Absorption Flashcards
What are the four processes affecting the movement of drugs through the body?
Absorption, Distribution, Metabolism, Excretion.
what makes a drug effective, using absorption principal.
it must no be inactivated before reaching its first target tissue.
what is bioavailability? What does bioavailability depend on?
the fraction of an administered dose of drug that reaches the systemic circulation unchanged. it depends of course on the route it takes in the body.
what is systemic circulation?
blood leaving the heart via the aorta to supply all the tissues of the body
What affects the rate of absorption?
the duration of dose, intensity of action, and the initial onset.
** also method of injection
There are two routes of administration, Enteral and parenteral. Define them.
- Enteral- via intestine, used to refer to the oral route of administration.
- Parenteral- routes that involve absorption though any other site than the stomach or intestine.
Describe the advantages and disadvantages of Oral administration.
A: simple, convenient for self-admin, and is usually safer than injection.
D: Absportion may be erratic, patient compliance problems, possible with unconscious patient, “first-pass” effect, slow
What is the first-pass metabolism?
This is when orally are absorbed into the portal vien (PV) and travel first to the liver where metabolism may inactivate a percentage of the drug molecules.
What is unique about drugs that are administered parenterally.
Enter the systemic circulation and reach other tissues before undergoing metabolism in the liver.
Describe the advantages and disadvantages of sublingual (under the tongue) administration.
its a type of trans-mucosal absorption.
A: relatively simple; no first-pass metabolism.
D: patient must no swallow (cooperate), and significant proportion of dose may be swallows despite efforts not to swallow.
Describe the advantages and disadvantages of subcutaneous injection (SC or SQ) administration.
A: suitable for solid pellets, insoluble suspensions, oily vehicles, easier than IV, and absorbs slower than IV, or IM.
D: not for large volumes, pain or necrosis with irritating drugs, absorption can be slow.
Describe the advantages and disadvantages of intramuscular injection (IM).
A: suitable for moderate volumes, drugs in aqueous solution will be rapidly absorbed, and those in oily vehicles will be slowly absord. Its safer and esier than IV
D: local pain and swelling possible, absorption slower than IV, avoid during anitcoagulant treatment.
Describe the advantages and disadvantages of intravenous injection (IV).
A: emergency use -> rapid onset of activity, large volumes (slowly), and irritating drugs (when diluted)
D: higher risk of adverse effects, often must inject slowly due to cardiac toxicity risk, not for oily or insoluble drugs, and requires more skill to administer.
Describe the advantages and disadvantages of topical administration.
(used for eye, ear, skin, mucous membranes)
A: drug delivered to site of need, and can achieve very high concentrations.
D: may be absorbed systemically, and may not remain in place/messy.
Describe the advantages and disadvantages of transdermal administration.
A: controlled released prolonged duration of action
D: slow onset of action, excessive absorption may occur if blood flow to skin is excessive.
