January 2016 archive

D.5 Anti viral medicines

Nature of Science

Collaboration between researchers in the scientific community has improved our understanding of how viruses interact with host cells to cause disease.

International-mindedness

The AIDS epidemic is a global disease which has had a huge impact upon society and life expectancy. How has it changed since its discovery in the early 1980s and how can the spread of the disease be halted?

After studying this topic students should be able to:

Understand

  • Viruses are more difficult to treat with drugs than bacteria as they lack a cellular structure. (Website with comparison of virus vs bacteria here) (Short video from Smithsonian)
  • Antiviral drugs may function by altering genetic material within a cell to prevent the virus from using it to multiply. Alternatively they may block enzyme activity within the host cell, which also prevent the viruses from multiplying.
    • collection of articles here on antiviral medications and a series of issues and concerns (as well as successes and breakthroughs)

Apply their knowledge to:

  • Explain the different ways in which antiviral medications function. (For the really seriously keen – a medical paper on all known antivirals other than for HIV. )
  • Describe how viruses differ from bacteria. (Difference between viral and bacterial infection here) (Website with comparison of virus vs bacteria here)
  • Explain how oseltamivir (Tamiflu) and zanamivir (Relenza) function as preventative agents against flu viruses.  (Video on how does Tamiflu work. )(General info sheet about ‘what you should know about flu viruses)
  • Compare the structures of oseltamivir (here) and zanamivir. (Here)
  • Discuss the difficulties associated with solving the AIDS problem. (How to treat HIV/AIDS and the options) (How AZT works in treatment – interactive resource)

In your notes, answer:

Part 1

  1. Why are viruses sometimes seen as non-living? Is a virus a cell? Explain
  2. How do drugs treat viral attacks/infections? Compare this with how penicillin works
  3. Explain the differences between the different types of antiviral medications (a chart may be useful)
  4. What are the similarities and differences between a virus and a bacteria?
  5. What common illnesses are viral? what are bacterial? Can you (or medical science) tell them apart?
  6. Influenza is a serious health concern. Two preventative drugs are oseltamivir and zanamivir.      How do they work?
    1. Why would you take them? Should everyone?
    2. Compare their chemical structures (functional groups, structure) to find similarities and differences.

Part 2

  1. What is AIDS? What is HIV?
  2. What drugs are available to fight it?
  3. What is the difference between a virus and a retrovirus?
  4. Why is AIDS hard to treat?

D4 Antacids and pH regulation in the body

Nature of Science

The symptoms of dyspepsia include the overproduction of stomach acid. There are several different ways in which this can be treated. These includes the prescription of antacids to neutralize the acid, the use of H2-receptor antagonists and the use of proton pump inhibitors which work by preventing the production of stomach acid. The effectiveness of these different treatments can be assessed through collecting data by sampling and trialling.

International-mindedness

The need for pH regulation of the stomach can be affected by the diet, lifestyle and genetics etc. of different cultures.

After studying this topic students should be able to:

Understand

  • Antacids reduce excess stomach acid. (Article here on how antacids work)
  • The active form(s) of a drug after it has been processed by the body are called active metabolites.

Apply their knowledge to:

  • Explain how excess acidity in the stomach can be reduced by the use of different bases. (Article here on how antacids work)
  • Construct and balance equations for neutralization reactions and apply theses equations using their stoichiometry. (For example : cheesy video here)
  • Solve buffer problems using the Henderson–Hasselbalch equation. (What is a buffer and how to write K expressions video Here)
  • Explain how compounds, such as ranitidine (Zantac), can be used to inhibit stomach acid production. (VIDEO Here on How ranitidine works)
  • Explain how compounds, such as omeprazole (Prilosec) and esomeprazole (Nexium), are used to suppress acid secretion in the stomach. (Video here on proton pump inhibitors such as omeprazole)

Vocabulary list

dyspepsia
antacid
metabolite
Henderson-Hasselbalch equation
ranitidine
omeprazole
esomeprazole
H2 receptor antagonist
proton pump inhibitor

 

D3 Opiates

Want to know about the biochemistry of drug actions on the brain? Try Mouse Party from the University of Utah. Look in particular at the heroin mouse, and then compare to other drugs you may have heard of.

All sorts of interesting information on drug action on the body in handy, somewhat interactive charts and slides. This is useful for the option as a whole, not only D3.

Safety and data sheet (full information) on diamorphine.

Here is a video on Organic reactions and mechanisms applied to the synthesis of codeine. (Making codeine from morphine).  A little more detail but a good reminder of curly arrows and mechanisms, HL…

Organic chemist Rob Stockman discusses painkillers such as morphine and heroin. Video here from periodic videos at the University of Nottingham. (You have seen their element video collection, right??) (5 min).

