Medicines and drugs Essay
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A drug or medicine is a chemical that alters incoming sensory sensations, mood or emotions, or physiological state.
Painkillers, hallucinogens and alcohols are examples of drugs and medicines that alter incoming sensory sensations.
Prozac and alcohol alter mood or emotions
Steroids, cigarettes and heart medicines alter physiological state, including consciousness, activity level or coordination.
Drugs such as antiseptics, antibiotics and antivirals are infection fighters; hormones and vitamins affect body chemistry or metabolism; stimulants, depressants, analgesics and anesthetics affect the central nervous system and the brain.
It is also important to understand that the human body has great natural healing processes; some drugs just increase the rate of natural healing.
Also, there could be a placebo effect, it is when a pharmacologically inert substance that make seems to help because the person taking the substance was told that it would work.
Placebo effect is examined by giving sugar pills to one group of tests patients, and real drugs to another group (when they are not aware of which they receive).
B.1.2: Outline the stages involved in research, development and testing of new pharmaceutical products.
This takes a very long time and costs a fortune, and is often controlled by the government. Before drugs are tested on humans, they must be testing on various animals (start with small animals and then go to bigger ones).
The range of effective doses, the doses in which side-effects arise and the lethal doses have to be determined.
There are 3 phases then; clinical trial; clinical evaluation (more in depth analysis); human studies with more evaluation,
Very few drugs make it to the market, and the development would have cost a lot.
Sometimes, things can still go wrong, like Thalidomide. It was given to pregnant women to treat morning sickness, but it cause deformities in babies! Now it is still used, but to treat skin sores.
B.1.3. Describe the different methods of administering drugs
* Oral: Very convenient. However, it might not be reliable as the rate of absorption depends on drug concentration, stomach content and pH value. As most is absorbed in the small intestines, so the drug must survive the gastric acid. Therefore it often lays in time release capsules.
* Rectal: Good when drug cannot be taken orally due to vomiting or because the drug is pH sensitive.
* Inhalation: Rapid, as there are loads of blood vessels in the lungs, and therefore a drug would have a reliable effect. Good for general anaesthesia, and asthma medicine.
o Just below the skin; slower than for intravenous. Used often for dental injections
o Into muscles; for large doses, or when immediate response is not needed (vaccines etc).
o Intravenous; almost instantaneous, but cannot be undone when injected!
Fatty lipids may bind some kinds of drugs, so the drugs won’t leave the body so fast
The half life of a drug is the time for half the dose in the body to be eliminated.
B.1.4. Discuss the terms lethal dosage (LD50), tolerance and side effects.
LD50 is the lethal dose for 50% of the population; and it varies a lot from drug to drug.
When one is tolerant, then one has to take a larger dose in order to feel the wanted effects.
Some people after often use of a drug becomes dependant on it; physically (they must have it to be able to function physically) or psychologically (they must have it to feel right). Tolerance doesn’t necessarily mean that one gets used to the harmful effects.
Sometimes it is hard to know the difference between main effect and side effect. A drug has many effects, and some patients benefit from a few of those effects; then those are the main effects, and all the other are side effects. Someone else, with another disease may benefit from other effects, and then those become the main effects. There are always harmful effects too.
The risk : benefit ratio should also be considered.
B.2.1. State and explain how excess acidity in the stomach can be reduced by the use of different bases.
Bases, most often metal oxides, hydroxides, carbonates or hydrogen carbonates are used as antacids. These react with acid in the stomach to adjust the pH value.
The purpose of gastric acid is to kill off bacteria, and help in digestion. However, over-eating or stress stimulates more production of acid, causing discomfort.
The active ingredients tend to be; this react only with HCl:
Sodium Hydrogen Carbonate:
Some of the products; Carbon dioxide is a gas. So a foaming agent has to be added to prohibit excessive belching. Also alginates are used, to prevent acid reflux.
If too much antacid is used, the stomach becomes too basic, and that hurts too; then more antacid might be wrongly taken. This leads to alkalosis.
