• what the body does to the drugs
• absorption
• distribution
• biotransformation/metabolism
• excretion

movement of drug; site of absorption into blood

• what the drug does to the body
• how drugs interact with body tissue

• rate which the drug goes into solution
• active ingredient now free to enter body fluids
• fast dissolution = faster action

• cellular level
• cell membrane: lipids, proteins spaced throughout
• proteins: carriers, receptors, form channels

• nature of absorbing surface
• blood flow to site
• pH
• length of contact with absorbing surface
• drug concentration
• dosage form
• route of administration

• single cell (intestines) vs. multiple layers --> single absorbs faster
• surface area --> larger surface area increases absorption (lungs, intestines)

• rich blood flow = high absorption (muscles, intestines, sublingual)
• decreased blood flow = decreased absorption (subcutaneous)
• disease states may alter (peripheral artery disease - blood flow not good to end extremities therefore absorption is not as good at feet and legs)

• acidic drug = increased absorption in acidic environment (aspirin in stomach)
• basic drug = increased absorption in basic environment (small intestine, most drugs)

• food = increased motility, decreased absorption
• elderly = decreased motility, increased absorption

• high concentration = rapid movement to low concentration

• manipulate additives, vehicle to resist digestive action of stomach
• enteric coating = aspirin, resists acid of stomach so can wait till in the intestine
• delays action

• enteral
• parenteral
• pulmonary
• topical

• sublingual, buccal
• dissolve in saliva
• no destruction by GI fluids, liver

• pH slows absorption of most
• food delays
• medications on empty stomach with glass of water - movement and dissolution

• large surface
• highly vascular
• alkaline pH = enhanced absorption
• decrease in motility = high absorption

• high vascularity
• no "first pass effect"
• erratic absorption related to fecal contents

• slow absorption
• sustained effects
• may be tissue irritating

• greater blood flow

• immediate effect
• no absorption needed

• into spinal arachnoid space
• bypass blood brain barrier

• large surface area
• rich capillary supply
• local or systemic effects

• skin
• local effects or delayed systemic
• lipid soluble only
• intact skin only
• heat/cold affect
• massage = capillary dilation, more absorption
• eyes/ears - local only

• affected by regional blood flow
• storage reservoirs - allows accumulation, sustains effect, plasma protein binding

• drugs have preference to marry a plasma protein by percentage
• in circulation, attach to proteins
• protein too large to leave vessel
• inactivates drugs
• binding = reversible process (can be separated)
• released from binding as free drug eliminated and interact with tissue
• drugs may compete for binding sites
• competition may cause displacement - warfarin displaced by ASA, excessive levels of warfarin, causes bleeding
• low plasma proteins