NSC 330 drug therapy

NSC 330: The Basics Part 2

Instructor

  • Brigette Holleran, DNP, APRN, FNP

Medication Orders

Medication orders should include the following essential elements:

  • 1. Full name of client

  • 2. Generic or trade name of drug

  • 3. Dose

  • 4. Route of administration

  • 5. Frequency of administration

  • 6. Date, time, and signature of prescribing clinician

Example Medication Order:

  • Date: Today's date

  • Time: 11:00

  • Medication: Percocet

    • Dosage: 1 capsule

    • Route: PO (by mouth)

    • Frequency: BID (twice a day)

Learning Check

  • Evaluate the following medication order for errors:

  • Patient Name: Sonny Day

  • Medical Record Number (MR): 123456

  • Medication Ordered: Acetaminophen 650mg q 4h prn pain

  • Prescriber: Brigette Holleran, APRN

  • Date and Time: 1/1/2043 11:54 am

5 Rights of Drug Administration

The five rights of drug administration are crucial for ensuring patient safety and effective medication delivery:

  • 1. Right Client

  • 2. Right Drug

  • 3. Right Dose

  • 4. Right Time

  • 5. Right Route

Absorption

  • The process of drug absorption refers to how drugs enter the bloodstream from the site of administration. Factors affecting absorption include the drug form, concentration, and the presence of food.

  • Energy Requirements: Some drugs require energy (in the form of ATP) to cross cell membranes, while others utilize facilitated diffusion through proteins.

  • Concentration Impact: High concentrations often lead to higher absorption rates, but in reality, the absorbed portion may be considerably low due to metabolism and other physiological factors.

Distribution

  • Protein Binding:

    • Most drugs bind to plasma proteins, particularly albumin.\

    • Bound (Inactive): Drug molecules that are not free to act on the body's cells.

    • Unbound/Free (Active): Only the free portion of a drug exerts a pharmacological effect.

Barriers in Drug Distribution

  • Blood-Brain Barrier: Protects the brain from potential toxins.

  • Placental Barrier: Prevents toxins and harmful substances from crossing from mother to fetus.

    • To cross these barriers, drugs should ideally be:

    • Lipid soluble

    • Small in molecular size

Metabolism

  • Definition: Metabolism is the process through which the body chemically alters drugs to convert them into different compounds known as metabolites.

  • Purpose of Metabolism:

    • Convert active drugs into inactive metabolites for excretion.

    • Create prodrugs that have an active metabolite requiring conversion to elicit therapeutic effects.

Sites of Drug Metabolism

  • Primary site: Liver

    • Other sites include the lungs, kidneys, placenta, and intestinal mucosa.

  • Most metabolism involves converting lipid-soluble drugs into water-soluble forms for renal excretion.

Cytochrome P450 System

  • The Cytochrome P450 system is the major enzyme system that metabolizes drugs.

  • Involves hepatic microsomal enzymes that catalyze the conversion from lipid-soluble to water-soluble compounds and is involved in most drug-drug interactions.

Elimination

  • Half-Life:

    • Defined as the time required for the concentration of a drug in the bloodstream to decrease by half.

    • Generally takes 4-5 half-lives for a drug to be completely eliminated from the body.

  • Importance: Helps determine the dosing intervals for medications. A drug with a short half-life requires more frequent dosing.

Learning Check: Understanding Half-life

  • Scenario: A nurse administers an antihypertensive medication. Client states, "I have been on this medication for 2 days and my BP is still high. Maybe it’s not working."

    • Half-life of Medication: 24 hours

    • Calculation for Steady-State Achievement: Achieved at 4 x 24 hours = 96 hours (4 days)

    • Counseling Point: Inform the client that optimal effects will be observed in a few more days.