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D.1 Medicines and drugs
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A quick introduction to medicines and drugs.
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D.1 Methods of drug administration
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Applications and skills:
Discussion of drug administration methods. |
D.1 Bioavailability
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Understandings:
Bioavailability is the fraction of the administered dosage that reaches the target part of the human body. Applications and skills: Comparison of how functional groups, polarity and medicinal administration can affect bioavailability. Discussion of how aspirin can be chemically modified into a salt to increase its aqueous solubility and how this facilitates its bioavailability. |
D.1 Therapeutic window
Guidance:
For ethical and economic reasons, animal and human tests of drugs (for LD50/ED50 and TD50/ED50 respectively) should be kept to a minimum. |
Understandings:
In animal studies, the therapeutic index is the lethal dose of a drug for 50% of the population (LD50) divided by the minimum effective dose for 50% of the population (ED50). In humans, the therapeutic index is the toxic dose of a drug for 50% of the population (TD50) divided by the minimum effective dose for 50% of the population (ED50). Applications and skills: Discussion of experimental foundations for therapeutic index and therapeutic window through both animal and human studies. |
D.1 Stages in drug development
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This video is a quick look at the stages in drug development.
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D.2 Synthesis of aspirin
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Understandings:
Aspirin is prepared from salicylic acid. Applications and skills: Explanation of the synthesis of aspirin from salicylic acid, including yield, purity by recrystallization and characterization using IR and melting point. Discussion of how the aspirin can be chemically modified into a salt to increase its aqueous solubility and how this facilitates its bioavailability. Guidance:
Students should be aware of the ability of acidic (carboxylic) and basic (amino) groups to form ionic salts, for example soluble aspirin. Structures of aspirin and penicillin are available in the data booklet in section 37. |
D.2 Solubility and bioavailability of aspirin
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Understandings:
Discussion of how the aspirin can be chemically modified into a salt to increase its aqueous solubility and how this facilitates its bioavailability. Guidance: Students should be aware of the ability of acidic (carboxylic) and basic (amino) groups to form ionic salts, for example soluble aspirin. Structures of aspirin and penicillin are available in the data booklet in section 37. |
D.2 Uses of aspirin
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Understandings:
Aspirin can be used as an anticoagulant, in prevention of the recurrence of heart attacks and strokes and as a prophylactic. Applications and skills: Description of the use of salicylic acid and its derivatives as mild analgesics. Discussion of the synergistic effects of aspirin with alcohol. |
D.2 Discovery of penicillin
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Understandings:
Penicillins are antibiotics produced by fungi. |
D.2 Penicillin mode of action
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Understandings:
A beta-lactam ring is a part of the core structure of penicillins. Some antibiotics work by preventing cross-linking of the bacterial cell walls. Applications and skills: Explanation of the importance of the beta-lactam ring on the action of penicillin. |
D.2 Antibiotic resistance
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Understandings:
Modifying the side-chain results in penicillins that are more resistant to the penicillinase enzyme. Applications and skills: Discussion of the effects of chemically modifying the side-chain of penicillins (increased resistance to the the penicillinase enzyme and to produce penicillins that are not broken down in stomach acid). |
D.3 Strong analgesics
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Understandings:
Opiates are natural narcotic analgesics that are derived from the opium poppy. Morphine and codeine are used as 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. Applications and skills: Description and explanation of the use of strong analgesics. Discussion of side-effects and addiction to opiate compounds. Discussion of the advantages and disadvantages of using morphine and its derivatives as strong analgesics. |
D.3 Blood-brain barrier
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Understandings:
The ability of a drug to cross the blood–brain barrier depends on its chemical structure and solubility in water and lipids. Medical use and addictive properties of opiate compounds are related to the presence of opioid receptors in the brain. Discussion of side-effects and addiction to opiate compounds. |
D.3 Structures of morphine, codeine and diamorphine (heroin)
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Applications and skills:
Comparison of the structures of morphine, codeine and diamorphine (heroin). Guidance: Structures of morphine, codeine and diamorphine can be found in the data booklet in section 37. |
D.3 Synthesis of codeine and diamorphine
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Applications and skills:
Explanation of the synthesis of codeine and diamorphine from morphine. Explanation of the increased potency of diamorphine compared to morphine based on their chemical structure and solubility. |
D.4 Antacids
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Understandings:
Non-specific reactions, such as the use of antacids, are those that work to reduce the excess stomach acid. Applications and skills: Explanation of how excess acidity in the stomach can be reduced by the use of different bases. Construction and balancing of equations for neutralization reactions and the stoichiometric application of these equations. Guidance: Antacid compounds should include calcium hydroxide, magnesium hydroxide, aluminium hydroxide, sodium carbonate and sodium bicarbonate. |
D.4 Stomach acid inhibitors
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Applications and skills:
Explanation of how compounds such as ranitidine (Zantac) can be used to inhibit stomach acid production. Explanation of how compounds like omeprazole (Prilosec) and esomeprazole (Nexium) can be used to suppress acid secretion in the stomach. Guidance: Structures for ranitidine and omeprazole can be found in the data booklet in section 37. |
D.4 Calculating the pH of buffer solutions
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Applications and skills:
Solving buffer problems using the Henderson–Hasselbalch equation. |
D.5 Viruses and bacteria
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Applications and skills:
Description of how viruses differ from bacteria. |
D.5 Antiviral drugs
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Understandings:
Viruses lack a cell structure and so are more difficult to target with drugs than bacteria. Antiviral drugs may work by altering the cell’s genetic material so that the virus cannot use it to multiply. Alternatively, they may prevent the viruses from multiplying by blocking enzyme activity within the host cell. |
D.5 Oseltamivir and zanamivir
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Applications and skills:
Explanation of how oseltamivir (Tamiflu) and zanamivir (Relenza) work as a preventative agent against flu viruses. Comparison of the structures of oseltamivir and zanamivir. Guidance: Structures for oseltamivir and zanamivir can be found in the data booklet in section 37. |
D.5 Solving the AIDS problem
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Applications and skills:
Discussion of the difficulties associated with solving the AIDS problem. |
D.6 Radioactive waste
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Understandings:
High-level waste (HLW) is waste that gives off large amounts of ionizing radiation for a long time. Low-level waste (LLW) is waste that gives off small amounts of ionizing radiation for a short time. Applications and skills: Describe the environmental impact of medical nuclear waste disposal. |
D.6 Antibiotic waste
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Understandings:
Antibiotic resistance occurs when micro-organisms become resistant to antibacterials. Applications and skills: Explanation of the dangers of antibiotic waste, from improper drug disposal and animal waste, and the development of antibiotic resistance. |
D.6 Solvent waste
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Applications and skills:
Discussion of environmental issues related to left-over solvents. |
D.6 Green chemistry
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Applications and skills:
Discussion of the basics of green chemistry (sustainable chemistry) processes. Explanation of how green chemistry was used to develop the precursor for Tamiflu (oseltamivir). |