Powders Are Intimate Mixtures of Dry, Finely Divided Drugs And/Or Chemicals That May Be Intended for Internal Or External Use
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Powders are intimate mixtures of dry, finely divided drugs and/or chemicals that may be intended for internal or external use. Advantages/Disadvantages flexibility in compounding good chemical stability Ease of administration time-consuming not well-suited to dispense unpleasant tasting, hygroscopic or deliquescent drugs inaccuracy of dose Types Medicated Aerosol Preparation Weighing of ingredients Comminuting Blending or mixing Weighing of individual dose Materials Active ingredients Packaging Types of material used to pack/dispense divided powders Foil plastic bag used for volatile vegetable parchment thin, semiopaque, moisture-resistant white bond without moisture-resistant properties Glassine glazed, transparent, moisture-resistant paper used for volatile to a certain extent Waxed transparent-water-proof paper used for hygroscopic and volatile drugs Seidlitz powder is the name with which is commonly known a medication composed by a mixture of tartaric acid, sodium bicarbonate, and potassium sodium tartrate, used as a mild cathartic by dissolving in water and drinking. After ingestion, the powder combines with gastric juices developing intestinal gases which are somewhat helpful in evacuating the bowels. This medication's name comes from the Seidlitz Saline Springs of Bohemia (now Sedlčany in the Czech Republic), which were rather famous in Europe at the time this medication was first marketed in the late 19th century, even though the foregoing laxative constituents do not represent those of the springs named. Use of Each ingredient – act as acid and base which react in the presence of water to cause effervescence Use of Preparation - mild cathartic/laxative Appearance – white powder Storage – store in air tight containers Granules are prepared agglomerates of powdered materials, may be used per se for the medicinal value of their content or they may be used for pharmaceutical purposes, as in making tablets. Granules generally fall within the range of 4-12 sieve size Preparation Wet – moistening of the powder/mixture, passing resulting paste thru a sieve, drying in trays by air or heating. Granules are periodically moved about to prevent adhesion - Fluid bed processing in which particles are placed in a conical chamber and vigorously dispersed and suspended while a liquid excipient is sprayed Dry - Passing through a compactor and granulating machine - Slugging where the powder is compressed into slugs and then granulated to the desired size Advantages/Disadvantages Flow better than powders More stable Wetted faster Decreased dissolution rate Types Effervescent granulated salts - prepared by dry/fusion method and wet method Formulation Citric acid 1 Tartaric acid 2 NaHCO3 3.4 Total 6.4 Use of Each ingredient – act as acid and base which react in the presence of water to cause effervescence Use of Preparation – effervescent vehicle Appearance – white granules Storage – store in air tight containers Tablets A tablet is a pharmaceutical dosage form. It comprises a mixture of active substances and excipients, usually in powder form, pressed or compacted from a powder into a solid dose. The excipients can include diluents, binders or granulating agents, glidants (flow aids) and lubricants to ensure efficient tabletting; disintegrants to promote tablet break-up in the digestive tract; sweeteners or flavours to enhance taste; and pigments to make the tablets visually attractive. A polymer coating is often applied to make the tablet smoother and easier to swallow, to control the release rate of the active ingredient, to make it more resistant to the environment (extending its shelf life), or to enhance the tablet's appearance. The compressed tablet is the most popular dosage form in use today. About two-thirds of all prescriptions are dispensed as solid dosage forms, and half of these are compressed tablets. A tablet can be formulated to deliver an accurate dosage to a specific site; it is usually taken orally, but can be administered sublingually, buccally, rectally or intravaginally. The tablet is just one of the many forms that an oral drug can take such as syrups, elixirs, suspensions, and emulsions. Medicinal tablets were originally made in the shape of a disk of whatever color their components determined, but are now made in many shapes and colors to help distinguish different medicines. Tablets are often stamped with symbols, letters, and numbers, which enable them to be identified. Sizes of tablets to be swallowed range from a few millimeters to about a centimeter. Some tablets are in the shape of capsules, and are called "caplets". Medicinal tablets and capsules are often called pills. This is technically incorrect, since