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Early medicines were made up of multiple ingredients requiring complex preparation, and Latin was adopted as the standard language of the prescription to ensure understanding between physician and pharmacist and consistency in pharmaceutical composition. Latin no longer is the international language of medicine, but a number of commonly used abbreviations derive from old Latin usage. The symbol "Rx" is said to be an abbreviation for the Latin word recipere, meaning "take" or "take thus," as a direction to a pharmacist, preceding the physician's "recipe" for preparing a medication. The abbreviation "Sig" for the Latin Signatura, is used on the prescription to mark the directions for administration of the medication.
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The prescription consists of the superscription, the inscription, the subscription, the signa, and the name and signature of the prescriber, all contained on a single form (Figure AI–1).
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The superscription includes the date the prescription order is written; the name, address, weight, and age of the patient; and the Rx (Take). The body of the prescription, or inscription, contains the name and amount or strength of the drug to be dispensed, or the name and strength of each ingredient to be compounded. The subscription is the instruction to the pharmacist, usually consisting of a short sentence such as: "make a solution," "mix and place into 30 capsules," or "dispense 30 tablets." The signa or "Sig" is the instruction for the patient as to how to take the prescription, interpreted and transposed onto the prescription label by the pharmacist. In the U.S., prescriptions should always be written in English. Many physicians continue to use Latin abbreviations; for example, "1 cap tid pc," will be interpreted by the pharmacist as "take one capsule three times daily after meals." However, the use of Latin abbreviations for these directions only mystifies the prescription and is discouraged. This can be a hindrance to proper patient-physician communication and is an otherwise unnecessary source of potential dispensing errors. Because the pharmacist always writes the label in English (or, as appropriate, in the language of the patient), the use of such abbreviations or symbols is unnecessary. Many serious dispensing errors can be traced to the use of abbreviations (Cohen, 2007).
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The instruction "take as directed" is not satisfactory and should be avoided by the physician. Such directions assume an understanding on the part of the patient that may not be realized and inappropriately exclude the pharmacist from the pharmaceutical care process. Such directions are inadequate for the pharmacist, who must determine the intent of the physician before dispensing the medication, and who shares the responsibility for the patient's safe and proper use of the medication. The best directions to the patient will include a reminder of the intended purpose of the medication by including such phrases as "for relief of pain" or "to relieve itching." The correct route of administration is reinforced by the choice of the first word of the directions. For an oral dosage form, the directions should begin with "take" or "give"; for externally applied products, the word "apply"; for suppositories, "insert"; and for eye, ear, or nose drops, "place" is preferable to "instill."
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Prescriptive Authority
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In many states in the U.S., healthcare practitioners other than M.D. and D.O. physicians can write prescriptions. Licensed physician's assistants (P.A.), nurse practitioners, pharmacists, and clinical psychologists can prescribe medications under various circumstances.
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Doses always should be listed by metric weight of the active ingredient; doses for liquid medications should include the volume. Older systems of measure such as minims for volume (15 minims = 1 mL) and grains for weight (1 grain = 60 mg) are obscure and should not be used. Writing "μg" for micrograms can very easily be misinterpreted as "mg" (milligrams). Even the abbreviation "mcg" for micrograms can be misinterpreted (Koczmara et al., 2005). Writing out the word micrograms or milligrams is preferable. When specifying the dose to be dispensed, a zero should be used before a decimal (0.# milligrams, rather than .# milligrams) but not after (use # milligrams rather than #.0 milligrams). The metric system should be used in place of common household measurements such as "dropperful" and "teaspoon" in the directions for the patient except when the dropper is provided with the prescription, as in the case of pediatric antibiotic suspensions. Both the doctor and the pharmacist should be sure that the patient understands the measurement prescribed. For medical purposes, a "teaspoon" or "teaspoonful" dose is considered to be equivalent to 5 mL and a "tablespoon" equivalent to 15 mL, but the actual volumes held by ordinary household teaspoons and tablespoons are far too variable to be used reliably for measurement of medications. Prescribing oral medications in "drops" likewise can cause problems when accuracy of dose is important, unless the patient understands that only the calibrated dropper (for drops or teaspoon measures) provided by the manufacturer or pharmacist should be used to dispense the medication. Thus, one possible dosage for a pediatric iron product would be more accurately written "15 milligrams (0.6 mL) three times daily" instead of "one dropperful three times daily," because a true dropperful could result in iron overdose.
