This is referring to the "first pass effect" of oral meds. Meds absorbed through the GI tract that pass thru the liver can undergo some degree of metabolism on the first pass thru the liver. At times, the effect can be so significant that the oral dose must be much HIGHER than the parenteral dose in order to assure effective serum concentration levels after the intial pass thru the liver (p. 9)
Explanation
Principles of Pharm (Pgs. 9-18)
Examples include: intra-thecal (spine), intra-arterial, intra-cardiac, intra-venous, subcutaneous, intramuscluar
Topical creams have a very low absorption rate. Eye drops have a lower absorption than IV, but higher than topical creams. pg. 16
Oral metoprolol goes through the liver and is reduced by approx 10x by the time it reaches the serum. IV metoprolol bypasses the liver and therefore the administered dose is the same as the effective dose in the serum. (pg. 9)
Drugs such as insulin which are denatured by acid are not effective when administered orally bc they may be destroyed in the low pH environment of the stomach. pg. 9
Oral agents SHOULD be able to be absorbed and passed through the intestinal lining in order to enter the bloodstream
Topical drug administration includes: opthalmic, dermatologic, nasal, vaginal, otic (ear), inhalation
Drug metabolism and excretion also relate to duration of action...if there is an abnormal issue with the metabolism or excretion of a drug, the half life will be LONGER (duration of action will be longer).
This is only required if requested by the patient
For continuous infusion, steady state is indicated by a flat (horizontal) drug concentration (see pg. 17 top graph) For intermittent dose, steady state is indicated when the peaks/troughs are equal in amplitude
pg. 11
The National Patient Safety Guidelines discourages the use of SL as an abbrev due to the potential for being mistaken as SC (subcutaneous).
Azithromycin tablets has a rapid and wide distribution throughout the body and concentrates intracellularly. The half life after a single dose is 11-14 hour, but after several doses the half life increases to 2-4 days. (pg. 16)
This is the definition of buccal drug administration (not directly in notes, but I had it written in the margin) Sublingual: meds placed under the tongue for absorb. into the bloodstream thru sublingual capillaries
Single Dose serum concentration rises as the drug is distributed in the circulation. However, because only one dose is administered, the serum concentration decreases as the drug is distributed in the body and then eliminated. Continuous Infusion serum concentration of the drug will reach steady state after 4-5 haf lives. (pg. 16-17)
T.I.D. = three times per day (B.I.D. = two times per day) qs = up to Sig = directions or "label as" qtt = drops
qD should never be used for 'once a day'...instead qDay should be used supp = suppository (not supplemental)
not directly in notes, but I had it written in the margin
This describes the 'intended use of the drug' Clinical Situation: the urgency of a situation many dictate the the form of the drug preferred for use i.e. emergency situations may require IV administration whereas less urgen situations may be given via oral, subcutaneous, ophthalmic etc (pg. 9)
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