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State Laws Impact on Prescriptive Authority
The regulation of prescriptive authority is under the jurisdiction of a health
professional board. This may be the State Board of Nursing, the State Board of
Medicine, or the State Board of Pharmacy, as determined by each state.
Although the federal government controls drug regulation, it has no control over
prescriptive authority.
Full Practice Authority
In a full practice environment, NPs can conduct client evaluations, diagnose,
order, and interpret diagnostic tests, and initiate and manage treatments,
including prescribing medications and controlled substances. This level of
practice occurs under the state board of nursing's exclusive licensure and is the
preferred model by leading national nursing and medical organizations.
Nurse Practitioner Role: Prescriptive Authority
- Prescriptive authority for nurse practitioners regulates prescribing rights
beyond medications and controlled substances. These rights include therapeutic
devices and services and are outlined in state practice laws and regulations and
include durable medical equipment (DME) such as wheelchairs, power scooters,
hospital beds, portable oxygen equipment, handicap placards, etc., and medical
services such as physical therapy (PT), occupational therapy (OT), home health
services, etc.
- Prescriptive authority encompasses more than writing a prescription correctly.
It requires adherence to ethical guidelines to ensure that patients are
safeguarded from harm. Ethical prescribing starts with being well-informed
about medications. Appropriate selection, dosing, and duration of
pharmaceutical agents are key to maximizing outcomes and minimizing adverse
effects.
Metabolic influences on drug administration
- Age
- Induction and inhibition of drug-metabolizing enzymes (P450)
- First-pass effect:
,- Nutritional status
- Competition between drugs
Renal Disease Impact on Pharmacodynamics
Kidney disease can reduce drug excretion, causing drugs to accumulate in the
body. If the dosage is not lowered, drugs may accumulate to toxic levels.
Accordingly, if a patient is taking a drug that is eliminated by the kidneys, and if
renal function declines, the dosage must be decreased.
Generic vs Brand Name
Generic drugs are chemically identical to their brand-name counterparts but are
typically less expensive. Brand-name drugs are marketed under a proprietary
name and often have higher costs due to research, development, and marketing
expenses. Generic drugs must meet the same standards for quality, safety, and
efficacy as the brand-name drugs.
Duration of Therapy
This refers to the length of time a medication should be taken to effectively treat
a condition. It's important to follow prescribed durations to ensure that the
medication works as intended and to prevent issues such as drug resistance or
relapse of the condition.
Role of Formularies
Formularies are lists of medications that are preferred and covered by a
particular health insurance plan or healthcare system. They are designed to
guide prescribing practices by promoting cost-effective treatments while
ensuring that effective and safe medications are available.
Blood Flow Impact on Absorption
Drugs are absorbed most rapidly from sites where blood flow is high because
blood containing a newly absorbed drug will be replaced rapidly by drug-free
blood, thereby maintaining a large gradient between the concentration of drug
outside the blood and the concentration of drug in the blood. The greater the
concentration gradient, the more rapid absorption will be.
Bioavailability and Variable Drug Responses
- Bioavailability = the amount of an active drug that reaches the systemic
circulation from its site of administration.
, - Different formulations of the same drug can vary in bioavailability. Factors
such as tablet disintegration time, enteric coatings, and sustained-release
formulations can alter bioavailability and thereby make drug responses variable.
- Differences in bioavailability occur primarily with oral preparations.
- Differences in bioavailability are of greatest concern for drugs with a narrow
therapeutic range.
Drug Metabolism & Therapeutic Index
For drugs that have a high therapeutic index (TI), altered rates of metabolism
may have little effect on the clinical outcome. However, if the TI is low or
narrow, then relatively small increases in drug levels can lead to toxicity and
relatively small decreases in drug levels can lead to therapeutic failure.
Genetic Variants & Drug Metabolism
- The most common mechanism by which genetic variants modify drug
responses is by altering drug metabolism.
- These gene-based changes can either accelerate or slow the metabolism of
many drugs. The usual consequence is either a reduction in benefits or an
increase in toxicity.
Genetic Variants That Alter Drug Metabolism
- CYP2D6 variants: Tamoxifen: reduced effect
- CYP2C19 variants: Clopidogrel: reduced effect
- CYP2C9 variants: Warfarin: increased toxicity
- TMPT variants: Thiopurines: increased toxicity
Absorption
The process by which a drug moves from its administration site into the
bloodstream.
Distribution
Once in the bloodstream, a drug must be distributed to sites of action throughout
the body via the vascular system.
Metabolism
The process where the body chemically alters drugs for therapeutic use and
forms them into components that can be more easily excreted.
Excretion