Medicines and drugs
Analgesics
Analgesics – reduce pain
Pain
 Pain is detected in the brain when nerve messages are
sent from pain receptors in the body.
 The receptors are stimulated by chemicals
(prostaglandins) released from cells that are damaged.
Mild analgesics
Mild analgesics, such as aspirin, paracetamol
(acetaminophen) and ibuprofen , function by
stopping the transmission of pain from the source
to the brain as they intercept the pain stimulus at
the source.
They do this by interfering with the production of
substances, such as prostaglandins, that are
produced by injured tissues and that cause pain,
swelling or fever.
These are all non-narcotics – do not interfere with
the function of the brain
Strong analgesics - Opiates
 Strong analgesics such as morphine, codeine,
and diamorphine (heroin) work by
temporarily bonding to receptor sites in the
brain preventing the transmission of pain
impulses.
 This prevents the transmission of pain
impulses i.e. blocking the signal without
depressing the central nervous system.
 Alters your perception of pain.
 These are called narcotics b/c they act on the
brain.
Mild or strong?
 Mild analgesics eliminate pain at source
 Strong analgesics alter our ability to
perceive pain
Structures of analgesics
aspirin
paracetamol
 benzene
 benzene
 ester
 hydroxyl
 carboxylic acid
 amide
 carbonyl
Structure of analgesics
ibuprofen
 benzene
 carboxylic acid
Aspirin – a
derivative
salicylic acid…. (caused vomiting)
A derivative = a new
compound from
changing another
compound
To convert salicylic acid
(2-hydroxybenzoic acid)
into aspirin the hydrogen
atom of the OH group is
replaced by a COCH3
group to form an ester
functional group which
makes the compound less
irritating to the stomach
and easier to take.
into aspirin
aspirin
advantage
 reduces fever more effectively –
antipyretic (=drug which reduces
fever)
 also useful in preventing the
recurrence of heart attacks and
strokes and also thins the blood
(beneficial side-effects) and
reduces blood clotting
 also anti-inflammatory – reduces
inflammation or swelling
disadvantage
 ulceration
 stomach bleeding due
to its acidic properties
 allergic reactions
 Reye’s syndrome in
children (a potentially
fatal liver and brain
disorder) - not so
suitable for children
(baby aspirin is
available)
paracetamol
advantage
 reduces fever –
antipyretic
 very safe in the correct
dose as it does not upset
the stomach or cause
bleeding
 suitable for children
disadvantage
 can, in rare cases, cause
blood disorders and kidney
damage.
 easier to overdose and over
dosage can lead to serious
liver/kidney damage, brain
damage and even death.
 not a good anti-inflammatory
Structures of Strong
Analgesics
All structures above are in the IB data booklet
Morphine + ethanoic acid
Heroin and Water
Strong analgesics
morphine
• benzene
 hydroxyl
/alcohol (2)
 ether
 double bond
 tertiary amine
diamorphine/her
oin
 benzene
 ester (2)
 ether
 double bond
 tertiary amine
codeine





Benzene
hydroxyl (1)
ether (1)
double bond
tertiary amine
Increase in effects: Codeine  Morphine  Heroin
Structures of Strong
Analgesics
Structures of Strong
Analgesics
Derivatives of Morphine
 Morphine is a natural substance made from opium in
poppy plants.
 Diamorphine (heroin) and codeine are derivatives of
morphine.
 An opiate is a class of drugs or chemicals which have the
same physiological effect as morphine.
 Heroin’s structure is only slightly different from morphine.
Both the hydroxyl or alcohol groups in morphine have been
replaced with ester groups. This is achieved by reacting the
morphine with ethanoic acid; as a result an esterification
occurs during which also water is produced.
 Demerol is also a strong analgesic, but it is synthetically
made.
Using morphine - advantages
 strong analgesics and therefore can relieve
extreme pain
 wide therapeutic window
 relieves anxiety
 induces relaxation
 can be administered intravenously which
results in faster distribution of drug
Using morphine - advantages
 Short Term Effects:
 Euphoria – happy (this could be a disadvantage)
 Relieves pain from heart attacks and injuries
 Prevents coughing
Morphine - disadvantages
 Constipation, increase or decrease in weight, kidney failure, loss
of libido
 addiction or physical dependence which leads to withdrawal
symptoms when drug is not taken e.g. restlessness, sweating,
fever, cramping, …
 tolerance can become an issue with this type of drug as more of
the drug needs to be taken to achieve the same effect; in order to
achieve the desired effect heroin users may take doses which
exceed the lethal dose
 Social:
 users are more likely to commit crimes to pay for gradually
increasing doses of the drug
 loss of job
 diversion of energy and money
 when administered intravenously can lead to transmission of
dangerous infections e.g. AIDS.