As always, read the section in your text book please. Take notes 🙂

Syllabus: (critical vocab includes : lipids, blood-brain barrier, opiates, morphine, codeine, diamorphine, receptor sites (and opioid receptors), central nervous system, derivatives, addiction, potency)

Students should Understand:

  • The chemical structure and solubility of a drug in water and lipids affects its ability to cross the blood–brain barrier.
  • Opiates are derived from the opium poppy and are natural narcotic analgesics.
  • Morphine, codeine and diamorphine (heroin) are examples of strong analgesics. Strong analgesics function by temporarily bonding to receptor sites in the brain. They prevent the transmission of pain impulses without depressing the central nervous system.
  • The medical use and the addictive properties of opiate compounds are related to the presence of opioid receptors in the brain.

Apply their knowledge to:

  • Explain the synthesis of codeine and diamorphine from morphine.
  • Describe and explain the use of strong analgesics.
  • Compare the structures of morphine, codeine and diamorphine (heroin).
  • Discuss the advantages and disadvantages of using morphine and its derivatives as strong analgesics.
  • Discuss the side effects and addiction to opiate compounds.
  • Use their chemical structure and solubility to explain the increased potency of diamorphine compared to morphine.

 

Functional groups present in some strong analgesics are clear from your sketches of each compound in your notes! Remember they are in the DB, but you need to recognize the chemistry.

morphine diamorphine/heroin codeine
·       benzene ring

·       hydroxyl (2)

·       ether;

·       tertiary amine;

·       double bond/alkene;

·       benzene ring

·       tertiary amine

·       alkene

·       ester (2)

·       ether

·       benzene ring

·       hydroxyl/alcohol

·       ether (2)

·       alkene

·       tertiary amine

 

All three compounds are derived from opium which is an extract from poppy seeds. Both codeine and diamorphine are derived from morphine and are called semi-synthetic opiate. An opiate is any chemical that has the same physiological effect as morphine.

As the structures above show, 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.

The amine in morphine, diamorphine and codeine is a tertiary amine as the nitrogen atom has three alkyl groups bonded onto it.

(From IB Chemistry at Dulwich, Wikispaces, 2014)

DP Chem, Option D, section 2

D.2 Students should:

Understand:

  • Aspirin, and other mild analgesics, function by intercepting the pain stimulus at the source. They interfere with the production of substances responsible for pain, swelling or fever.  (An article here may help)
  • Aspirin can be prepared from salicylic acid. (see your lab from last year)
  • Aspirin is also used as an anticoagulant, to prevent the recurrence of heart attacks and strokes and as a prophylactic.
  • Penicillins are antibiotics produced by fungi.
  • Part of the core structure of penicillins consists of a beta-lactam ring.
  • Some antibiotics function by preventing the cross-linking of bacterial cell walls. (How does penicillin work is here, also brief history)
  • Penicillins can be made more resistant to the penicillinase enzyme by modifying the side-chain.

Vocabulary list: (be able to define and use in a sentence) 

analgesic
synergy
antibiotic
antibacterial
anticoagulant
beta-lactam ring
overprescription
salicylic acid (2-hydroxybenzoic acid)

Apply their knowledge to:

  • Describe the use of salicylic acid and its derivatives as mild analgesics.
  • Explain the synthesis of aspirin from salicylic acid, including yield, purity by recrystallisation and characterization using infrared spectroscopy and melting point.
  • Discuss the synergistic effects of aspirin with alcohol. (See Mr Thornley here)
  • Discuss how aspirin can be chemically modified into a salt to increase its solubility in water and how this facilitates its bioavailability.
  • Discuss the effects of chemically modifying the side-chain of penicillins.
  • Discuss the importance of patient compliance and the effects overprescribing penicillin. (what is antibiotic resistance is here)
  • Explain the importance of the beta-lactam ring on the action of penicillin.

One of the only things aspirin and penicillin have in common (other than being medicines most people have heard of)  is that we use their history of discovery and development as examples of scientific discovery and development not being straightforward.

What is controversial about the discovery and development of aspirin and penicillin? (Hint: some of it was discussed in Pain, Pus, and Poison).

Here are some questions to answer from the InThinking site, once you have read the chapter section D 2.

SNow day for Grade 6 science

Dear grade 6,

Magic extension! Please bring your finished poster to class on Friday, and we will print them at the start of the lesson. So, you have until Friday to get it done. I am looking forward to seeing your excellent work on these Forces and backpacks posters.

On Friday we have a quiz on forces. Here is a review sheet for you to work on today. I think it should take about 20-30 minutes, if you have your notes. If not, you could check out this website for some help.

I will give you the answer key in homeroom tomorrow morning. You can write the answers in your notebook or on any paper you have at home.

Stay safe but maybe you can enjoy the snow near you! Good thing you came up with an idea in homeroom for what to do if you got a surprise snow day! I hope your wish comes true.

Option D – section 1 Pharmaceutical products and drug action

You have access to your text book and the extra material from class. Do read it!

Some questions from InThinking on this section.

A video on Youtube about How drugs are developed

Another video on drug testing through clinical trials, and the history of clinical trials.

Is it ethical to test drugs on people? On animals? Why? In what circumstances? What safety policies need to be in place?

See Thalidomide links in Organic.