B.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)
Salicylic acid is used as an anti-pyretic (fever reducer) and mild analgesic (painkiller), but it is a strong acid and hurts the stomach and mouth; so variations of salicylic acid was used. One is Acetyl Salicylic Acid (ASA) or Aspirin, which has the benefits of salicylic acid and does not irritate so much due to the acetyl group.
When ASA reacts with water, it becomes salicylic acid, and the by-product of ethanoic acid.
GOOD: It is good for killing minor pain, reducing fever, acting as an anti-inflammatory agent and prevents abnormal blood clot.
BAD: Upsets stomach and bleeding; allergy; accidental poisoning in infants and Reye’s syndrome.
Acetaminophen is also an anti-pyretic and analgesic. However it does not upset the stomach and is safe. However, overdose can still occur and lead to liver and brain damage. And it is not anti-inflammatory.
Ibuprofen is like aspirin and cause fewer stomach problems. It is anti-inflammatory and is very safe.
B.3.3. Compare the structures of morphine, codeine and the semi-synthetic opiate heroin.
These are strong analgesics and are often called opiates, narcotics or narcotic analgesics. The major pain relieving substance originates from the opium poppy plant is sleep inducing and pain relieving.
All three share the same skeleton. Remember the group C2H3O2 is called an acetyl group.
B.3.4. Discuss the advantages and disadvantages of using morphine and its derivatives as strong analgesics.
These affects: The Central Nervous System, the Eye and the Gastrointestinal tract (the digestive system)
They are used as: Strong analgesics (severe pain from injury and chronic diseases); treatment of diarrhoea, relieve coughing.
However they are very addictive and are rather replaced with something else.
They also produce mood changes, drowsiness and mental clouding.
Tolerance can arise by adaptation of the liver and neurons in the brain.
Some people can’t function without the drug, feeling restlessness, sweating, fever, chills, vomiting, aches etc due to abstinence of the drug.
There is often severe psychological dependence too (one might feel extremely depressed).’ï¿½
Short term effects: Sedation, stupor, pain relief, euphoria, reduced tension, worry, couching reflex. One might die of overdose.
Long term effects: Loss of appetite, sterility, withdrawal illness, crime, diversion of energy.
B.4.1. Describe the effects of depressants
Tranquilizers, sedatives and hypnotics, which calm and relax; they slow down heart rate and breathing.
Tranquilizers include alcohol, Valium and Librium and are weaker than the others. These relieve anxiety and tension.
Sedatives: Barbituates that soothe distress without producing much sleep in small doses.
Hypnotics: Like chloral hydrate. These induce sleep. Too much can lead to coma or teach.
B.4.2. Discuss the social and physiological effects of the use and abuse of ethanol.
Social effects: Major costs from alcohol are from sickness and death, as in hospital treatments and lost efficiency. Property crimes and crimes against people; drinking while driving.
Physiological effects: Harmful to relationships, and may physically or emotionally harm others. One may lose control and develop dependence and tolerance.
It increases blood pressure when drinking and nausea, sweating and anxiety as withdrawal of use.
Short-term effects: CNS depressant reduces tension. It triggers Euphoria, Talkativeness, Dilation of blood vessels, Violent behaviours, Inertia, Coma, Death.
Long term effects: Cirrhosis, liver cancer, coronary heart disease, high blood pressure, strokes, gastritis, low birth mass etc.
Alcohol can be used for antiseptics such as mouthwashes.
B.4.3. Describe and explain the techniques used for the detection of ethanol in the breath of in the blood or urine.
Ethanol passes from the stomach into the blood and therefore it passes into the lungs and ethanol vapour is formed.
The breathalyser test might involve a redox equation with potassium dichromate: as oxidizing agent.
Color change: Red-Orange to Green
The gas liquid chromatography works as follows: Small samples of gases and volatile liquids such ethanol are separated. These are pushed through a column using an unimportant gas, such as Nitrogen gas and different gases take different time to come to the detector, where concentration of gases are measured.
