Learning Outcomes
After completing this chapter, you will be able to
Explain why medications are often available in more than one dosage form.
List three advantages of liquid medication dosage forms over other dosage forms.
List three disadvantages of solid medication dosage forms.
Outline characteristics of solutions, emulsions, and suspensions.
Describe two situations in which an ointment may be preferred over a cream.
Explain the differences in use among various solid medication dosage forms, such as tablets, capsules, lozenges, powders, and granules.
List six routes of administration by which drugs may enter or be applied to the body.
Identify special considerations for five routes of administration.
List five parenteral routes of administration.
Distinguish between sublingual and buccal routes.
Key Terms
| aerosol | A suspension of very fine liquid or solid particles distributed in a gas, packaged under pressure, and shaken before use, after which medication is released from the container as a spray. |
| aqueous solution | A liquid solution that contains purified water as the vehicle. |
| buccal | A solid medication dosage form that is placed in the pocket between the cheek and gum and absorbed through the cheek into the bloodstream. |
| douche | An aqueous solution that is placed into a body cavity or against a part of the body (e.g., the internal vaginal cavity) to clean or disinfect. |
| elixir | A clear, sweet, flavored water-and-alcohol (hydroalcoholic) mixture intended for oral use. |
| emulsion | A mixture of two liquids that normally do not mix, in which one liquid is broken into small droplets (the internal phase) and evenly scattered throughout the other (the external or continuous phase) and an emulsifying agent prevents the internal phase from separating from the external phase. |
| endotracheal | Administering a medication into the trachea (windpipe); intratracheal. |
| enema | A solution that is inserted into the rectum to empty the lower intestinal tract or to treat diseases of that area; often given to relieve severe constipation or to clean the large bowel before surgery. |
Liquid Medication Dosage Forms
Semi-Solid Medication Dosage Forms
Miscellaneous Medication Dosage Forms
Sublingual, Buccal, Transmucosal, and Subgingival
Dosage Form versus Route of Administration |
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When most people think about taking a medication, they imagine swallowing a tablet or a capsule. Although this is the most common way people take medications, other forms of medication are used to introduce medicines into the body by routes other than the mouth. Solutions, suspensions, suppositories, and sprays can be used to deliver medications into body areas such as the ears, nose, eyes, rectum, or bloodstream.
This chapter describes many medication dosage forms and routes of administration. It is not intended to be all-inclusive, but rather to serve as an introduction to commonly used and not-so-commonly used dosage forms and administration routes. Pharmacy technicians must be familiar with these concepts, since they are important as the technicians prepare, dispense, store, and otherwise manage medications.
Medication Dosage Forms
The most common medication dosage forms are liquids and solids. Liquid formulations deliver medication in a fluid and may be poured from a bottle or vial; solid medication dosage forms hold their original shape. Both dosage forms are usually administered orally, but may sometimes be administered by other routes. Availability of medications in different dosage forms offers options to prescribers, patients, caregivers, and manufacturers. For example, liquid medications are easier for children to take than solid ones. On the other hand, some medications are degraded by digestive enzymes found in the stomach or have poor absorption, so manufacturers formulate them to be given into a vein, thus bypassing the gastrointestinal tract.
A local effect refers to an action of a medication that takes place at the area of contact. Contact may be with the skin, mucous membranes, respiratory tract, gastrointestinal system, eyes, or other organ systems. Absorption of the medication into the bloodstream does not usually occur. In contrast, a systemic effect is the result of an action of a medication that affects the whole body or takes place at a location distant from the medication’s initial point of contact. Absorption of the medication must occur.
Liquid Medication Dosage Forms
Liquid medication dosage forms deliver medication in a fluid medium. The fluid serves as a carrier, or delivery system, for the medication and is referred to as the vehicle. Common medication vehicles are water, alcohol, glycerin, and mineral oil. The medication can be dissolved in the vehicle or can be present as very fine solid particles that are suspended, or floating, in the vehicle. Liquid medication dosage forms may pour as freely as water or may have the thickness of heavy syrup. They may be meant for oral intake or for use in, or on, other parts of the body.
