Medication Administration: Engage Fund

pharmacokinetics

Study of the absorption, metabolism, distribution, and excretion of drugs in the human body.

ADME (four stages of pharmacokinetics)

Absorption, Distribution, Metabolism, and Excretion

Factors that affects rate of absorption

• Route of administration: The point where the medication enters the body.

• Ionization: The pH of the medication and the site of absorption.

• Dissolution: The medication must be dissolved before absorption takes place.

• Blood flow: Medications are absorbed more rapidly where blood flow is high.

• Lipid solubility: The medication’s formulation can have either high lipid solubility or low lipid solubility.

• Surface area of the absorptive site: The size of the surface area where the medication will be absorbed.

• Client-specific factors: Pathophysiological processes, diseases or injury, age, and so on.

ionization

Affects the degree of absorption and the rate at which the drug permeates the cell membranes, which ultimately impacts the distribution of a medication.

dissolution

Medication must be dissolved in solution before absorption takes place. The dissolution of a medication is dependent upon its initial state and route of administration. Dissolution: the process where a gaseous, liquid, or solid phase dissolves in a solvent to form a solution.

a medication is absorbed more rapidly if lipid solubility of a medication is lower or higher?

higher. Lipid-soluble medications can easily pass through cell membranes, enhancing absorption.

what is the movement of medication into the circulatory system, which means that blood flow will affect absorption of a medication as well.

absorption

why are many enteral medications designed to be absorbed in the small intestine?

They have a larger surface area for absorption, facilitating faster and more efficient uptake into the bloodstream. (most enteral medications are absorbed this way with some in the stomach)

why are enteral routes slower than other medication routes

the mucous membranes slow down medication movement while moving into the circulatory system

why do intramuscular injections often have a faster absorption rate than subcutaneous injections

due to the large blood vessels found in the muscles.

what is the order absorption for intramuscular, enteral, and subcutaneous from fastest to slowest

Intramuscular, subcutaneous, enteral.

intravenous

is the fastest route of medication absorption, as drugs are delivered directly into the bloodstream.

topical/transdermal medication

placed directly on affected area and is absorbed through local capillaries

enteral route

enters through the GI tract: oral, sublingual, and rectal administration.
GI tract must be functional

patient experiencing vomiting or diarrhea

may not be able to retain oral medications, requiring alternative administration routes.

why do pregnant patients might require lower doses of enteral medications?

decreased GI motility, which means a medication has more time to be absorbed

distribution

the process of medication delivery to the target organ or tissues following absorption into the circulatory system

highly vascular areas that receive the greatest blood suply

brain, liver, heart, kidneys

areas with lesser amount supply

bones, skin, and adipose tissue

Protein binding

The process by which medication molecules attach to proteins in the blood, preventing that portion from leaving circulation.

Free (unbound) medication

The active fraction of a drug not attached to plasma proteins, capable of leaving the bloodstream to reach tissues and produce an effect.

Effect of low blood protein levels on protein-bound drugs

Increases the proportion of free, active medication in circulation, leading to heightened drug effects and a greater risk of toxicity.

Effect of lipid solubility on drug distribution

High lipid solubility allows medications to cross cell membranes and reach tissues more readily than water-soluble medications.

Blood-brain and fetal-placental barriers

Protective anatomical barriers that restrict the movement of specific substances and medications into the central nervous system or the developing fetus.

Medication characteristics facilitating passive diffusion across protective barriers

Small molecular size and high lipid solubility.

Metabolism, or biotransformation,

is the chemical process of converting a medication’s structure. Metabolism can result in amplified medication activity, inactivation of the medication, or increased excretion via the kidneys, and it can toxicity levels of medications

where are most medications metabolized?

liver
with some in kidneys and small intestines

Cytochrome P-450

A group of liver enzymes that transforms medications into active and inactive substances to facilitate excretion.

Effect of liver and kidney disease on drug clearance

Slows the rate of clearance because medications are primarily metabolized and eliminated by these organs.

Clinical rationale for evaluating renal and hepatic function before prescribing

Identifies impaired clearance capacity to prevent drug accumulation and toxicity when selecting doses.

Nursing assessment responsibilities for hepatic and renal medication safety

Checking diagnostic lab work and monitoring current illnesses that may compromise organ function prior to drug administration.

toxicity

An adverse effect in which the body is unable to metabolize or excrete a medication; it can cause irreversible damage to organs.
Older adults and those with impaired cardiac, liver, and kidney function are at high risk for developing medication toxicities

Metabolism may transform a specific medication to another form, resulting in a more active or potent form. For example, codeine is transformed to ______, resulting in increased pain relief.

morphine,

Prodrugs

are inactive chemicals that are activated through metabolism to exert their therapeutic effects

The passage of oral medications from the small intestine to the hepatic circulation via the mesenteric and portal veins flowing into the liver, before reaching systemic circulation.

First-pass effect

Precipitous metabolism

refers to a medication being broken down very rapidly by the liver when it is absorbed from the gastrointestinal tract.

Oral route: The patient swallows the medication.

• Absorption: The medication is absorbed from the gastrointestinal tract and travels through the portal blood to the liver.

• Liver metabolism: The liver breaks down a large amount of the medication before it reaches the general circulation.

• Result: Less active medication reaches the bloodstream, so the desired therapeutic effect may be reduced.

Why use another route when medications undergo precipitous metabolism

Routes such as sublingual (under the tongue), transdermal (through the skin), or parenteral (such as IV) can bypass the initial passage through the liver, allowing more of the medication to reach the systemic circulation unchanged.

Effect of first-pass metabolism on drug bioavailability

Reduces the concentration of active medication reaching the systemic circulation when a significant portion is metabolized into an inactive form before entering the bloodstream.