Intoxilyzer, Infra-red spectroscopy: Infra-red energy make molecules vibrate. Different types of bonds absorb and vibrate at different infer-red frequencies. By measuring how much energy is not absorbed by the molecules, one can find the number of certain bonds in the molecules.
B.4.4. Describe the synergistic effects of ethanol with other drugs.
Alcohol is easily absorbed in the stomach, so drugs that can be dissolved in alcohol will be absorbed much quicker, and the dosage will seem higher as in normal conditions the liver removes a part of the drug. So performance of the drug is enhanced and may lead to devastating effects such as death, especially if alcohol is combined with barbituates. Alcohol with aspirin increases the risk of stomach bleeding.
B.4.5 . List other commonly used depressants and describe their structures.
Valium (diazepam) is a tranquilizer, Mogadon (Nitrazepam) is a hypnotic drug (used to control seizures and infantile spasms), Prozac (hydrochloride) is an anti-depressant drug used to treat mental depression.
Diazepam and Nitrazepam have similar carbon skeletons meanwhile Prozac is different.
B.5.1. List the physiological effects of stimulants.
Stimulants are chemicals that stimulate the brain and the central nervous system. It is the opposite of a depressant. These increase alertness. Examples are amphetamine, nicotine and caffeine.
B.5.2. Compare amphetamines and adrenaline
They both derive from the phenylethylamine structure, and therefore look similar. Furthermore, amphetamines mimic the effects of adrenaline (they are sympathomimetic drugs), as they constrict arteries and thus increases sweat production. They increase heart rate, blood pressure, respiration and insomnia.
Medical uses: Treat mild depression, narcolepsy and asthma.
They use up the body’s reserve energy and can lead to a collapse.
B.5.3 Discuss the short- and long-term effects of nicotine consumption.
Tobacco is a source of nicotine which is a mild stimulant with a short lived effect. The response is followed by depression and thereby makes one pushed to use it more often.
Short-term: Increase in heart-rate and blood pressure. It constricts blood vessels and therefore strains the heart. Nicotine also reduces urine output.
Long term effects of nicotine: It stresses hard and may lead to heart diseases and blood clot; May lead to increase of fatty acids in the blood. Smoking leads to more carbon monoxide in the blood making the blood less able to carry blood. It also increases the gastric acid production and may lead to ulcer.
Smoking causes: Cancer in lungs and mouth; heart and blood vessel disease; breathing difficulties and chronic bronchitis; air pollution; fires; bad teeth; insomnia.
B.5.4. Describe the effects of caffeine and compare its structure with that of nicotine.
Caffeine stimulates the respiratory system (more energy is available from respiration), so heart and brain gets more energy. So one becomes more alert, motivated and well-being. In small amounts in is rather harmless, but too much causes insomnia. One gets more urine as well.
Caffeine leads to some tolerance but no physical addiction. It can be given to babies to help their breathing. It also constricts blood vessels and therefore helps against migraines.
Both caffeine and nicotine contain a tertiary amine group. Caffeine has more of those though.
B.6.1. Describe the historical development of penicillins.
In 1928, Fleming accidentally saw that some types of fungi killed off a certain bacterium and started to try to isolate the fungi, but it was too hard to purify it. In 1940, Floray and Chain continued with penicillin testing and development, and in 1943 it was available clinically.
The first penicillin was Penicillin G. However it was deactivated by stomach acid so it had to be injected. Acid resistance penicillins such as penicillin V was developed by modifying the side chains of the basic penicillin structure. Some bacteria could deactivate penicillin G by synthesising an enzyme, therefore one had to make other synthetic penicillins. 6-APA penicillin is inert, but an extra amino group H2N would activate it.
B.6.2. Compare broad spectrum and narrow spectrum antibiotics
A broad spectrum antibiotics is effective against a wide variety of bacteria. Examples are tetracyclines.
Narrow ones are effective only against certain types of bacteria; most penicillins are narrow spectrum antibiotics.
