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Medicine and Drugs
Transcript of Medicine and Drugs
Melatonin is naturally occurring in foods (small quantities) therefore classified as food in US.
Causes modification to physiological state (induces sleep / used to cure jet lag) therefore classified as drug in Europe. IB Definition:
Alters physiological state (includes consciousness, activity level, and coordination)
alters incoming sensory stimulation
alters mood and emotion By this definition, are the following considered medicines or drugs?
vitamins Research / Development Placebo effect
many people have therapeutic effect from pharmacologically inert substances - called a placebo
Belief that the drug is beneficial seems to be enough in some cases
Example: pain relief - brain scans of patients taking placebo pain reliever shows release of opioids in brain
Bottom line: Researchers expect 1/3 of patients to experience a placebo effect
What are medical ramifications of the placebo effect? Administration of Drugs Drugs must enter bloodstream to reach site of injury. Methods of Administration:
3. injection /parenteral
4. rectal What are some considerations when determining mode of entry? Considerations for mode of entry:
How fast do you want to feel results?
Is drug affected by pH or acid - will it decompose in stomach?
Can patient take pills?
Will patient take pills? Types of Injections:
1. Intramuscular - in the muscle
2. Subcutaneous - directly under surface of skin
3. Intraveneous - directly in bloodstream Overall stages to research and development
2. Animal Research
3. Initial Human Trials
4. Expanded Human Trials
5. Approval by Drug Administrations
6. Marketing Animal Trials used to determine
•Lethal Dose, LD50
•Effective Dose, ED50
•Therapeutic Index = LD50 / ED50 Discovery - new drugs are isolated from an existing species or are synthesized (produced) in a lab Initial Human Trials:
Volunteers are recruited
control group - given a placebo
used to determine side effects, risk to benefit ratio, and tolerance Vocabulary
side effects - unintended physiological effects (Are they always negative?)
risk to benefit ratio - Weighs benefits and risks (What circumstances would influence this?)
tolerance - when repeated dosages cause smaller and smaller physiological effects. This is not the same as addiction. In addiction, patient will undergo withdrawal symptoms when drug is removed. (What are the dangers of tolerance?) Expanded Human Trials
determine dosing regime- how drug will be administered to obtain a consitent (or close to consistent) level in bloodstream - considers all characteristics of patient
determine therapeutic window - range that must be in bloodstream so that side effects do not occur and drug is still effective
determine interaction with other drugs Approval
Country by country basis
Decide if it will be prescription or over the counter (OTC)
Post market safety surveillance programs Problems in Drug Research
It can take 10-12 years for the average drug to make it to market. If it does not, the drug company will lose a great deal of money. Therefore, the drug company has a vested interest in making sure the drug is produced and sold for as many uses as possible. Thalidomide
Produced in Germany, it was originally used as a sedative and antiinflammatory drug
Used in late 1950s to reduce morning sickness in pregnant women (prescription not needed in all countries)
At time, it was not known that drugs could cross through placenta to baby
Result: over 10,000 babies born with missing / malformed limbs, even more died
Drug pulled from market in 1961, even though reports of the birth defects were made in 1959 and clinical trials showed problems in 1956 Who do you think should be in charge of determining risk to benefit ratio?
patient Antacids Analgesics Depressants Stimulants Antibacterials Antivirals Thalidomide Victims Ability to sense pain can be a good defense. (It can prevent further injury.) However, it can also be debilitating. Therefore, analgesics (medications that limit / prevent pain) can be useful. Note: analgesics eliminate the symptom. They do not correct the cause. The cause must still be determined and treated. Two types of analgesics
1. mild analgesics
work at site of pain
prevent release of prostaglandins
reduces pain, swelling, and fever
do not alter brain function
2. strong analgesics
binds to opioid receptors in brain
prevents transmission of pain signals to brain
called narcotics - alters brain function
change perception of the pain 1. Pain receptor is stimulated – releases prostaglandins 2. Prostaglandins will start inflammatory response (fever and swelling) 3. Pain signals travel along spinal cord to brain 4. Pain signal is received by brain – pain is perceived Mild Analgesics
Around 400 BC, people discovered that chewing willow bark would reduce pain and fever.
Willow bark contains salicylic acid.
Negative side: tasted very bad and caused patient to vomit Salicylic Acid Aspirin –
ester derivative of salicylic acid Bayer Company in 1890 created an ester derivative of salicylic acid. Desire was to maintain ability to regulate pain while reducing negative side effects. Paracetamol / Acetaminophen Strong Analgesics
Related to opium - extract of poppy seeds
called opioids or narcotics
we will study (in order of increasing narcotic effects and side effects) codeine, morphine, and heroin Heroin is a semi synthetic drug. Like codeine and morphine, it can be found in nature. But usually made from morphine. Codeine Morphine Heroin Morphine Heroin CH3COOH CH3COOH + What are the other products?
What is the name of this type of reaction? Strong Analgesics
(Opioids / Narcotics) Strong Analgesics
(Opioids / Narcotics) Long term use will increase tolerance therefore more narcotic is required for same response. This increases chances of overdose.
Dependence is the result of long term use. When the patient stops taking the drug, withdrawal symptoms result. These include: anxiety, cold and hot sweats, diarrhea, and cramps. Methadone is given to many addicts to reduce withdrawal symptoms without producing euphoria. Depressants
drugs that act on brain and spinal cord (CNS)
alters concentration and activity of brain chemicals called neurotransmitters
cause depression of CNS (decrease in brain activity) Examples of depressants include:
ethanol Positive uses of ethanol include:
antiseptic to clean small wounds
because it is has anticlotting effect, it can be used to improve circulation and reduce heart disease
can harden skin so can be rubbed on feet to prevent blisters Low Dose Moderate Dose High Dose ExtremelyHigh Dose Effect may not be noticeable induce sedation (calmness, reduction of anxiety) may induce sleep, altered perception, slurred speech respiratory depression, coma, death Effects of Depressants Note: Sometimes called an antidepressant because it relieves symptoms of clinical depression. Abuse of Ethanol can be short term or long term. Can impact health, family, and society Short Term Effects of Ethanol Abuse
loss of inhibitions, memory, concentration
loss of balance
dehydration --> hangover and loss of productivity
vomiting, loss of consciousness, coma, and death
increased violent behavior
increased risk of domestic abuse / family breakdown
accidents from driving / operating machinery under the influence Long Term Effects of Ethanol Abuse
dependence therefore withdrawal when stopped
high blood pressure
fetal alcohol syndrome
permanent brain damage Note: Ethanol has synergistic effects with other medications. This means it can increase the activity of other drugs. For example:
Aspirin - increased bleeding and ulcers in stomach
depressants - lead to heavy sedation and death Detection of Ethanol Ethanol is tested in the
Blood and urine
gas liquid chromatography Detection of Ethanol Breathalyzers
Ethanol will react with Cr2O72- by redox to form ethanoic acid and Cr3+. Resulting color change of orange to green is monitored by photo cell. Detection of Ethanol Intoximeter
More accurate than breathalyzer.
Uses infrared spectroscopy
Different functional groups will absorb different parts of electromagnetic spectrum
Based on what part of spectrum is absorbed and the size of the band, blood alcohol content is determined.
Uses fuel cell
Energy produced by reduction of ethanol to ethanoic acid is converted to electrical voltage In Blood or Urine by Gas Liquid Chromatography
Blood or urine is vaporized
Injected into stream of inert gas and passed over non-volatile liquid
Rate to pass through depends on solubility in the gas and liquid– called the retention time
Retention time will identify substance
Area under peak shows concentration Detection of Ethanol Other Depressants Such as prozac, valium, and mogadon
major group of depressants
Used to relieve anxiety, stress, and insomnia
However, cause dependence and do not remove the cause
Many times used with therapy Stimulants
increase rate of brain activity
increase mental alertness /decrease drowsiness Physiological effects of stimulants
relax air passages therefore aiding in breathing
palpitations or tremors
restlessness, hallucinations, and dilusions Amphetamines are a type of stimulant which mimics adrenaline Adrenaline Amphetamine How are the above drugs similar?
How are they different? Also called epinepherine
Used in “fight or flight” response
Released in times of stress
Increases heart rate and blood pressure
Increases blood flow to brain and muscles
Increases air flow to lungs
Increases mental awareness
Part of sympathetic nervous system Adrenaline Effects of Amphetamines Regular use can cause tolerance and dependence. Other Stimulants Nicotine
1/3 of world population is addicted. Caffeine
Most widely used stimulant in world. Effects of Nicotine Short Term
Increased heart rate and blood pressure
Reduction in urine output
Increased concentration / reduces drowsiness
Increased risk heart disease
Leads to Dependence Effects of Caffeine Increase concentration / reduce fatigue
Speeds up effects of painkillers
diuretic Alexander Fleming Historical Development of Penicillin Alexander Fleming of Scotland was working on bacterial cultures. He noticed that the cultures had been contaminated with a mold. When he was going to throw them away, he noticed that regions around the mold were clear of all bacteria. He determined that something in the mold prevented the bacterial growth. Historical Development of Penicillin Howard Florey Ernst Chain Australian Howard Florey and German Ernst Chain worked to isolate the chemical, penicillin, from the mold. Human trials started in 1941 on a policeman dying from septicaemia. He began to improve, but the penicillin supply ran out. The policeman relapsed and died. Historical Development of Penicillin At this point, it became important to find ways to isolate penicillin in bulk. In fact, penicillin was in such short supply towards the end of WWII, that the urine of treated patients was isolated and used to obtain penicillin for reuse.