tablets are made by compression, whereas pills are ancient solid dose forms prepared by rolling a soft mass into a round shape. Other products are manufactured in the form of tablets which are designed to dissolve or disintegrate; e.g. cleaning and deodorizing products. Tabletting formulations In the tablet-pressing process, it is important that all ingredients be fairly dry, powdered or granular, somewhat uniform in particle size, and freely flowing. Mixed particle sized powders can segregate during manufacturing operations due to different densities, which can result in tablets with poor drug or active pharmaceutical ingredient (API) content uniformity but granulation should prevent this. Content uniformity ensures that the same API dose is delivered with each tablet. Some APIs may be tableted as pure substances, but this is rarely the case; most formulations include excipients. Normally, an pharmacologically inactive ingredient (excipient) termed a binder is added to help hold the tablet together and give it strength. A wide variety of binders may be used, some common ones including lactose, dibasic calcium phosphate, sucrose, corn (maize) starch, microcrystalline cellulose, povidone polyvinylpyrrolidone and modified cellulose (for example hydroxypropyl methylcellulose and hydroxyethylcellulose). Often, an ingredient is also needed to act as a disintegrant to aid tablet dispersion once swallowed, releasing the API for absorption. Some binders, such as starch and cellulose, are also excellent disintegrants. Small amounts of lubricants are usually added, as well. The most common of these is magnesium stearate and calcium stearate. [edit] Advantages and disadvantages Variations on a common tablet design, which can be distinguished by both color and shape Tablets are simple and convenient to use. They provide an accurately measured dosage of the active ingredient in a convenient portable package, and can be designed to protect unstable medications or disguise unpalatable ingredients. Colored coatings, embossed markings and printing can be used to aid tablet recognition. Manufacturing processes and techniques can provide tablets special properties, for example, sustained release or fast dissolving formulations. Some drugs may be unsuitable for administration by the oral route. For example, protein drugs such as insulin may be denatured by stomach acids. Such drugs cannot be made into tablets. Some drugs may be deactivated by the liver when they are carried there from the gastrointestinal tract by the hepatic portal vein (the "first pass effect"), making them unsuitable for oral use. Drugs which can be taken sublingually are absorbed through the oral mucosae, so that they bypass the liver and are less susceptible to the first pass effect. The oral bioavailability of some drugs may be low due to poor absorption from the gastrointestinal tract. Such drugs may need to be given in very high doses or by injection. For drugs that need to have rapid onset, or that have severe side effects, the oral route may not be suitable. For example salbutamol, used to treat problems in the pulmonary system, can have effects on the heart and circulation if taken orally; these effects are greatly reduced by inhaling smaller doses direct to the required site of action. [edit] Tablet properties Tablets can be made in virtually any shape, although requirements of patients and tableting machines mean that most are round, oval or capsule shaped. More unusual shapes have been manufactured but patients find these harder to swallow, and they are more vulnerable to chipping or manufacturing problems. Tablet diameter and shape are determined by the machine tooling used to produce them - a die plus an upper and a lower punch are required. This is called a station of tooling. The thickness is determined by the amount of tablet material and the position of the punches in relation to each other during compression. Once this is done, we can measure the corresponding pressure applied during compression. The shorter the distance between the punches, thickness, the greater the pressure applied during compression, and sometimes the harder the tablet. Tablets need to be hard enough that they don't break up in the bottle, yet friable enough that they disintegrate in the gastric tract. Tablets need to be strong enough to resist the stresses of packaging, shipping and handling by the pharmacist and patient. The mechanical strength of tablets is assessed using a combination of (i) simple failure and erosion tests, and (ii) more sophisticated engineering tests. The simpler tests are often used for quality control purposes, whereas the more complex tests are used during the design of the formulation and manufacturing process in the research and development phase. Standards for tablet properties are published in the various international pharmacopeias