Liquid medication dosage forms offer some advantages over other medication dosage forms, including
Oral liquid medication dosage forms are usually faster-acting than solid medication dosage forms. Medications are absorbed into the bloodstream in a dissolved state. The medication in a liquid medication dosage form either is already dissolved or is present in small particles which then dissolve in fluids in the gastrointestinal tract, so the medication can be readily absorbed into the bloodstream. In contrast, tablets must first dissolve in the stomach (or other place where they may be administered, such as the vagina) before they can be absorbed, so it takes more time for the medication to be absorbed and to act.
For patients who have difficulty swallowing, oral liquid medications may be easier to take than oral solid medication dosage forms.
Liquid doses have more flexibility than some other dosage forms because liquid medications are usually dispensed in bulk containers rather than distinct dosage units. For example, a liquid medication contains 500 mg of a drug in 10 mL of liquid. The same medication is also available in 500 mg tablets. To take a 600 mg dose of the liquid medication, a patient would simply need to measure out 12 mL of liquid. However, to take a 600 mg dose of the tablet, the patient would need to take 1.2 tablets, which would be difficult.
Liquid medications may be used where solid medication dosage forms are not practical to administer. For example, medications that need to be placed directly into the ears or eyes can be administered more easily as a liquid than as a solid.
There are also some disadvantages to liquid medication dosage forms, such as
Often, liquid medication dosage forms have shorter times to expiration than other dosage forms.
Many drugs have an unpleasant taste as the drug dissolves or is chewed into small particles. Drug particles are already present in oral liquid medications and come in contact with the taste buds of the tongue. People often find the taste or sensation of these drug particles unpleasant. Sweeteners and flavoring agents are necessary to make these liquid medications taste better. Even with such sweetening or flavoring, the taste of some liquid medications may remain unpleasant. Tablets and capsules, on the other hand, are often coated and can be swallowed quickly to avoid contact with the taste buds.
Patients sometimes find liquid medications inconvenient because they may be spilled, require careful measuring before administration, or have special storage or handling requirements, such as refrigeration or shaking before use.
Liquid medication dosage forms are grouped based on several characteristics: the vehicle (e.g., water or alcohol) in which the medication is delivered, whether the medication is dissolved or suspended as particles in the liquid, or the intended use of the medication. Table 12-1 gives examples of solutions, emulsions, and suspensions.
Table 12–1. Liquid Medication Dosage Forms
| Dosage Form | Examples |
| Solutions |  Aqueous (water-based) |
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 Nonaqueous | |
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| Extractives |  Extracts |
 Tinctures | |
 Fluidextracts | |
| Emulsions |  Oil-in-water |
 Water-in-oil | |
| Suspensions |  Lotions |
 Magmas and milks | |
 Gels | |
 Mucilages |
Gargles
Oral rinses
Washes and mouthwashes
Douches
Irrigants
Enemas
Sprays
Viscous (thick) aqueous
Syrups
Jellies
Hydroalcoholic
Elixirs
Spirits
Alcoholic
Collodions
Spirits
GlyceritesSolutions. Solutions are evenly distributed, homogeneous (even) mixtures of dissolved medication in a liquid vehicle. Because the medication is already dissolved in the solution, the upper gastrointestinal tract, skin, or other site of administration absorbs it more quickly than other medication dosage forms.
Solutions should appear clear with no visible particles present. If particles or cloudiness are noted, the solution should not be used.
Solutions may be subdivided on the basis of the characteristics of the vehicle into a) aqueous b) nonaqueous and c) miscellaneous solutions.
Aqueous solutions. Aqueous solutions use purified water as the vehicle and can be ingested orally, applied topically (externally), or injected into the bloodstream.
