3. Opiates

Question 1

The action of opiates as painkillers

Answer 1

• They suppress pain impulses in the brain
• They bind to opioid receptors in the brain
• They resemble endorphins/ natural chemical painkillers which are produced in the brain or the spine

Question 2

Advantages of Opiates

Answer 2

• Relief for acute & extreme pain
• Wide therapeutic window
• Relieves anxiety
• Improves quality of life

Question 3

Disadvantages of Opiates

Answer 3

• Euphoria, lack of self-control
• Prolonged use can build tolerance, increasing the risk of overdose
• Increased risks associated with intravenous drug administration

Question 4

Opiates are addictive because:

Answer 4

• Interact with opioid receptors in the brain
• Alter the structure of brain cells
• Brain only works when opiates are present
• Prevents transmission of pain impulses inside the brain
• Released dopamine

Question 5

Blood-Brain Barrier (BBB)

Answer 5

Restricts the passage of substances from the bloodstream into the brain.

• Greatly composed of lipids (non-polar hydrophobic)
• For a substance to pass through, must be lipid-soluble
• Polar, hydrophilic substances have difficulty passing through
• Non-polar, hydrophobic substances may pass through easily

Analgesic’s property depends on the ability to move from
Bloodstream => Brain

Question 6

Opioid Receptors

Answer 6

• Opioids attach to receptors in the brain to reduce the perception of pain
• Causing drowsiness, mental confusion, nausea, and constipation.
• High dosages depress respiration

Question 7

Codeine properties

Answer 7

weakest opiate

(1x Hydroxyl (O-H), 2x Ethers (R-O-R’))

Codeine has lower activity and a lower risk of overdose
Has a wide therapeutic window

Question 8

Morphine properties

Answer 8

(2x Hydroxyl (O-H), 1x Ether (R-O-R’))

Has two –OH/hydroxyl groups
polar/hydrophilic (harder to pass BBB)

Question 9

Diamorphine properties

Answer 9

(1x Ether (R-O-R’), 2x Ester (O-C=O))

Has a ester group
Less polar/hydrophilic than hydroxyl
Diamorphine is more soluble in lipids

Question 10

General Opiates properties (structure)

Answer 10

-C=C (Alkene)
- Benzene group
- Tertiary amine group
- Ether

Question 11

Codeine Synthesis

Answer 11

Codeine is synthesised from morphine: attachment of a methyl group

Synthesized by reacting:
- Morphine
- Methyl halide (Eg. CH3I)

(Nucleophilic substitution / Sn2)(methylation reaction)

Question 12

Diamorphine Synthesis

Answer 12

Diamorphine is produced from morphine in the esterification reaction

Synthesized by reacting:
- Morphine
- Ethanoic acid / acetic anhydride

(Esterification)