D.3+Analgesics

toc

** D.3 Analgesics **

** D.3.1 **
** Describe and explain the different ways that analgesics prevent pain ** Analgesics are a class of drugs that allow for the relieving of pain. They are categorized into two broad classes, which are explained in the table below: **(narcotics)** || **Mild Analgesics** **(non-narcotics)** ||  || ** D.3.2 ** ** Describe the use of derivatives of salicylic acid as mild analgesics and compare the advantages and disadvantages of using aspirin and paracetamol (acetaminophen). **
 * **Strong Analgesics**
 * * Prevent the transmission of pain by binding with pain receptors in the **brain** and **blocking** the transmission of pain signals between brain cells. || * Intercept the pain stimulus at its **source** by Interfering with the production of **prostaglandins**, chemicals that cause pain. (**reduce pain**) ||
 * * Mimic the body's own natural painkillers (endorphins) producing analgesia (a sense of well being). || * Constricts blood vessels near the pain source **reducing** **inflammation**. ||
 *  Examples of this include heroin, codeine and morphine. || * Prevent an increase in body temperature that causes **fever**. (**reduce fever**) ||
 * || * Aspirin also has **anti blood clotting** properties and so is used in the treatment of heart heart or stoke . Paracetamol and ibuprofen do not do this. ||
 * ||  Examples of this include aspirin, paracetamol and ibuprofen. ||

Salicylic acid reacts to form aspirin in a condensation reaction:

 C₇H₆O₃ + C₄H₆O₃ → C₉H₈O₄ + C₂H₄O₂

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;"> Salicylic Acid + Acetic Anyhydride → Acetylsalicylic acid + Acetic Acid <span style="font-family: Verdana,Geneva,sans-serif;"> <span style="font-family: Verdana,Geneva,sans-serif;"> The H atom on the hydroxy group (-OH) attached to the benzene ring of the carboxylic acid is substituted for a CH3CO group on the acetic anhydride.

<span style="font-family: Verdana,Geneva,sans-serif;"> Aspirin, a derivative or product of salicylic acid, helps treat some of the same conditions as salicylic acid, but does so without the unpleasant taste. Aspirin is considered a NSAID (non-steroidal anti-inflammatory drug) and can help treat "headaches, toothaches, and sore throats...[as well as minimize] fever... and inflammation" (Brown and Ford 341).

<span style="font-family: Verdana,Geneva,sans-serif;"> **Aspirin**
 * <span style="font-family: Verdana,Geneva,sans-serif;">prevents the formation of prostaglandin at its source (this makes it a mild analgesic)
 * <span style="font-family: Verdana,Geneva,sans-serif;">stops transmission of the pain from source to brain

<span style="font-family: Verdana,Geneva,sans-serif;"> __Positive side effects__
 * <span style="font-family: Verdana,Geneva,sans-serif;">minimizes blood clotting so people with risk of heart attack/stroke take daily low dose of aspirin
 * <span style="font-family: Verdana,Geneva,sans-serif;">if someone's blood doesn't clot easily or undergoes operation, aspirin can be harmful

<span style="font-family: Verdana,Geneva,sans-serif;"> __Negative side effects__
 * <span style="font-family: Verdana,Geneva,sans-serif;">stomach bleeding
 * <span style="font-family: Verdana,Geneva,sans-serif;">connected to Reye's syndrome - affecting children under 12
 * <span style="font-family: Verdana,Geneva,sans-serif;">asthma
 * <span style="font-family: Verdana,Geneva,sans-serif;">deafness

<span style="font-family: Verdana,Geneva,sans-serif;"> **Paracetamol (acetaminophen in the USA)**
 * <span style="font-family: Verdana,Geneva,sans-serif;">mild analgesic
 * <span style="font-family: Verdana,Geneva,sans-serif;">minimizes production of prostaglandin in the brain; the rest of body's production of prostaglandin is unaffected

<span style="font-family: Verdana,Geneva,sans-serif;"> __Advantages / Positive side effects__
 * <span style="font-family: Verdana,Geneva,sans-serif;">reduces fevers
 * <span style="font-family: Verdana,Geneva,sans-serif;">helps relieve pain.
 * <span style="font-family: Verdana,Geneva,sans-serif;">Cannot lead to addiction.
 * <span style="font-family: Verdana,Geneva,sans-serif;">Does not irritate the stomach
 * Allergic reactions are rare

<span style="font-family: Verdana,Geneva,sans-serif;"> __Disadvantages / Negative side effects__
 * Does not reduce inflammation
 * <span style="font-family: Verdana,Geneva,sans-serif;">Overuse can possibly cause kidney/liver damage
 * <span style="font-family: Verdana,Geneva,sans-serif;">negative effects also magnified by alcoholic consumption

