PRESCRIBED MEDICATIONS
A dose is a single amount of a medication administered to achieve a therapeutic effect (e.g., 250 mg penicillin). A dosage contains the dose and scheduled times (e.g., 250 mg, three times a day, in equal intervals). A therapeutic dose is the amount of medication required to obtain a desired effect in most clients. A blood sample may be obtained to determine the client’s blood level of a drug. This helps to establish the therapeutic dose for that client. The minimal dose is the smallest amount of drug necessary to achieve a therapeutic effect. A loading dose (larger than the usual continuing dose) may be given as the first dose of a newly prescribed medication, to establish a minimum blood level. A maximal dose is the largest amount that can be given safely without causing an adverse reaction or toxic effect. A toxic dose is the amount of medication that causes symptoms of poisoning or toxicity. A lethal dose is the amount that will cause death. These doses may vary between individuals and often depend on the client’s weight.
Factors Affecting Medication Prescription
When healthcare professionals prescribe medications, numerous factors must be considered.
Age
Children cannot tolerate the same amount of medication as adults because of their smaller size and different metabolism. Older adults also may be unable to tolerate normal adult dosages of medications because of the effects of the aging process on liver and kidney function, which may lead to incomplete metabolism of some medications. This can cause the drug to accumulate in the body or to be excreted without being absorbed. Either situation can result in serious adverse reactions. In addition, older adults, as well as children, may exhibit paradoxical responses to medications— the opposite of the desired response.
Gender
Some medications are more soluble in fat; others are more soluble in water. Because women usually have more body fat and tend to be smaller, and men have more body fluid, effects of medications differ across genders. Women usually require smaller doses than men. In addition, many medications and herbal supplements cross the placental barrier and can harm the fetus in a pregnant woman. Breast milk absorbs some medications in lactating women, which could harm breastfeeding babies. Therefore, pregnant or lactating women should consult their maternal-child healthcare provider before taking any medications, including over-the-counter medications, dietary supplements, and herbal preparations.
Weight
Dosage is often prescribed in relation to a client’s weight. This is especially true for children. Heavier clients may require larger dosages than thinner clients to reach therapeutic levels. Body weight is usually expressed in grams or kilograms for dosage calculations.
Client’s Condition
A disease’s nature and severity may influence the prescribed dosage of a medication. For example, the person in severe pain often will require a higher level of pain-relieving medication than does the person experiencing less pain. The client’s condition may also affect his or her activity level, which can influence medication absorption.
Disposition and Psychological State
The client’s personality and culture may affect the amount of medication he or she needs. For example, a client with a relatively high pain threshold will require less pain medication than the client with a very low pain threshold. A highly agitated individual may require a larger dose of a sedative than the person who is experiencing less anxiety. A client’s cultural values and ethnic background may also affect the client’s willingness to take medications.
Method of Administration
Administration route affects the amount of time for the medication to enter the general circulation and become effective. IV and IM injections act more rapidly than do oral medications. Rectally administered and transdermally applied medications often are absorbed more slowly than are those administered by injection. Sublingual medications are usually absorbed quickly.
Distribution
The body distributes some medications evenly to reach all cells; other medications reach only certain body fluids or tissues. For example, nitroglycerin targets vascular smooth muscles; acetaminophen (Tylenol) reduces fever by acting on the heat-regulating center in the hypothalamus; acyclovir (Zovirax) inhibits the DNA replication of viruses and is used to help manage human immunodeficiency virus (HIV) infections; and simvastatin (Zocor) inhibits a specific enzyme involved in cholesterol synthesis. On the other hand, penicillin kills bacteria throughout the body.
Environmental Factors
Temperature may influence a medication’s speed of absorption. For example, heat causes vasodilation and therefore faster absorption, whereas cold causes vasoconstriction and decreases absorption. This might be a factor in administering IM medications.
