Option D - Medicines and drugs Flashcards
What are the effects of medicines and drugs on the functioning of the body?
- Alters the physiological state, including consciousness, activity level, or coordination
- Alters incoming sensory sensations
- Alters mood or emotions
What is the placebo effect?
When patients gain therapeutic effect from their belief that they have been given a useful drug, even when they have not
What is the definition of a drug?
A chemical that affects how the body works
What is the definition of a medicine?
A substance that improves health (beneficial drugs)
What are the methods of administering drugs?
- Oral
- Parenteral (injection)
- Inhalation
- Rectal
What are the three ways of administering drugs by injection?
- Intravenous: directly into the bloodstream
- Intramuscular: into a muscle
- Subcutaneous: directly under the surface of the skin (fat tissue)
What is the difference between therapeutic effect and side-effect?
Therapeutic is the intended physiological effect whereas side-effects are unintended physiological effects
What is the therapeutic window?
The range of a drug’s concentration in the blood between its therapeutic level and its toxic level
What is tolerance?
When a patient is given repeated doses of a drug, a reduced response to the drug develops. Higher doses are needed to produce the same effect.
What are the stages of drug development?
- Discovery research (3 years)
- Development research (6 years)
- Regulatory review (2 years)
- Post-marketing and monitoring (1 year)
What is done during the discovery research of drug development?
- Identifying and extracting compounds that show biological activity known as lead compounds
- Often show low levels of activity or have negative side-effects
- Provide a start for the drug design
- Often derived from plants
- The effectiveness of the lead compound is optimised by making and testing many chemically related chemical compounds known as analogues
- A potential medicine is tested on animals. This helps scientists to determine the dose to be administered in human trials (therapeutic index)
What is the therapeutic index?
- Shows if a drug is worth the risk
- The ratio of lethal dose and effective dose
What is the lethal dose of a drug?
The dose required to kill fifty percent of the animal population, LD50
What is the effective dose of a drug?
The dose required to bring about a noticeable effect in fifty percent of the population, ED50
What is done during the development research stage of drug development?
- Human trials
- Three consecutive phases with increasing number of patients
- The effectiveness is judged by the relative improvement on patients who have received the real medication compared to those on a placebo
- Very costly due to human subjects
What was the problem with the drug thalidomide?
- Marketed as a cure to morning sickness in pregnant women
- Two enantiomers, one that helped in morning sickness, one that made malformations in fetuses
- Lots of kids were born with malformed or missing limbs and some died
- After this a post-marketing monitoring system was established to track medications once the population had access to them
What are the three problems that can be caused by excess acid secretion in the stomach?
- Acid indigestion
- Heartburn
- Ulcer
What is acid indigestion?
A feeling of discomfort from too much acid in the stomach
What is heartburn?
Acid from the stomach rising into the oesophagus (acid reflux)
What is ulcer?
Damage to the lining of the stomach wall due to excess acid, resulting in loss of tissue and inflammation
What are antacids?
Weak bases that are used to relieving symptoms due to excess acid
What are antacids often composed of?
- Metal oxide or hydroxide, carbonate, hydrogencarbonate
- Antifoaming agents
- Alginates
How do antacids combat excess acid?
They react with the acid to produce a salt and water, neutralising the acid
What are alginates?
Added to antacids to form a neutralising layer on the top of the stomach, which acts as a barrier preventing reflux into the oesophagus
What is the reaction of the antacid aluminium hydroxide, Al(OH)3, with stomach acid?
Al(OH)3(s) + 3 HCl(aq) → AlCl3(aq) + 3 H2O
What is the reaction of the antacid magnesium hydroxide, Mg(OH)2, with stomach acid?
Mg(OH)2(s) + 2 HCl(aq) → MgCl2(aq) + 2 H2O
What is the reaction of the antacid sodium hydrogencarbonate, NaHCO3, with stomach acid?
NaHCO3(aq) + HCl(aq) → NaCl(aq) + H2O(l) + CO2(g)
What are antifoaming agents? Give one example
Compounds that are added to antacids to prevent bloating due to the CO2 produced in some antacids
e.g. dimethicone
Why are magenisium and aluminium hydroxides often used together in antacid compounds?
- They complement each other well
- Magnesium functions faster so is a quick help
- Aluminium reacts more slowly but provides a longer lasting effect
What are the two types of analgesics?
Mild and strong analgesics
How do mild analgesics function?
They intercept the pain stimulus at the source, often by interfering with the production of substances that cause pain, swelling or fever.
How do strong analgesics function?
They temporarily bond to receptor sites in the brain, preventing the transmission of pain impulses without depressing the central nervous system
What is the difference between narcotics and non-narcotics
Analgesics that do not interfere with the functioning of the brain are considered non-narcotics whereas analgesics that do act on the brain are considered narcotics
What are examples of mild analgesics?
- Aspirin
- Paracetamol
- Ibuprofen
What are examples of strong analgesics?
- Morphine
- Codeine
- Heroin
What are the side-effects of strong analgesics?
- Drowsiness
- Changes in behaviour and mood
- Dependence
What is aspirin?
An analgesic made out of an ester derivative of salisylic acid
What are aspirin’s effects on the body?
- Blocks the syntheiss of prostaglandins
- Analgesic effect
- Reduces fever and inflammation
- Reduces the blood’s ability to clot → prevents heart attacks and strokes
What are the side effects of aspirin?
- Irritation and ulceration of the stomach and duodenum
- Allergic reactions
- Reye’s syndrome (fatal liver and brain disorder)
How does paracetamol function?
It reduces the production of prostaglandins in the brain, thus not effective in reducing inflammation
What are the advantages of paracetamol?
- One of the safest of all analgesics
- Does not irriate the stomach
- Allergic reactions are rare
- Safe for children
What are the side-effects of paracetamol when abused?
Fatal damage to kidneys, liver, and brain.
What is the effect of aspirin with alcohol?
Increased risk of stomach bleeding
What is the effect of paracetamol with alcohol?
Toxic side-effects can be increased
What are the long term effects of strong analgesics?
- Constipation
- Loss of sex drive
- Disrupts menstural cycle
- Poor eating habits
- Risk of AIDS, hepatitis, etc. through shared needles
- Social problems
What are the short term effects of strong analgesics?
- Euphoria
- Dulling of pain
- Depress the nervous system
- Slow breathing and heart rate
- Suppresses the cough reflex
- Nausea and vomiting (first timers)
- High doses lead to coma or death
Describe the structure of morphine
Functional groups:
- Benzene ring
- Ether
- Alkene
- Alcohol (2)
- Tertiary amine