gelling agents, such as animal protein or plant polysaccharides or their derivatives. Other ingredients can be added to the gelling agent solution including plasticizers such as glycerin or sorbitol to decrease the capsule's hardness, coloring agents, disintegrants and surface treatment. Since their inception, capsules have been viewed by consumers as the most efficient method of taking medication.
For this reason, producers of drugs such as OTC analgesics wanting to emphasize the strength of their product developed the “caplet”, a portmanteau of “capsule-shaped tablet”, in order to tie this positive association to more efficiently-produced tablet pills, as well as being an easier-to-swallow shape than the usual disk-shaped tablet. In 1833, Mothes and Dublanc were granted a patent for a method to produce a single-piece gelatin capsule, sealed with a drop of gelatin solution, they used individual iron molds for their process, filling the capsules individually with a medicine dropper. On, methods were developed that used sets of plates with pockets to form the capsules. Although some companies still use this method, the equipment is no longer produced commercially. All modern soft-gel encapsulation uses variations of a process developed by R. P. Scherer in 1933, his innovation used. They were filled by blow molding; this method was high-yield and reduced waste. Softgels can be an effective delivery system for oral drugs poorly soluble drugs.
This is because the fill can contain liquid ingredients that help increase solubility or permeability of the drug across the membranes in the body. Liquid ingredients are difficult to include in any other solid dosage form such as a tablet. Softgels are highly suited to potent drugs, where the reproducible filling process helps ensure each softgel has the same drug content, because the operators are not exposed to any drug dust during the manufacturing process. In 1949, the Lederle Laboratories division of the American Cyanamid Company developed the "Accogel" process, allowing powders to be filled into soft gelatin capsules. James Murdock of London patented the two-piece telescoping gelatin capsule in 1847; the capsules are made in two parts by dipping metal pins in the gelling agent solution. The capsules are supplied as closed units to the pharmaceutical manufacturer. Before use, the two halves are separated, the capsule is filled with powder or more pellets made by the process of Extrusion & Spheronization and the other half of the capsule is pressed on.
With the compressed slug method, weight varies less between capsules. However, the machinery required to manufacture them is more complex; the powder or spheroids inside the capsule contains the active ingredient and any excipients, such as binders, fillers and preservatives. Gelatin capsules, informally called gel caps or gelcaps, are composed of gelatin manufactured from the collagen of animal skin or bone. Vegetable capsules are composed of a polymer formulated from cellulose. Or Pullulan, polysaccharide polymer produced from tapioca starch; the process of encapsulation of hard gelatin capsules can be done on manual, semi-automatic and automatic capsule filling machines. Softgels are filled at the same time as they are produced and sealed on the rotary die of a automatic machine. Capsule fill weight is a critical attribute in encapsulation and various real time fill weight monitoring techniques such as near-infrared spectroscopy and vibrational spectroscopy are used, as well as in-line weight checks, to ensure product quality.
Capsule endoscopy OROS Pharmacy Automation - The Tablet Counter Pharmaceutical formulation Pill splitting Tablet Oblaat L. Lachman. A. Lieberman. L. Kanig; the Theory and Practice of Industrial Pharmacy. Lea & Febiger, Philadelphia. ISBN 0-8121-0977-5
In humans, the respiratory tract is the part of the anatomy of the respiratory system involved with the process of respiration. Air is breathed in through the mouth. In the nasal cavity, a layer of mucous membrane acts as a filter and traps pollutants and other harmful substances found in the air. Next, air moves into the pharynx, a passage that contains the intersection between the esophagus and the larynx; the opening of the larynx has a special flap of cartilage, the epiglottis, that opens to allow air to pass through but closes to prevent food from moving into the airway. From the larynx, air moves into the trachea and down to the intersection that branches to form the right and left primary bronchi; each of these bronchi branch into secondary bronchi that branch into tertiary bronchi that branch into smaller airways called bronchioles that connect with tiny specialized structures called alveoli that function in gas exchange. The lungs which are located in the thoracic cavity, are protected from physical damage by the rib cage.