Gargles are solutions that treat conditions of the throat. The gargle is held in the throat as the patient gurgles air through the solution. Although gargles are used in the mouth, they should not be swallowed. A familiar commerical gargle is Cepacol antiseptic mouthwash/gargle. Oral rinses, such as chlorhexidine (Peridex), are used to treat conditions inside the mouth. Oral rinses are also not supposed to be swallowed and should be spit out after swishing in the mouth.
A wash is a solution used to cleanse or bathe a body part, such as the eyes or mouth. Massengill Feminine Cleansing Wash is a vaginal wash intended to cleanse the external vaginal area. A mouthwash is a solution used to deodorize, refresh, or disinfect the mouth, primarily for cosmetic reasons. Although many people use mouthwashes as gargles, the two are technically in different classes of solutions: gargles are used to treat throat conditions, such as a sore throat, while mouthwashes are used to freshen the mouth. Like gargles, mouthwashes should not be swallowed. Common mouthwashes include Advanced Formula Plax and Listerine.
A douche [doosh] is an aqueous solution placed into a body cavity or against a part of the body to clean or disinfect. Douches are commonly used to cleanse the internal vaginal cavity, but a douche may also be used to remove debris from the eyes or to cleanse the nose or throat. Examples of commercially available vaginal douche products are Massengill and Summer’s Eve.
Irrigating solutions, or irrigants, are used to wash or cleanse part of the body, such as the eyes, the urinary bladder, open wounds, or scraped skin. These solutions often contain medication, such as antibiotics or other antimicrobial agents, and are usually sterile. Irrigating solutions may be used in surgical procedures to clear the body area of blood and surgical debris. A common irrigating solution used in the eye is balanced salt solution (BSS). Although similar to douches, irrigating solutions are usually used in larger volumes and over larger areas of the body for a more general cleaning than douches.
Enemas are solutions that are inserted into the rectum to empty the lower intestinal tract or to treat diseases of that area.
Enemas, such as Fleet enema, are often given to relieve severe constipation or to clean the large bowel before surgery.
Sprays are solutions that are applied as a mist to the area to be treated. Some sprays are for use on the mucous membranes of the nose and throat, while other sprays are used on the skin. Nasal decongestants (e.g., oxymetazoline [Afrin 12-Hour Original] and phenylephrine [NeoSynephrine 4-Hour]) and antiseptic throat solutions (e.g., phenol [Cheracol Sore Throat Spray]) are spray products for the nose and throat.
Viscous aqueous solutions are sticky, thick, sweet solutions that are either liquid or semisolid. A syrup is a concentrated mixture of sucrose, or another type of sugar, and purified water. The high sugar content makes syrups different from other types of solutions. Syrups may or may not contain medication or added flavoring agents. Syrups without a medication are called non-medicated syrups. Simple syrup, which contains only sucrose and water, is one such example. Flavored syrups have an added flavoring agent and are often are used as vehicles for unpleasant-tasting medications; the result is a medicated syrup. The amount of sugar present in syrups makes them likely to be contaminated by bacteria, so they often contain a preservative. The high sugar content also makes syrups a poor choice for patients who have diabetes mellitus. Some medications are available as “sugar-free syrups,” but they are not true syrups since by definition, syrups are mixtures of sugar and water. They would be more appropriately labeled as “liquids.”
The advantage of syrups is that their sweet taste can disguise the unpleasant taste of medications. Because syrups are thicker than aqueous solutions, only a portion of the medication dissolved in the syrup comes in contact with the taste buds. The remainder of the medication is held above the tongue by the thick syrup, so it is not tasted as it is swallowed. For this reason, syrups are commonly used for medications taken by children. The thick nature of syrups also has a soothing effect on irritated tissues of the throat, so syrups are often used for cough formulations. Robitussin is an example of a common line of cough and cold syrup products.
Jellies are semisolid solutions that have a high liquid content, usually water. K-Y Jelly is an example of a commonly used lubricant jelly. It may be used to make insertion of rectal thermometers or other medical instruments into body openings more comfortable, as a sexual lubricant, or to reduce friction and enhance transmission of sound waves during ultrasound procedures. Lidocaine jelly is used as a local anesthetic for patients who are to have endotracheal tubes placed down their throats or urinary catheters (tubes) placed into their urethras. Jellies are also used as vaginal lubricants or as vehicles for vaginal contraceptive agents.
