lecture 2 Flashcards
4 routes of drug administration
oral, parenteral (systemic), absorption through skin and mucous membrane
routes of parenteral administration
- subcutaneous (slowest)
- intramuscular
- intravenous (most rapid)
advantages of oral administration
- convenient
- acceptable by patient
- relatively safe
- economic (cost less)
disadvantage of oral administration
- longer or unpredictable absorption
- slow onset of action
- GI irritation (aspirin)
- requires consciousness
advantages of parenteral administration
- rapid
- doesn’t require consciousness
- more accurate and predictable dosage
disadvantage of parenteral administration
- more painful
- more costly
- danger of infection
- essentially irreversible
parenteral administration of drugs to CNS into cerbral spinal fluid
intrathecal (intraventricular)
types of absorption through skin and mucous membranes
- inhalation
- cutaneous
- rectal-vaginal
- intranasal
- intra-ocular
- sublingual (nitroglycerine)
mechanisms of drug entry into cell
- passive diffusion (most important)
- facilitative diffusion (carrier on membrane)
- active transport and pinocytosis (require energy)
Factors that influence passive diffusion
- size of molecule
- solubility in lipids
- degree of ionization of a drug
can predict if ionized or not
henderson-hasselbalch equation
the non-ionized form is more soluble in ___
lipid
the ionized form is more soluble in ___
aqueous environment
weak acid equation
ph = pk + log (A-/HA)
weak base equation
ph = pk + log (B/BH+)
anything other than the drug itself is an _____
adjuvant
an adjuvant changes ___
viscosity, buffer, etc….
sites of non-specific drug binding
- proteins in plasma (albumin)
- adipose tissue
blood brain barrier excludes:
- lipids and ionized drugs
placental barrier stops:
- molecules > 1000mw
