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Mid-Term 2 Notes (part 1).pdf

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CHEM 183
Joe Schwarcz

World of Chem Drugs: Midterm 2 Notes ALLERGIES - Allergy: any adverse reaction to a substance that is generally harmless to most people. - Mistake that the immune systems make, perceives a substance to be dangerous when it is not - Can develop at anytime, in some cases child allergies may be outgrown - 10–20% of the population suffers from some sort of allergy (probably more) - Anaphylaxis: ultimate allergic reaction – rapidly progressing and life threatening, causes blood pressure problems and circulatory issues - Reactions can occur within a few minutes of contact to an allergen, death can ensue - EpiPen contains Adrenalin (Epinephrine) can temporarily reverse an anaphylactic reaction, only buys time does not stop the reaction permanently. Have an expiry date, short half-life - Atopy: genetic tendency to develop classic allergic diseases (atopic dermatitis, allergic rhinitis, asthma, food allergies) - People with an atopic nature are more prone to these diseases based on genetics - Why the Increase in Allergy Rates? - Ex. Asthma rates have doubled since 1980 - Better at diagnosing disease, people are more likely to see a doctor - Increasing exposure to more substances, since WWII 80,000 new chemicals introduced (the more substances that exist, the higher the probability that people will develop allergies) - Greater chemical exposure in all daily products - Hygiene Hypothesis – overuse of cleaning products creating a clean and germ-free environment, resulting in children being underexposed to microbes. May cause immune system to be underdeveloped, the immune system does not encounter common invaders leaving it under utilized. Less micro-organismal challenges allow the immune system to focus on harmless foreign substances and endogenous substances from the host’s cells (leads to auto-immune diseases). - Triclosan – antibacterial agent present in liquid soap, shampoo, toothpaste Mechanism of an Allergic Reaction - Most allergic reactions involve mast cells (specialized immune cells) - What is an Antibody? - Protein molecule produced by the body’s immune system in response to the first encounter with a foreign agent (in the case of an allergy, an allergen) - Members of specific family of proteins called Immunoglobulins (Ig), IgE is a specific type of antibody involved in allergic reactions - Antibodies allow body to neutralize the allergen, they do this by binding to the allergen - At every subsequent exposure, a reaction b/w the existing antibodies and the substance occurs - Antibodies on the surface of mast cells bind the allergen, causes a physiological change on the membrane of the cell, which triggers Degranulation: release of granules (pockets of histamine within cell) into extracellular space (mast cells appear to explode while degranulating) - When granules (contain histamine) are released outside the cell, they flood bloodstream, histamine causes many allergenic symptoms (responses) - Histamine is preformed in mast cells, waits to be released - Allergenic symptoms meant to get rid of the foreign invader (allergen) (ex. watery eyes, sneezing, coughing, vomiting...) - Swelling/inflammation due to influx of white blood cells (arrive to try and remove allergen) - Allergen-Antibody Reaction – required for all allergic reactions, it is this reaction that results in symptoms of allergic reactions - Body sees a substance it deems dangerous, produces antibodies, some antibodies (specifically IgE) attach to surface of mast cells - In order to be allergic to anything, an individual must have has previous exposure to the allergen - Allergen will be sensed by the immune system, antibodies will be produced to trap the allergen. After primary exposure, the following exposure will trigger the hyperactive response following subsequent exposure through previously generated antibodies - No one can be truly allergic to something the first time they encounter it Treatment - Histamine receptors in our nasal passages, eyes, throat, skin, gut... - Receptors are protein molecules in cells that act as locks - When a key (ligand) fits in this lock, it can unlock and trigger a reaction 1 World of Chem Drugs: Midterm 2 Notes - Histamine has 2 parts, one part fits into the receptor, the other part activates the receptor – therefore it can unlock the receptor - To block allergic reactions, you need to prevent histamine (key) from fitting into the receptor (lock) – Anti- Histamine is a key that fits into the lock, but does not unlock it - Anti-Histamines - Chlor-Tripolon - 1950s, first drug designed as an anti-histamine - Designed through trial and error - Fit into the receptor (lock), but did not activate it - Side effect – drowsiness - Diphenhydramine – anti-histamine, worse side-effects, used as a sleeping aid - Hismanal - Claimed to be non-sedating - Like Seldane, cross-reacted with Ketoconazol (an anti-fungal medication), which could result in irregular heart beats (arrhythmias) - Seldane ended up back on market as Allegra (the metabolically active form of seldane) - Claritin - generic name: Loratadine - Cetirizine – active ingredient found in Zyrtec and Reactine - Avoidance – avoid the allergen - Decongestants if symptoms are localized (ex. Sudafed, Beconase, Rhinocort, Flonase – nasal sprays containing steroids for instant relief) - Natural Products - Butterbur – petadolex contains an extract of this plant - Stinging Nettle – if plant touches skin you get a rash, but active ingredient in small doses can resolve allergies Allergy Testing - Immunological tests used to determine whether a person has certain allergies - Small samples injected under skin, test for inflammation, red swelling measured - Patch testing used to test many chemicals at once - Once allergy determined, can have allergy shorts to help prevent allergies - Small doses of a chemically modified allergen injected, not the exact same allergen you are allergic to, body does not recognize it as offending material but will produce antibodies against it - When injected in small doses IgE antibody not produced, IgG antibody produced - Idea: when exposed to allergen IgG antibody will bind to allergen before allergen can bind to IgE on mast cells and cause a reaction – place where IgE would bind is taken up by IgG a - Works for allergies involving bee stings, hay fever (allergenic rhinitis) Case Studies - Children who are exposed to parasites suffer fewer allergic reactions. Study of 3,000 school children in Ecuador, allergies less prevalent among those infected with parasitic worms because the immune system was preoccupied with a real threat - Children enrolled in daycare at a young are are less likely to develop allergies. In daycare children exposed to many microorganisms. Less likely to develop Leukemia or Hodgkin’s Lymphoma, postulated that immune system has learned to target microbes and viruses, can also recognize cancer cells as foreign invaders - Dairy famers are 5x less likely to develop lung cancer. Breathe manure dust containing bacteria, may learn to better fight off invaders and cancer - Cotton factor workers have lower rates of some cancers (lung cancer). Cotton contains chemicals belonging to the endotoxin family, which alert and activate the immune system - Bee Stings – dangerous allergies similar to peanuts and fish, results in skin reactions, full body reactions, bronchial constriction, anaphylaxis Allergic Diseases - Hay Fever – Allergic Rhinitis - Most common allergic reaction, can progress to a more serious condition (death can occur by anaphylactic reactions) - ~50% of people with hay fever develop asthma - Generally caused by seasonal allergies to pollen (in Montreal Ragweed is the most common cause) - Classic Hay Fever is a misnomer – not due to hay, due to pollen – hay is dead grass and has no pollen - Geographic Tongue is an unusual reaction where benign white spots appear on the tongue 2 World of Chem Drugs: Midterm 2 Notes - Perennial Allergic Rhinitis: triggered by allergies that last all year long (perennial = all year) - Pollen (relates to allergic rhinitis) - Pollen modulates plant reproduction - Pollen contains proteins, it is the proteins we have allergic reactions to - When pollen gets into the eyes and nasal passages the sack holding the proteins is released, and it is these proteins that cause the allergic reactions. The host’s adverse immune response dictates the allergy, which responds to a specific allergen - Atopic Dermatitis (Eczema) - Appears early in life, it is a skin reaction - Can react to a variety of substances (creams, lotions), most often develop other allergies like rhinitis - Dust Mites (microscopic organisms) - Wherever there is dust there are dust mites, they feed on dead skin cells - Not allergic to the creatures themselves, but to their feces (proteins within feces are the allergen) - Can cause asthma - Can be avoided by using plastic PVC mattress covers and household air filters - Total Allergy Syndrome (20th Century Disease) - React to a large number of substances – forced to live lives outside of society where they can be isolated and minimize exposure to potentially allergenic substances - Strong psychological component to these reactions, often lacking any immune system component - What Causes the Symptoms? - Rarely caused through a classical allergenic pathway - Shared Psychological Profile – people constantly worried about everything in life - Usual Symptoms – constant headache, burning eyes, feeling of unease, vertigo Animal Allergies - Cat is the animal that is most likely to cause an allergy - Allergen is the protein in the dead skin cells (dander), their saliva is also an allergen because they lick their hair - Black cats are