Nonaqueous solutions.Nonaqueous solutions are those that use solvents, or dissolving liquids, other than water. Commonly used nonaqueous solvents include alcohol (ethyl alcohol or ethanol), glycerin, mineral oil, and propylene glycol.
Hydroalcoholic solutions differ from aqueous solutions in that they contain alcohol as well as water. Elixirs and spirits are examples of hydroalcoholic solutions.
Elixirs [i-lick-serz] are clear, sweet, flavored water-andalcohol (hydroalcoholic) mixtures intended for oral use. The amount of alcohol in elixirs varies greatly depending on how well the other ingredients in the elixir dissolve in water. Many drugs do not dissolve easily in pure water but do so in a water-and-alcohol mixture. Some elixirs have as little as 3% alcohol, whereas others may contain almost 25%.
The alcohol content of an elixir is a disadvantage or a reason to avoid use in patients who should not or cannot ingest alcohol. In addition, alcohol can have undesired interactions with other medications the patients may be taking. Elderly and alcoholic patients, as well as parents of children, should be made aware of the alcohol content of elixirs, because these patients may be especially sensitive to even small amounts of alcohol. For this reason, some elixirs have been re-formulated to remove the alcohol and are no longer true elixirs, but may be still be known as such. Phenobarbital elixir and digoxin pediatric elixir are two prescription elixirs.
Aromatic and licorice elixirs are used as flavoring agents. An aromatic elixir is a nonmedicated elixir commonly used as a vehicle for other medications. Simple elixir, which contains orange, lemon, coriander, or anise oils in syrup, water, and alcohol, is one example.
Spirits, or essences, are alcoholic or hydroalcoholic solutions that contain volatile, or easily evaporated, substances. Because the volatile substances dissolve more easily in alcohol, spirits can contain a greater amount of these materials than aqueous solutions can. Perhaps the most familiar spirits administered internally are the alcoholic beverages brandy (Spiritus Vini Vitis) and whiskey (Spiritus Frumenti). Other spirits may be inhaled (e.g., aromatic ammonia spirits, commonly known as smelling salts and used for fainting), while still others, such as peppermint spirits, are used as flavoring agents.
A collodion [kuh-loh-dee-uhn] is a liquid preparation of pyroxylin [pie-rock-suh-lin] (found in cotton fibers) that is dissolved in ethyl ether and ethanol.
After the collodion is applied to the skin, the ether and ethanol evaporate and leave a pyroxylin film. Some medicated collodions are used to treat corns and warts (e.g., Compound W). Unmedicated collodions, such as liquid adhesive bandages (e.g., New-Skin) and skin protectants (e.g., BlisterGard), may be applied to the skin for protection or to seal small wounds.
Glycerites are nonaqueous solutions of medication dissolved in glycerin, a sweet oily fluid made from fats and oils. Glycerin can be used alone as a vehicle or in combination with water, alcohol, or both. Because glycerin easily mixes with water and alcohol, it can be used as a solvent for medications that do not dissolve in either alone. After a medication is dissolved in glycerin, the medication/glycerin mixture can then be added to a water vehicle or alcohol vehicle. Glycerin may be used in oral, otic (ear), ophthalmic (eye), topical (on the skin), and parenteral formulations. Most glycerite solutions are very viscous and thick, some to the point of being jellylike. Debrox Drops, used to remove earwax from ears, is an example of a product formulated in glycerin.
Extractives. Extractives are concentrated preparations of materials found in plant or animal tissue. The crude drug is extracted, or removed, from the dried plant or animal tissue by soaking it in a solvent. The solvent is then evaporated, leaving behind the tissue parts containing medical activity. Extracts, tinctures [tingk-cherz], and fluidextracts are examples of formulations prepared in this manner. They differ only in their strength or potency.
