15.1 Basic Principles of Drug addiction

Question 1

What are the four routes of drug administration

Answer 1

1. oral injestion
2. injection
3. inhalation
4. mucuous membrane absorption

Question 2

explain the process of oral ingestion

Answer 2

drugs dissolve in the stomach fluids and are then carried into the intestine, absorbed into blood stream

Question 3

what are the two ways that oral ingestion can be irregular?

Answer 3

1. some drugs do not have to pass into the intestines bc they can permeate the stomach wall
2. some drugs are not easily absorbed by the digestive tract, or are broken down into inactive metabolites, and won’t have any or very much effect

Question 4

what are the two main advantages of oral ingestion?

Answer 4

1. Ease

2. Relative safety

Question 5

what is the main disadvantages of oral ingestion?

Answer 5

1. unpredictability - absorption from GI to blood can be influenced by hard to gauge factors like the amount and type of food in the stomach

Question 6

why is injection common in medical practice? (3)

Answer 6

1. strong effect
2. fast acting
3. predictable

Question 7

what are the 3 methods of injection

Answer 7

1. Subcutaneously (SC) - into fatty tissue under the skin
2. intramuscularly (IM) - into large muscles
3. Intravenously (IV) - directly into veins where they run beneath the skin

Question 8

which is the typically preferred method of injection Among drug addicts
- why and why is it a problem (2)

Answer 8

intravenous, bc the blood brings it straight to the brain

• speed and directness also means its very difficult to counter act an overdose, an impurity or an allergic reaction
• can develop scar tissue, infections and collapsed veins are the few acceptable injection sites

Question 9

explain inhalation

Answer 9

absorption through he capillaries in the lungs

Question 10

what are the two main problems with inhalation

Answer 10

1. difficult to regulate dose precisely

2. damage to lungs with chronic use

Question 11

what is the main problem with mucous membrane absorption

Answer 11

damage to the membranes over time

Question 12

what makes it difficult for potentially dangerous drugs to pass from the blood vessels of the CNS into the extracellular space?

Answer 12

the blood brain barrier

Question 13

what are the two broad mechanisms of drug action?

Answer 13

1. diffuse action across neural membranes in the CNS

2. specific action

Question 14

what are the three main mechanisms of specific drug action?

Answer 14

1. binding to synaptic receptors
2. influencing synthesis, transport, release or deactivation of a neurotransmitter
3. influencing the chain of chemical reactions elicited in postsyn neurons by the activation fo their receptors

Question 15

what ends the action of most drugs?
how?
what is this called?

Answer 15

enzymes synthesized in the liver

- stimulate the conversion of active drugs into their non active forms (known as drug metabolism)

Question 16

what is the main way that drug metabolism inhibits their action?

Answer 16

prevents them from passing through lipid membranes so it can’t penetrate the BBB

Question 17

what is an additional way that drug metabolism inhibits action

Answer 17

small amounts of some psychoactivve drugs are passed into urien, sweat, faces, breath and mothers milk

Question 18

explain drug tolerance

Answer 18

state of decreased sensitivity to a drug that develops as a result of exposure

Question 19

what are the two ways we can demonstrate tolerance?

what does this mean generally?

Answer 19

1. given dose has less effect that it did before exposure
2. takes more time to produce the same effect
   - Dose - response curve has shifted to the right

Question 20

what are the three important facts about specificity of drug tolerance

Answer 20

1. Cross tolerance - one drug can produce tolerance o drugs with similar mechanisms
2. Can develop to some aspects of a drug but not others, may even sensitize to some aspect overr time
3. Noot a unitary phenomenon - no single mechanism that underlies all examples of it - several adaptive mechanisms

Question 21

what are the two categories of drug tolerance

Answer 21

1. metabolic

2. functional

Question 22

explain metabolic tolerance

Answer 22

tolerance that arises from a decrease in the amount fo drug that reaches its specific activity site

Question 23

explain functional tolerance

Answer 23

changes that reduce the reactivity of the sites of action to a drug

Question 24

what constitutes the majority of tolerance to psychoactive substances?

Answer 24

functional tolerance

Question 25

what are the examples of neural changes that promote tolerance?
What are causes many of these changes?

(3)

Answer 25

1. reduce receptors for the drug
2. decrease binding efficiency
3. diminish or impact binding o the cell’s activity
   - epigenetic mechanisms

Question 26

what is a withdrawal syndrome

Answer 26

the adverse physiological reaction that can occur after significant amounts of a drug have been in the body for some period of time, and then suddenly eliminated

Question 27

what are the effects of withdrawal syndrome?

what does this imply?

Answer 27

the exact opposite to the initial effects of the drug itself.
- that the effects of withdrawal are produced by the same neural changes that produce tolerance

Question 28

what are people who suffer withdrawal reactions when they cease drug consumption called?

Answer 28

physically dependent to that particular substance

Question 29

explain the theoretical mechanism of withdrawal syndrome

Answer 29

exposure to a drug produces compensatory changes in the NS that offset the drugs effects producing tolerance
- when the drug is eliminated, these compensatory changes manifest as withdrawal symptoms that oppose the initial effects of the drug

Question 30

what does the severity of withdrawal symptoms depend on?

Answer 30

the particular drug in question, the duration and degree of exposure and the speed with which it was eliminated
- in general, longer exposure to greater doses follow by more rapid elimination produce more severe withdrawal

Question 31

what defines a drug addicted individual

Answer 31

a habitual drug user who continues to use a drug despite its adverse effects on their health and social life, despite their repeated efforts to cease use

Question 32

What differentiates addiction from physical dependence

Answer 32

addicted individuals may take drugs to prevent withdrawal symptoms, but this is clearly not the only reason - if it were, waiting out the withdrawal would result in their addiction being removed, but this is rarely the case