One often has to determine the bacterium before getting antibiotics, because a broad-spectrum one can kill beneficial bacteria and give discomfort.
B.6.3. Explain how penicillins work and discuss the effects of modifying the side chain.
The cell walls of some bacteria are composed of polysaccharides, and these layers are supported by cross-links. However, penicillins interfere with the formation of these links and therefore weaken the structure. The bacteria can easily burst. Animals cells don’t have these cell walls and are therefore not affected.
It is important to modify the side chain to work against bacteria have evolved and are able to break down certain types of penicillin. Side chains are also added to make the penicillin work (as for the 6-APA) and to survive the gastric acid (Penicillin G)
B.6.4. Discuss and explain the effect over prescription of penicillins has, and the use of penicillins in animal feedstock
Repeated use may lead to allergic reactions.
They can also wipe out harmless and beneficial bacteria in the food canal, and harmful bacteria might eventually replace these.
Bacteria can become resistant against certain antibiotics and then pass on their immunity.
In feedstock: They are used to kill dangerous pathogens which may otherwise endanger humans and animals. They are also used to increase productivity.
However, this increases the chances that bacteria might become resistant.
B.7.1. State how viruses differ from bacteria
Bacteria are relatively large single cell microorganism with DNA strands. Viruses are noncellular and are much smaller and are not living. They can only reproduce within a host cell.
B.7.2. Describe the different ways in which antiviral drugs work
* Block the transfer of genetic information
* Control by inoculation, vaccines.
* Block the enzyme activity in a host cell, so that the virus can’t use it to replicate.
B.7.3. Discuss the difficulties associated with solving the AIDS problem
HIV molecules bind to proteins on T-type of white blood cells and hinder them from fighting infections by inactivating them. HIV virus is good at mutating and together with their similarities with human cells, it is very heard to treat with antiviral drugs and vaccines.
B.8.1. Describe the importance of geometrical isomerism in drug action.
Stereoisomers are isomers with the same molecular formula and the same structural formula, but different arrangement of atoms in space.
Geoemetric isomers have different physical properties such as polarity, boiling point, and solubility etc. They may also undergo different t chemical reactions although their functional groups are identical.
For example cisplatin is en effective anti-cancer drug (as it may enter the nucleus of a cancerous cell), but the trans-isomers is inactive in such purposes.
B.8.2. Discuss the importance of chirality in drug action.
Optical isomers differ from geometric isomers in two ways:
* Optical isomers are chiral (asymmetric)
* Optical isomers are non-superimposable mirror images of each other
One optical isomer rotates the plane polarized light one direction, meanwhile its other isomer rotates it the other way.
An equi-molar mixture of two enantiomers means a 50-50 ration and will not totate the plane of polarised light at all; this is a racemic mixture.
Penicillin V is active, but its enantiomer is inactive.
One enantiomer of Thalidomide could be used to treat morning sickness in pregnant women and was marketed as a racemix mixture, but its other enantiomer gave foetal deformities.
B.8.3. Describe the use of chiral auxiliaries to form the desired enantiomer.
It is very heard to separate racemic mixtures into separate enantiomers, as they have identical chemical properties in relation to non-chiral reagents. Instead, scientists use stereospecific synthesis to produce only one kind of enantiomer. Chiral auxiliaries are used to convert non-chiral molecules into a desired enantiomer by attching itself chemically to the non-chiral molecule so that only one type of enantiomer can be formed. After the procedure the auxiliary can be recycled. This is used when synthesising Taxol which isa drug effective against breast cancer.
B.8.4. Explain the use of combinatorial chemistry to synthesise new drugs.
This is when one creates lots of molecules and test them quickly for biological properties; one starts with a set of basic chemicals which are then combined in all possible combinations, and this allows a fast production of many different molecules, increasing the chance of finding better drugs.
A library is a collection of compounds that are screened to determine their usefulness as a drug, using parallel synthesis (identical processes with many different molecules at the same time).
