NorQuest Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms PDF

10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms Site: NorQuest...

10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms Site: NorQuest Printed by: Mary RECIO PHRM-1000-Introduction to Pharmacy Practice- Date: Wednesday, 9 October 2024, 10:33 PM Course: BL01,E01-XL-2024 Fall Module 5 Book: Drug Preparations Part 3: Oral Book: Liquid Dosage Forms https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 1/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Table of contents General Information: Oral Liquid Dosage Forms Solutions Aqueous (Simple) Solutions Non-Aqueous Solutions Dispersions Suspensions Emulsions Gels and Magmas Oral Liquid Dosage Form Visual https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 2/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest General Information: Oral Liquid Dosage Forms Liquid oral dosage forms include solutions and dispersed systems. Solutions include syrups, elixirs, aromatic waters, and tinctures. Suspensions, magmas, gels, and emulsions are all considered liquid dispersion systems. Advantages of oral liquid dosage forms: Swallowing liquids is easy, especially for children and the elderly. Accurate dosage can be given to a patient. Drug is in solution so is already disintegrated for quicker absorption (solutions only) Usually easy to make liquid compounds Disadvantages of oral liquid dosage forms: Requires measuring device Not suitable for all drugs Difficult to mask a drug that tastes bad Cannot change the release rate of the drug (modified release) Not as economical as other formulations Stability (most liquids have a shorter shelf life in comparison to solid dosage forms such as tablets, capsules) Not very portable (heavy, bulky bottles, sticky) Administration of Oral Liquids Most solutions are administered using an oral syringe or a calibrated measuring device. Household measuring devices should not be used as they are not accurate. Dosages and directions for use are on manufacturers’ labels. If a liquid is not commercially available, the product can usually be prepared at a local pharmacy. Compounded liquids should be dispensed with an appropriate measuring device. Calibrated droppers are used for babies. Manufactured products come with a separate calibrated dropper or have it built into the lid of the bottle. Oral syringes are used for babies and young toddlers who would not use a spoon well. These are also calibrated for exact dosing. Medication spoons are sometimes called alligator spoons because they have “legs”. The legs permit the user to put the spoon down without spilling. The spoon has a hollow handle with calibration markings for accurate measuring. Medication cups are small measuring cups with calibration markings on the side. These are used for older children and adults. Storage Requirements for Oral Liquids Storage requirements for liquids are product-specific as per the manufacturer. Certain products are stored at room temperature and other products may require refrigeration. For products that require reconstitution, the expiry date is altered at the time of reconstitution. They may also need to be refrigerated. Use EXPIRY DATE and REFRIGERATE auxiliary labels when appropriate. Packaging Compounded liquids (for oral or topical use) should be dispensed in glass or plastic light-resistant containers. Suspensions and emulsions need to be shaken prior to pouring each dose; therefore, the container should have enough head space to allow for thorough shaking. Suspensions and emulsions can also be quite viscous, so the container opening should be wide enough to allow for easy pouring. A SHAKE WELL auxiliary label must be put on suspensions and emulsions. https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 3/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Solutions Solutions are liquid preparations that contain one or more substances (solute) which are completely dissolved in a suitable solvent. A solute can be a solid or a liquid. The strength of the solution can be expressed as ratio strength, percentage strength, parts per million, or units of mass per volume. The solubility of a substance must be considered before preparing solutions. The solubility of a drug substance is the maximum amount of solute which will dissolve completely in a specific amount and type of solvent. Buffers may need to be added to ensure the final mixture is stable but within a usable pH range. Hydroalcoholic solutions are made by dissolving water-soluble substances in the aqueous portion of the solvent and dissolving the less water-soluble substances in the alcoholic portion and then combining the two. Physical characteristics of solutions can include: Homogenous Clear – does not scatter light Coloured Easy to pour Common solvents used in the preparation of pharmaceutical preparations are as follows: Purified The most common solvent in the preparation of oral liquids is water Water (USP) Alcohol USP Alcohol (ethanol) is the second most popular solvent used in pharmacy. It is a better solvent for many (95% v/v) organic compounds and it acts as a preservative and does cause hydrolysis. Oral preparations usually contain less than 50% ethanol since a more concentrated solution could burn mucous membranes. Concentrations of ethanol greater than 20% can produce the same effects as drinking alcohol. Ethyl alcohol is an effective antiseptic and disinfectant at concentrations greater than 60%. Glycerin A colourless, viscous sweet-tasting liquid that is miscible with alcohol and water. Glycerin is quite thick so it is difficult to dissolve substances in although it is generally a good solvent. Glycerin acts as a preservative in a higher concentration and it adds body, smoothness, and sweetness to liquid preparations. Propylene A colourless viscous liquid that is miscible with water and alcohol. It can also act as a preservative in high Glycol concentrations. It is a widely used solvent in conjunction with water in the preparation of oral drugs. Important note Propylene glycol is sometimes used as a solvent but is primarily used in topical preparations. For oral use, the maximum amount of propylene glycol is 25mg/kg/day because amounts more than this increase risk of seizures. https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 