What is pharmacology?
The study of medicine
The medication cycle:
Absorption
the process by which substance moves into the blood stream from the site where it was administered
What are the two ways that medication can be administered?
- enterally, which means the medication is given directly through the GI system, orally, rectally, or through a tube entering this system
- parenterally, all other routes that do not touch the GI system
Topical medications
act locally
Systemic Medications
act on one or more body systems
Affect the entire body and can be taken by mouth or administered intravenously, intramuscularly, or as a patch applied to the skin
Systemic Medication
Oral Medications must be transferred
through the stomach or intestinal mucosa into the circulating blood
Why when a systemic med is administered intramuscular is it absorbed so quickly?
because muscles have a rich supply of blood to provide rapid entry into the circulation
IV injections have the fastest absorption rate because
the medication is injected directly into the systemic circulation
Bioavailability
how much of the medication is absorbed for use
Fat or Lipid Solubility
the more soluble a medication is in fat or lipids, the more easily it is dissolved and absorbed through the stomach into the bloodstream
Ph
Medications with a low Ph (acidic) are easily absorbed into the stomach
- Higher Ph are less likely to be absorbed effectively
Concentration of the medication
the higher the medication concentration is, the more easily the medication is absorbed
Length of contact
the longer a topical medication remains on the skin or mucosa, the greater the absorption will be
- If a patient actually sucks on a lozenge, opposed to chewing it and swallowing it more medication is released
Age
Both children and older patients absorb more medication through the skin that do healthy adults, so topical medication is usually applied in a very thin layer
Food
A large amount of food slows the absorption of systemic medications, stomach acid facilitates absorption of systemic medications; therefore, medication is absorbed faster when acid in the stomach is increased
Depth of Breathing
for inhalants, the more deeper a patient breathes, the more medication they inhale
Distribution
Second phase in the medication cycle
- delivery of a medication to the appropriate site after the medication has been absorbed in the bloodstream
- Once in the bloodstream it rapidly distributes through the body
Why do well perfused organs receive majority of the medication?
The organs receiving the most blood flow are exposed to the medication first and fastest.
Permeable tissues
allows medications to pass from the bloodstream into the tissue relatively easily
Nonpermeable or less-permeable tissue
prevents or limits substances from passing through
What kind of medication can cross the blood brain barrier?
Psychotropic (mind-altering) medications
Metabolism
medications are metabolized by the liver, kidneys, and intestines,
Occurs when the body chemically alters medications so they can be excreted
Metabolism or biotransformation
Medications are chemically transformed to a less active or inactive form called a
metabolite
Once a medication has acted in the body, it is then
excreted, this process makes sure there is no medication buildup in the body (cumulation)
Therapeutic Level
Medication optimum desired effect
Agonist
Activates, stimulates a response
Antagonist
Blocks a response
Side effects
usually mild, such as nausea, constipation, or sensitivity to light
Adverse Reaction
a severe side effect that can cause harm or death such as hallucinations, hypotension, or anaphylactic shock
Receptors
activated or blocked by messengers to produce and effect