Transcript Convert
Drug
Administration
Lesson 3
Definitions
Pharmacokinetics
What the body does to the drug.
Administration, absorption,
distribution, & fate
Focus of next 2 sections
Pharmacodynamics
What the drug does to the body.
drug effects
Coming soon ~
How To Get From Here To There?
Drug
Target
Complex Journey ~
Routes of Administration
Critical to efficacy
Rapidity of onset
Duration of effects
Magnitude of effects
Systemic administration
Drug into circulatory system via ...
Enteral routes
Parenteral routes
Drug effects throughout body ~
Oral
Per Os (PO)
by
mouth
absorption across
membrane in GI
most common
most variable
st pass metabolism
1
Cooperation required
Can recall ~
Oral
Sublingual
Absorption:
mucous membrane
salivary glands
e.g., nitroglycerin,
buprenorphine
Chewing
absorbed across
lining of mouth ~
Injection
Intravenous (iv)
directly into vein
rapid onset of effects
Fastest
~
Injection
Intramuscular (im)
Location important
Deltoid - rapid
Thigh - moderate
Buttocks - slowest
Difference in blood
supply & distance ~
Injection
Subcutaneous (sc)
under skin
slow, steady absorption
Disadvantages
Variable absorption
limited volume
skin irritations ~
Injection
Intraperitoneal (ip)
into peritoneal cavity of abdomen
Can deliver large amounts
Not used in humans much
Danger of infection ~
Injection
Intrathecal (epidural)
under sheath of nerve fibers,
spinal cord
Mostly as local anesthesia
little importance for psychoactive
drugs ~
Injection
Intracranial
directly into brain
direct access to cells
intraventricular - into CSF
Peripheral vs. central effects
e.g. curare
peripheral
---> paralysis
central ---> convulsions ~
Inhalation
Smoking
Lungs
gases or vapors
densely lined with capillaries
large surface area
Fast absorption
Similar to iv ~
Intranasal
Particles of drug
insufflation = sniffed
Absorption across
mucous membrane of
nose
Not in lungs!
Slower absorption
effects not as strong as
inhalation ~
Other routes
Transdermal patches
absorbed by skin
slow continuous release
also
liposomes: via injection
Suppositories - rectal or vaginal
absorption incomplete &
unpredictable
Pellets - Norplant
Microcatheter & pump ~
The Future: Part 1
Polymer-to-gel
drug + water + biodegradeable polymer
45 C: liquid & injectable
37 C: solidified gel capsule
70% of drug released over 12 days ~
The Future: Part 2
Injections without NEEDLES!?
only some drugs enter via patch
e.g. nicotine, scopolamine
VLF - very low frequency sound
disrupts lipid layer of skin
more room for molecules to enter
insulin, interferon gamma, etc
works in rats & cadavers ~
Choice of route
Consider factors
Patient characteristics
Concentration in blood
Amount delivered
Rapidity of onset
Duration of effects
Magnitude of effects ~
related
In general...
Rapid onset of effects
higher magnitude
shorter duration
Slow onset of effects
lower magnitude
longer duration ~
i.v. & inhalation
Blood
Level
im, sc, ip
p.o.
sec min
hr
Time
hrs