NURS215 Lecture Notes - Lecture 2: Lipid Bilayer, Drug Injection, Loading Dose
12 Jul 2018
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Pharmacokinetics & dynamics: pharmacokinetics (cid:858)pha(cid:396)(cid:373)a(cid:859) = (cid:373)edi(cid:272)i(cid:374)es (cid:858)ki(cid:374)eti(cid:272)s(cid:859) = (cid:373)otio(cid:374) 4 phases: absorption, distribution, metabolism, excretion: pharmacodynamics (next class) Ionization (cid:862)a(cid:374)(cid:455) p(cid:396)o(cid:272)ess (cid:271)(cid:455) (cid:449)hi(cid:272)h ele(cid:272)t(cid:396)i(cid:272)all(cid:455) (cid:374)eut(cid:396)al ato(cid:373)s o(cid:396) (cid:373)ole(cid:272)ules a(cid:396)e (cid:272)o(cid:374)(cid:448)e(cid:396)ted to ele(cid:272)t(cid:396)i(cid:272)all(cid:455) (cid:272)ha(cid:396)ged (cid:858)io(cid:374)s(cid:859)(cid:863) (cid:894)b(cid:396)ita(cid:374)(cid:374)i(cid:272)a, (cid:1006)(cid:1004)(cid:1005)(cid:1006)(cid:895) positive or negative. Requires lipid solubility: (cid:858)non-io(cid:374)ized(cid:859) ph = acid-to-acid, base-to-base. If molecules: large, ionized, water-soluble (b/c membrane lipophillic) (cid:1007). fa(cid:272)ilitated diffusio(cid:374): (cid:858)(cid:272)ha(cid:374)(cid:374)els(cid:859) eg. amino acids, sugars, proteins. Rarely can the concentration of the drug be measured directly at the site of action so drug concentration is usually measured at an alternative and more accessible site such as plasma or urine. So usually concentration measured in plasma, then concentration extrapolated to other tissues depending on drug characteristics & tissue characteristics: absorption. Absorption plas(cid:373)a (cid:272)o(cid:374)(cid:272)e(cid:374)t(cid:396)atio(cid:374) i(cid:373)pa(cid:272)ted (cid:271)(cid:455) (cid:858)(cid:396)oute of ad(cid:373)i(cid:374)ist(cid:396)atio(cid:374)(cid:859) Single dose regimen ( if same dose given iv and po) Occurs when a drug is partially metabolized prior to reaching the systemic circulation. Fraction of the given drug now enter circulation.
