option D- medicinal chemistry (D.3) Flashcards
what are opiates?
natural narcotic analgesics that are derived from the opium poppy
what are morphine and codeine used as?
strong analgesics
how do strong analgesics work?
by temporarily binding to opioid receptors in the brain
describe the difference of the effects of low and high doses of strong analgesics
low/moderate doses: although they act as depressants if the CNS, they do not significantly affect perception, attention or coordination when taken in low to moderate doses.
high doses:
affect all functions of the CNS and can lead to drowsiness, confusion and potentially fatal asphyxia caused by respiratory depression.
what are opiates also known as and why?
narcotic analgesics because in addition to their painkilling properties, large doses of opiates cause a strong feeling of euphoria, provide relief from all forms of distress and stimulate sociability.
describe the primary bioactive ingredient of opium
morphine, a natural analgesic that belongs to the group of alkaloids (naturally occurring chemical compounds containing basic nitrogen atoms)
what are morphine and its derivatives (opiates) used for in medicine?
relieve severe pain caused by injury, surgical procedures, heart attack or chronic diseases such as cancer
describe the problems of addiction to opiates
non-medical use of opiates quickly leads to psychological dependence and tolerance, forcing the user to take constantly increasing doses of the drug to achieve the desired effect. This affects the metabolic processes in the body and leads to physiological dependence, further increasing the required dose of the drug and the risk of adverse effects
what does the physiological activity of opiates strongly depend on?
their ability to cross the blood-brain barrier
what is the blood brain barrier?
a series of lipophilic cell membranes that coat the blood vessels in the brain and prevent polar molecules from entering the CNS
what limits morphine’s ability to reach the opioid receptors in the brain?
the presence of one amino and two hydroxyl groups- these make morphine sufficiently polar to be soluble in water but reduce its solubility in lipids
how can the polarity of morphine be reduced?
by chemical modification of one or both hydroxyl groups in its molecule
describe how codeine differs from morphine
the phenolic -OH group is replaced with the less polar ether group, -OCH3
codeine is —- potent than morphine; why?
less; it readily crosses the blood-brain barrier but does not bind to the opioid receptor because of the steric effect of the ester group
how does codeine have similar pharmaceutical properties to morphine?
once codeine has crossed the blood-brain barrier, it is slowly metabolised into morphine.