At the base of the lungs is a sheet of skeletal muscle called the diaphragm. The diaphragm separates the lungs from intestines; the diaphragm is the main muscle of respiration involved in breathing, is controlled by the sympathetic nervous system. The lungs are encased in a serous membrane that folds in on itself to form the pleurae – a two-layered protective barrier; the inner visceral pleura covers the surface of the lungs, the outer parietal pleura is attached to the inner surface of the thoracic cavity. The pleurae enclose; this fluid is used to decrease the amount of friction. The respiratory tract is divided into lower airways; the upper airways or upper respiratory tract includes the nose and nasal passages, paranasal sinuses, the pharynx, the portion of the larynx above the vocal folds. The lower airways or lower respiratory tract includes the portion of the larynx below the vocal folds, trachea and bronchioles; the lungs can be included in the lower respiratory tract or as separate entity and include the respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli.
The respiratory tract can be divided into a conducting zone and a respiratory zone, based on the distinction of transporting gases or exchanging them. The conducting zone includes structures outside of the lungs – the nose, pharynx and trachea, structures inside the lungs – the bronchi and terminal bronchioles; the conduction zone conducts air breathed in, filtered and moistened, into the lungs. It represents the 1st through the 16th division of the respiratory tract; the conducting zone is most of the respiratory tract that conducts gases into and out of the lungs, but excludes the respiratory zone that exchanges gases. The conducting zone functions to offer a low resistance pathway for airflow, it provides a major defense role in its filtering abilities. The respiratory zone includes the respiratory bronchioles, alveolar ducts and alveoli, is the site of oxygen and carbon dioxide exchange with the blood; the respiratory bronchioles and the alveolar ducts are responsible for 10% of the gas exchange.
The alveoli are responsible for the other 90%. The respiratory zone represents the 16th through the 23rd division of the respiratory tract. From the bronchi, the dividing tubes become progressively smaller with an estimated 20 to 23 divisions before ending at an alveolus; the upper respiratory tract, can refer to the parts of the respiratory system lying above the sternal angle, above the vocal folds, or above the cricoid cartilage. The larynx is sometimes included in both lower airways; the larynx is called the voice box and has the associated cartilage that produces sound. The tract consists of the nasal cavity and paranasal sinuses, the pharynx and sometimes includes the larynx; the lower respiratory tract or lower airway is derived from the developing foregut and consists of the trachea, bronchi and lungs. It sometimes includes the larynx; the lower respiratory tract is called the respiratory tree or tracheobronchial tree, to describe the branching structure of airways supplying air to the lungs, includes the trachea and bronchioles.
Trachea main bronchus lobar bronchus segmental bronchus subsegmental bronchus conducting bronchiole terminal bronchiole respiratory bronchiole alveolar duct alveolar sac alveolusAt each division point or generation, one airway branches into two or more smaller airways. The human respiratory tree may consist on average of 23 generations, while the respiratory tree of the mouse has up to 13 generations. Proximal divisions function to transmit air to the lower airways. Divisions including the respiratory bronchiole, alveolar ducts and alveoli, are specialized for gas exchange; the trachea is the largest tube in the respiratory tract and consists of tracheal rings of hyaline cartilage. It branches off into a left and a right main bronchus; the bronchi branch off into smaller sections inside the lungs, called bronchioles. These bronchioles give rise to the air sacs in the lungs called the alveoli; the lungs are the largest organs in the lower respiratory tract. The lungs are suspended within the pleural cavity of the thorax.
The pleurae are two thin membranes, one
Thin-film drug delivery
Thin-film drug delivery uses a dissolving film or oral drug strip to administer drugs via absorption in the mouth and/or via the small intestines. A film is prepared using hydrophilic polymers that dissolves on the tongue or buccal cavity, delivering the drug to the systemic circulation via dissolution when contact with liquid is made. Prolific inventors in thin film drug delivery include Richard Fuisz, Joseph Fuisz, Garry Myers and Robert Yang; this group has contributed over thirty patents in this field. Thin-film drug delivery has emerged as an advanced alternative to the traditional tablets and liquids associated with prescription and OTC medications. Similar in size and thickness to a postage stamp, thin-film strips are designed for oral administration, with the user placing the strip on or under the tongue or along the inside of the cheek; these drug delivery options allow the medication to bypass the first pass metabolism thereby making the medication more bioavailable. As the strip dissolves, the drug can enter the blood stream buccally or sublingually.