Some medications are damaged by exposure to light and must be stored in dark bottles or opaque containers. Some medications require refrigeration to maintain their effectiveness. Certain liquid medications, when mixed in a syringe or cup, must be given immediately to prevent deterioration owing to exposure to room air or to prevent becoming so thick they are not possible to drink (e.g., psyllium). Some liquid medications cannot ever be mixed because they destroy or interact with each other. Other medications may also interact with each other and may need to be separated in administration times to ensure proper absorption. An example is the combination of calcium and fluoroquinolones (a family of antibiotics; e.g., ciprofloxacin).
Time of Administration
Time is an important factor. For example, the body will absorb a medication taken with meals more slowly than one taken on an empty stomach, although some medications must be taken with food to avoid stomach upset. A diuretic is best taken in the morning, so frequent voiding does not disrupt the client’s sleep. Antidepressants and vitamins are usually given in the morning. Medications with sedative effects or side effects are usually given in the evening or late afternoon. Certain insulins must be given before meals, whereas others are administered with meals. The goal is to provide insulin close to the same time carbohydrates enter the bloodstream. For example, insulin glargine (Lantus) is usually given in the evening and is used to provide a basal level of insulin throughout the entire day.
Elimination
The body eliminates medications through urine, feces, breath, and perspiration. Some medications leave the body in their original forms; others are made inactive by chemical changes in their structure. If these processes are slowed, a medication’s effects may be prolonged. Medication that leaves the body too quickly may be excreted before it has a therapeutic effect. If the body cannot eliminate a medication because of kidney or liver dysfunction, toxic levels may accumulate in the blood. Chemical changes also may form substances that are harmful to the body if it is unable to dispose of them rapidly enough. Excess fluid intake can flush medications out of the body before they can take effect.
Prescriptions
A prescription (medication order) is a written or verbal formula for preparing and giving a medication. Only certain healthcare providers are licensed to prescribe medications. A legend drug is a medicine that under federal law cannot be dispensed without a prescription from a licensed practitioner. Medications that can be purchased without a prescription are called over-the-counter [OTC] drugs. Prescription drug orders may be communicated to the pharmacist via written order, verbal order, fax, and electronically via e-scribe. All prescriptions cannot be refilled more than 1 year after the date they were originally written. Some prescriptions, such as those for narcotics, must be rewritten more frequently. Schedule II drugs are not refillable and require a new written prescription each time the drug is dispensed. Schedule III to V drugs may be phoned in or written, but are limited to five refills in a 6-month time period. Each state in the United States may regulate some aspects of prescription drug orders differently. It is important to be aware of the laws of the state in which you are practicing. Nurses may give medications only on direct orders from one of the healthcare professionals listed at the beginning of this topic.
A licensed pharmacist prepares medications following the practitioner’s order contained in the prescription. In the healthcare facility, the prescription is written on the physician’s order sheet or entered into the computer by the physician, and then is sent to the hospital pharmacy for preparation. The orders contain a start time and date. The medication is to be given for the specific length of time stated in the order or until the order changes or is discontinued. Table 61-1 lists the parts of a prescription. Nurses need to be aware of medical terminology, symbols, and abbreviations used in prescriptions.
Nursing Alert Be aware that some abbreviations and symbols used in the past are not used today because of the danger of misinterpretation and errors.
Verbal Orders
In emergencies, physicians and other primary providers may give verbal medication orders, either directly or by telephone. Most acute care facilities allow only registered nurses to accept verbal orders; however, practical/vocational nurses in extended-care facilities and physician’s clinics usually are allowed to take them as well.
