DRUGS

Question 1

D.2.1 State and explain how excess acidity in the stomach can be reduced by the use of different bases.

Answer 1

Excessive acid production causes heartburn and damage of the mucus covering the walls of the stomach. Moreover, excess production of acid creates an ideal environment for the bacteria Helicobacter pylori, causing peptic ulcers.

Heartburn – the situation when gastric juices overflow through esophagus
Ulcers ­– scars on the walls of stomach, indirectly caused by an excessive acidity.

Antacids are weak bases, utilized to neutralize the excess acidity in a human stomach. They relieve the pain of ulcers and prevent ulcers and heartburn from happening. Antacids are metal oxides, hydroxides, carbonates or hydrogen carbonates.

Question 2

Alginates .

Answer 2

create a layer of mucus on the walls of stomach and in esophagus, which prevents the heartburn

Question 3

Anti-foaming

Answer 3

agents prevent flatulence (farting) and burping. A common anti-foaming agent is dimethicone.

Question 4

Describe and explain the different ways that analgesics prevent pain.

Answer 4

Analgesics are drugs that relieve pain. They can be mild or strong.
Mild analgesics intercept the pain stimulus at its source. Modes of operation: (1) interfere with the production if prostaglandins, chemicals that cause pain; (2) reduce fever; (3) reduce swelling.

Strong analgesics (narcotics) relieve pain by temporarily bonding to the pain receptors in in the brain. They prevent the transmission of pain impulses into the brain.

Question 5

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).

Answer 5

Salicylic acid was an analgesic obtained from the bark of willow trees. However, salicylic acid had severe side effects. Therefore, researchers modified the structure of salicylic acid, creating derivatives. Derivative molecules mean they have different active groups attached to them.

Derivatives of salicylic are used as mild analgesics. They control the release of prostaglandins and thus reduce pain. Two examples of derivatives of salicylic acid are aspirin and paracetamol. Both medicines are painkillers and reduce fever (antipyretic). However, only aspirin reduces inflammation.

Question 6

MORPHINE

Answer 6

Benzene ring
Ether
Alkene
Alcohol (x2)
Tertiary amine

Question 7

Codeine

Answer 7

Benzene ring
Ether (x2)
Alkene
Alcohol
Tertiary amine

Question 8

Diamorphine (heroin)

Answer 8

Benzene ring
Ether
Alkene
Ethanoate (x2)
Tertiary amine

Question 9

Morphine + ethanoic acid →

Answer 9

heroin + water

Question 10

Depressants

Answer 10

are drugs that depress (calm and relax) the central nervous system by interfering with the transmission of nerve impulses in the neurons.

Question 11

MORE DEPRESSANTS

Answer 11

Effect by dose:
Low doses – increase feeling of calm, drowsiness, increased spontaneity, slower mental activity
Moderate doses – soothing, reduction of anxiety, altered perception
High doses – slurred speech, faltering movement, altered perception, sleep
Extremely high doses – low breathing and heart rates, sleep, coma, death

Effect by type:
Tranquilizers (alcohol, valium) reduce nervous tension without inducing sleep in moderate doses.
Sedatives (barbiturates) sooth distress without inducing sleep in moderate doses.
Hypnotics (chloral hydrate) induce sleep.

Question 12

How can you tell if youve had alc

Answer 12

Breath analyzer contains acidified potassium dichromate(VI) crystals, which turn from orange to green as they are reduced by ethanol in breath. Works because ethanol passes from stomach to the blood and to the lungs, where blood-air equilibrium is established.

Fuel cell may also contain acidified chromium(VI) crystals. In this device, the ethanol is oxidized using an oxidizing agent, which generates electricity. The potential difference, generated by the redox reaction, is proportional to the alcohol contained in the blood.

Infrared absorption intoximeters use infrared spectroscopy to determine the alcohol content. The C-H bond in ethanol absorbs particular infra-red wavelength and the apparatus measures how much at this wavelength is absorbed. Depending on how much light the sample absorbs, the amount of ethanol in breath can be determined. May not work with diabetics, who breathe out a lot of ketones, which shows a false positive.

Gas-Liquid Chromatography (blood and urine)

Question 13

D.4.4 Describe the synergistic effects of ethanol with other drugs.

Answer 13

Ethanol may increase the effect of a drug: alcohol increases the risk of stomach bleeding with aspirin and boosts the potency of sedatives. Also, ethanol increases toxic effects of paracetamol. Alternatively, ethanol may reduce/negate effects of some drugs.

Question 14

D.4.5 Identify other commonly used depressants and describe their structure.

Answer 14

Other commonly used depressants include Valium, Mogadon and Prozac. They can be all found in the data booklet. Valium and Mogadon have a similar structure, but Valium contains Cl on its benzene ring, while Mogadon contains NO­2 on its benzene ring.

Uses:
Valium – treats anxiety and tension
Mogadon – sleeping pill, contains seizures and infant spasms
Prozac – improves mood by making serotonin more available

Question 15

D.5.1 List the physiological effects of stimulants

Answer 15

Stimulants are drugs which increase a person’s state of mental alertness. All stimulants tend to increase concentration, but other psychological effects vary according to the given stimulant. Stimulants decrease appetite.