Evaluating the systemic transmucosal drug delivery, the buccal mucosa is the preferred region as compared to the sublingual mucosa. Different buccal delivery products have been marketed or are proposed for certain diseases like trigeminal neuralgia, Meniere's disease and addiction. There are many commercial non-drug product to use thin films like Mr. Mint and Listerine PocketPaks breath freshening strips. Since thin-film products for other breath fresheners, as well as a number of cold, anti-snoring and gastrointestinal medications, have entered the marketplace. There are several projects in development that will deliver prescription drugs using the thin-film dosage form. Formulation of oral drug strips involves the application of both aesthetic and performance characteristics such as strip-forming polymers, active pharmaceutical ingredient, sweetening agents, saliva stimulating agent, flavoring agents, coloring agents and thickening agents. From the regulatory perspectives, all excipients used in the formulation of oral drug strips should be approved for use in oral pharmaceutical dosage forms.
The polymer employed should be non-irritant and devoid of leachable impurities. It should have good spreadability property; the polymer should exhibit sufficient peel and tensile strengths. The polymer should be available and should not be expensive. Film obtained should be tough enough so that there won't be any damage while handling or during transportation. Combination of microcrystalline cellulose and maltodextrin has been used to formulate Oral Strips of piroxicam made by hot melt extrusion technique. Pullulan has been the most used film former Plasticizer is a vital ingredient of the OS formulation, it reduces the brittleness of the strip. Plasticizer improves the strip properties by reducing the glass transition temperature of the polymer. Glycerol, Propylene glycol, low molecular weight polyethylene glycols, phthalate derivatives like dimethyl and dibutyl phthalate, Citrate derivatives such as tributyl, acetyl citrate and castor oil are some of the used plasticizer excipients. Since the size of the dosage form has limitation, high-dose molecules are difficult to be incorporated in OS.
5%w/w to 30%w/w of active pharmaceutical ingredients can be incorporated in the oral strip. An important aspect of thin film drug technology is its color; the sweet taste in formulation is more important in case of pediatric population. Natural sweeteners as well as artificial sweeteners are used to improve the flavor of the mouth dissolving formulations for the flavors changes from individual to individual. Pigments such as titanium dioxide is incorporated for coloring; the stabilizing and thickening agents are employed to improve the viscosity and consistency of dispersion or solution of the strip preparation solution or suspension before casting. Drug content uniformity is a requirement for all dosage forms those containing low dose potent drugs. To uniquely meet this requirement, thin film formulations contain uniform dispersions of drug throughout the whole manufacturing process. Since this criterion is essential for the quality of the thin film and final pharmaceutical dosage form, the use of Laser Scanning Confocal Microscopy was recommended to follow the manufacturing process.
An increasing number of film-based therapeutics are in development, including: Montelukast indicated for the treatment of asthma and allergy, is being developed for use as a film by Monosol Rx. Midatech, a company specializing in nanotechnology, is partnering with Monosol Rx to create a film-based insulin. Rizatriptan indicated for the treatment of migraine, is being developed for use as a film by Monsoon Rx and Zim Laboratories Ltd. Monosol Rx is developing a testosterone film-based therapeutic for the treatment of male hypogonadism; the product is in phase 1. Undergraduate biomedical engineering students at Johns Hopkins University have created a new drug delivery system based on the thin-film technology used by a breath freshener. Laced with a vaccine against rotavirus, the strips could be used to provide the vaccine to infants in impoverished areas. Other molecules like Sildenafil citrate, Tadalafil and Vitamin D3 are developed by Zim Laboratories Ltd. Hariharan, Madhu. Arli