PHARM; Lecture 13, 14 and 15 - Drugs of Abuse I, II and Alcohol Flashcards Preview

Y2 LCRS 1 - Pharm, Endo, Reproduction > PHARM; Lecture 13, 14 and 15 - Drugs of Abuse I, II and Alcohol > Flashcards

Flashcards in PHARM; Lecture 13, 14 and 15 - Drugs of Abuse I, II and Alcohol Deck (56)
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1

Why are drugs of abuse used?

For euphoria -> cell bodies in the ventral tegmental area which project into nucleus accumbens, releasing DA to induce a euphoric high

2

What are the methods of admin of drugs of abuse?

Intra-nasal (Mucous membranes of nasal sinuses, slow absorption), oral (GIT, v. slow), inhalation (Small airways and alveoli = rapid), IV (veins, rapid)

3

What are the classes of drugs of abuse?

Narcotics (opiates - heroin), depressant (alcohol, benzodiazepines, barbiturates), stimulants (cocaine, amphetamine, caffeine, methamphetamine), misc. (cannabis, ecstasy)

4

What is cannabis?

  • From the cannabis sativa plant;
  • cannabinoids being the main compound (delta-9 THC is the main compound)
  • main part of plant are the trichomes on the plant.
  • Main aim of new versions of cannabis are to increase levels of delta-9 THC (seem to increase -ve consequences)

5

What are the methods of admin of cannabis?

Oral - 5-15% (delayed onset/slow absorption with 1st pass metabolism); inhalation - 25-35% to be absorbed in blood stream

6

Once in the blood stream, what occurs to cannabis?

  • VERY lipid soluble
  • Diffuses to highly perfused tissues first and slow accumulation in not well perfused tissues
  • slowly accumulated in poorly perfused fatty tissues, with ratio 10^4 fatty tissue : 1 plasma, which will slowly release back into the plasma.
  • Distributes also to the brain and sits in the brain tissues for a long time, with prolonged effect as it isn't clearing from the tissues

7

What occurs to cannabis when broken down?

In the liver - a more potent cannabinoid is formed (11-OH-THC) from the cannabinoid; In the GIT (65%), most of it goes into the bile (to be excreted) so it is recycled in the enterohepatic circulation; excreted 25% via urine. Poor correlation between plasma cannabinoid concentration and degree of intoxication

8

How long after smoking a cannabis cigarette will the effects persist in the body? 5 hours 12 hours 7 days 30 days 10 years

30 days

9

What are the receptors that cannabis acts on?

  • CB1
    • hippocampus
    • cerebellum
    • cerebral cortex
    • basal ganglia.
  • CB2 - on immune cells.
  • Acts on adenylate cyclase to inhibit it (hence depressant).
  • Body's cannabinoid = endogenous anandamide

10

What is the pharmacodynamics of euphoria?

  • GABA maintains the pathway inhibited to prevent constant euphoria.
  • Cannabis depresses the GABA inhibition, inhibiting the inhibition, to increase firing of VTA so NAcc releases more DA

11

What are the functions of cannabis?

  • Euphoria,
  • paranoia/schizophrenia,
  • hunger,
  • immunosuppressant,
  • memory loss (limbic regions with amnestic effects with decreased BDNF),
  • psychomotor performance (cerebral cortex),
  • tachy/vasodilation (red eyes via vanilloid receptor),
  • medulla (low CB1 receptor expression so it is very difficult to OD on cannabis so no decrease to cardioresp centre in medulla)

12

What does the Anterior cingulate cortex do and what occurs to it with cannabis?

  • Involved with performance monitoring with behavioural adjustment in order to avoid losses
  • hypoactivity in cannabis users;
  • can increase psychosis and schizophrenia

13

What is the effect of cannabis on food intake?

  • Positive effect on orexigenic neurones in lateral hypothalamus
  1. presynaptic inhibition of GABA increases MCH activity;
  2. inceased orexin production

14

How does cannabis cause immunosuppression?

15

What are the medical uses of cannabis?

  • Increased regulation of CB receptors;
  • MS/pain/stroke = regulatory;
  • fertility = in males with upregulation of CB1 receptors interferes with sperm production;
  • and in obesity there is an upregulation of CB1

16

What are the functions of the drugs that affect the CB receptors?

  • Dronabinol/nabilone used as anti-emetic for cancer patients;
  • sativex as analgesic for MS;
  • rimonobant used for obesity as downregulates hunger but now withdrawn as instances of suicide associated

17

What is the t1/2 of cannabis and the elimination method?

t1/2= 7d; elimination = synth into 11OH THC - 65% in gut, urine 25%

18

What is cocaine and the different forms?

Plant derived (erythroxylum coca).

19

How do you admin cocaine?

Oral isn't a good admin method

20

How do you metabolise cocaine?

21

How do cocaine pharmacokinetics contribute to the addictive potential of the drug?

Short elimination time means that it's effects are short lived so want constant admin; also quick method of admin makes it more likely to be admin

22

What are the functions of cocaine?

  • Local anaesthetic,
  • reuptake inhibition,
  • euphoria -> mild-moderate effects are positive/reinforcing effects and severe effects are negative/stereotypical effects;
  • cardiovascular, MI

23

How does cocaine act as a local anaesthetic?

High dose -> blocks Na channels

24

How does cocaine act as a reuptake inhibitor?

  • Blocks uptake systems so more DA in the synapse
  • doesn't affect affinity/efficacy,
  • but increase DA in synapse,
  • so more present to try to bind to the receptor to outcompete

25

How does cocaine cause euphoria?

Blocks DA transporter in the NAcc to increase DA in synapse which is released

26

How does cocaine cause MI/cardiovascular problems?

  • With dose increasing as you go down;
  • Releases endothelin-1 which increases vasoconstriction;
  • CNS effects -> vasoconstriction and hyperpyrexia (caused by increase ANS activation) which can affect epilepsy

27

What is nicotine?

  • From plant;
  • present in cigarettes;
  • tar droplets deposited in lung and nicotine diffuses through that into the alveoli.
  • Nicotine in particulate side

28

How is nicotine admin?

Cigarettes are acidic and nicotine is alkaline, so is ionised in cig smoke, but then diffuses across the alveoli as the membrane is so thin.

29

How is nicotine metabolised?

Met by cytochrome P450 in liver (70-80%) into cotinine. T1/2= 1-4h Eliminated via urine

30

Where does nicotine act?

Acts on ANS nAChR

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