WEEK 5 | DRUGS Flashcards

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1
Q

Define psychoactive drugs

A

substances that contain chemicals similar to those found naturally in our brains that later consciousness by changing chemical processes in neurons.

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2
Q

what is the site of action for psychoactive drugs

A
  • Site of action on the CNS( central nervous system)
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3
Q

Define pharmacokinetics

A

refers to the movement of the drug through the body that involves absorption, distribution, metabolization and excretion

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4
Q

Define pharmacodynamics

A

refers to the mechanism of action of drugs

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5
Q

Types of drugs (4 in total)

A

1) Depressants: decreases activity of CNS. Initial high but followed by sleepiness, slower thinking, and impaired concentration.
- Examples: alcohol
2) Stimulants: increases activity of the CNS. Increases sense of alertness, well-being and energy.
- Examples: tobacco(nicotine), cocaine, caffeine
3) Opiates: sense of euphoria and decreased pain
- Examples: heroine, morphine, cocaine
4) Psychedelics: dramatically altered perception, mood and thoughts
- Examples: Marijuana, LSD, ecstasy

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6
Q

what is the meaning of sedative and hypnotic?

A

Meaning of sedative = calming

Meaning of hypnotic = sleep-induced

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7
Q

Define blood brain barrier

A

seal to separate body compartment

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8
Q

What is the blood brain barrier composed of?

A

Astrocytes

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9
Q

What makes up the blood brain barrier?

A

1) Glial tissues
2) Tight junctions of the brain capillary walls
3) Lack of pores

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10
Q

What is the only way drugs enter the brain?

A

Because of the blood brain barrier drugs cannot enter the brain unless they are lipid soluble enough to diffuse through the capillary walls and the glia.

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11
Q

What is the blood brain barrier compared to?

A

watchdog

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12
Q

What does the blood brain barrier provide?

A

Not only does it keep things out but it prevents neurotransmitters to leak out and get lost because the brain needs it.

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13
Q

Why is the blood brain barrier not found in the pituitary and the hypothalamus?

A

the hormones it secretes need to go into circulation and pass through the rest of the body.

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14
Q

Define solubility

A

refers to its ability to dissolve

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15
Q

What are the 2 types of solubility that are most significant for drugs?

A

1) Dissolve in water

2) Dissolve in lipids

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16
Q

Do drugs dissolve?

A

Drugs do not dissolve. For the most part, will not cross membranes and they will be eliminated from the gastrointestinal tract. Injected into the bloodstream they can remain and cause blockage.

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17
Q

Why is lipid solubility important to drugs?

A

Membranes have a lipid structure thus they are able to pass through them and diffuse to the other side.

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18
Q

Define and give an example of hydrophobic

A
  • Refers to being “afraid of water” and an example is oil, rain runs off from a ducks back
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19
Q

Ionization

A

the process by which electrically neutral atoms are converted to charged atoms. Ex: NaCl becomes Na+ and Cl- . we say that table salt ionizes

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20
Q

How does ionization compare to drugs?

A

When drugs enter the extracellular fluid, they may ionize somewhat as they dissolved yielding a solution that contains both ionized and unionized portions of the drug. Since the ionized portion carries a charge, it has difficulty crossing the membrane because of equilibrium of charges.

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21
Q

What is a major factor of absorption?

A

How much of the drug was in its ionized form

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22
Q

Which drugs are hardest to absorb?

A

Water-soluble drugs because they ionize in bodily fluid and then cannot readily cross membranes

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23
Q

What case can a lipid-soluble drug not cross the membrane?

A

If they ionize, the ionized portion loses its lipid solubility

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24
Q

What is the BEST form for drugs that yield the greatest absorption rate

A

Lipid-soluble , unionized and small

25
Q

Why is pH important for drugs?

A

Acidic drugs tend to ionize in an alkaline medium and vice versa

26
Q

What factor determines ionization in terms of pH?

A

How far apart the drug and the medium are on the pH scale. The greater the difference, the greater the ionization

27
Q

Scenario: an alkaline drug like heroin is injected met with stomach acids after being swallow. Explain what happens

A
  • Acidic drugs ionize if they are injected into the alkaline environment of the blood. This will reduce lipid solubility and absorption and leads to weaker effects
    pH value of gastric juice and blood
  • Gastric juice is 1.2 (very acidic)
  • Blood is 7.4 (slightly alkaline)
28
Q

For oral administration where are drugs absorbed?

A

The GI tract

29
Q

Which route for taking drugs take a long time to reach their site of action?

A

Drugs taken orally

30
Q

What are the advantages of taking drugs orally?

A
  • Economical, convenient, and easy

- Safe in case of emergencies as drugs can be vomited

31
Q

What are the disadvantages of taking drugs orally?