esp. allergenic, dander produced by them is more potent and contains more allergenic proteins - Allergies to cats make other allergies worse – inhalation of dander irritates the lungs and amplifies symptoms of allergies to other substances - Common Misconception – people believe that they are allergic to the animals’ hair - (Ex. people seem to have more allergies to dogs with long hair, it is not the hair, it is because there is more of the allergen on the hair Food Allergies - Common: fish, peanuts, milk, shellfish, legumes, nuts - 4% of adults have food allergies - 30% of adults have food intolerances - Anaphylactic shock can kill a person within a short amount of time following exposure. Trace amounts of an allergen can be lethal when it comes to the immune system - Allergies do not always present themselves through common symptoms - Can cause gastrointestinal issues - Ex. Yellow Dye #5 and #6 - Peanut allergies rare in Israel – Bamba, Israeli peanut snack, first solid food given to young children because it helps with teething. Early exposure may lead to tolerance of the substance, while later exposure could lead to allergies - Allergic reactions to sesame seeds increasing – more people eating bagels – more exposure, the greater the change a reaction will develop - Soy Beans – as we eat more soy (e.g. vegetarians), allergies increase. Soy commonly used in animal food because it is cheap to grow, high in protein, naturally low in methionine - Brazil Nuts – rich in Methionine (amino acid) - Food Intolerances – not allergies b/c they are not involved with antibodies - Lactose Intolerance – caused by lack of an enzyme, lactase, which converts lactose (milk/sugar molecule) to galactose and glucose. Cannot break down lactose, not absorbed and passes through intestines to colon where bacteria can break it down, produces gases that cause bloating, burping, diarrhea. Affects 70% of the population 3 World of Chem Drugs: Midterm 2 Notes - Sulfites – dried fruit, shrimp, wine; Nitrates – cured meat; Tyramine – red wine, cheese (causes headaches) Contact Dermatitis - Contact Dermatitis: any type of contact-dependent outbreak on the skin characterized by redness or hives - Two Types: 1. Irritant – not related to allergies, only to exposure to caustic or irritating substances. Can happen to anyone exposed to the irritant, not antibody dependent 2. Immune System Mediated (Allergic Type) – allergic reaction is one that occurs only in certain people and is mediated by the immune system. Reactions to allergic dermatitis only occur where there had already been contact - Ex. Poison Ivy – reaction is antibody mediated (not everyone reacts to it, 10–20% of people do not), poison ivy contains urushiol, the allergen responsible for the reaction - Urushiol also found in poison oak, japanese lacquer tree - Nickel – common cause of allergic contact dermatitis – surprising as most allergies due to proteins not metals - Cell phones cause of allergic contact dermatitis – contain nickel - Test for Nickel using dimethylglyoxine, turns pink in presence of Nickel - Gold – has to be mixed with other metals like nickel - Rubber comes from the Latex of a tree – cause of allergic contact dermatitis - Rubber allergies due to reactions from the protein in the latex, if the latex is properly processed the change of an allergic reaction is reduced - Increased latex allergies due to greater exposure to latex - Dr. Everett Koop (US general surgeon) – developed a latex allergy, led to increased research on it - Papaya, Latex and Bananas are cross-reactive allergies: if you are allergic to one, you are allergic to all - Henna, Detergent, Glue, Flip-Flop, Ring Cleaner, Plastic Currencies (Germany), Glue (Cyanoacrylate) – used to put on fake fingernails, Garlic – moderate skin rash, rare - Allergic material can seep into the skin and get into the blood vessels – can result in an allergic reaction all over the body - Black hair dye (containing phenylene diamine) caused this reaction - Hydrocortisone – steroid cream, powerful anti-inflammatory compound - Benadryl – anti-histamine - Aquagenic Pruritis – allergy to water - Contact with water causes rashes, allergy is rare and only involves the skin so you are still able to drink water - Can you alcohol to clean, or wash and dry quickly - Photoallergy – exposure to a material followed by exposure to UV light can trigger serious reactions - Ex. Hannelore Kohl, once treated with Penicillin which made her permanently sensitive to light Asthma - Allergic disease, not rare, no cures only treatments - Leukotrienes: chemicals that cause Asthma, resealed from mast cells - Anti-Leukotrienes (Singulair – produced by Merck), medications targeted for Asthma - Generic Name: Montelukast (Mont – Montreal, where it was developed) - Singulair effective in treating exercise-induced Asthma, not for acute Asthma - Non-Steroid Based Inhalers – Anti-Leukotrienes - Treat an