B.9.1. Compare local and general anaesthetics in terms of their modes of action
Local anaesthetics block the pain in specific areas when they are injected under the skin or used as a crï¿½me. Examples are cocaine, procaine, benzococaine, lidocaine etc. These block local nerve transmissions and decrease blood supply to that area. Procaine and lidocaine do not affect the brain, meanwhile cocaine does.
General anaesthetics affect the brain and produce unconsciousness. But it is easy to reverse the unconsciousness. Examples are nitrous oxide, diethyl ether, chloroform, cyclopropane and halothane.
B.9.2. Compare the structures and effects of cocaine, procaine and lidocaine.
All three have the benzene ring and the tertiary amine.
Cocaine also stimulates the central nervous system. It constricts blood vessels which leads to high blood pressure, and can’t be safely used. Although it doesn’t produce withdrawal symptoms and tolerance, it produces a strong psychological addiction. An overdose suppresses heart and respiration.
Cocaine has a very short half life as it is metabolized by the liver fast, and is poorly absorbed when taken orally.
Procaine gives prolonged relief from pain which is good for surgery and dental procedures. It is non-toxic and non-irritant.
Lidocaine is used topically to produce numbness. It is more potent that procaine, but may cause swelling and itching.
B.9.3. Discuss the advantages and disadvantages of nitrous oxide, ethoxyethane, trichloromethane, cyclopropane and halothane.
Nitrous oxide is not very potent, and makes one feel good
Trichloromethane is nonflammabe, but leads to liver damages. Narrow safety margin
Ethoxyethane alleviates the pain in surgery well, but it is very flammable and nonstable.
Cyclopropane is a very potent anaesthetics, however it forms explosive mixtures with air and is very flammable. It also causes vomiting and nausea.
Halothane is widely used as it is not flammable and one may recover fast from it. It doesn’t irritate the respiratory tract. However, it takes time to become unconscious. It is potentially harmful to the ozone layer as it produces chlorine and bromine free radicals.
B.9.4. Calculate the partial pressures of component gases in an anaesthetic mixture
The partial pressure ratios of the total pressure equal the molar ratios of different gas molecules.
It is important to have enough oxygen in the anaesthetic mixture so that the patient can live. At least 20% oxygen is needed
B.10.1 Describe the effects of lysergic acid diethylamide (LSD), mescaline, psilocybin and tetrahydrocannabinol.
Psychadelic drugs like these alter the mind and produces a change in thought, perception or mood and induce vivid fantasies. Colors seem more brilliant for the user.
There are the effects of the mentioned mind altering drugs:
LSD: This is a powerful hallucinogen that strongly magnifies perception and may destroy the sense of judgment. No physical addiction, and not very strong psychological dependence.
Mescaline: Color hallucinations which last 12 hours.
Psilocybin: Similar to LSD, especially at high doses, but at low doses produces relaxation. Shortlasting; 4 hours
THC: Milder drug similar to alcohol. At larger doses, changes in perception occurs – sees bright colors and gets sharper hearing. May get extreme anxiety, depression, uneasiness, panic attacks etc. There is no tolerance, but could lead to psychological dependence.
B.10.2 Discuss the structural similarities and differences between LSD, mescaline and psilocybin.
LSD and psilocybin both have the Indole ring (Heterocyclic amine compound where the nitrogen atom is part of a ring).
However, mescaline includes the benzene ring but not the indole ring; it does have a primary amine.
Serotonin also has the indole ring.
B.10.3 Discuss the arguments for and against the legalization of cannabis.
Cannabis offers relief from symptoms from AIDS, cancer and glaucoma. Marijuana may increase the appetite, and relieves nausea. Cannabis helps terminally ill patients to relieve tension and anxiety. Marijuana relieves pressure inside the eyeball for glaucoma patients.
However there are many bad sides to it too. Smoking marijuana may lead to lung problems and may suppress the immune system. It might lead to decreased fertility for men and cause brain damage and birth defects. Users may also start using harder drugs too.
Users of prohibited drugs need to obtain it from criminal sources and may therefore be forced into crime to support their habit. It damages the society a lot.