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Application Exercise 9 – Unit 9: Molecules and Drugs

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  1. In allergy sufferers, histamine causes runny noses, red eyes, and other symptoms. Here is its structural formula.

Image result for histamine functional group amineb) Histamine – amine groups

a)  Give the chemical formula for this compound.

C5H9N3

b) Circle the amine functional groups in histamine.

(circled in red on diagram)

c) Which part (or parts) of the molecule make the compound water-soluble?

The amine groups contribute to the solubility of the molecule due to the highly electronegative nature of nitrogen atom that makes the molecule polar and so able to interact with the polar water molecules.

2. Antihistamines are widely used drugs for treating symptoms of allergies caused by reactions to histamines compound. This class of drugs competes with histamines, occupying receptor sites on cells normally occupied by histamines.

a) Give the chemical formula for this compound.

C16H21N3

b) What similarities do you see between this structure and that of histamine that would allow for antihistamine to compete with histamine.

Ethylamine moiety (-CH2-CH2-N-)

3. Consider this statement. “Drugs can be broadly classed into 2 groups: those that produce a physiological response in the body and those that inhibit growth of substances that cause infections.” 

Drugs that illicit physiological response:

Estrogen, amphetamine, morphine

Drugs that inhibit growth of infection-causing substances:

Penicillin, aspirin, antibiotic (Keflex)

4. Herbal or alternative medicines are not regulated in the same way as prescription or OTC medicines. In particular, the issues of concern are identification and quantification of active ingredient, quality control in manufacture, and side effects when herbal remedy is used in conjunction with another alternative/prescription medicine.

a) What do you think is the evidence from herbal supplement manufacturers that address these issues?

All prescription and non-prescription are regulated in the US by the Food and Drug Administration (FDA). However, herbal and alternative medicines are treated more like special foods, and not considered as drugs. Therefore herbal and alternative medicines will not be put under the same strict safety and effectiveness measurements as prescription or OTC medicines. Prescription or OTC medicines are considered unsafe until proven safe, whereas herbal and alternative medicines are considered safe until proven unsafe. Hence, herbal supplement manufacturers are not required to put their products under clinical trials to find potential risks and interactions with drugs or other substances.

b) Do  you know anything about Singapore’s legislation on the topic?

Under the health science authority (HSA) of Singapore, the requirements of drugs in Singapore are as follows:

(a)  Traditional medicinal materials do not contain any substances controlled under the Poisons Act and other prohibited substances such as Pangamic acid including its salts, Danthron, Suprofen including its salts and Rhodamine B.

(b)  The heavy metal contents of the traditional medicinal materials do not exceed the following limits: Arsenic (5 ppm), Copper (150 ppm), Lead (20 ppm) and Mercury (0.5 ppm).

(c)  The labels and packaging materials of the traditional medicinal materials (if any) do not stipulate any of the 19 diseases/conditions specified in the Schedule of the Medicines (Advertisement and Sale) Act, namely, blindness, cancer, cataract, drug addiction, deafness, diabetes, epilepsy or fits, hypertension, insanity, kidney diseases, leprosy, menstrual disorders, paralysis, tuberculosis, sexual function, infertility, impotency, frigidity, conception and pregnancy.

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Application Exercise 5 – Water for Life

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  1. How can you purify your water when you are hiking? Name 2 or 3 possibilities. Compare these methods in terms of cost and effectiveness. Are any of these methods similar to those used to purify municipal water supplies? Explain.  3 ways hikers are able to purify water are: boiling water, using filters or purifiers, and using purification tablets (chlorine dioxide tablets).Out of the aforementioned possibilities to purify water on a hike, the cheapest method is most likely boiling water as it uses simple tools such as a tin can to place the water in and fire starters to start the fire. This method requires just 1 to 3 min for the water to be prepared. However, this method wastes fuel in lighting the fire which are essential for cooking.

    Using filters or purifiers does effectively purifiers water obtained from streams or other water bodies easily, but the cost for these equipments may not be cheaply available, although of recent years the equipment have become more affordable.

    Purification tablets is the preferred choice based on efficiency and convenience as the tablets are lightweight and will not take up much space to be carried on a hike. They are also easy to use by just dropping the tablet into the water container and waiting 30 minutes, the water will become drinkable.

  2. Explain why desalination techniques, despite proven technological effectiveness, are not used more widely to produce potable drinking water. Desalination of water is very expensive costing hundreds to thousands of dollars due to the large amount of energy it requires. As salt dissolves very easily, forming strong hydrogen bonds with water, the intermolecular bonds would be difficult to overcome. Expensive technological equipment is another contributing factor to the high costs of desalination technique. It is much cheaper and accessible to use local freshwater especially for the less developed countries whereby amenities are less available.
  3. Water quality in a chemical engineering building on campus was continuously monitored because testing indicated water from drinking fountains in the building had dissolved lead levels above those established by NEA. a. What is the likely major source of the lead in the drinking water?b. Do the research activities carried out in this chemistry building account for the elevated lead levels found in the drinking water? Explain.

    a. Corrosion of lead pipes which transports water to the drinking fountains.

    b. Research activities uses water from a different pipe from drinking water which may not be contaminated with elevated lead levels.

  4. Some vitamins are water-soluble, whereas others are fat-soluble. Would you expect either or both to be polar compounds? Explain.

Fat-soluble vitamins are non-polar so as to interact with non-polar lipid molecules while water-soluble vitamins would have polar properties enabling interaction with polar water molecules. Similar polarity properties with the solvents are important to allow the vitamins to dissolve and be transported to the respective regions within the body.