What is metabolism?
The sum of all biochemical reactions occurring in the body of an organism.
What is a drug?
A drug is a chemical that affects the functions of the body either in a negative or positive way.
What is medicine?
Substance that has a therapeutic effect on the body, also known as a beneficial effect.
What are the methods of administering drugs?
- Suppositories: inserted into the rectum for digestive illnesses or hemorrhoids
- Parenterals: Intramuscular (vaccine), intravenous (anaesthetics), subcutaneous (dental injections)
What is dosage?
How much of a drug is administered at a certain frequency. Many factors such as age, sex, severity of condition, possible side effects affect dosage. Although it is impossible to keep the level of the drug in blood at a specific level and fluctuations are unavoidable, drug level in the blood must be kept within the therapeutic window, which is the range between the toxic level and the therapeutic level.
What is bioavailability?
The fraction of the administered dosage that reaches the bloodstream.
What factors affect bioavailability?
- The administration of the drug: first-pass effect (the alteration of drugs due to enzymes present in the digestive system) may be effective. Intravenous administration has a higher bioavailability by rule of thumb.
- The solubility of the drug: Water solubility is important for blood circulation. Lipid solubility is important for crossing membranes.
- Functional groups in the drug: The functional groups affect the acid-base properties of the drug, thus affecting its solubility and reactivity in different parts of the body.
What are side effects?
Physiological effects that are not intended. May either be beneficial (aspirin protecting against heart disease) or benign (drowsiness etc.)
What is tolerance?
Occurs when repeated dosages result in smaller results.
What is addiction?
Occurs when patient becomes dependent on drug to normally carry out life and experiences withdrawal symptoms.
What is the therapeutic index?
- Ratio of the dose that causes a medically adverse effect on the population and the dose that causes a therapeutic effect on the population.
- Defined as LD50/ED50 in animal studies and TD50/ED50 in human studies.
- Higher the therapeutic index, the larger the therapeutic window and safer the drug. Drugs with low therapeutic index are typically those whose therapeutic effects are highly affected by bioavailability.
What is ED50?
It is the minimum effective dose. The minimum dose that creates a beneficial effect on 50% of the population.
What is LD50?
Is the dose that is lethal to 50% of the population. This is only used in animal trials for ethical reasons.
What is TD50?
It is the dose that is toxic to 50% of the population. This is only used in human trials.
What does the action of a drug depend on?
The action of a drug depends on drug-receptor interactions. The receptors can be DNA, enzymes (proteins) or chemical structures on the cell membrane. The bonds are usually non-covalent interactions such as ionic bonding, Van der Waals forces, hydrogen bonding etc. The better the fit between the receptor and the drug, the higher the activity of the drug.
Can you explain the process of drug design?
Rational drug design identifies a target molecule and designs a drug to interact with the target receptor. A lead compound (such as a plant extract etc.) is identified. Analogues to that drug are designed and produced. The drug is first tested on 50-100 healthy volunteers, then 200-400 patients and 3000 patients with placebo. After the drug is marketed, most countries continue monitoring.
-OH functional group
C double bond C functional group
C double bonded to O in the middle of molecule functional group
Cyclical with circle in the middle functional group
C O OH functional group
R O R functional group
NH2 functional group
N bonded to one H and two R functional group
N bonded to 3 R functional group
C double bonded to O and NH2 functional group
C double bonded to O and O R functional group
- Heterocyclic (no circle) with N or sth instead of C functional group
- Heterecyclic ring
What are prostaglandins?
Chemicals that stimulate pain receptors located on the body. This sends nerve signals to the brain for the sensation of pain, fever (temperature regulation), and inflammatory response (widening of veins)
What are mild analgesics?
Drugs that inhibit the release of prostaglandins and the site of pain/ injury (not the brain), such as aspirin. Because they don’t interfere with the functioning of the brain, they’re also called non-narcotics.
How is aspirin produced?
- Salicylic acid undergoes esterification in the presence of ethanoic anhydride, producing aspirin and ethanoic acid
- Concentrated sulfuric acid or phosphoric acid is is added and the mixture is gently warmed.
- The mixture is left to cool and is then washed with water. As aspirin has very low solubility, the acids are washed away as aspirin is isolated.
