Module 3 Pharmacodynamics Flashcards
Pharmacodynamics
What the drug does to the body/ how they impact the body
Receptor theory
After the drug has been metabolized it competes w/ hormones & neurotransmitters for cell receptor sites. Where it bonds determines the affect
ex: The cell produces diff reactions in the body. A pain receptor site will produced more pain relieving substances
Agonist drugs
Drugs that produce similar effects as the naturally occurring substances like hormones and neurotransmitters. Triggers a “natural response”
ex: epinephrine acts on the heart to accelerate the heart rate and acetylcholine acts on the heart to slow the heart rate
Antagonistic Drug
Block or oppose “natural responses” by competing for cell receptor sits and then inhibit the cell function by occupying receptor sites not allowing the body to release the natural substances to attach.
They inhibit cell function
Where do the drugs go once they have taken affect
They will detach from the cell and flow in the blood stream to then circulate to the liver for metabolism and then to the kidney’s for excretion
Non-recpetor drug actions
*Very few drugs work with a non-receptor action
-Antacids: act chemically to neutralize the hydrochloric acid that’s produced in the gastric system which increases the ph of the gastric fluid
-Osmotic diuretics: increase urine output by creating an osmotic gradient in the kidney’s. Increase the osmolarity of the plasma and pull water out of the tissue and into the blood.
Variables that affect drug actions:
Dosage
Route
Diet
Age
Body weight
polypharmacy
pharmacogenomic
Dosage
How much drug is flowing in the body.
Determined by: Frequency med is given, the size of the dose, and the # of doses
-Goal is to reach a therapeutic level. Ensuring there is enough drug molecules present to actually do what we want it to do
-Too small: no pharmacological action because there is not enough to compete with cell receptor sites
-Too big: toxicity/ poisoning may occur or overdose
Rapid Action Routes
IV route: distributes right into the blood stream = no absorption delay
-quickest and most dangerous
IM Route: Muscles have a lot of blood supply so the meds get absorbed quickly
Slowest Route
Oral: Has to be digested and absorbed through the stomach and into the blood stream
Fentanyl effect as tablet vs IV
Tablet: accidentally given you have 10-15 minutes to figure out a solution
IV: accidentally given you have a few seconds
Treatment is Naloxone/ Narcan
Diet
When taking some meds certain foods have to be avoided
ex: High acidic/ citrus drinks have to be avoided since it can affect some medications
Polypharmacy
Taking more than 1 med at a time. For the same or different desired effect.
The drug on drug action can either increase or decrease the interaction with almost any other drug in the body.
The drug on drug action can either help, hinder, or ignore each other or their effect on the body
Age
Especially important to consider w/ newborn, infant, and older adults.
Start low and go slow: Start with a low dose and monitor
Body Weight
The heavier the person is the higher the dose might be. This is because there are more cells in the body for the medication to work on. Many drugs given are weight based (g/kg of body weight)
Pharmacogenomic variations
Some drugs act differently in different people because of their genetics. You could give the same drug to two different people and get two completely different outcomes. It might effect one and not the other etc.
Adverse Effects
Refers to any undesired response from the drug administration
-most drugs produce both therapeutic and adverse effects.
-All drugs MAY have adverse effects
-might be mild or severe
-can be localized or widespread
Boxed warnings
Some prescription drug medications can cause serious or life threatening adverse effects.
The FDA requires drug manufacturers to put a warning on these medications that have a box or border around the warning describing what the adverse effects are.
This is the strongest warning the FDA can give consumers and often includes prescribing and monitoring info to improve the safety of the med.
*recently added to antidepressant drugs, non opioid analgesics, and immediate release analgesics.
Pregnancy
When a pregnant patient takes a medication more often then not it will cross the blood placenta barrier and the fetus has no way of metabolizing or handling the drug given.
Teratogenic
A drug that causes structural or functionally defects in an embryo or fetus during pregnancy
Toxicology
Drug toxicity aka drug overdose/ poisoning results from excessive amounts of the drug that can damage body tissues.
Recognizing drug toxicity
S/s: non specific and may indicate other diseases
-common in both pediatric and adult populations
-caused by both a single large dose or prolonged ingestion of small doses
ex: alcohol, prescription meds, otc. meds, or elicit drugs
Reversal agents of toxicity
Nalaxone: (Narcan) antagonist to opioids. Available w/o prescription. Comes in IM, IV, and Nasal spray.
Flumazenil: Antagonist to benzodiazepine such as valium or zanex. Usually in ED