Eventually, the structure of penicillin was determined. This allowed chemists to synthesize penicillin without the use of mold. It also allowed for penicillin derivatives to be produced. How Does Penicillin Work? Penicillin prevents formation of cross links in cell walls. This weakens the cell walls and causes them to rupture.
Other forms of antibiotics work by interfering with chemical processes inside the bacteria. Penicillin Derivatives Many different medicines are made by modifying the side chain of a known medication.
The modification of the side chain is done to create a drug that will, hopefully, maintain the positive effects of the original drug while minimizing the negative side effects.
Many forms of penicillin will decompose when exposed to stomach acid. This required penicillin to be injected. However, modifications to side chains have produced penicillins that can be taken orally. Overuse of Antibiotics When penicillin, or antibiotics in general, are prescribed, it will kill the weakest bacteria first.
If the patient does not complete his / her prescription, then the stronger bacteria will live. Many of these bacteria were producers of penicillinase. This is an enzyme that causes the ring structure of penicillin to break open and be worthless.
This leads to bacteria that are
resistant to antibiotics. Overuse of Antibiotics Ways to prevent rise of antibiotic resistant bacteria:
Do not over-prescribe.
Education to increase patient compliance.
Continue to modify side chains of penicillin to be resistant against penicillinase.
Reconsider the use of antibiotics in animal feed. Virus Structure Central core of DNA or RNA
Protein coat How do Viruses and
Bacteria Differ? Viruses do not have a nucleus or cytoplasm. Bacteria do. Therefore, bacteria are cells and viruses are not.
Viruses do not feed, excrete, or grow. Bacteria do.
Viruses cannot reproduce outside of host. Bacteria are able to survive and reproduce independently of other living cells. Multiplication of Virus Viruses can survive outside of host. However, they only replicate inside the host.
Viruses will inject their DNA or RNA into cell cytoplasm. Virus then takes over cell machinery to replicate its own DNA or RNA.
Host cell will die. Virus will move to new cell. How do Antiviral Drugs Work? Two main ways antiviral drugs work:
Alter cell’s genetic material. Example: a drug to treat cold sores contains a chemical similar in structure to what the virus needs. As a result, the virus is not able to duplicate its DNA. However, it is hard to eliminate the virus completely, so flare ups will occur.
Preventing virus from leaving cell. Example: Chemical in flu vaccine attaches to enzyme needed by flu virus to leave cell. Enzyme is now useless. How do Antiviral Drugs Work? Issues with treating viruses with drugs:
Virus lives in the cell which makes it hard to target.
Do not have a cell structure so antibiotics do not work.
Multiply very fast. By the time the symptoms appear, they have already spread to many areas of body.
Mutate rapidly so drugs need to change frequently as well. How Does HIV Attack? HIV contains a protein coat. This protein coat binds with specific receptor sites on T cells.
T cells are white blood cells. The T cells trigger the immune response. When attacked, the body cannot fight infection from the virus or other illnesses. Why is HIV Hard to Treat? T cells are destroyed. Since T cells trigger the immune system, the immune system is repressed.
HIV mutates extremely rapidly. Therefore, the immune response must continually change.
Virus will lie dormant. Therefore, the immune response is not activated.
Antiretroviral drugs (HIV / AIDS drugs) are very expensive.
Societal issues makes it difficult to begin preventative practices. Digestion In the stomach, gastric juices are produced. This includes enzymes to break down the food, destroy bacteria, and maintain an optimal pH for these enzymes.
Optimal pH is around pH of 1-2. Because of this high acidity environment, the stomach must continually coat the stomach lining with mucus and regenerate new stomach cells.
If to much acid is produced, the stomach lining will be damaged. Ulcers, indigestion, and heartburn can occur. Antacid Side Effects Al(OH)3
Prevents absorption of phosphate which leads to bone damage
Bloating and belching from CO2 production Treatment for Indigestion There are three main types of antacids. How does each neutralize stomach acid?
NaHCO3 Antacid Additives Alginates – float on top of gastric juices to reduce heartburn from gastric juices entering esophagus
Anti-foaming agents – example is dimethicone, reduces flatulence