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21 Cards in this Set
- Front
- Back
What does phamacokinetics mean?
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mathematical description of the disposition and fate of administered drugs
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What does ADME stand for?
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Absorption
Distribution Metabolism (biotransformation) Excretion |
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Examples of dosage forms:
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tablets, caplets, volatile liquids, aerosols, gases
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Route of administration depends on :
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convenience
physical drug properties bioavailability (proportion of drug that reaches the systemic circulation) Desired onset, duration, and intensity of action patients condition |
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What is main goal of drugs?
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To get into the systemic circulation
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Topical/Local
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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) |
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Enteral Routes
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GI-by way of small intestine oral and rectal
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Oral
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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 |
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Rectal
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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 |
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Inhalation
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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.
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Parenteral routes
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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 |
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I.V.
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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. |
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IM
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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 |
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Subcutaneous
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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 |
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Transdermal
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convenient painless, slow steady release, very slow absorption, prolonged duration, no first pass, bioava = 80-100,
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Intrathecal
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used for chemo and diagnostic procedures,injected into lumbar or cisterna magna,must be nonirritating, and strict asepsis maintained
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Intra arterial
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small volume of highly concentrated drug to specific tissued/organs for minimize effects elsewhere dilution in general circulation
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Most drugs cross membranes by
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passive diffusion (concentration gradient)
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Physiochemical props
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lipid soluble high = can get thru membrane easier, molecular weight, product formulation, ionization degree
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rate of dissolution
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increases as drug particle size decreases. Reducing particle size increases area exposed to solution
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All equilibrium btw systemic circulation and Actionsite,other tissues, excretion, biotransformation
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Bound drug becomes free if exctreted and comes back from all other sources to replenish the equilibrium all over. Bound - reservoir
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