3. Opiates

• 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

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

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

• 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

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

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

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

(2x Hydroxyl (O-H), 1x Ether (R-O-R’)) Has two –OH/hydroxyl groups polar/hydrophilic (harder to pass BBB)

(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

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

Codeine is synthesised from morphine: attachment of a methyl group Synthesized by reacting: - Morphine - Methyl halide (Eg. CH3I) (Nucleophilic substitution / Sn2)(methylation reaction)

Diamorphine is produced from morphine in the esterification reaction Synthesized by reacting: - Morphine - Ethanoic acid / acetic anhydride (Esterification)