Influence of genetics on medication metabolism

Variations in specific genes associated with race and ethnicity alter how rapidly medications are metabolized.

Reason for reduced drug metabolism rate in infants

Immature liver function.

Hepatic changes that decrease medication metabolism in older adults

Reduced liver size and function, decreased hepatic blood flow, and slower enzyme production.

Excretion

The pharmacokinetic process by which a medication is removed from the body.

Primary organ responsible for drug excretion

Kidneys.

Secondary organs and tissues involved in drug excretion

Skin, lungs, exocrine glands, liver, mammary glands, and intestines.

Organ systems that influence the rate of medication excretion

Kidneys, heart, and liver.

Effect of kidney, liver, or heart failure on drug concentration between doses

Causes medication levels to remain at higher concentrations prior to the next scheduled dose.

Medication adjustments required for older adults or clients with kidney dysfunction

Reducing medication dosages or discontinuing the drug to prevent toxicity.

Nursing priority for clients with impaired elimination capacity

Vigilant assessment and evaluation for adverse effects and signs of toxicity.

the 10 rights of medication administration

1. Right patient

2. right time

3. right dose

4. right medication

5. right route

6. right documentation
   
   

7. right assessment

8. right evaluation

9. right education.

10. right to refuse

first five should be verified 3 times during the process

Pharmacodynamics

the study of how a medication works and how the body responds as medication concentration changes, with the aim of achieving therapeutic effects without toxicity (therapeutic range).

Therapeutic drug monitoring (TDM)

 is a method used by health care providers to monitor medication concentrations in a client’s blood.

therapeutic range

A method used by health care providers to monitor drug concentrations to determine therapeutic dose and avoid toxicity.

trough blood level

is the lowest level of concentration of a medication that correlates to the rate of elimination. It is measured before administering the next scheduled dose.

Household measurements

Round only at the end rule when working with conversions

Carry the entire number (six digits) through the entire equation.

angle & locations of needles for IM, SUBQ, & Intradermal

Needle Gage size for for IM, SUBQ, & Intradermal

Needle length in inches for for IM, SUBQ, & Intradermal

enteric-coated

Medications that are formulated to be dissolved and released in the small intestines for a slower release and can be administered less frequently during the day.

Ophthalmic medications

are applied to the mucous membranes of the eyes or conjunctiva.

Ophthalmic solutions are instilled into the lower margin of the eyelid (conjunctival sac)

Otic medications

are used for the treatment of local infections and inflammation; they are instilled into the outer ear. When administering otic medications, assure that the medication is at room temperature. Never administer cold solutions into the ear canal, as this may cause the client to become dizzy and cause pain.

Nasal medications

drops or sprays instilled within the nostrils, then absorbed through the mucous membranes and into the bloodstream. Medications that can be administered via the nasal route include nicotine (smoking cessation), calcitonin (osteoporosis), sumatriptan (migraines), and corticosteroids (allergies).

Decongestant nasal sprays

can be purchased as OTC medications for the treatment for congestion. If the nasal decongestant is used too frequently or for too long, the client can experience rebound congestion.

Intravaginal medications

are used to treat infections, administer estrogen during menopause, as hormonal support during in vitro fertilization and for contraception. Forms of medication given by the vaginal route include solution, tablet, cream, gel, suppository, or ring options. With this route of administration, the medication is absorbed through the vaginal wall.

Inhaled medications (aerosols)

take the form of very small droplets that, upon inspiration, pass through the trachea into the lungs. The smaller the droplets, the deeper they will travel into the lungs, which increases the amount of the medication absorbed.

used to treat asthma, chronic obstructive pulmonary disease, cystic fibrosis, and infectious pulmonary disease.

The most common methods of aerosol delivery are metered-dose inhalers (MDIs), dry powder inhalers (DPIs), and nebulizers.

parenteral route

Injection: intradermal, intramuscular, subcutaneous, and IV
bypasses GI tract

Needle Filters

Needle filters draw any glass particles from the ampule therefore preventing them from being pulled into the syringe while withdrawing the medication.

Ampule

Intradermal medications

are often used for diagnostic purposes, such as testing for allergies or tuberculosis. The dermis layer of the skin does not have a rich blood supply, so medication injected there is absorbed slowly. The maximum amount of medication that should be injected into the dermis should be 0.1 mL in the Ventral aspect of forearm

Medications by subcutaneous route

delivered into the adipose tissue. Although the adipose tissue has a generous supply of capillaries, it lacks larger blood vessels. In consequence, absorption from this tissue will be slower and more controlled than when a medication is administered via the intramuscular or intravenous route. Common medications administered subcutaneously include insulin and low-molecular-weight heparins.

Sites for Injection and Maximum Amount of Medication/Dose No more than 1.5 mL

lipohypertrophy

The formation of small lumps beneath the skin due to irritated fatty tissue.

Why should subcutaneous injections require pinching the skin?

to reduce the risk of administering the medication into the muscle. This pinching is especially necessary for children and adults who have minimal adipose tissue. The angle of the needle can be anywhere between 45° and 90°, depending on the amount of estimated adipose tissue.

The intramuscular (IM) route :

permits medication to be delivered into a large skeletal muscle, where a faster rate of absorption can be achieved and a larger volume of medication can be administered compared to a subcutaneous or intradermal injection. In addition, the large muscles have fewer pain receptors and, therefore, are better sites for administering viscous or irritating medications. Three muscles are commonly used for IM injections: vastus lateral, ventrogluteal, and deltoid.

Sites for Injection and Maximum Amount of Medication/Dose

Ventrogluteal: Up to 5 mL

Deltoid: Up to 2 mL

Vastus lateralis: Up to 5 mL

The dorsogluteal site should be avoided due to higher risk of error/adverse effects (sciatic nerve damage)