Describe the different methods ofgetting a drug into the human body and reasons why each method is chosen (include 3 types of parenteral administration)
Syllabus References• D1.4 Side effects, therapeutic window, tolerance.
Side Effects• Depends on the medicines intended use, e.g. morhpine…..
Tolerance• With constant use over time need more of the drug to produce the same physiological effect.
LD50 / ED50• Measure of safety• If ED is small and LD is large then a wide therapeutic window exists.
Dependence• Physical – Users body can only function normally with the drug• Psychological – Intensifies craving for a drug.• The above are both forms of drug addiction.
Syllabus Reference• D2 Antacids – state and explain how acidity in the stomach cab be reduced by the use of different bases.
Placebo• Where an inert substance produces a significant reaction purely on the belief of the individual.
Common Antacid Remedies• Magnesium Oxide• Magnesium Hydroxide• Aluminium Hydroxide• Calcium Carbonate• Sodium Hydrogen Carbonate• Magnesium Trisilicate• 1. Stomach acid is HCl – write balanced chemical equations for the rxn of HCl with the above.• 2. Which is a better buy ? Sodium Bicarbonate or Calcium Carbonate – explain using 1g of each.
Mild Analgesics• Mild analgesics function by intercepting the pain stimulus at the source, often by interfering with the production of substances (for example,prostaglandins) that cause pain, swelling or fever.
Strong Analgesics• Strong analgesics work by temporarily bonding to receptor sites in the brain, preventing the transmission of pain impulses without depressing the central nervous system.
(MILD) Aspirin vsParacetamol• Create one side of A4 which must include :- – Full structural formulae – Identification of and designation of all functional groups – Elucidate all bond angles with a single example of each different value. – Advantages and disadvantages of both, including but not limited to; Reye’s syndrome, ulceration, stomach bleeding, allergic reactions, blood disorders, overdosage, kidney problems. – Mechanism of action
Advantages and Disadvantages of Using Opiates• Short Term - sedation, stupor, relief from pain, euphoria, impaired functioning, reduced tension, worry and fear – occasional OD.• Long term – malnutrition, constipation, risk of AIDS due to shared needles, withdrawal, loss of job, crime, sterility.• Tolerance and dependence are both major factors in opiate addiction.
Depressants• At low doses a depressant may exert little or no effect. At moderate doses the compound may induce sedation (soothing, reduction of anxiety).• At higher doses it may induce sleep. At extremely high doses it may cause death. Depressants are often described as antidepressants because they relieve depression.
Types of Depressants• Tranquilisers – slow down body and brain, include ethanol and valium. Produce sleep, relieve anxiety and tension.• Sedatives – may be considered as strong tranquilisers – sooth distress.• Hypnotics – produce sleep, e.g. chloral hydrate.
Oxidation of alcohols• Set up oxidation of alcohols practical
Ethanol – complete for homework• Name two routes by which this drug can be synthesised.• List some of the short and long term effects of alcohol use / abuse.• Illustrate how this can be chemically changed from the primary alcohol to aldehyde and carboxylic acid, include conditions, and reagents.• How does the breathalyser work ?• How does blood and urine analysis determine alcohol content in a person ?• Explain synergistic effect with Aspirin.
Starter• Write the reduction and oxidation half ion equations for ethanol / dichromate.• HL: What is hybridisation in ethanol ?• How many lone pairs ?• What are the bond angles ?• Name a nucleophile that would replace the alcohol group, include curly arrow mechanism.
Stimulants D5• What is a stimulant ?• Amphetamines, nicotine and caffeine are al examples.• They stimulate the CNS increasing wakefulness, often accompanied by a decrease in appetite.• Constrict arteries, increase sweat production, increase heart rate, blood pressure, respiration, then fatigue, irritability, depression.
What do PEAs DO ?• They are sympathomimetic – their actions mimic the bodies natural stimulant – adrenalin.• Medical uses; treats mild depression, narcolepsy, and asthma,• http://www.youtube.com/watch?v=qyXFN4oc N_o
D5.3 Nicotine• Mild stimulant, followed by depression which encourages frequent use.• ST Effects; increases heart rate, and blood pressure, so stresses the heart, diuretic.• LT Effects; heart disease, thrombosis, excess stomach acid, ulcers, cancers of the larynx, emphysema, and fires !!• HIGHLY ADDICTIVE !!! Psychological and physiological.• http://www.youtube.com/watch?v=x4c_wI6kQyE
Effects of Caffeine• Caffeine; increases cellular metabolism, stimulates CNS, increases alertness, energy, motivation and concentration. Diuretic. No physical addiction, mild psychological.• Weak diuretic.
D6 Antibacterials• Research the role of Florey, Chain and Fleming in the serendipitous discovery of penicillin.• Produce a one piece info sheet on the discovery, production and impact on the world.
Viruses vs Bacteria• TB, typhoid, syphillis, gonnorhea, fever• Note: Viruses are different and include; influenza, the common cold, hepatitis, measles and AIDS.
Action of Antibacterials• Fleming – found an open petri dish with mould in it – no bacterium YEY• Subsequently Florey and Chain scaled this up to an industrial process.• Saved thousands of lives in the closing years of WW2.
Notes• Penicillin is deactivated by stomach acid so is injected.• The side chain has been modified to counteract this.• Some bacteria have evolved to deactivate the bacterium.
Penicillin Mode of Action• Penicillin is incorporated into the cell wall of the bacterium.• Ring strain causes the molecule to break and create holes in the cell wall.• Water enters by osmosis, the cell wall expands, bursts, and the bacterium dies.• http://www.youtube.com/watch?v=vK3nxfKM 4Q4
Broad and Narrow Spectrum Antibacs• Broad – a wide variety of bacteria – the tetracyclines – from soil fungi – Prolblematic as kill all bacteria• Narrow – only a small number ( sometimes only one ) – this is the majority of penicillins
Over Prescription• Safe for MOST people ( 10% allergic ) – shock and death• Can kill good bacteria – allowing bad bacteria to proliferate• Genetic resistance – typhoid, TB, gonnorhea have all evolved resistance• Mutated strains – no treatment• Animal feedstocks – encourages drug resistance
D7 Antivirals• Submicroscopic, non cellular, parasitic, no nucleus, much smaller than bacteria.• Note : an antibiotic may have antiviral properties• Most viruses are controlled by inoculations – polio, smallpox, yellow fever, influenza.• UN Smallpox vaccination programme has eradicated this virus.
How do Antivirals Work ?• http://www.youtube.com/watch?v=HhhRQ4t9 5OI• Research focusses on blocking the viral enzyme activity within the host cell.• Acyclovir and Zovirax are common antivirals.
AIDS• Viruses can cross species, mutating as they go.• HIV contains RNA not DNA.• Specific proteins on the surface of HIV bind to CD4 receptors on white blood cells. These are the bodies immune system.• HIV mutates, and control is difficult due to the high price of anti retro viral drugs.
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