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Abbreviations lead to dispensing errors (Teichman and Caffee, 2002). A prescription intending every-other-day dosing (qod) may be miswritten as "od" by the physician for "other-day dosing"; the pharmacist may interpret "od" as the abbreviation of the Latin for "right eye." Once-daily dosing at bedtime (qhs) may be misinterpreted as "qhr" for "every hour." The use of a slash mark (/) to separate names and doses can result in the incorrect drug or dose being dispensed; the slash mark may be interpreted as a letter or number. When medications are measured in units, or international units, the abbreviation "U" or "I" must NOT be used, as it leads to errors such as misinterpretation of "U" as 0 or 4, or "IU" as 10 or 14. The word "unit" should be written as such. Drug products available in the U.S. that are dosed in units (e.g., corticotropin) or international unit measures are "harmonized" by those responsible for drug standardization to avoid errors in dosing (see "Drug Standards and Classification"). Examples of confusion in the interpretation of a physician order abound (Kohn, 2001) and are considered further in "Errors in Drug Orders." To avoid errors, practitioners in the U.S. must write out the Rx fully in English, and pharmacists must clarify their concerns with prescribers, not patients.
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Proper Patient Information
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The patient's name and address are needed on the prescription order to ensure that the correct medication goes to the proper patient and also for identification and recordkeeping purposes. For medications whose dosage involves a calculation, a patient's pertinent factors, such as weight, age, or body surface area, also should be listed on the prescription. Prescribers should view this effort as one that serves their goal of protecting their patient from errors rather than a burden (safety first).
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Prescribers often commit errors in dosage calculations (Lesar et al., 1997) that can be prevented (Kuperman et al., 2001; Conroy et al., 2007). When prescribing a drug whose dosage involves a calculation based on body weight or surface area, both the calculated dose and the dosage formula used, such as "240 mg every 8 hours (40 mg/kg/day)," should be included to allow another healthcare professional to double-check the prescribed dosage. Pharmacists always should recalculate dosage equations when filling such prescriptions. Medication orders in hospitals and some clinic settings, such as those for antibiotics or anti-seizure medications that are sometimes difficult to adequately dose (e.g., phenytoin), can specify the patient diagnosis and desired drug and request dosing by the clinical pharmacist.
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Proper Use of Prescription Pad
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All prescriptions should be written in ink; this practice is compulsory for schedule II prescriptions under the U.S. Controlled Substances Act (CSA) of 1970, because erasures on a prescription easily can lead to dispensing errors or diversion of controlled substances.
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Prescription pad blanks normally are imprinted with a heading that gives the name of the physician and the address and phone number of the practice site (Figure AI–1). When using institutional blanks that do not bear the physician's information, the physician always should print his or her name and phone number on the face of the prescription to clearly identify the prescriber and facilitate communication with other healthcare professionals if questions arise. U.S. law requires that prescriptions for controlled substances include the name, address, and Drug Enforcement Administration (DEA) registration number of the physician.
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The date of the prescription is an important part of the patient's medical record, and it can assist the pharmacist in recognizing potential problems. For example, when an opioid is prescribed for pain due to an injury, and the prescription is presented to a pharmacist 2 weeks after issuance, the drug may no longer be indicated. Compliance behavior also can be estimated using the dates when a prescription is filled and refilled. The CSA requires that all orders for controlled substances (Table AI–1) be dated as of, and signed on, the day issued and prohibits filling or refilling orders for substances in schedules III and IV >6 months after their date of issuance. When writing the original prescription, the physician should designate the number of refills allowed. For maintenance medications without abuse potential, it is reasonable to write for a 1-month supply and to mark the prescription form for refills to be dispensed over a period sufficient to supply the patient until the next scheduled visit to the physician. A statement such as "refill prn" (refill as needed) is not appropriate, as it could allow the patient to misuse the medicine or neglect medical appointments. If no refills are desired, "zero" (not "0") should be written in the refill space to prevent alteration of the prescriber's intent. Refills for controlled substances are discussed later, in "Refills" under "Controlled Substances."