- The mixture is purified through recrystallization. The mixture is dissolved in ethanol, as the impurities are more soluble in it than aspirin. Aspirin is then removed through filtration as the impurities and unreacted salicylic acid remain in the solution.
How can the purity of aspirin be determined?
- Melting point determination
- Or infrared spectroscopy. The dip indicating OH group in phenol will only be present in salicylic acid. Ester group will only be present in aspirin.
How can the yield be determined?
Mass of salicylic acid used to mass of aspirin produced
What does prophylactic mean?
Drugs taken to prevent diseases (such as aspirin taken to prevent heart disease or rectal cancer)
What are some possible side effects of aspirin?
- May cause stomach ulcers
- May have synergy with alcohol and cause ulcers
- May cause Rye’s in children
- May be dangerous for people whose blood does not clot normally, as it is an anticoagulant
How can we increase the bioavailability of a drug?
If it isn’t soluble enough, it can be turned into an ionic salt through the reaction with NaOH or NaHCO-, increasing its solubility and polarity. However, this can only be done with a drug that contains an acidic or basic functional group (such as OH)
What are beta-lactam rings and what makes them special?
- 4 membered ring containing a cyclic amide group (N and 3 carbon atoms) is the part of the molecule responsible for antibacterial properties.
- The bonds are weak and break easily, resulting in the biological activity of the compound.
- These rings are found in penicillin.
How does penicillin work?
The beta-lactam ring inhibits the enzyme transpeptidase, responsible for the building of cell walls. The beta lactam ring breaks and bonds to the active site of the enzyme. These antibiotics are only effective against bacteria and not plant or animal cell walls, as a different amino acid is used in the formation of bacterial cell walls.
What are the limitations of penicillin use?
- Many people are allergic to it.
- Penicillin G must be injected into blood.
- Improper use may cause superbugs and antibacterial resistance. (Resistant bacteria produce penicillinase, rendering it ineffective.)
What are some ways of improper use of antibiotics?
- Not completing the treatment
- Overuse and overprescription
- Use of the antibiotics in the food chain
How can we fight antibacterial resistance?
- By producing different antibiotics such as methicillin. (Modification of R group deems it resistant to penicillinase)
- Limiting the use of antibiotics through legislation (making them prespcription only drugs)
- Education of patients
What are strong analgesics?
These drugs prevent pain by eventing the transmission of pain at the brain rather than at the site of injury. Opiates (drugs produced from the opium poppy) are examples of stron analgesics?
How do opiates have analgesic properties?
The drugs bind to opioid receptors in the brain, preventing the transmission of signals. Because they affect the brain, they’re narcotics. Although they’re the most effective way to manage pain, they have a large capacity to cause dependence or addiction and have heavy side effects, which means they must be used under heavy medical supervision.
What affects the strength of the effect of opioids?
The drugs must pass through the blood-brain barrier, which is a membrane made from lipids. Thus, low polarity and high solubility in lipids ensure higher effect.
What are the properties of codeine?
- Usually prepared from morphine, least effective, second stage of pain management, found in cough medication and used to treat diarrhea.
- It’s a semisynthetic drug
- Although it is less polar than morphine and thus more likely to cross the blood-brain barrier, the reaction of replacing one OH group with an ether group causes a significant drop in its binding with opioid receptors, rendering it a weaker analgesic.
What are the properties of morphine?
Can be obtained directly from opium. Used in the management of severe pain. May cause dependency.
What are the properties of diamorphine (heroin)?
- Usually obtained from morphine, highly effective, only used in select countries, initially produces euphoric effects, high risk of addiction and abuse.
- It’s a pro-drug, as the ester functional groups are broken down by esterases in the brain and most of the drug’s functionality comes from the metabolic product that is morphine. It can be thought that diamorphine is sort of like a package that delivers the morphine to the brain in a faster and more efficient manner.
What are the 3 steps of pain management?
- Weak analgesic
- Weak opioid such as codeine
- Strong opioid such as morphine
What are the side effects of opioids?
- Suppression of cough reflex
- Constriction of the pupil in the eye
- Narcotic effects (depression of brain function, causing sleep and addiction)
- Methadone may be used as an alternative to opioids in the treatment of opioid dependency / addiction.
What are parietal cells?
Cells in the inner lining of the stomach wall which release stomach acid (HCl)
What can cause excess production of acidic secretion?
Alcohol, smoking, caffeine, stress
What problems can result from the excess production of acidic secretion?