4/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Aqueous (Simple) Solutions Aqueous (simple) solutions are compounds dissolved in water by adding the solute to the water solvent. Heat or agitation is usually required. The preparation may require the addition of a solubilizing agent to dissolve high concentrations of solute. Advantages of aqueous (simple) solutions include quick absorption and flexible dosing. They are suitable for water-soluble drugs. Disadvantages of simple solutions include difficulty in masking the taste. They are not a very stable formulation for many drugs. Aromatic Solutions (also known as Aromatic Waters) Aromatic solutions are clear, aqueous solutions saturated with volatile oils and are usually used as flavours or perfumes. Examples include peppermint oil, rose oil, rosewater, wintergreen oil, and camphor. Syrups Most commercially available syrups are mixtures of medication, preservatives, colouring and flavoring agents, stabilizers and additional solvents such as glycerin. Syrup is a solution that contains a high concentration (~ 65% w/w or 85% w/v) of sugar (e.g., sucrose) or sugar substitute in water. The preparation of syrup usually requires agitation and/or heat to dissolve the sugar. Clean containers and equipment must be used to avoid contamination which may destabilize the syrup. Simple syrup is commonly used in the preparation of compounds and does not require an antimicrobial preservative if it is used soon after preparation. Simple Syrup NF can be purchased as a manufactured product or can be compounded as 85 g of sucrose in 100 mL Purified Water NF. Advantages: Suitable for water-soluble drugs Sugar and flavouring help to mask bad tastes. High concentration of sugar has preservative properties (e.g.. Simple Syrup NF). Disadvantages: Product may crystallize https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 5/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Non-Aqueous Solutions Elixirs Elixirs are defined as sweetened hydro-alcoholic solutions (made of water and alcohol) used orally. Elixirs are used as flavours and vehicles, but are not as sweet or viscous (thick) as syrups and are therefore poorer at masking the taste of drugs. The higher alcohol content makes elixirs better solvents for drugs and they become more resistant to microbial growth. Elixirs may contain glycerin and syrup. The alcohol content may vary from 8% v/v to 78% v/v. Advantages: Suitable for water-soluble and alcohol-soluble drugs Disadvantages: Incompatibilities with alcohol; inorganic salts may cause precipitation Spirits Spirits (also known as aromatics or essences) are solutions most commonly used for flavouring. They contain aromatic substances and a high percentage of alcohol. Spirits can be alcoholic or hydroalcoholic solutions. Camphor Spirit is an example used in pharmacy. Advantages: Suitable for water-soluble and alcohol-soluble Disadvantages: Volatile Limited use (flavouring) Tinctures Tinctures are drugs (derived from plant materials) dissolved in alcohol or hydro-alcohol solvent (15–80% alcohol). Tincture of Iodine 2.5% has medicinal use, whereas other tinctures are used as flavourings. Fluidextracts Fluidextracts are liquid extracts taken from plants. These are generally not used alone as a vehicle for medication. Rather, they are often used in syrups as flavouring agents. An example is vanilla extract. (Although the name implies it is an extract, vanilla is actually a fluidextract.) Extracts Extracts are solid or semi-solid extracts from plants or animal sources. Initially, they are made from a fluidextract. Then, the solvent is allowed to evaporate completely. The remainder is the concentrated extract. Extracts are mostly used in the manufacturing process but are not commonly used today. A product containing thyroid hormone derived from animal sources is still made today. https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 6/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Dispersions Dispersions are liquid preparations of undissolved or immiscible drug particles distributed throughout a vehicle. Dispersions with large or coarse particles include suspensions and emulsions. Dispersions with small or fine particles are called colloidal dispersions and include magmas and gels. Oral suspensions and emulsions are opaque mixtures (non-transparent) of undissolved particles (solids or liquids) in a fluid. These types of mixtures are physically unstable because the solute tends to settle to the bottom of the liquid and/or liquid globules blend together to form a separate layer. A colloidal dispersion is a mixture in which small particles (powder form) are permanently dispersed throughout a solvent. Colloids consist of two separate phases – a dispersed phase (or internal phase) and a continuous phase (or dispersion medium). The size of the particles differentiates colloidal dispersions such as magmas and gels from suspensions. In colloidal dispersions, the particle size is smaller, making the solute more resistant to settling out. Despite the disadvantages of instability and the challenges of preparing the mixtures, these dosage forms have the following advantages: Drugs unstable in a solution are more stable as insoluble particles in a suspension. Drugs with a very unpleasant taste in a solution will be more palatable in a dispersion. Some drugs are not soluble in any suitable solvent and need to be suspended (e.g., antacid preparations). https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 7/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Suspensions Suspensions are preparations containing finely divided drug particles distributed throughout a vehicle. Certain drugs are chemically unstable in solution, but are stable when suspended. Poor-tasting drugs are put into suspensions since their taste is difficult to mask in a solution. Compounding of a suspension might be necessary if a particular drug does not come in a commercially available liquid dosage form. Packaging and Dispensing Suspensions Suspensions should be packaged in a container with a sufficiently wide mouth for ease of pouring. Suspensions should be packaged with sufficient airspace above the liquid to permit adequate mixing by shaking – this will ensure uniform distribution of particles in the vehicle. Suspensions must have a SHAKE WELL