Sublingual and rectal drugs – do not pass through liver first (no first-pass metabolism)

  Skin absorption – based on lipid solubility through the epidermis

  CSF absorption – restricted to nonionized, lipid-soluble drugs

  Albumin – largely responsible for binding drugs (PCNs and warfarin 90% bound)

  Sulfonamides – will displace unconjugated bilirubin from albumin in newborns (avoid in newborns)

  Tetracycline and heavy metals – stored in bone

  0 order kinetics – constant amount of drug is eliminated regardless of dose

  1st order kinetics – drug eliminated proportional to dose

  Takes 5 half-lives for a drug to reach steady state

  Volume of distribution = amount of drug in the body divided by amount of drug in plasma or blood

•  Drugs with a high volume of distribution have higher concentrations in the extravascular compartment (eg fat tissue) compared with intravascular concentrations

  Bioavailability – fraction of unchanged drug reaching the systemic circulation

•  Assumed to be 100% for intravenous drugs, less for other routes (ie oral)

  ED₅₀ – drug level at which desired effect occurs in 50% of patients

  LD₅₀ – drug level at which death occurs in 50% of patients

  Hyperactive – effect at an unusually low dose

  Tachyphylaxis – tolerance after only a few doses

  Potency – dose required for effect

  Efficacy – ability to achieve result without untoward effect

  Drug metabolism (hepatocyte smooth endoplasmic reticulum, P-450 system)

•  Phase I – demethylation, oxidation, reduction, hydrolysis reactions (mixed function oxidases, requires NADPH/oxygen)

•  Phase II – glucuronic acid (#1) and sulfates attached (forms water-soluble metabolite

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