Generally speaking, the physiological effects of stimulants are:

1) Increased blood pressure and heart rate
2) Constriction of arteries
3) Dilation of pupils
4) Sweating
5) Reduced appetite

Question 16

D.5.2 Compare amphetamines and epinephrine (adrenaline).

Answer 16

Amphetamines mimic the effects of adrenaline (epinephrine), the “flight or fight” hormone. Amphetamine is a sympathomimetic drug: it mimics the stimulation of the sympathetic system, a structure responsible for subconscious reflexes, by adrenaline.

Structural similarities: Both adrenaline and amphetamine have (1) a benzine ring and (2) an amine.
Strutural differences: In adrenaline the amine is primary, while in amphetamine it is secondary. Also, adrenaline contains three alcohol groups, while amphetamine does not.

Both amphetamine and adrenaline speed up the heart rate and blood pressure. Thus, they work to avoid sleeping (narcolepsy=uncontollable desire to sleep). In the short term, amphetaines increase mental energy, reduce apetite and induce a sense of euphoria. In the long-term, amphetamines can lead to severe addicition and depression.

Question 17

D.5.3 Discuss the short and long term effects of nicotine consumption.

Answer 17

icotine is a sympathomimic drug, contained in tobacco leaves.

Short-term effects:
1) Increased heart rate and blood pressure
2) Reduction in urine outpute
3) Increased mental alertness and physical energy
4) Constricts blood vessels which puts stress on the heart
Long-term effects:
1) Risk of heart disease and coronary thrombosis due to the strain it puts on the heart
2) Risk of peptic ulcers due to excess production of gastric juices
3) Tolerance and addiction
4) Cost to society and family – smokers spend large amount of money on cigarettes

Question 18

D.5.4 Describe the effects f caffeine and compare its structure with that of nicotine.

Answer 18

Effects of caffeine include,

(a) In small amounts
1) Frequent unrination
2) Increased concentration and alertness
3) Increased breathing rate
(b) In large amounts
1) Anxiety
2) Irritability
3) Sleeplessness (insomnia)
4) Addiction and withdrawal symptoms such as nausea

caffine has a secondary amide

Question 19

D.6.1 Outline the historical development of penicillin.

Answer 19

Discovery of penicillin is usually attributed to the Scot Alexander Fleming. Fleming left an open dish with Staphylococcus aureus, in his laboratory and when he returned from a holiday, a mold grew inside the petri dish. This mold inhibited the growth of bacteria. Fleming publishes his results in 1929, but he did not pursue the discovery.

Penicillin was pursued by Howard Florey and Ernst Chain, who isolated and purified penicillin. They also showed the penicillin was harmless on mice and as the first used the drug on humans. The two men received a Nobel Prize for Chemistry. In the US, companies started mass production of penicillin. First, by growing the fungi in large tanks and then by synthetizing the drug.

Question 20

D.6.2 Explain how penicillins work and discuss the effect of modifying the side chain.

Answer 20

Penicillin is bactericidal, which means it kills bacteria.

1) Penicillin interferes with the enzymes that bacteria need to form normal cell walls.
2) Attempting cell division, bacteria swell and osmotic pressure puts stress on their cell wall
3) The cell walls burst and bacteria disintegrate

All penicillins have common structure, including the beta-lactam ring. The beta-lactam ring is a square arrangement of carbon and nitrogen atoms with other atoms attached. The R- is a functional group attached to the penicillin.

side chain- can be taken orally

Question 21

D.6.3 Discuss and explain the importance of patient compliance and the effects of penicillin over prescription.

Answer 21

Due to the use of antibiotics to cure minor ailments, some bacteria became resistant to certain kinds of penicillins.

2) Harmless and helpful bacteria in the digestive system can be wiped out.
3) Bacteria mutate, which results in “superbugs” resistant to antibiotics. This requires costly development of new antibiotics.

Patient compliance is important to avoid mutation of bacteria, but also to ensure no allergic reaction will occur (many people are allergic to penicillin).

Farmers often add antibiotics into feedstock to prevent illnesses and to bolster the growth of animals. This may result in a mutation of harmless bacteria. Humans consume the meat, taking in the antibiotics as well as the resistant bacteria in.

Question 22

D.7.1 State how viruses differ from bacteria.

Answer 22

Relevant points:

1) viruses are 20x smaller than bacteria;
2) unlike bacteria viruses are not cellular – bacteria have cell wall and nucleus
3) viruses do not have cytoplasm, while bacteria do
4) viruses do not feed, excrete and grow, while bacteria does
5) viruses use cell material of the invaded cell to reproduce themselves, while bacteria use cell division

Viruses inject their RNA or DNA into their host cell’s cytoplasm and use the cell to replicate. The new cell either releases the virus or releases other infected cell. This change in cell structure cause symptoms of viral infection.

Question 23

D.7.2 Describe the different ways in which antiviral drugs work.

Answer 23

1) Prevent viruses from leaving the host cell.
2) Block the reverse transcriptase enzyme activity to avoid a conversion of the virus into a form that can enter the host cell.
3) Alter the host cell’s genetic material, so that viruses cannot use it to multiply.
4) Block the enzyme activity within the host cell, so viruses cannot multiply.

Question 24

D.7.3 Discuss the difficulties associated with solving the AIDS problem

Answer 24

The antiviral agents are very expensive, which makes treatment of HIV difficult in developing countries. People cannot afford the drugs.

There are sociocultural issues fostering the spread of HIV, too: