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21 Cards in this Set

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What does phamacokinetics mean?
mathematical description of the disposition and fate of administered drugs
What does ADME stand for?
Absorption
Distribution
Metabolism (biotransformation)
Excretion
Examples of dosage forms:
tablets, caplets, volatile liquids, aerosols, gases
Route of administration depends on :
convenience
physical drug properties
bioavailability (proportion of drug that reaches the systemic circulation)
Desired onset, duration, and intensity of action
patients condition
What is main goal of drugs?
To get into the systemic circulation
Topical/Local
direct application of small quantity to site of intended action so only a LOCAL response produced
ointments, creams, lotions, powder, sprays
local may be desired in specific body cavities (ie corticosteroids into a joint or intrathecal injection)
Patch (transdermal/percutaneous not considered local)
Enteral Routes
GI-by way of small intestine oral and rectal
Oral
per os PO, safest, economical, most convenient route.strong first pass effect in GI and liver. bioavail only 5-<100
absorption may be affected by stomach contents (pH or digestive enzymes may destroy drugs), drugs may alter digestive process. NOT USEFUL unconscious or vomiting patients
Rectal
fast absorption, local effect, good for when drugs that would be irritating to stomach, less first pass effect compared to PO, bioavail = 30-100
USEFUL in unconscious or vomiting patients
Inhalation
gases, vapors, aerosols, absorbed very rapidly thru bronchial mucosa/aveolar surface into systemic circ to produce effects elsewhere (general anaesthetics, amyl nitrate for angina pectoris) Bioavail = 5-100. Can be used for local affect on bronchioles. USEFUL uncon or vomit.
Parenteral routes
IV
IM
subcutaneous
Transdermal
Intrathecal
Intra-arterial
(not in gut, painful, sterility, more rapid absorption, uniform, predictable, allows more accurate dosage selection, more expensive)USEFUL uncon vomiting
I.V.
injected directly into vein,immediate and total absorption,bioavail = 100. may give as slow infusion (20min) lessen risk of irrevocable overdose,obtain constant drug levels, bc more difficult to undo if overdose inject too rapidly =too high local concentrations
must be in soluble, nonparticulate form.
IM
injected deep in muscle mass
faster absorption than oral
bioavail = 75-100
prolonged even absorption of drug depots dissolved in oil
strong acid/base cause sterile abscesses
irritation at injection site possible
painful in large volumes
Subcutaneous
drug under skin
absorption almost rapid as with IM, administration very slow,bioavail=75-100, suitable for small volume, can only use nonirritating drugs, pain/irritation at injection site
Transdermal
convenient painless, slow steady release, very slow absorption, prolonged duration, no first pass, bioava = 80-100,
Intrathecal
used for chemo and diagnostic procedures,injected into lumbar or cisterna magna,must be nonirritating, and strict asepsis maintained
Intra arterial
small volume of highly concentrated drug to specific tissued/organs for minimize effects elsewhere dilution in general circulation
Most drugs cross membranes by
passive diffusion (concentration gradient)
Physiochemical props
lipid soluble high = can get thru membrane easier, molecular weight, product formulation, ionization degree
rate of dissolution
increases as drug particle size decreases. Reducing particle size increases area exposed to solution
All equilibrium btw systemic circulation and Actionsite,other tissues, excretion, biotransformation
Bound drug becomes free if exctreted and comes back from all other sources to replenish the equilibrium all over. Bound - reservoir