- Acid indigestion (feeling of discomfort)
- Heartburn (acid reflux)
- Ulceration (damage to inner lining of gut wall, leading to inflammation and loss of tissue)
- These are all called dyspepsia.
What are the drugs that work against the production of excess acid?
- Antibiotics against the bacteri helicobacter, which may cause ulcers
- H2 receptor antagonists (which limit histamine- H2 receptor interaction and thus prevent the release of acid from parietal cells)
- Proton pump inhibitors such az Zantac (which limit ATPase, which produces energy for the function of proton pumps)
- Antacids (weak basic compounds such as metal oxides, hydroxides, carbonates or hydrogencarbonates, which neutralize HCl)
- They neutralize HCl and produce salt. Mg used for faster relief. Al for longer relief. Al may cause Alzeihmer’s.
- Antacids containing carbon groups may cause bloating, so they usually also have antifoaming components. You may also alginates which float on top of the mixture to prevent reflux.
How to calculate pH of buffer solutions?
[H] = Ka x [acid] / [salt]
Why is the Henderson thing useful?
Because as long as the mixture has equal amounts of acid/ base and salt, we just have to choose an acid/ base with a pKa or pKb to the intended pH and it’s super easy.
What are the assumptions made in the buffer solution pH calculations?
- Salt dissociates fully
- Dissociation of weak acid/ base is negligible or = 0
Why are stronger metal oxides not used as antacids?
They are corrosive.
Why are viruses particularly hard to treat?
- They have no specific components which can be targeted like bacteria.
- They multiply very quickly, and thus have high mutation rates.
How do antivirals work?
- They may alter the cell’s DNA
- They may block enzyme activity in the cell to prevent the virus from reproducing.
- They may cause changes in the cell membrane of the host cell, preventing the virus from entering the cell.
- It is, however, better to use prophylactic treatments such as vaccines to prevent the sickness before it occurs.
How do Relenza and Tamiflu work?
They prevent the virus from exiting the host cell. Thus, they must be taken shortly after the symptoms are observed. Otherwise, too many viruses will have already been released.
What does retrovirus mean?
- Viruses that have RNA instead of DNA such as HIV.
- Why is HIV hard to treat?
- Virus lies dormant in host cells so there’s nothing to treat
- Virus directly targets white blood cells
- Virus mutates rapidly, forcing the body to react differently in short periods of time.
How is HIV treated?
- It is treated through the use of antiretroviral drugs.
- The drugs work by:
- Preventing the virus from binding to receptors on the cell membrane
- Preventing the reverse transcription of RNA into DNA in the host cell
- Preventing new virus to exit the cell membrane
What are limitations to AIDS pandemic?
- Sociocultural taboos
- Costs, distribution and availability
- Patient compliance and regimen
What are successes in how we deal with the AIDS pandemic?
- Combination or specific ARVs
- Cheaper and quicker determination of HIV positivity
- Reduction in taboo
What processes of drug production may pose a threat to the environment?
- Drug preparation
Explain solvent waste
Solvents used must be safe to use and cause minimal negative effects to the environment. Waters, alcohol or esters must be preferred instead of chlorinated compounds. Additionally, minimal solvents must be used. Solvents must be recycled rather than burned, which releases GHG into the atmosphere. Leftover solvents cause problems in workers, contaminate soil or water or pose environmental danger bc they’re GHG.
Explain nuclear waste
- Most of the waste produced is low level waste (short half lives) such as protective gear. These are stored for hours or days in safe, secure and environmental containers and are disposed of traditionally in landfills or sewers for liquids.
- High level waste is put deep under ground.
What are innovative ways to deal with nuclear waste
Use of fluorescent dyes instead of radioactive isotopes in diagnosis.
What are the causes of antibiotic waste?
- Use in food chain
- Improper disposal
- Widespread use of antibacterial things in homes
- This may lead to superbugs
What are some alternative ways to get skimiate precursor (which is hard to obtain from the shikimate tree and can only be achieved after lengthy chemical processing)
Fermentation through genetically engineered bacteria
Examples of Green Chemistry success stories?
Production of viagra producing ¼ of the waste
How does one apply green chemistry?
- Reduction of amount of solvent used
- Adoption of shorter synthesis pathways
- Replacement of inorganic catalysts with enzymes
- Recycling of waste