Medical prescription

A prescription is a health-care programme that governs the plan of care for an individual patient and is implemented by a qualified practitioner. A qualified practitioner might be a physician, dentist, nurse practitioner, pharmacist, psychologist, or other health care providers. Prescriptions may include orders to be performed by a patient, caretaker, nurse, pharmacist, physician, other therapist, or by automated equipment, such as an intravenous infusion pump. Formerly, prescriptions often included detailed instructions regarding compounding of medications but as medications have increasingly become pre-packaged manufactured products, the term "prescription" now usually refers to an order that a pharmacist dispense and that a patient take certain medications. Prescriptions have legal implications, as they may indicate that the prescriber takes responsibility for the clinical care of the patient and in particular for monitoring efficacy and safety. As medical practice has become increasingly complex, the scope of meaning of the term "prescription" has broadened to also include clinical assessments, laboratory tests, and imaging studies relevant to optimizing the safety or efficacy of medical treatment.

Format and definition
Prescriptions may be entered into an electronic medical record system and transmitted electronically to a pharmacy. Alternatively, a prescription may be handwritten on preprinted prescription forms that are assembled into pads, or printed onto similar forms using a computer printer. In some cases, a prescription may be transmitted from the physician to the pharmacist verbally by telephone, although this practice may increase the risk of medical error. The content of a prescription includes the name and address of the prescribing provider and any other legal requirement such as a registration number (e.g. DEA Number in the United States). Unique for each prescription is the name of the patient. In the United Kingdom and Ireland, the patient's name and address must also be recorded. Each prescription is dated and some jurisdictions may place a time limit on the prescription. In the past, prescriptions contained instructions for the pharmacist to use for compounding the pharmaceutical product but most prescriptions now specify pharmaceutical products that were manufactured and require little or no preparation by the pharmacist. Prescriptions also contain directions for the patient to follow when taking the drug. These directions are printed on the label of the pharmaceutical product.

 is a symbol meaning "prescription". It is sometimes transliterated as "Rx" or just "Rx". This symbol originated in medieval manuscripts as an abbreviation of the Late Latin verb recipe, the imperative form of recipere, "to take" or "take thus". Literally, the Latin word recipe means simply "Take...." and medieval prescriptions invariably began with the command to "take" certain materials and compound them in specified ways.

Folk theories about the origin of the symbol  note its similarity to the Eye of Horus, or to the ancient symbol for Zeus or Jupiter, (♃), gods whose protection may have been sought in medical contexts.

The word "prescription", from "pre-" ("before") and "script" ("writing, written"), refers to the fact that the prescription is an order that must be written down before a compound drug can be prepared. Those within the industry will often call prescriptions simply "scripts".

The fact that a prescription instructs someone to "take" rather than "give" is not a trivial distinction, but makes clear it is directed at the patient, and is not directly an instruction to anyone else. In certain states medical marijuana legislation has been drafted calling for a health care professional's written or oral "recommendation", in the belief that a written one would be legally distinguishable from a prescription, but since written advice to a patient is what a prescription is, that belief is mistaken. Jurisdictions may adopt a statutory definition of "prescription" which is applicable as a term of art only to the operation of that statute (see below about prescriptions that may legally be filled with prescription-only items), but the general legal definition of the word is this broad one.

Contents
Many brand name drugs have cheaper generic drug substitutes that are therapeutically and biochemically equivalent. Prescriptions will also contain instructions on whether the prescriber will allow the pharmacist to substitute a generic version of the drug. This instruction is communicated in a number of ways.

In some jurisdictions, the preprinted prescription contains two signature lines: one line has "dispense as written" printed underneath; the other line has "substitution permitted" underneath. Some have a preprinted box "dispense as written" for the prescriber to check off (but this is easily checked off by anyone with access to the prescription). Other jurisdictions the protocol is for the prescriber to handwrite one of the following phrases: "dispense as written", "DAW", "brand necessary", "do not substitute", "no substitution", "medically necessary", "do not interchange". In other jurisdictions may they use completely different languages, never mind a different formula of words. In some jurisdictions, it may be a legal requirement to include the age of child on the prescription. For pediatric prescriptions some advise the inclusion of the age of the child if the patient is less than twelve and the age and months if less than five. (In general, including the age on the prescription is helpful.) Adding the weight of the child is also helpful.

Prescriptions often have a "label" box. When checked, the pharmacist is instructed to label the medication. When not checked, the patient only receives instructions for taking the medication and no information about the prescription itself.

Some prescribers further inform the patient and pharmacist by providing the indicator for the medication; i.e. what is being treated. This assists the pharmacist in checking for errors as many common medications can be used for multiple medical conditions.