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Concern about the rising cost of healthcare has favored the dispensing of so-called "generic" drugs. A drug is called by its generic name (in the U.S., this is the U.S. Adopted Name or USAN) or the manufacturer's proprietary name, called the trademark, trade name, or brand name. In most states in the U.S., pharmacists have the authority to dispense generic drugs rather than brand-name medications. The physician can request that the pharmacist not substitute a generic for a branded medication by indicating this on the prescription ("do not substitute"), although this generally is unnecessary because the U.S. Food and Drug Administration (FDA) requires that generic medications meet the same bioequivalence standards as their brand-name counterparts. In some jurisdictions, prescriptions may not be filled with a generic substitution unless specifically permitted on the prescription. Occasions when substituting generic medications is discouraged are limited to products with specialized release systems and narrow therapeutic indices, or when substantial patient confusion and potential noncompliance may be associated with substitution.
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Choice and Amount of Drug Product Dispensed
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Inappropriate choice of drugs by physicians is a problem in prescribing. As learned recently with the cyclooxygenase-2 (COX-2) inhibitors, a drug's therapeutic promise or popularity is not proof of its overall clinical superiority or safety (Topol, 2004). Physicians must rely on unbiased sources when seeking drug information that will influence their prescribing habits; use of the original medical literature will ensure instruction of the prescriber's best judgment.
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The amount of a drug to be dispensed should be clearly stated and should be only that needed by the patient. Excessive amounts should never be dispensed, because this not only is expensive for the patient but may lead to accumulation of medicines, which can lead to harm to the patient or members of the patient's family if used inappropriately. It is far better to have several refills of a prescription than to have more than necessary prescribed at one time.
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The Prescription as a Commodity
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Prescribers must be aware that patients may visit their doctor to "get" a prescription. Indeed, in an era when the time spent between physician and patient is ever shorter due to limits and pressures of physician reimbursements, patients often feel that a trip to the doctor that does not result in a new prescription somehow is a failed visit or a lost opportunity. Similarly, physicians may feel that they have fulfilled their role if the patient leaves with a prescription. Physicians must educate their patients about the importance of viewing medicines as to be used only when really needed and that remaining on a particular medicine when their condition is stable may be preferable to seeking the newest medications available.
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Prescription Drug Advertising
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The Federal Food, Drug, and Cosmetic Act as amended (Food and Drug Administration Modernization Act of 1997) permits the use of print and television advertising of prescription drugs. The law requires that all drug advertisements contain (among other things) summary information relating to side effects, contraindications, and effectiveness. The current advertising regulations specify that this information disclosure needs to include all the risk information in a product's approved labeling or must direct consumers to healthcare professionals to obtain this information. Typically, print advertisements will include a reprinting of the risk-related sections of the product's approved labeling (package insert), while television advertising will not. In addition, advertisements cannot be false or misleading or omit material facts. They also must present a fair balance between effectiveness and risk information.
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The benefits of these types of direct-to-consumer (DTC) advertising, including Internet advertising, are controversial (Findlay, 2001). Dramatizations employed by television commercials may be a disservice to the physician's ability to educate and care for the patient if such advertisements only create brand loyalty. Alternatively, patients who learn about drugs on television may interact more effectively with their healthcare providers by asking questions about the medicines they take. Prescription drug advertising has alerted consumers to the existence of new drugs and the conditions they treat, but it has also increased consumer demand for drugs. This demand has increased the number of prescriptions being dispensed (raising sales revenues) and has contributed to the higher pharmaceutical costs borne by health insurers, government, and consumers. In the face of a growing demand for particular brand-name drugs driven by advertising, physicians and pharmacists must be able to counsel patients effectively and provide them with evidence-based drug information (Khanfar et al., 2007).