Help me learn about strengths and dosage Forms, how drugs are administered to prepare for the PTCE, here's additional context: Drugs are commercially available in various strengths and dosage forms. The strength of a drug is the amount contained in a unit of the product, whether a tablet or a teaspoonful of a liquid (for example, diazepam 5-mg tablets or amoxicillin suspension 150 mg/5 mL). When preparing a prescription, you must be very careful to select the correct strength of the drug. Some drugs, such as digoxin and warfarin, have doses that can be therapeutic in one patient but toxic in another. Such medicines are said to have narrow therapeutic ranges or indexes. In the pharmacy, you may find that the various strengths of such drugs are placed on shelves away from each other. These drugs are separated to decrease the chances of someone accidentally picking up the wrong strength. Many drugs also come in various dosage forms. Table 1-2 defines the most common dosage forms and provides considerations about the use of each. While giving a patient the wrong dosage form may not be as serious an error as the wrong drug or strength, it can still be problematic. For instance, an elderly patient may not be able to swallow tablets or capsules and therefore may require liquid preparations. Or a patient who is vomiting may require a rectal suppository rather than oral dosage forms. Be sure you have the correct dosage form—don’t assume anything!---**Table Extraction:** **Table Title:** (Implicitly a table of Pharmaceutical Dosage Forms) **Table Headers:** * Dosage Forms * Description * Considerations **Table Content:** **Solid Dosage Forms** * **Pills** * **Description:** Solid oral dosage forms that are made from a paste, rolled between the first finger and thumb, and then dried. * **Considerations:** Common when pharmacists made pills in this manner in years past, but hardly any true pills are on the commercial market. Solid oral dosage forms are now tablets or capsules, and they should be referred to by these more correct names. * **Tablets** * **Description:** Powders that are compressed with enough force that they stay together during shipping and handling but not enough force to prevent them from dissolving in the body. * **Considerations:** May be swallowed, chewed and then swallowed, dissolved under the tongue or in the buccal pouch (the space in the mouth between the teeth and the cheek), or sometimes ground up for patients who cannot swallow the whole tablet. Dosage forms that contain timed-release, controlled-release, or delayed-release features should not be crushed (unless otherwise indicated on package labeling) as it disrupts these processes. * **Capsules** * **Description:** Gelatin containers with loose powders or timed-release beads inside. These are easily made commercially or in the pharmacy when a prescription must be compounded. * **Considerations:** Capsules are cheapest and easiest solid oral dosage form to make. They typically present no bioavailability problems since they dissolve easily in the fluids of the stomach and small intestine. **Liquid Dosage Forms** * **Solutions** * **Description:** Liquids in which the drug is completely dissolved in the vehicle, making the product clear (but not necessarily colorless). * **Considerations:** Because most drugs taste bitter, few oral solutions are used (suspensions mask the taste better). Rather, solutions are more often used for topical preparations, such as antibiotic solutions used for acne or sterile solutions that are used in the eyes. * **Suspensions** * **Description:** A common liquid oral dosage form in which the drug is present in small particles in a flavored vehicle. Suspensions are never clear and must be shaken well to disperse the drug before a dose is measured. * **Considerations:** Examples include liquid antibiotics used orally, anti-infective products used in the ears, and other agents prepared for pediatric or elderly patients, such as antipsychotic agents that can be given to those who will not or cannot swallow. * **Syrups and elixirs** * **Description:** Also used to mask the bitter taste of medicines. Syrups are sweetened vehicles, whereas elixirs contain alcohol. * **Considerations:** Examples include most cough syrups and elixirs such as phenobarbital. **Topical and Other Dosage Forms** * **Creams and ointments** * **Description:** Semisolid preparations used to deliver drugs to the skin or mucous membranes (nose, vagina). Creams are water based and therefore easily washed off, while ointments are fat based and resistant to removal with water. * **Considerations:** Examples include hydrocortisone cream and ointment. It should be noted that creams and ointments are not always interchangeable. In fact, when dealing with a prescription product, selection must be exactly what the prescriber intended. * **Lotions (also called emulsions)** * **Description:** Lotions, or products used to soften or deliver drugs to the skin, are liquid preparations that contain 2 "phases." Similar to how drugs can be dissolved in a solution, a water phase can be dispersed in a fat (lipid) phase, or small lipid globules can be dispersed in a water phase. * **Considerations:** Examples include Calamine lotion and the many lotions, such as Curel and Vaseline Intensive Care, that are used to rehydrate or soften the skin. * **Transdermal patches and subdermal inserts** * **Description:** Drugs can be delivered through the skin using patches that control the rate of drug administration and through the use of inserts that are surgically implanted under the skin. * **Considerations:** Examples include Nitrodern patches and Implanon contraceptive inserts. A commonly asked question by patients regarding patches is whether or not they can be cut. Be careful not to advise the patient either way without consulting the pharmacist, as each patch has specific instructions for use that are specified in the product labeling. **Vaginal, Urethral, and Rectal Dosage Forms** * **Suppositories** * **Description:** Dosage forms designed to remain solid at room or refrigerator temperature and to melt and release the drug when inserted into an orifice (or opening) of the body. The 2 most commonly used suppositories are inserted into the rectum or vagina, and a few suppositories are used in the urethra of men. * **Considerations:** Numerous agents are formulated as rectal suppositories, including Phenergan, which is used when patients' nausea and vomiting are so severe that they cannot keep down the oral form of this drug. Vaginal suppositories include antifungal agents such as Monistat. Vaginal contraceptives are marketed as gels, foams, and jellies. **Injectable Dosage Forms** * **Injectable solutions** * **Description:** Most injectable drugs are formulated as sterile solutions. Depending on the specific drug in the solution, these can be injected into arteries, veins, or tissues or can be used to make large-volume solutions that are then infused into the body through a vein, artery, or the peritoneal cavity (the space around the stomach, intestines, liver, and other nearby organs). * **Considerations:** Because of the high concentrations of drugs in most injectable products, be extremely careful that you use the right drug and strength. Also, remember that some drugs cannot be given intravenously, while others cannot be injected into the muscle. * **Injectable suspensions** * **Description:** A few injectable products are formulated as suspensions. These are always injected in muscle, where they are absorbed into the blood. Suspensions should never be injected into veins or arteries, since the particles in them can get stuck in the lungs and capillaries, causing serious injury or death. * **Considerations:** Most injectable suspensions are antibiotics; these are absorbed from intramuscular injections fairly quickly. Other products, including antipsychotic agents, are made to be absorbed over a 3- or 4-week period. Since patients with schizophrenia and other psychoses are often afraid to take their medicines (they think the doctors are trying to kill them), these "depot" injections provide a way to give these patients their needed medications. * **Injectable emulsions** * **Description:** When patients are unable to take food by mouth, they must be fed through the veins and arteries ("parenterally"). Lipid emulsions provide the fat that people normally get from their diets. * **Considerations:** Examples include Liposyn, Intralipid, and Nutrilipid.