Some prescriptions will specify whether and how many "repeats" or "refills" are allowed; that is whether the patient may obtain more of the same medication without getting a new prescription from the medical practitioner. Regulations may restrict some types of drugs from being refilled.

In group practices, the preprinted portion of the prescription may contain multiple prescribers' names. Prescribers typically circle themselves to indicate who is prescribing or there may be a checkbox next to their name.

Who can write prescriptions (that may legally be filled with prescription-only items)
Any jurisdiction that allows freedom of written communication generally must therefore allow anybody to write a prescription to anybody, inasmuch as the prescription itself is just written advice. Therefore "who can write prescriptions" will be explained below as shorthand for "whose prescriptions may legally be filled with items restricted to dispensing via the order of certain persons".

National or local (i.e. state or provincial) legislation governs who can write a prescription. In North America, physicians (either M.D. or D.O.) have the broadest prescriptive authority. All 50 states and the District of Columbia allow licensed certified Physician Assistants (PAs) prescription authority (with some limitations to controlled substances). All 50 states allow registered certified nurse practitioners and other advanced practice registered nurses (such as certified nurse-midmives) prescription power (with some states including limitations to controlled substances). Many other healthcare professions also have prescriptive authority related to their area of practice. Veterinarians, dentists, and podiatrists have prescribing power in all 50 states and the District of Columbia. Clinical pharmacists are allowed to prescribe in some states through the use of a drug formulary or collaboration agreements. Florida Pharmacists can write prescriptions for a limited set of drugs. In all states, optometrists prescribe medications to treat certain eye diseases, and also issue spectacle and contact lens prescriptions for corrective eyewear. Several states have passed RxP legislation, allowing clinical psychologists (PhD's or PsyD's) who are registered as medical psychologists and have also undergone specialized training in script-writing to prescribe drugs to treat emotional and mental disorders. Physicians who practice chiropractic medicine may have the ability to write a prescription, depending on scope of practice laws in a jurisdiction.

Legibility
Prescriptions, when handwritten, are notorious for being often illegible. In the US, medical practitioners' sloppy handwriting kills more than 7,000 people annually, according to a July 2006 report from the National Academies of Science's Institute of Medicine (IOM). Historically, physicians used Latin words and abbreviations to convey the entire prescription to the pharmacist. Today, many of the abbreviations are still widely used and must be understood to interpret prescriptions. At other times, even though some of the individual letters are illegible, the position of the legible letters and length of the word is sufficient to distinguish the medication based on the knowledge of the pharmacist. When in doubt, pharmacists call the medical practitioner. Some jurisdictions have legislated legible prescriptions (e.g. Florida). Some have advocated the elimination of handwritten prescriptions altogether and computer printed prescriptions are becoming increasingly common in some places.

Conventions for avoiding ambiguity
Over the years, prescribers have developed many conventions for prescription-writing, with the goal of avoiding ambiguities or misinterpretation. These include:
 * Careful use of decimal points to avoid ambiguity:
 * Avoiding unnecessary decimal points: a prescription will be written as 5 mL instead of 5.0 mL to avoid possible misinterpretation of 5.0 as 50.
 * Always using zero prefix decimals: e.g. 0.5 instead of .5 to avoid misinterpretation of .5 as 5.
 * Avoiding trailing zeros on decimals: e.g. 0.5 instead of .50 to avoid misinterpretation of .50 as 50.
 * "mL" is used instead of "cc" or "cm³" even though they are technically equivalent to avoid misinterpretation of 'c' as '0' or the common medical abbreviation for "with" (the Latin "cum"), which is written as a 'c' with a bar above the letter. Further, cc could be misinterpreted as "c.c.", which is an uncommonly used abbreviation for "take with meals" (the Latin "cum cibo").
 * Directions written out in full in English (although some common Latin abbreviations are listed below).
 * Quantities given directly or implied by the frequency and duration of the directions.
 * Where the directions are "as needed", the quantity should always be specified.
 * Where possible, usage directions should specify times (7 am, 3 pm, 11 pm) rather than simply frequency (three times a day) and especially relationship to meals for orally consumed medication.
 * The use of permanent ink.
 * Avoiding units such as "teaspoons" or "tablespoons."
 * Writing out numbers as words and numerals ("dispense #30 (thirty)") as in a bank draft or cheque.
 * The use of apothecary/avoirdupois units and symbols of measure -- pints (O), ounces (℥), drams (ℨ), scruples (℈), grains (gr), and minims (♏) -- is discouraged given the potential for confusion. For example, the abbreviation for a grain ("gr") can be confused with the gram, abbreviated g, and the symbol for minims (♏), which looks almost identical to an 'm', can be confused with micrograms or metres.  Also, the symbols for ounce (℥) and dram (ℨ) can easily be confused with the numeral '3', and the symbol for pint (O) can be easily read as a '0'.  Given the potential for errors, metric equivalents should always be used.
 * The use of the degree symbol (°), which is commonly used as an abbreviation for hours (e.g., "q 2-4°" for every 2 – 4 hours), should not be used, since it can be confused with a '0'. Further, the use of the degree symbol for primary, secondary, and tertiary (1°, 2°, and 3°) is discouraged, since the former could be confused with quantities (i.e. 10, 20 and 30, respectively).