A
  • Not good in emergencies (takes too long to act)
  • Require proper drug pH (drugs require to be acidic)
  • Food in stomach delays gastric emptying (food has to be digested first and the drugs might get broke down along with food)
  • Fast pass metabolism(drugs through the mouth can be broken down before destination so might have to give higher dosage to compensate)
32
Q

Should oral drugs be alkaline, basic or acidic?

A

acidic

33
Q

What are the passage steps of how the drug gets from mouth to cell?

A

GI tract, blood vessel, into blood, out of capillary walls, into the extracellular fluid, cell membrane, cell

34
Q

What are advantages of IV drugs administration?

A
  • Most accurate means of controlling dosage level
  • Intense effect ex: heroin
  • Short delay of effect especially in emergencies. It takes less than 15 seconds for the drugs to go from forearm to the brain
35
Q

What are some disadvantages of IV drug administration?

A
  • Frequent use of vein can lead to irritation or collapse
  • Drugs must have aqueous solution and an aqueous vehicle(meaning they need to be soluble in the veins or else they can get clogged)
  • Drugs can’t be recalled unless an antagonist for the drug is administered
  • A drug (ex: heroin) that may exert minimal effects when administered per mouth, can have extremely toxic effect when given through IV
  • Sterility of needs, cost, pain
36
Q

What are some advantages to drug inhalation?

A
  • The alveoli provides a huge surface area with blood vessels lying behind it so it gets to the blood stream quickly
  • We have an efficient way of getting oxygen into our bodies so inhalation of drugs can benefit from this
  • Inhalation of drugs is compared to IV administration. Inhalation takes 5-8 seconds.
37
Q

What are some disadvantages to drug inhalation?

A
  • Long term hazards for breathing particles that not only contain the active drug but other things like tar
  • Lung cancer can result
  • Lining of throat and lungs will become irritated over time
38
Q

Effective dosage

A

the dosage of a drug that produces a select effect in a given % of people

39
Q

lethal dosage

A

the dosage that causes death

40
Q

therapeutic index and equation

A

: a measure of a drugs safety. LD/ED number should be as large of possible

41
Q

what is the therapeutic index for alcohol, marijuana and LSD?

A
  • Alcohol is 6
  • Marijuana is a joke, 900 joints smoked at once. Safe drugs in terms of mortality
  • LSD is unknown but very high. Safest drug
42
Q

Define potency

A

if drug A produces a given effect at a lower dose than drug B, then drug A is more potent

43
Q

maximum efficacy

A

the dosage needed to produce an effect fully

44
Q

define half-life

A

the time it takes for the blood concentration of drug to drop to half

45
Q

How to get duration of drug?

A

Multiply half life by 6 to get an approximation of duration of effect

46
Q

First order kinetics vs zero order

A
  • First order is basically half life

- Zero kinetics is metabolization at a constant rate over time ex: alcohol

47
Q

define Biotransformation(aka metabolism)

A

process whereby enzymes modify a molecule chemical properties.

  • Drugs effects are terminated by liver enzymes that act by ionizing the drugs to help prevent reabsorption
  • If orally, the must pass the GI tract. Due to first pass metabolism, circulating levels to excrete are lower
48
Q

What liver enzyme breaks down drugs to excrete?

A

Cytochrome P-450, a microsomal liver enzyme and it is non specific so it can break down anything

49
Q

Define inducibility and what it is a form of?

A
  • Inducibility is when there’s increased exposure to any substance broken down by P-450, it results in an increased production of P-450.
  • One form of tolerance
50
Q

Metabolic Tolerance

A

involves liver enzyme induction. Increase enzyme = more drug needed to achieve effect

51
Q

Cellular tolerance

A

involves the adaptation of individual nerve cells to the presence of a drug

52
Q

cross tolerance

A

when the use of one drug produces tolerance for another

53
Q

define Dependence and the 2 types

A

state where the removal of a drug leads to withdrawal symptoms

1) Physical dependence: body requires the drug to continues functioning normally. Discontinuation of drug produces withdrawal.
2) Psychological dependence: continued use of a drug motivated by intense cravings(ex: internet gambling

54
Q

What organ is responsible to excreting drugs?

A

kidneys

55
Q

How do the drugs get excreted from the body?

A

The kidneys strain the blood and remove used or useless material.

56
Q

Where does excretion begin and end ?

A

Bowmans capsule and ends at the nephron tubule

57
Q

how can drug concentration increase during excretion?

A

If a drug is unionized and lipid soluble, it follows the gradients and water and diffuses through the tubule wall back into the capillaries, rejoining circulation and remaining active

58
Q

define ion-trapped in terms of excretion

A

If drugs are ionized, they will be ion-trapped in the tubule and excreted unless active transport rescues them

59
Q

how does the body eliminate lipid soluble, unionized drug molecules?

A

The liver must first ionize them so when they reach the nephron tubule, they can be ion trapped and prevented from returning to the circulation.