Psych 179 Lecture wk# 1-1
Pharmacology
•
Inhale drug: lung
heart
brain
•
IV drug: heart
lung
heart
brain
A.
Figure 5-1. (In the hand out)
•
Absorption and distribution. Drugs entering the body by way of the gastrointestinal
tract, skin or lungs must first traverse an epithelial barrier before entering the
interstitium. Drugs given subcutaneously or intramuscularly bypass the epithelial
barrier. Drugs given by any of the routes shown must traverse the capillary wall in
order to enter the circulation.
B.
Drug Elimination:
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Half-life: time it takes to remove 50% of drug from bloodstream
o
Independent of drug concentration
o
Constant rate (Exam questions)
o
Examples:
T=0
10 mg IM morphine = 70 ng/ml in blood
T=2.5 hr
35 ng/ml
T=5.0 hr
17.5 ng/ml
T=7.5 hr
8.75 ng/ml
C. Where is it occurring in the half life?
•
Kidney- most other drugs; 1
st
order kinetics
o
It’s constant rate to remove
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Liver- alcohol metabolism; 0 order kinetics
o
No half life in alcohol.
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o
It’s constant amount remove
•
Half-life – time to remove half drug from the blood; constant.

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- Fall '09
- Koob
- drug dependence, substance dependence Graph, Lifetime Drug Dependence
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