Chapter Outline
History of Prescription Writing
Evidence-Based Approach to Medical Decision Making
Personalized Medicine and Pharmacogenomics
Barriers to Patient Compliance
Interprofessional Collaboration with a Pharmacist
All states, the District of Columbia, the Commonwealth of the Northern Mariana Islands, and Guam permit delegated prescribing of various drugs and medical devices by physician assistants (PAs). PAs must possess foundational knowledge and be efficient in accessing pertinent, evidence-based information related to the safety, tolerability, efficacy, price, and use of prescribed medications and devices. To support effective prescribing, this chapter offers a historical perspective on prescribing, key information about controlled substances, guidance for evidence-based decision making, highlights of scientific factors related to medications, tips about safe and effective prescribing for special populations, challenges commonly faced by patients in adhering to prescribed therapies, the rationale for interprofessional collaboration with drug therapy experts, and ethical considerations. Vast and rapidly expanding knowledge about drug therapies exists, and PAs must become expert in analyzing emerging scientific data about medications and incorporate an assessment of that evidence with preferences of patients and families in an approach to optimize health, manage illness, provide cures, and prevent disease. The right to prescribe is accompanied by a tremendous responsibility to safeguard patient safety and quality of care as well as accountability to various regulators for responsible, ethical prescribing.
History of Prescription Writing
Rx is an abbreviation for the Latin word “recipe” meaning “take.” Today the abbreviation Rx is used to signify a drug, procedure, or therapy prescribed by a practitioner to a specific patient in the prevention, treatment, or maintenance of his or her clinical diagnosis. A prescription drug refers to medications that require a prescription because they are considered potentially harmful if not used under the supervision of a licensed health care practitioner.
Rules and regulations regarding prescribing are dictated by both federal (i.e., U.S. Food and Drug Administration [FDA]) and state governing bodies (i.e., boards of pharmacy). The drug formulary for PAs has evolved immensely in the past decade to a more extensively sophisticated formulary, the scope of which is ultimately dictated by individual state laws and supervisory agreements with a physician. The responsible use of this privilege is an essential component of prescribing. With a large selection of medications available to prescribers, the choice among agents can be daunting and must take legal, evidence-based, pharmacologic, and patient-specific factors into consideration.
Controlled Substances
Controlled substances are regulated by the Drug Enforcement Agency (DEA) based on schedule or class system. Classes of controlled substances range from Class I, which are not recognized by the federal government as having medicinal use, through Class V medications ( Table 17.1 ). Lower classes of controlled substances have higher abuse potential. Specific regulations exist regarding each class of scheduled drugs in regard to their prescribing and oversight and should be considered in the prescription process. Among these restrictions are often the ability to prescribe electronically or via fax, quantity supplied, refills prescribed, and expiration date.
| Class | Description | Drug Examples |
|---|---|---|
| I |
| Heroin, marijuana, cocaine, LSD |
| II |
| Morphine, oxycodone, methamphetamine |
| III |
| Acetaminophen combined with codeine or hydrocodone |
| IV |
| Chloral hydrate, phenobarbital, diazepam |
| V |
| Pregabalin, small quantities of codeine, diphenoxylate with atropine |
Effective Prescribing
A prescription is an order from a practitioner to a pharmacist for a medication, product, or device for a specific patient. Prescribing requires a basic working knowledge of the essential parts of a prescription. Laws and regulations regarding mandatory components of a prescription vary from state to state and are discussed next.
Content of a Prescription
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Date of issuance: Prescriptions have an expiration date. This also helps the pharmacist determine that the medication remains appropriate for the particular patient at this time.
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Name and address of the patient
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Name, address, and telephone number of the prescriber: This information is usually preprinted on the prescription.
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DEA number when prescribing a controlled substance
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Name and strength of the medication: The generic name is preferred.
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Dosage form: Many medications are available in tablets, liquids, capsules, and suppositories.
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Route of administration and directions for use: Directions for use differ based on indication. Only standard abbreviations should be used. However, to avoid errors, it is preferred that abbreviations be avoided altogether.
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Quantity supplied and refills
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Most important, a prescription should be legible and clear.
Traditionally, prescriptions were written on a prescription pad and were brought to the pharmacy to be filled. With advances in technology and a push toward more secure prescribing, this has changed in the past few decades. Written or paper copies of prescriptions are often “tamper resistant” and contain details to assist prescribers and pharmacists to know that a prescription is authentic ( Box 17.1 ). Medicaid prescriptions are required by law to contain three tamper-resistant features as of 2008. Other modes of prescribing include electronic and fax. Federal and state regulatory bodies determine which medications are appropriate for these modes of prescribing.
One or more industry-recognized features designed to prevent unauthorized copying of a completed or blank prescription form
One or more industry-recognized features designed to prevent the erasure or modification of information written on the prescription by the prescriber
One or more industry-recognized features designed to prevent the use of counterfeit prescription forms
When writing inpatient prescriptions in the hospital, the process is much more simplified with the addition of computerized physician order entry (CPOE). This process allows providers to place orders into a computer system directly and into the chart of a patient, bypassing the need for many of the components of a prescription. These orders are directed toward a pharmacist for verification and dispensing.
Ms. M. is a 28-year-old woman who presents to clinic for management of her allergic rhinitis. She has seasonal allergies and manages her symptoms of itching, rhinorrhea, and congestion with loratadine and pseudoephedrine. She is 6 weeks pregnant and wants to know what is the safest and most effective treatment for her to use during pregnancy. The management of allergic rhinitis in pregnancy does not require any controlled substances, so you will likely electronically prescribe her medication to her local pharmacy.
Evidence-Based Approach to Medical Decision Making
The World Health Organization created a guide to good prescribing and suggests that all drug therapy decisions should consider efficacy, safety, cost, and sustainability. The process of rational prescribing is further broken down into six steps. These steps are discussed in detail in Table 17.2 .
| Step | Description |
|---|---|
| Disease state Signs or symptoms of underlying disease Psychological or social problems Side effect of a drug Refill request Nonadherence to treatment Preventive treatment |
| Goals of treatment
|
| Effectiveness: ability to produce an effect in your patient Safety: think about contraindications, drug–drug, or drug–disease interactions and allergies Convenience: route, duration of treatment, dosing schedule Cost |
| Refer to the section on effective prescribing. |
| Effects of the drug
|
| Passive monitoring: Explain what to do if the treatment is ineffective, inconvenient, or causing side effects; monitoring is done by the patient. Active monitoring: The patient must schedule an appointment for you to determine whether the treatment is effective (i.e., laboratory studies, examinations). |
Assessing effectiveness of a medication, step 3, in your patient is particularly challenging because it requires the review of evidence-based literature to support your management decision. Considerations should include what is the drug of choice in this disease state? Is the drug of choice safe and effective in my patient (i.e., no allergies or contraindications to use)? Does the literature supporting efficacy of this medication in a large population correlate to my patient population as well? This is referred to as a risk–benefit analysis during which you must decide that the benefit of the medication regimen in your patient far outweighs any risk of using this medication regimen (e.g., cost, adverse effects, morbidity, mortality).
