PMHNP PREP exam 100%
What routes of med admin are parenteral - ✔✔All Injections ( IM Sub Q IV, Intrathecal), AND Inhaled ,
transdermal (patches) , transmucosal (sublingual, nasal, rectal) . All PO meds = enteral; Topical is all
ointments placed on the skin
PO meds absorption pattern - ✔✔Varies greatly due to:
»»Stability and solubility of the medication
»»Gastrointestinal pH and emptying time
»»Presence of food in the stomach or intestines
»»Other medications currently being administered
»»Forms of medications (enteric-coated pills, liquids)
Rectal medication admin is? - ✔✔Unreliable/ inconsistent absorption/ good for unconscious, vomiting
pts or small children
parenteral = - ✔✔any route of administration other than oral or rectal ; injections, irrigation solutions,
dialysis solutions
Pharmacokinetics - ✔✔What the body does to drug/ how it processes it.
The process by which drugs are absorbed, distributed within the body, metabolized, and excreted.
factors that impact drug absorption - ✔✔Body Factors: Area of absorptive surface i.e. in GI the
microfolds increase surface area, gut pH level, GI motility, presence of other substances. other diseases;
In elderly less acidic stomach ph and less blood flow to GI. Drug Factors: Formulation , molecular size ,
lipid water solubility, concentration etc.
Pharmacodynamics - ✔✔= study of what a drug does to body relationship between drug concentration
@ site of action and resulting effect, including time course and intensity of therapeutic and adverse
effects. The effect of a drug present at site of action is determined by that drug's binding with a
, receptor. Receptors may be present on neurons in central nervous system (i.e., opiate receptors) to
depress pain sensation, on cardiac muscle to affect intensity of contraction, or even within bacteria to
disrupt maintenance of bacterial cell wall
Pharmacology - distribution - ✔✔= process by which drug passes from bloodstream to body tissues and
organs .The following factors influence drug distribution: · Lipophilicity: Lipophilic drugs pass through
cell membrane/dissolves much easier vs hydrophilic.
· Drugs are redistributed in organs according to their fat and protein content.
· Most psychotropic medications are lipophilic and highly protein-bound.
-Only unbound (free) portion of drug is active. Therefore, people with low protein (albumin) levels, such
as in malnutrition, wasting, or aging, can potentially experience toxicity.
- People with high fat-to-lean body mass ratio (as in older adults) will have erratic amounts of active
drug in their system.
· Membrane permeability: To enter an organ, drug must permeate all membranes that separate it from
site of drug admin. i.e benzodiazepines, (very lipophilic) readily cross gut wall, capillary wall, and
blood~brain barrier; THUS they distribute to brain rapidly and are useful for treating anxiety and
convulsions. In contrast, some ABX cannot penetrate blood brain barrier so those meds cannot be used
to treat infections in brain. The blood~placenta barrier prevents fetal exposure to some drugs but allows
passage of others. Brain has stronger barrier- no slit junctions in brain cell membrane.
· Plasma protein binding=binding of drugs to plasma proteins, i.e. albumin, reduces amount of "free"
drug in blood. "Free" drug molecules, but not protein+bound molecules, reach an equilibrium between
blood and tissues. only free drug is active. Drugs w/ high molecular weight tend to be extensively
protein bound
· Depot storage: Lipophilic drugs, i.e. sedative thiopental, accumulate in fat. These agents are released
slowly from fat stores. Thus, an obese person might be sedated for a greater period of time than a lean
person to whom same dose of thiopen
The apparent volume of distribution (Vd) - ✔✔=· a calculated value that describes nature of drug
distribution. Vd is volume that would be required to contain adminstered dose if that dose was evenly
distributed at concentration measured in plasma. You could predict that a drug with Vd "" 3 liters is
distributed in plasma only (plasma volume"" 3 liters), whereas a drug with Vd 16 liters is likely
distributed in extraceliuJar water (extracellular water"" 3 liters plasma plus tD-13liters interstitial fluid).
A drug with Vd > 46 liters is Likely sequestered in a depot because body only contains 40-46 liters of
fluid.