TABLE 61-1. Parts of a Prescription
|
PART |
PURPOSE |
|
Client’s full name |
Avoids confusion with another client with the same surname; in some facilities, or if two clients have the same name, the client’s room number, medical record number, and/or birth date may also be included. |
|
Date and time of day |
Tells when order is to be started; may tell when order is to be discontinued; prescription must be rewritten if medication is to be continued after discharge date. |
|
Name of drug |
States the exact name (generic name preferred to trade name; sometimes both are used). |
|
Dosage/amount of drug |
States measurement system used by healthcare facility; may also be expressed as number of capsules or tablets or as fluid volume. |
|
Time/frequency of dose |
Aids in determining the schedule for administration; nursing service usually determines medication routine schedules, such as the hours for medications ordered four times per day or those ordered every 6 hours; the prescribing healthcare provider may give less-definite directions. (However, the nurse needs to know that certain medications must be given before meals, whereas others must be given with or after meals for maximum effect. For example, it is important to differentiate between a medication to be given every 6 hours and one that is to be given four times a day.) |
|
Method/route |
Determines the route by which the medication is to be given (e.g., oral [PO], intramuscularly [IM]). In most situations, giving a medication via the wrong route could be dangerous, possibly fatal. For example, administration of an IM medication given intravenously (IV) could increase the dose received or speed of absorption. |
|
Primary healthcare provider’s signature (written or electronic) |
Identifies the prescribing individual; essential for legal reasons or if some question exists about the order An unsigned order may mean that the person has not finished writing it, or that it was not written by an authorized person. |
If, as a licensed nurse, you are permitted by your facility to take verbal orders, be sure to read the order back to the healthcare provider and to document it in the prescribed location. It is important to document that the order was taken by a nurse and that it was read back to the provider. Rationale: Reading back the order helps to assure that the order as written is the order that was intended. Documentation states who gave the order and who took the order, and verifies that it was read back. This provides a permanent record of events for reference and protection of clients and healthcare personnel.
A verbal order must be verified and is documented as VORB, “verbal order, read back” or TORB, “telephone order, read back.” Make sure the order is cosigned by the prescribing person as soon as possible, at least within 12-24 hours.
Key Concept A verbal or telephone order is not legal unless the nurse reads it back to the primary provider Only licensed nurses are permitted to take verbal or telephone orders. Nursing students or other unlicensed personnel cannot legally take verbal or telephone orders at any time.
Clarification of Orders
Nurses are responsible for carrying out orders as given and cannot make any changes to them. If there is any reason to question an order, if the handwriting is not legible or if it is confusing, clarify it with the ordering provider. In some cases, the nurse manager, charge nurse, team leader, or supervisor may be able to clarify the order. If an order is clarified by telephone, it is written as a “clarification” under the order in question, dated, and signed by the nurse as a TORB. The primary care provider who was consulted is also identified. This clarification is treated as a telephone order and must be cosigned by the ordering healthcare provider within 12-24 hours.
Key Concept All medication and other orders must be clear; understandable, and open to only one interpretation before the nurse takes any action. If you cannot read or understand the order, it must be clarified. The safe administration of medications is one of the nurse’s most important responsibilities.
If a nurse questions the validity or appropriateness of an order, it is the nurse’s responsibility to question the order If the matter is not resolved, it might be necessary to consult references or the nursing supervisor
KEY POINTS
• Medications are substances that modify body functions. They are used to prevent disease or pregnancy, to aid in diagnosis and treatment of disease, or to restore and maintain bodily functions.
• Many laws, rules, and regulations concern the prescription, storage, and administration of medications.
• Clients have the right to know what medications they are receiving and to request available generic forms of medications. They may refuse to take medications, unless it is an emergency or a court order exists to the contrary.
• Medication administration is a nursing task that must be taken very seriously, to prevent harm to clients.
• Nurses are required to know how and where to obtain information concerning medications. Several drug references and computer Websites are available.
• Drugs are available in many forms: liquids, solids, semisolids, and transdermal patches.
• Factors that affect medication dosages include the client’s age, gender, weight, condition, and psychological state.
• Many medications are considered unsafe for use without a healthcare provider’s supervision and, thus, require a specific prescription. OTC medications can be purchased by the consumer without a prescription.
• Medication orders must be carried out exactly as written. If any questions arise, the prescribing healthcare provider must be consulted for clarification. No medication can be given legally without a valid and clear order.
