Medicines and drugsAnalgesics

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

benzene

ester

carboxylic acid

paracetamol

benzene

hydroxyl

amide

carbonyl

Structure of analgesics

ibuprofen benzene carboxylic acid

Aspirin – a derivative

salicylic acid…. (caused vomiting)

into aspirin

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.

aspirinadvantage disadvantage

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

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 disadvantage reduces fever –

antipyretic

very safe in the correct dose as it does not upset the stomach or cause bleeding

suitable for children

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 diamorphine/heroin

codeine

• benzene hydroxyl

/alcohol (2) ether double bond tertiary amine

benzene ester (2) ether double bond tertiary amine

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

injuriesPrevents 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.