Topic 12: Medicinal Chemistry Flashcards
Define “drug”
a substance that affects how the body works. Could be for better or worse
Define “medicine”
a substance that improves health. These could be natural or synthetic. Synthetic could contain other non-active ingredients to help administration of the medicine
What are three possible effects of a drug or medicine?
alters incoming sensory sensations, alters mood/emotions, alters physiological state
Four methods of administering drugs?
oral, inhalation, rectal, parenteral (injection)
What are three types of parenteral (injection) drug administrations?
intramuscular, subcutaneous (injected under skin), intravenous (most rapid effect as drug enters bloodstream directly)
What is the lethal dose?
The dose that causes death in 50% of the animal population
What is the effective dose?
The dose that causes noticeable effect in 50% of the animal population
What is therapeutic index?
Ratio of lethal/toxic dose to effective dose
How do you calculate therapeutic index for humans?
TD50/ED50 (Toxic dose/effective dose)
How do you calculate therapeutic index for animals?
LD50/ED50
What is therapeutic window?
Range of dosages between the minimum amounts of the drug that produce the desired effect and a medically adverse effect
What is drug tolerance? What can it lead to?
It occurs as the body adapts to the action of the drug, so a person needs larger doses to achieve the same effect. It can lead to addiction
What is bioavailability?
The fraction of the administered dosage that actually reaches the target part of the human body
What are three factors affecting bioavailability?
solubility, administration method, functional group
What are analgesics?
Painkiller drugs
What do prostglandins do?
When cells are damaged, they release prostglandins with stimulate pain receptors in the body, which send nerve messages to the brain, causing it to feel pain. Prostglandins also dilate blood vessels near an injury, leading to swelling and increased pain as part of the inflammatory response.
How do analgesics work?
They block the pathway between the injury and pain receptors. They prevent the nerves at the injury from being stimulated and prevent prostglandins from being released, thereby relieving pain and inflammation.
Mild analgesics do not alter brain function, so they are known as…
non narcotic
What is an antipyretic?
A fever-reducing drug
What is the chemical reaction for the synthesis of aspirin?
salicylic acid + ethanoic anhydride —> aspirin and ethanoic acid
After the first reaction is complete, how is aspirin produced?
The aspirin product is recrystallized from hot water to obtain aspirin
How can you confirm the purity of aspirin?
By its melting point. Impurities lower the melting point. Pure aspirin melts at 138-140 C.
Also through infrared spectrum. It has a peak at 1750 and 1680 because of the two C=O bonds, and very broad absorption between 2500-3500 due to carboxylic acid
How can aspirin be made more soluble?
Aspirin is slightly polar but not very soluble in water. By reacting it with sodium hydroxide to form an ionic salt, it becomes more soluble. Once it reaches a strongly acidic environment like the stomach, it becomes un-ionized.
Aspirin in the form of ionic salt is also called…
soluble/dispersible aspirin
How can the side effects of aspirin be reduced?
Coatings and buffers can delay activity until the small intestine to reduce side effects
What are the physiological effects of aspirin?
Anticoagulant: reduces blood’s clotting ability. Can cause irritation and ulceration of the stomach.
What is synergy?
The phenomenon in which the effects of a medicine/drug are more acute when drinking alcohol. With aspirin, a person should not be drinking to avoid ulcers and bleeding in the stomach
How does penicillin work?
It has a ring attached to the molecule called beta-lactam, which has one N atom and 3 C atoms. The ring is easily broken due to strained bonds. Beta-lactam binds near the active site of transpeptidase and breaks off of the penicillin molecule, preventing transpeptidase from working. Transpeptidase is the enzyme that helps bacteria build cell walls. Without a cell wall, the bacterium dies.
What are a few disadvantages of penicillin?
Many people have penicillin allergies. Also, penicillin G is broken down in the stomach, so it is often most effective when injected into the blood or taken as a pill.
How does antibiotic resistance to penicillin form?
When penicillin or other antibiotics are overprescribed, the bacteria with penicillinase are able to multiply because of less competition. Penicillinase (aka beta-lactamase) is an enzyme that breaks the beta-lactam ring and deactivates it, rendering the penicillin ineffective. Resistance can also develop because some livestock are given antibiotics, which humans then consume.
How have people combatted resistance to penicillin?
Development of methicillin and oxacillin; legislation to prevent over-prescription of penicillin; patient education
How do strong analgesics work?
They temporarily interact with the receptor sites in the brain without depressing the central nervous system, causing the pain signals in the brain and spinal cord to be blocked.
What are some examples of strong analgesics?
Morphine, opiates like heroin, codeine, demerol
Why are opiates supposed to be strictly controlled?
They are all addictive and can lead to tolerance.
Heroin is also called…
diamorphine
What are 7 short term effects of strong analgesics?
Euphoria, dulling pain, depress nervous system, slow breathing and heart rate, cough reflex inhibited, nausea and vomiting, coma/death in high doses
What are 6 long term effects of strong analgesics?
Constipation, loss of sex drive, disruption of menstrual cycle, poor eating habits, risk of AIDS, hepatitis, etc. thru shared needles, social problems like theft and prostitution