Medicines and drugs Analgesics - PowerPoint Presentation

Slide1

Medicines and drugs

AnalgesicsSlide2
Slide3

What is an analgesic?

How do you feel pain?

What does “physical dependence” mean?

What does ‘tolerance’ mean in this context?Slide4

Analgesics – reduce painSlide5

Mild analgesics

Mild analgesics, such as

aspirin

and

paracetamol

, function by stopping the transmission of pain from source to 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. Slide6

Strong analgesics - opioids

Strong analgesics such as

morphine

and

diamorphine

(

heroin

) work by temporarily bonding to receptor sites to pain impulses in the brain or other parts of the central nervous system such as the spinal cord.

This prevents the transmission of pain impulses i.e. blocking the signal without depressing the central nervous system.Slide7

Mild or strong?

Mild analgesics eliminate pain at source

Strong analgesics alter our ability to perceive pain

Consider the relative value of these two approaches to pain managementSlide8

Structures of analgesics

aspirin

benzene

ester

carboxylic acid

paracetamol

benzene

hydroxyl

amide

carbonyl Slide9

Structure of analgesics

ibuprofen

benzene

carboxylic acidSlide10

Aspirin – a derivative

salicylic acid….

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 COCH

3

group to form an ester functional group which made the compound less irritating to the stomach and easier to take

. Slide11

morphine

morphineSlide12

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

ether (2)

double bond

tertiar

y amineSlide13

heroin- another derivative

Diamorphine

or heroin is a derivative of morphine or a semi-synthetic opiate. An opiate is a chemical which has 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.

Also codeine is a morphine derivative

. Slide14

aspirin

advantage

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

)

so not so suitable for childrenSlide15

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

overdosage

can lead to serious liver damage, brain damage and even death

.

not a good anti-inflammatory Slide16

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 Slide17

Morphine - disadvantages

euphoria, lack of self-control even dangerous

behaviour

kidney failure.

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:

heroin 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.