IB SL Option B: MEDICINES AND DRUGS Compiled by Minna Pöntinen 06/04/03 ----------------------------------------------------------------------------- PHARMACEUTICALS Drugs have been used for centuries to - provide relief from pain - heal injuries - cure diseases A drug alters one or more of the following: - sensory sensations - mood/emotions - physiological state Methods of adminstring drugs: - Oral x2, rectal, parenteral - Parenteral (injections): - Intramuscular - Subcutaneous - Intravenous How is a new drug born? - Lab/animal studies -> LD50 & noticeable effect in 50% - Trials on humans -> clinical studies - More clinical studies -> review by the drug admin -> new drug ----------------------------------------------------------------------------- ANTACIDS (treat indigestion) - The gastric juices (pH = 1.5-2.5) may damage the mucus lining of the stomach -> antacids neutralize the acidity - Causes for ulcers/other discomfort caused by the stomach acids: overeating, alcohol, smoking, anxiety, certain drugs - Antacids are simple bases - Side effects: diarrhea, constipation, bloating, belching - Alginates float on the content of the stomach -> preventing heartburn ----------------------------------------------------------------------------- ANALGESICS (treat pain) Aspirin - Found from the bark of the willow tree, nowadays synthesized - Prevents prostaglandin synthase from being formed - Possible side effects: bleeding in the stomach, allergies, lowering of the pH of the blood - Other mild anaesthetics: paracetamol, ibuprofen Strong analgesics - Are used to relieve severe pains - They interact with receptor sites in the brain - Active part of the morphine -> - Morphine - Codeine (natural) - Heroine (semi-synthetic; formed through a diesterification reaction) - Demerol (synthetic) Effects of opiates - Short term effects: feeling of euphoria, dulling of pain, depress of nervous system etc. - Long term effects: constipation, loss of sex drive, disrupted menstrual cycle, social effects - Withdrawal symptoms (after 6-24 hours): sweats, diarrhea, anxiety, cramps -> treament: methadone ----------------------------------------------------------------------------- DEPRESSANTS (depress the nervous system) - Slow down the functions of the body - Diazepam (Valium), nitrazepam (Mogadon), fluozetine hydrochloride (Prozac) Effects of alcohol - Relaxation, dilated blood vessels etc. -> judgement & concentration are impaired etc. -> coma -> death - Liver cirrhosis and - cancer, heart diseases, high blood perssurse, strokes, dementia, miscarriage, DTs - Enhances the effect of many other drugs Drinking & driving - Legal limit for driving; 80 mg of ethanol / 100cm³ of blood - Unit of alcohol = ½ pint of beer, glass of wine, a measure of spirits - Detection of alcohol: - Breath: acidified potassium dichromate crystals turn green as alcohol reduces them - Breath: C-H bonds absord infrared radiation of certain wavelength -> intensities of a beam of infrared light are compared in a machine; the beam passes through a chamber with no alcohol in it and a chambre into which the breath sample is - Blood/urine: gas liquid chromatography ----------------------------------------------------------------------------- STIMULANTS (increase mental alertness) Amphetamines - related to adrenaline - used in treating narcolepsy; before given to soldiers & using as an anti- depressant & slimming pill - effects: increased heart rate, dilation of the pupils, decrease in appetite -> fatigue, depression, weight loss, emotional instability Caffeine - Present in coffee, tea, chocolate & cola - Effects: diuretic, increases alertness, concentration & restlessness - An alkaloid; N-containing compound with heterocyclic rings and a tertiary amine group - Caffeine contents: cup of coffee: 100 mg cup of tea: 40 mg can of cola: 40 mg 100g of choc: 80 mg Nicotine - Withdrawal: craving, nausea, weight gain, insomnia, depression - effects: relieves tension, increase heart rate, acts as an antidiuretic; increased risk of heart & lung diseases and cancers Ecstacy - one of the "designer drugs"; used to treat Parkinson's disease - effects: relaxation, increased sensitivity to stimuli, hallucinations Classification of amines - primary (one R group attached to the N) -> secondary (2R) & tertiary (3R) ----------------------------------------------------------------------------- ANTIBACTERIALS - Bacteria, viruses, fungi, yeasts & protozoa cause infections - All bacteria are not harmful Basic structure of a bacterium: - outside: cell wall, slime capsule, (flagellum) - inside: chromosome (DNA strand), cytoplasnm, glycogen granules Types of bacteria & examples of diseases - cocci/spherical (sore throats, pneumonia) - bacilli/rod-shaped (tuberculosis) - spirochete/spiral-shaped (syphilis, infections of the gum) Different kinds of antibiotics - Narrow-spectrum: work against certain types of bacteria (penicillins) - Broad-spectrum: work against a broad range of bacteria (tetracyclines) - Bacterial infection -> broad-spec drug -> sample -> analyzing -> narrow-spec drug How antibiotics work (two methods) - Preventing bacteria from making cell walls (or exploding the walls via osmotic pressure) - Messing inside the bacteria & interfering with their chemical activities Resistance to penicillin - Bacteria multiply and mutate very fast -> they become resistant to known types of penicililn -> new types have to be developed - This problem is enhanced by the fact that penicillins are also given in great amounts to animals Discovery of penicillin in 1928 by Alexander Fleming - Accident -> gee, mold inhibits the growth of bacterium - Howard Florey & Ernest Chain -> isolating & purifying penicillium - in 1950s synthesizing begun ----------------------------------------------------------------------------- ANTIVIRALS - Structure: DNA or RNA inside a protein coat - Can only reproduce inside the cells of living organisms - Multiplication: injecting DNA/RNA into a cell's cytoplasm -> takes over the cell -> the cell produces new viruses Modes of action - Body's own mechanisms usually overcome viral infections (chicken pox, influenza) - Difficulty: viruses multiply & mutate fast - Altering cell's genetic material so the viruses can't use it to multiply (example: acyclovir) - Preventing new viruses from leaving the cell (amantadine) AIDS - Caused by a retrovirus HIV (contains RNA) - Invades the white blood cells -> the body can't fight infections - How can the HIV virus (or other viruses) be possibly eradicated? - Preventing the virus attaching to host cell - Altering the cell wall so that the virus can't enter the cell - Preventing the virus from losing its protein coat once inside the cell - Blocking the action of reverse transcriptase (which converts the viral RNA so that it can enter the host cell and start to new viral RNA) - Inhibiting the production of new viral RNA & proteins - Preventing the viruses from leaving the cell -----------------------------------------------------------------------------