Abbreviations
Many abbreviations are derived from Latin phrases. Hospital pharmacies have more abbreviations, some specific to the hospital. Different jurisdictions follow different conventions on what is abbreviated or not. Prescriptions that do not follow area conventions may be flagged as possible forgeries.

Some abbreviations which are ambiguous, or which in their written form might be confused with something else, are not recommended and should be avoided. These are included in a separate list in Appendix 1. However, all abbreviations carry an increased risk for confusion and misinterpretation and should be used cautiously.

In Continental Europe
In continental Europe, prescriptions differ from their counterparts in the Anglosphere. With the exception of patient directions, they are written out entirely in abbreviations deriving from the Latin language. Furthermore, a larger proportion of prescriptions are compounded, and appropriate abbreviations and phrases exist for this. Many medical schools require up to two years of Latin as part of the curriculum for medical doctors and pharmacists.

Parts of a European prescription
A continental European prescription consists of three parts:


 * the inscritio, also known as the superscriptio, is the header of the prescription and consists of the patient's name, address, and identity document number, as well as the identifying number of the patient's private health insurance company, if applicable; and
 * the praescriptio is the prescription itself; that is, directions to the dispensing pharmacist to supply medication, made up of the following:
 * the invocatio, consisting of the abbreviation Rp; this is analogous to the Rx used in the Anglosphere, and stands for recipe, Latin for take [from the shelf]; and
 * the ordinatio, also known as the compositio, which consists either of the brand name, strength, and number and type of dosage units of a particular drug, or else of directions written entirely in the Latin accusative case, with the exception of ingredient names, written in the genitive case. Masses are written in grammes, without the unit name.  The compositio is followed by
 * the subscriptio, which consists of the directions according to which the medicament is to be prepared. An important part of this is the signatura, which is directed towards the patient and explains how to use the medication.  Unlike the rest of the prescription, the signatura is written in the national vernacular.

Other conventions
Should a patient require a dosage in excess of the maximum as established by the appropriate governmental body, this is marked by an exclamation mark and the highest recommended dosage in Latin. If this is not done, it is the responsibility of the pharmacist to contact the doctor as to dose requirements, or amend the dose to the highest recommended one.

In emergency situations, a prescription pad may not be available. In this situation, any piece of paper will do, provided it is marked Periculum in mora!; that is, danger in delay (other designations, such as Cito! or Statim!, are also used and understood). Such ad-hoc prescriptions have a limited period of validity; typically, this is the day after the prescription is written.

A doctor may self-prescribe, or prescribe for his family; this is done by replacing the signatura by the Latin phrase pro manus medici (for medical hands) or ad usum proprium (for own use). This is to be done with caution; certain drugs self-prescribed will arouse suspicion, and may result in investigation by the medical board or another governmental body.

Brand-name drugs may be swapped for generics; if this is not wanted by the doctor, he may write dispense as written in the local language on the prescription.

Non-prescription drug prescriptions
Prescriptions are also used for things that are not strictly regulated as a prescription drug. Prescribers will often give non-prescription drugs out as prescriptions because drug benefit plans may reimburse the patient only if the over-the-counter medication is taken under the direction of a medical practitioner. Conversely, if a medication is available over-the-counter, prescribers may ask patients if they want it as a prescription or purchase it themselves. Pharmacists may or may not be able to price the medication competitively with over-the-counter equivalents. If the patient wants the medication not under prescription, the prescriber is usually careful to give the medication name to the patient on a blank piece of paper to avoid any confusion with a prescription. This is applied to non-medications as well. For example, crutches, and registered massage therapy may be reimbursed under some health plans, but only if given out by a prescriber as a prescription. Some software now require a prescription.

Prescribers will often use blank prescriptions as general letterhead. Legislation may define certain equipment as "prescription devices". Such prescription devices can only be used under the supervision of authorized personnel and such authorization is typically documented using a prescription. Examples of prescription devices include dental cement (for affixing braces to tooth surfaces), various prostheses, gut sutures, sickle cell tests, cervical cap and ultrasound monitor.

