Paper 3 Flashcards
Lethal dose vs. toxic dose
LD50: amount/dose that kills 50% of the
population
Lethal - animal trails
Toxic- human studies
Therapeutic index in animal studies vs. therapeutic index in humans
Animals: amount that causes death
Human: toxicity amount
maximum bioavailability
Intravenous
State the meaning of the term therapeutic window.
range of dosages between effective level and toxic level
Suggest why a narrow therapeutic window may be a problem.
need close medical supervision
side-effects
undesired effects of drug
Advantage to oral drugs
easily taken
disadvantage to oral drugs
only small fraction of drug absorbed
List three methods, other than orally, that can be used for the administration
of a drug.
intravenous, skin patches, eye/ear/nose drops
Bioavailability
fraction of the administered dosage that reaches the bloodstream
Factor affecting bioavailability
- Method of administration
- Solubility of the drug
- Functional groups
More polar and contains functional groups that can hydrogen bond to water will be more soluble in water- > higher bioavailability
Tolerance
repeated doses of a drug result in smaller physiological effects
Aspirin
mild analegesic
State other uses of aspirin
blood thinner, lowers risk of heart attacks
Outline how the bioavailability of aspirin may be increased
intravenous
How does penicillin combats bacterial infections
ring breaks and cells cannot reproduce
Consequence of prescribing antibiotics such as penicillin unnecessarily
leads to resistance of bacteria
State how penicillin may be modified to increase their effectiveness
modify R group
Mild analgesics function
intercept the pain at the source by preventing the synthesis that causes pain
why is aspirin slightly soluble in water
Non polar @ benzene
Polar contains COOH
Difference in melting point compared to that of pure aspirin
sample is impure and fewer intermolecular forces
Opiates
strong analgesic
opiates function
prevents the transmission of pain impulses n the brain (rather than at the source)
why is codeine more widely used than morphine as an analgesic
codeine has a wider therapeutic window
How can codeine be synthesized from morphine
react with methyl iodide
Why are opiates addictive
gives a feeling of pleasure that a person craves and alters the structure of brain cells
Why diamorphine passes more readily than morphine through the blood-brain barrier
diamorphine has ester and morphine has hydroxyl
diamorphine ester groups - less polar
reagents used to prepare diamorphine from morphine
ethanoic/acetic anhydride
Why is codeine available without a prescription in some countries while morphine is administered under strict medical supervision
morphine has a smaller therapeutic window
SImilar functional groups in methadone and diamorphine
phenly
Different function groups in methadone and diamorphine
ester
withdraw symptom an addict may have
feeling depressed
How prilosec regulates pH in the stomach
PPI prevent cid from traveling to stomach
How zantac reduces stomach acid production
prevent parietal cells from producing acid
histamine
a chemical transmitter that stimulates stomach acid production by binding at H2 receptors.
way to reduce stomach acid secretion
block the histamine- H2 interaction
H2 - receptor antagonists
drugs that prevents histamine binding to H2 receptors and triggering acid secretion
PPI
directly prevent the release of acid into the stomach
PPI
Proliosec
Antacids
weakly basic compounds that neutralize the acid
Antacids: Metal Hydroxides
Acid + Base -> H20 + Salt
Anatacids carbonates and Hydrogen Carbonates
Carbonate + Acid -> H20 + CO2 + Salt
Potassium hydroxide also neutralizes hydrochloric acid . Can it be used as an antacid?
KOH is a strong base and any group 1 metal + base creates a strong base and strong bases can burn human tissue
2 functional groups in zanamivir
ether, carboxyl
Distinguish between bacteria and viruses
Bacteria: is a single cell organism where virus is not
Virus: Lack cell structure where bacteria does not
Antiviral
prevents virus from leaving cell (blocking neuraminidase)
Two difficulties associated with the development off drugs for effective treatment of AIDS
HIV mutates
HIV detroyes helper T Cells
How does tamiflu work against the flu?
blocks the neuraminidase enzyme, which prevents the virus from leaving host cell and so it cannot infect other cells
Antiretroviral drugs (ARVs)
- change cell membrane that inhibits the entry of virus into the cells
- prevents virus replication
- prevents viruses from leaving the cell (after reproducing)
one difficulty with synthesizing tamiflu from star anise
low concentration in plant
low environmental impact of most medical nuclear waste
low radioactivity and exist for a short period of time
environmental effect of antibiotics
resistance in bacteria
how green chemistry can solve the environmental problems
use water as a solvent