auxiliary label to ensure that the drug particles are dispersed evenly throughout the vehicle. Suspensions can be supplied as a ready-to-use suspension or a powder to be reconstituted. Good physical characteristics of a suspension include: Viscosity: Product should pour readily and evenly. Settling rate: Particles should settle slowly. Particles should re-suspend quickly once shaken. Particle size should be consistent throughout product. Advantages of suspensions: Offers suitable alternative when drug is insoluble in a suitable liquid May have more success in masking poor taste since drug is not in solution Chemically more stable than solutions Disadvantages of suspensions: Preparation of a compounded suspension can be complex in order to produce a high-quality product. Reconstituting a Powder/Granule to Produce a Suspension Many products are not stable as a suspension so will be supplied as powders/granules. The pharmacy staff will reconstitute the product by adding purified water to produce a suspension at the time of dispensing. Many liquid antibiotics are supplied this way. To reconstitute a product, follow these steps: Read the manufacturer’s directions on the side of the product to determine the amount of water to add to produce the required concentration. The expiry date of the suspension will also be noted, as will storage requirements. (Directions differ among manufactured products so it is extremely important to always read the bottle carefully.) Measure purified water into a graduated cylinder. The water is usually added in two portions. Solvent (water) will be added directly to the product. The product must be shaken vigorously to distribute the particles evenly. The product should not be transferred to a different bottle. Auxiliary labels for the reconstituted product are important. A SHAKE WELL label must be affixed to the product. The stability of the product changes once the solvent is added to the product, so an EXPIRY DATE auxiliary label should be attached to the product as well. Many products will require refrigeration in order for the product to stay stable so a REFRIGERATE auxiliary label must be attached. The patient prescription label should be affixed directly to the product container. (Reconstituted products are dispensed to the patient in the original container. Do not repackage.) https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 8/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Emulsions Most oils are less dense than water so oil will float on the water’s surface. In emulsions, the oil is dispersed as liquid droplets through the continuous phase, usually in water. The droplets will tend to combine to form a single blob of oil. To prevent the droplets from doing this, emulsions contain a surfactant (emulsifying agent) which coats the surface of each drop and prevents the droplets from combining with each other. An emulsion is a two-phase system consisting of two liquids – one phase of droplets dispersed throughout a second phase of liquid with which it is immiscible. The dispersed phase is the internal phase and the dispersion medium is the external or continuous phase according to emulsion terminology. Oral emulsions are viscous, and topical emulsions may be liquid (lotions) or semi-solid creams and ointments. There are two types of emulsions: (O/W) – Oil in water is the most common type of emulsion and is usually used for internal use products. The oil is the internal phase (dispersed phase), and the water is the external phase (dispersion medium/external). When oil droplets are dispersed in water the internal phase is oily and the external phase is aqueous. (W/O) – Water in oil can be used for internal or external use. This type is used when lubricating or protective properties are desired. Oral liquid emulsions are less acceptable to patients because of the oily feel of emulsions in the mouth. Castor oil (O/W) is used as a laxative and in the preparation of the colon for endoscopic examinations. An example of an emulsion is simethicone drops used for colicky babies. The rate of separation of the two phases is affected by the particle size of the dispersed phase, the relative density of the phases, and the viscosity of the external phase. Problems Specific to Emulsions Creaming is when the two phases of an emulsion separate. Oil is less dense than the water so each drop is prone to floating upwards. This process is called creaming – the oil droplets will gradually form a dense layer at the top of the product. An emulsion is therefore described as unstable with respect to creaming. Shake or agitate the product to reverse creaming. Phase inversion occurs when the dispersed phase and the dispersion medium reverse roles. The emulsion changes from w/o to o/w or vice versa. Cracking (also called coalescence or breaking) occurs when there is complete and irreversible separation of the phases (cannot re-combine). Watch the video: What Are Emulsions? https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 9/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Gels and Magmas Gels and magmas are examples of colloidal dispersions because of the very small particle size in the dispersed phase. Gels and magmas have the smallest particle sizes of all the dispersions. Gels are semi-solid like a jelly. Some gels are clear and some are turbid. A magma (also known as a milk) is a gel mass in which the particles are distinct. Gels and magmas tend to remain fairly uniform when standing. Moderate shaking will restore uniformity prior to administration. Some chemicals gel on heating and others gel on cooling, so it is important to store these products properly. Milk of Magnesia® is an example of a magma. https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 10/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Oral Solution https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 11/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Image preview https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 12/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Oral Syrup Oral Suspension https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 13/14 10/9/24, 10:33 PM Module 5 Book: Drug Preparations Part 3: Oral Liquid Dosage Forms | NorQuest Oral Elixir https://myclass.norquest.ca/mod/book/tool/print/index.php?id=3233186 14/14