In some jurisdictions, hypodermic syringes are in a special class of their own, regulated as illicit drug use accessories separate from regular medical legislation. Such legislation will often specify a prescription as the means by which one may legally possess syringes.

Related usage of the term prescription
Prescription may also be used as a short form for prescription drugs to distinguish from over-the-counter drugs. In reference to the entire system of controlling drug distribution (as opposed to illicit drugs), "prescription" is often used as a metaphor for healthy directions from a prescribing medical practitioner. A green prescription is direction from a medical practitioner to a patient for exercise and healthy diet.

History
The concept of prescriptions dates back to the beginning of history. So long as there were medications and a writing system to capture directions for preparation and usage, there were prescriptions.

Modern prescriptions are actually "extemporaneous prescriptions" from the Latin (ex tempore) for "at/from time". "Extemporaneous" means the prescription is written on the spot for a specific patient with a specific ailment. This is distinguished from a non-extemporaneous prescription which is a generic recipe for a general ailment. Modern prescriptions evolved with the separation of the role of the pharmacists from that of the physician. Today the term "extemporaneous prescriptions" is reserved for "compound prescriptions" which requires the pharmacist to mix or "compound" the medication in the pharmacy for the specific needs of the patient.

Predating modern legal definitions of a prescription, a prescription traditionally is composed of four parts: a "superscription", "inscription", "subscription" and "signature".

The superscription section contains the date of the prescription and patient information (name, address, age, etc.). The symbol "" separates the superscription from the inscriptions sections. In this arrangement of the prescription, the "" is a symbol for recipe or literally the imperative "take." This is an exhortation to the pharmacist by the medical practitioner, "I want the patient to have the following medication" - in other words, "take the following components and compound this medication for the patient."

The inscription section defines what is the medication. The inscription section is further composed of one or more of:
 * a "basis" or chief ingredient indended to cure (curare)
 * an "adjuvant" to assist its action and make it cure quickly (cito)
 * a "corrective" to prevent or lessen any undesirable effect (tuto)
 * a "vehicle" or "excipient" to make it suitable for administration and pleasant to the patient (jucunde)

The "subscription" section contains dispensing directions to the pharmacist. This may be compounding instructions or quantities.

The "signature" section contains directions to the patient and is often abbreviated "Sig." or "Signa." It also obviously contains the signature of the prescribing medical practitioner though the word "signature" has two distinct meanings here and the abbreviations are sometimes used to avoid confusion.

Thus sample prescriptions in modern textbooks are often presented as: : medication Disp.: dispensing instructions Sig.: patient instructions

Use of technology
As a prescription is nothing more than information among a prescriber, pharmacist and patient, information technology can be applied to it. Existing information technology is adequate to print out prescriptions. Medical information systems in some hospitals do away with prescriptions within the hospital. There are proposals to securely transmit the prescription from the prescriber to the pharmacist using smartcard or the internet. In the United Kingdom a project called the Electronic Transfer of Prescriptions (ETP) within the National Programme for IT (NPfIT) is currently piloting such a scheme between prescribers and pharmacies.

Within computerized pharmacies, the information on paper prescriptions is recorded into a database. Afterwards, the paper prescription is archived for storage and legal reasons.

A pharmacy chain is often linked together through corporate headquarters with computer networking. Walgreens, for example, uses satellite technology to share patient information. A person who has a prescription filled at one Walgreens can get a refill of that prescription at any other store in the chain, as well as have their information available for new prescriptions at any Walgreens.

Some online pharmacies also offer services to customers over the internet. Walgreens' web site, for example, allows customers to order refills for medicine over the internet, and allows them to specify the store that they will pick up the medicine from. Their web site also allows consumers to look up their prescription history, and to print it out.

Many pharmacies now offer services to ship prescription refills right to the patient's home. CVS, for example, will ship refills free of charge. They also offer mail service where you can mail in a new, original prescription and a signed document, and they will ship the filled prescription back to you.

Pharmacy information systems are a potential source of valuable information for pharmaceutical companies as it contains information about the prescriber's prescribing habits. Prescription data mining of such data is a developing, specialized field.

Many prescribers lack the digitized information systems that reduce prescribing errors. To reduce these errors, some investigators have developed modified prescription forms that prompt the prescriber to provide all the desired elements of a good prescription. The modified forms also contain pre-defined choices such as common quantities, units and frequencies that the prescriber may circle rather than write out. Such forms are thought to reduce errors, especially omission and handwriting errors and are actively under evaluation. (See: Kennedy AG, Littenberg B. A Modified Outpatient Prescription Form to Reduce Prescription Errors. Joint Commission Journal of Quality and Safety 2004; 30:480-487.)