Fundamentals Flashcards
What is pharmacology?
What is a drug?
What is pharmacotherapy?
Pharmacology - the study of how drugs work in the body
Drug - any substance that is taken to prevent, cure or improve symptoms of a medical condition
Pharmacotherapy - use of drugs for disease prevention and treatment of suffering
CLASSIFICATION OF DRUGS
Therapeutic
Pharmacologic
Therapeutic -
- describes what condition is being treated by the drug
- decease specific
- prefix “anti” generally refers to therapeutic classification
- drugs may be placed in several therapeutic categories
Pharmacologic -
- describes how the drug acts in the body or “mechanism of action”
May use a drugs chemical name
DRUG NAME TYPES
Chemical
Trade
Generic
Chemical
- name assigned according to chemical structure
Trade
- brand name for a drug that is selected by the company that develops it and hold the patent
- always capitalized
Generic
- contains the same ingredients as a trade drug and mush do the same thing
- may differ in color, shape, and taste from trade drug
- are not capitalized
- cost is cheaper
DOSING INTERVALS
Schedules
STAT
PRN
Schedules - regularly ordered
STAT - a medication that is needed immediately, usually in a life threatening situation
PRN - administered as needed by the patients condition
WHAT ARE DRUG ADMINISTRATION ROUTES?
- Enteral - gastrointestinal(orally), nasogastric (NG), or gastrostomy tube (GT)
- Sublingual
- Topical
- Ophthalmic
- Otic
- Intranasal
- Rectal
WHAT IS PARENTERAL?
- Parenteral- dispensing of medications via needle into:
- Skin layers – intradermal (ID)
- subcutaneous tissue (SQ)
- Muscle- intramuscular (IM)
- Veins- intravenous (IV)
WHAT IS PHARMACOKINETICS AND ITS 4 PROCESSES?
- Pharmacokinetics- study of drug movement throughout the body or what the body does to drugs after they are administered.
- 4 Processes:
- Absorption- Stomach and Intestines (GI tract)
- Distribution- Bloodstream
- Metabolism- Liver
- Excretion- Kidneys
HOW DO DRUGS RACH THEIR TARGET CELLS?
- Drugs use diffusion and active transport to cross membranes to reach the cells.
- Diffusion- is the movement of a chemical from an area of higher concentration to an area of lower concentration.
- Example- perfume
- Example- Pool
- Active transport- some drugs cross membranes against the gradient from a low concentration to a higher concentration. Requires expenditure of energy on the part of the cell and carrier protein. These carriers are also called pumps.
- Example- person pushing a wheelbarrow up a hill
WHAT DRUCH WILL AND WILL NOT PASS ACROSS MEMBRANES?
More likely to cross:
- -Small drugs
- -Non-ionized drugs
- -Lipophilic
Less likely to cross:
•-Hydrophilic
•-Large drugs
•-Ionized drugs
WHAT ARE THE SITES OF ABSORPTION AND WHY DOES THIS HAPPEN?
Key- medications must be absorbed into the body from the site of administration to the bloodstream in order to have their intended action
•Sites of Absorption:
•Mouth- SL tablets, buccal
•Stomach/intestine - oral medications may be absorbed in the stomach but many are absorbed in the duodenum
•Dermal- patches
•Inhaled- intranasal
•Rectal/vaginal- suppositories, or vaginal creams
•Intramuscular/subcutaneous- directly from these layers into bloodstream
•Intravenous- directly from veins into bloodstream
WHAT TYPED OF MEDICATION WILL ABSORB FASTER OR SLOWER?
FASTEST TO SLOWEST
- liquids, elixirs, and syrups
- suspension solution
- powders
- capsules
- tablets
- coated tablets
- enteric-coated tablets
WHAT IS ABSORPTION AND WHAT FACTORS INFLUENCE IT?
- Dose form- extended release or enteric coated medications designed to be released more slowly
- Food- some medications require food to be absorbed, and others are required to be taken on an empty stomach
- pH- some medications require an acidic environment like the stomach or a more basic one like the intestine to have maximal absorption
- Drug interactions- minerals (calcium, magnesium, iron) hinder, fat
- Surface area- lungs or intestine
- Disease states- Crohn’s disease and accompanying malabsorption, diarrhea
- Absorption- primary pharmacokinetic factor that influences the onset of drug action, i.e., length of time it takes for a drug to produce its effect
WHAT IS DISTRIBUTION AND WHAT ARE SOME FACTORS OF IT?
- Phase of movement of the drug once it is absorbed.
- Drugs interact with blood components and may be physically and chemically changed before they reach their targets
- Tissues with the greatest blood flow receive the drug first
- examples-
- Solubility- some drugs are water soluble and some are fat soluble
- Tissue storage– some drugs have a higher affinity for muscles, while others are lipophilic
- Drug-protein binding- many drugs bind to protein such as albumin and this complex is too large to cross capillary membranes and be distributed; trapped until release.
- *unbound or free drug is the one that has ability to exert its action
WHAT IS METABOLISM?
- Metabolism is the process by what your body converts what you eat and drink into energy
- Also called “biotransformation.”
- Involves multiple complex biochemical pathways and reactions that alter drug structure so it can be excreted from the body.
- LIVER is the primary organ for drug metabolism.
- There are different liver enzyme pathways that metabolize medications and this complex is known as P450 system with its isoenzymes.
- These isoenzymes influence the speed that drugs are metabolized.
- Challenges of CYP system- drugs predictability influenced by enzyme inhibition, induction, competition (drug interaction of binding for same site).
WHAT ARE SOME FACTORS THAT INFLUENCE METABOLISM?
- Drug interactions- some drugs compete for the same site or enzymes; may increase or decrease metabolism and produce unwanted toxicity or subtherapeutic level
- Hepatic dysfunction- patient with liver disease may not be able to metabolize certain drugs
- Patient variability
- First pass effect- drugs are entered into the hepatic portal system circulation, and are inactivated before they reach general circulation. May be problematic, as only a portion of the drug reaching the target.