<span style="font-family: Verdana,Geneva,sans-serif;"> **Structure of Aspirin**
 * <span style="font-family: Verdana,Geneva,sans-serif;">benzene ring
 * <span style="font-family: Verdana,Geneva,sans-serif;">carboxylic acid group
 * <span style="font-family: Verdana,Geneva,sans-serif;">ester group

<span style="font-family: Verdana,Geneva,sans-serif;"> __Advantages / Positive side effects__
 * <span style="font-family: Verdana,Geneva,sans-serif;">helps relieve pains
 * <span style="font-family: Verdana,Geneva,sans-serif;">Stops blood from clotting
 * <span style="font-family: Verdana,Geneva,sans-serif;">Reduces fever
 * <span style="font-family: Verdana,Geneva,sans-serif;">Does not irritate the stomach
 * Allergic reactions are rare

<span style="font-family: Verdana,Geneva,sans-serif;"> __Disadvantages / Negative side effects__
 * <span style="font-family: Verdana,Geneva,sans-serif;">Allergic reactions are relatively common
 * <span style="font-family: Verdana,Geneva,sans-serif;">Increased risk of stomach bleeding when taken with alcohol
 * <span style="font-family: Verdana,Geneva,sans-serif;">Irritates the stomach



<span style="font-family: Verdana,Geneva,sans-serif;"> **Structure of Paracetamol** <span style="font-family: Verdana,Geneva,sans-serif;">**Structure of Ibuprofen**
 * <span style="font-family: Verdana,Geneva,sans-serif;">benzene ring
 * <span style="font-family: Verdana,Geneva,sans-serif;">hyroxy group
 * <span style="font-family: Verdana,Geneva,sans-serif;">amide group
 * <span style="font-family: Verdana,Geneva,sans-serif;">benzene ring
 * <span style="font-family: Verdana,Geneva,sans-serif;">carboxylic acid group

<span style="font-family: Verdana,Geneva,sans-serif;"> Ibuprofen is a chemical optical isomer, meaning that it has two isomers, or molecules with the same molecular formula but different molecular arrangements, that rotate differently on a plane of polarized light. These two isomers are called enantiomers. More about this in Topic 10.

D.3.3
**Compare the structures of morphine, codeine and diamorphine (heroin, a semi-synthetic opiate)**

Interacts with receptor sites within brain and block pain signals within the brain
 * Heroin (diamorphine) **
 * two [|ester]groups
 * [|tertiary amine group]
 * <span class="wiki_link_ext">[|benzene ring] (C6H6)
 * <span class="wiki_link_ext">alkene group (C=C)
 * <span class="wiki_link_ext">[|ether group] (C-O-C).




 * Codeine (below) contains a <span class="wiki_link_ext">[|hydroxy groups], a tertiary amine, an [|alkene group] and a [|benzene ring] and an ether group.



** Discuss the advantages and disadvantages of using morphine and its derivatives as strong analgesics ** <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Morphine and its derivatives are much stronger than aspirin and are the strongest pain relievers. However, they are very addictive, must be injected, and can cause mood changes.

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;"> **Morphine** <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Short term effects:
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Effective at treating sever pain
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Major side effect - constipation
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Other possible side effects - suppressing the cough reflex, and constriction of pupils.

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Long term effects
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Habit forming leading to dependence

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;"> **Heroine** <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Short term effect
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Feeling of well being
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Dulls the pain
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Lessens fear and tension

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Long term effect
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">consipation
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Loss of appetite
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">high potential for addiction
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">tolerance (more and more is needed to feel the same therapeutic effect).
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">Danger of overdose

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;"> **Codeine**
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">may not completely treat the pain
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">fewer side affects than morphine and heroine
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 110%;">not addictive.

<span style="font-family: Verdana,Geneva,sans-serif;"> **Works Cited** <span style="font-family: Verdana,Geneva,sans-serif;"> Neuss, Geoffrey. __IB Diploma Programme Chemistry Course Companion.__ Oxford: Oxford University Press, 2007. <span style="font-family: Verdana,Geneva,sans-serif;"> IB Chemistry Data Booklet <span style="font-family: Verdana,Geneva,sans-serif;"> Bro wn, Catra and Mike Ford. __Standard Level Chemistry.__ Heinemann Baccalaureate, 2008. <span style="font-family: Verdana,Geneva,sans-serif;">Derry, Lanna, Maria Connor and Carol Jordan. __Chemistry for use for the IB Diploma Standard level.__ Melbourne: Pearson Education, 2008. "Paracetamol - side effects, recommended dose, avoiding overdose." Mar. 2007. Bupa. 13 May 2009 [] [] [|www.wolframalpha.com] [|http://www.chemguide.co.uk/basicorg/isomerism/optical.html#top]