Pharmacokinetics 1 Flashcards
Pharmacokinetics
What the body does to the drug
pharmacology
origin, nature, chemistry, effects and uses of drug
toxicology
study of the adverse effects of chemical, physical or biological agents
pharmacodynamics
what the drug does to the body
What are the 5 stages of pharmacokinetics
Liberarion Absorption Distribution Metabolism Excretion
LAD ME
possible routes of administration
Oral Sub-lingual Transdermal Intramuscular intravenous
what is bioavailability
the fraction of unchanged drug that reaches the systemic circulation
IV = gives 100% as its direct into the systemic circulation
what are the four ways that small molecules cross the cell membranes
- diffuse directly through the lipid = lipid solubility highly important
- diffuse through aqueous pores = diffusion of gases
- transmembrane carrier protein = solute carriers
- pinocytosis = macromolecules not drugs
queous, polar media
Blood plasma, cytosol and interstitial fluid
non-polar
interior of the lipid bilayer and fat
weak to strong acid drugs
paracetamol phenytoin warfarin aspirin penicillins
weak to strong base drugs
diazepam codeine noradrenaline atropine amphetamine
pH around the body
Gastric acid (pH 1.0–3.0) Large intestine (pH 8.0) Small intestine (pH 5.0–6.0) Plasma (pH 7.4)
factors that effect drug absorption
lipophilicity and ionisation
what factors effect distribution
degree of drug ionisation lipid solubility pH of compartments cardiac output and blood flow capillary permeability plasma protein binding
biphosphonates and bone
these have a high affinity for calicum and quickly distribute around the skeleton
these are taken orally as alendronate
and through IV yearly as zoledronate
what kinds of plasma proteins to drugs bind to
- albumin
- alpha 1 acid glycoprotein
- lipoproteins
- globulins
% of body mass compartments
trans-cellular water = 2% plasma water = 5% interstitial water = 16% fat = 20% intercellular water = 35%
what effects distribution between body fluid compartments
- permeability across tissue barriers
- binding within compartments
- pH partition
- fat:water partition
pilocarpine
non-selective muscarinic agonist USES: - contraction of pupils - glaucoma - xerostomia
bethanechol
non-selective muscarininc agonist
USES:
- bladder and GI hypotonia