asthma attack - Ventolin (Albuterol – immediately dilates bronchial tubes, allows for inflow of air - Serevent (Salmeterol Xinafoate) – not steroidal, chemically similar to Ventolin - Steroid Based Inhalers - Steroids have an anti-inflammatory effect - Take regularly to prevent inflammation (to prevent Asthma attacks) - Important to have both types of inhalers because one helps prevent and the other treats - Plumicort, Flovent – steroid based - Sodium Cromoglycate (Brand: Intal) – Asthma prophylaxis, taken regularly as an inhaler to prevent attacks (believed to coat mast cell and prevent release of histamine) - Advair (Fluticasone propionate/Salmeterol) – contains steroidal (preventative) and anti-leukotrienes (attack relief) 4 World of Chem Drugs: Midterm 2 Notes STOMACH CHEMISTRY AND ANTIBIOTICS The Gastrointestinal Tract - Role of gastrointestinal tract is the digestion of ingested substances - Hydrochloric Acid is the chemical responsible for the breakdown of food in stomach (as acidic as lemon juice, mild) - The Stomach – first organ of the GI tract – pouch-shaped organ above the belly button around the chest - Responsible for the breakdown of larger molecules before they are fed into the small intestine - Cleavage of carbs and proteins – uses an acidic medium (hydrochloric acid) to perform its tasks - The Small Intestine – called ‘small’ because it is narrow (2cm) - Responsible for metabolizing fats (hydrolysis of fats) - Uses basic medium in its digestive role - Neutralization of acid required to shift digestive role of small intestine, since food coming in is from the acidic stomach environment – Pancreas secretes alkaline juice (basic juice) into small intestine to neutralize acid (decrease acidity, increase basicity) - Pancreas delivers enzymes that digest fats into small intestine - Stomach may produce more hydrochloric acid (HCI) than necessary, causes hyper-acidity – what factors control this? - Eating too much, eating too fast, eating spicy food, smoking, stress, some pain relieving medications (only Non-Steroidal Anti-Inflammatory Drugs can cause this, ex. Aspirin, because these drugs target prostaglandins which are involved in regulation of digestive activities) Treatment for Stomach-Rooted Problems - Antacids – common reliever of stomach pain - Used to treat pain in stomach caused by excess acid - Acid neutralized with a base to produce salt and water - Weak bases use, strong ones would damage stomach lining - Sodium Bicarbonate (no longer used as an antacid) - Hydrochloric Acid + Sodium Bicarbonate = Water + Sodium Chloride (salt) + Carbon Dioxide = HCI + NaHCO —> 3aCl + H O + CO 2carbon d2oxide causes gas and burping) - Properties: fast-acting, cheap to make, does not last long, high in sodium - Side Effects: can lead to acid rebound (body overproduces acid in response to treatment with the weak base), if used frequently can result in systemic alkalosis (body and blood more alkaline) - Alka-Seltzer – most well known stomach remedy - Active Medical Ingredient: Sodium Bicarbonate (turns out to be baking soda) - Contains small amount of ASA (Aspirin) – but can upset stomach by increasing acidity - Alka-Seltzer Gold does not contain ASA - Aside: Baking Soda and Baking Powder are not the same thing, they contain the same ingredients but have different ratios – BP used when dough needs to rise, contains acid - Calcium Carbonate – most popular antacid used today - HCI + CaCO (C3lcium Carbonate) —> CaCl (Calcium2Chloride) + H O + CO 2 2 - Brand Name: Tums - Chalk made of Calcium Carbonate - Good source of calcium, used to help osteoporosis - Properties: fast-acting, cheap to make, long lasting - Side Effects: can cause acid rebound, can lead to formation of kidney stones, affects absorption of some antibiotics (e.g. tetracycline) - Aluminum Hydroxide (Al(OH) ) and3Magnesium Hydroxide (Mg(OH) ) 2 - Safest of the antacids, weaker bases - Milk of Magnesia contains Magnesium Hydroxide (in excess causes diarrhea); Amphogel contains Aluminum Hydroxide (in excess causes constipation) - Addition of both neutralizes diarrhea/constipation effects – product containing both is Maalox - Maalox Plus contains Simethicone, compound to help expel gases produced during reaction of antacid and stomach acid, acts as an aggregator of gas molecules 5 World of Chem Drugs: Midterm 2 Notes Ulcers - Caused by excess acidity - Occurs when lining of stomach has been attacked superficially by excess acid - Untreated Ulcer: deepen into tissue leading to a bleeding ulcer, further damage leads to a perforated ulcer (acid eaten through lining of stomach) - Two Types of Ulcers: 1.Gastric (Peptic) Ulcers – affect stomach - Older people at higher risk, caused by weakened stomach wall - Can lead to stomach cancer 2.Duodenal Ulcers – affect small intestine, specifically the duodenum (12 fingers wide) - Younger people frequently affected - Caused b/c pancreas is not producing