Extracts are prepared in the same manner as tinctures and fluidextracts and are two to six times as potent as the crude drug. Vanilla, almond, and peppermint extracts, commonly used in cooking and baking, are examples of extracts.
Tinctures are alcoholic or hydroalcoholic solutions whose potency is adjusted so that each milliliter of tincture contains the equivalent of 100 mg of crude drug. Iodine tincture and opium tincture are two examples.
Fluidextracts are more potent than tinctures; each milliliter of fluidextract contains the equivalent of 1,000 mg of crude drug. Cascara sagrada fluidextract and senna fluidextract are extracts that, in the past, were commonly used to clear the bowels.
Emulsions. Emulsions are mixtures of two liquids that normally do not mix. In an emulsion, one liquid is broken into small droplets and evenly scattered throughout the other. The liquid present in small droplets is referred to as the internal phase; the other liquid is called the external, or continuous, phase. To keep the two liquids from separating, an emulsifying agent is added to the formulation to prevent the small particles of the internal phase from coming together and eventually separating from the external phase to form two distinct layers. Oil-and-vinegar salad dressing is a common household emulsion that is formed by shaking the two liquids together. Because no emulsifying agent is added, the oil and vinegar separate within seconds after shaking and the emulsion is broken.
In most emulsions, the two liquids are oil and water. An oil-in-water (O/W) emulsion consists of small oil droplets scattered throughout water. O/W emulsions are desirable for oral use for several reasons. Unpleasant oily medications are broken into small particles and dispersed throughout a sweetened, flavored aqueous vehicle. These small particles are carried past the taste buds and swallowed without the patient tasting the oily medication. The small particle size increases medication absorption from the stomach and small intestine into the bloodstream. One formulation of cyclosporine (Neoral), a medication used to prevent rejection of transplanted organs, is such an example.
In water-in-oil (W/O) emulsions, water droplets are spread throughout the oil. W/O emulsions are often used on unbroken skin. They spread more evenly than O/W emulsions because the natural oils of the skin mix with the external oil phase of the emulsion. They soften the skin better because they hold moisture and are not easily washed off with water. However, they have a heavy, greasy feel and may stain clothing.
The choice of O/W or W/O emulsion for preparations applied to the skin depends on several factors. As an example, medications that are irritating to the skin feel better when applied as small particles in the internal phase. The external phase keeps them from directly contacting and irritating the skin. O/W emulsions may be more desired in some cases because they are water-washable and do not stain. They feel lighter and nongreasy and have an advantage when the emulsion is to be applied to a hairy part of the body, such as the scalp.
Some emulsions may also be injected into the bloodstream. Intravenous fat emulsion (Intralipid, Liposyn II) and the anesthetic medication propofol (Diprivan) are examples of O/W emulsions that are given intravenously.
Suspensions. Suspensions are mixtures of fine particles of an undissolved solid spread throughout a gas or, more commonly, a liquid. The difference between a solution and a suspension is that in a solution the particles are dissolved, whereas in a suspension they are not. Suspensions are useful for administering a large amount of solid medication that would be inconvenient to take as a tablet or capsule. The fine particles dissolve more quickly in the stomach or small intestine and are absorbed into the bloodstream more quickly than the medication of a solid tablet or capsule. Suspensions need to be shaken before use to redistribute particles that may have settled to the bottom or risen to the top of the container after standing.
Most suspensions are for oral use, but some may be taken by other routes, such as the rectal, otic, ophthalmic, or parenteral routes. Suspensions taken by mouth usually use water as the vehicle, although suspensions that are given by parenteral routes, such as into muscles or joints, may use oil as the vehicle. Medication particles suspended in oil dissolve more slowly than in water. This imparts a “depot” effect and gives the medication extended-release properties. Haloperidol decanoate 50 is formulated in sesame oil, which allows it to be given intramuscularly (IM) on a monthly basis.
Parenteral suspensions should NEVER be given intravenously. Serious adverse effects such as cardiorespiratory (heart and lung) failure, coma, or death may occur.
