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 ester carboxylic acid benzene hydroxyl amide carbonyl

Structure of analgesics ibuprofen benzene carboxylic acid

A derivative = a new compound from changing another compound 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.

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) - 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 ester (2) Benzene hydroxyl (1) ether (1) 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.