sufficient basic juices to neutralize the acid - Ulcers generated in duodenum b/c it is the first part of the small intestine that acidic juices hit - Gastro Esophageal Reflux Disorder (GERD) - Affects esophagus – b/w esophagus and stomach there is a valve made of tissue that prevents gastric juices from spinning from stomach into esophagus - Valve not working leads to reflux, causing heartburn - 20M people affected in US Causes of Ulcers - Previously stress believed to be primary cause of ulcers, thought to increase acid production - 1950s: Executive Monkey Experiment – electrical shocks give to monkeys, executive monkey option to stop shock from occurring, executive monkey developed an ulcer, others did not – unethical, not properly controlled - 1983: Barry Marshall, Robin Warren – disproved idea that stress led to ulcer formation - Hypothesized that ulcers were caused by bacterial infections – H. Pylori - Marshall ingested H. Pylori and developed gastritis (inflammation of stomach) - Most ulcers are known to be caused by bacterial infections – bacteria called Helicobacter Pylori (H. Pylori) - Bacteria can survive in stomach (digestive enzymes and hydrochloric acid) - Bacteria makes use of urea (body waste) and converts it to carbon dioxide and ammonia (Basic), ammonia produced protects against harsh acidic environment - 10–20% of population infected with H. Pylori, does not mean they have an ulcer - 1–4% of population has gastrointestinal disease caused by H. Pylori - How to test for presence of H. Pylori? - Bacteria uses urea to produce ammonia, by product is carbon dioxide - Urea labeled with a radioactive marker – the carbon atom on urea swapped with a radioactive carbon (Carbon 13) - When bacteria react with urea, carbon atom because Carbon Dioxide - If you give someone radioactive urea, they are infected with H. Pylori if radioactive CO 2s expelled with Carbon-13 as oppose to just Carbon Treatment of Ulcers - Ulcers can be treated using antibiotics since the cause of ulcers in most instances is bacterial - Individuals treated with Zantac – recurrence rate of 42/52 - Individuals treated with Zantac + Antibiotics – recurrence rate of 1/52 - Two Types of Triple Therapies to Treat Ulcers: 1.Proton Pump Inhibitor + 2 Antibiotics 2.Stomach Protector + Proton Pump Inhibitor + Antibiotic - Drugs regulate amount of acid secreted within the body – number of molecules/enzymes involved in process of acid secretion within the stomach: acetylcholine, protaglandins, gastrin, histamine (H r2ceptors), proton (acid) pumps - Histamine (H R2ceptors) - Histamine is released by stomach wall and binds to H re2eptors - H2Receptor Antagonists – block binding of histamine to H rec2ptors - Tagamet (Cimetidine) – first product (drug) that could potentially relieve and help heal an ulcer - Side Effects: mental changes, sexual dysfunction, gynecomastia (breast growth in males) - Cimetidine, the active compound, targeted H re2eptors and bound to androgen receptors - Zantac (Ranitidine) – did not bind to androgen receptors (OTC) - Pepcid AC (Famotidine) – OTC 6 World of Chem Drugs: Midterm 2 Notes - Proton (Acid) Pumps - Protons are H+ ions (Hydrogen ions) – acids are chemicals that produce H+ ions - Losec (Omeprazole) – known as Prilosec in US - H+,K+ – ATPase Inhibitor – inhibits production of H+ (protons) - How Does This Work? - Proton pump is an enzyme at cell membrane, border b/w inside and outside of a cell - Pump recruits potassium ions (K+) from outside and ATP (energy) and hydrogen ions (H+) from inside – enzyme normally takes H+ from inside cell and pumps to outside which recruiting K+ into cell, ATP energy is the source that drives this process - Omeprazole blocks action of pump, prevents release of H+ into stomach, decreases acidity - Nexium (Esomeprazole Magnesium), purple pill related to Omeprazole - Omeprazole is a mixture of 2 optical isomers – compound exists in 2 forms, with identical chemical bonding structure, mirror images - S-Omeprazole (S = sinister = left) – marketed as Esomeprazole – less metabolized (detoxified) by the liver than the R-isomer - R-Omeprazole (R = rectus = right) - Nexium/Esomeprazole/S-Omeprazole reduces stomach acidity more than Losec/R- Omeprazole, because the R-Omeprazole metabolizer more and is therefore less readily available in the body – Nexium is the more effective proton pump - No proven real difference in healing of ulcers as a result of two medications (Esomeprazone/Nexium or Omeprazone/Losec) Antibiotics - Leading cause of death is Canada is Cancer, used to be Heart Disease – 1990s leading causes of death were pneumonia and tuberculosis – this has changed due to the introduction of antibiotics - Many causes of death today are preventable (smoking, obesity) - Leading cause of death in US is heart disease due to prevalence of obesity - Humans have a tendency of overus
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