PHARMACOLOGY BLOCK 1- basic intro

pharmacokinetics
1. The way the body acts on the drug once it is administered. •Involves 4 processes: 1. Absorption 2. Distribution 3. Metabolism (biotransformation) 4. Excretion
general mechanism of drug action:
1. therapeutic window IS:
  1. the gap between response in 50% of population and undesired effect
    1. therapeutic dose
      1. the smallist amount that will get a change and the max that can be tolerated
        therapeutic index IS:
        margin of safety narrow or broad
        narrow monitoring is: the gap between therapeutic and toxic BUT REMEBR EACH PERSON HAS THERE OWN WINDOW
2. is how the drug effects body regardless of form in comes in
pharmacodynamics
1. The study of a drugs effect on cellular physiology & biochemistry in the body and the drugs mechanism of action. ‘How the drug acts on the body’
pharmacogeneitics:
1. •The ways in which many drugs are metabolised vary from person to person and can be genetically determined. •In a small number of individuals variation in drug response is determined by a mutation in a single gene and can have serious and potentially life threatening consequences
2. Pharmacogenetics can be defined as the study of genetic variation in the body’s response to drugs. –due to factors involved in the processing of a drug (pharmacokinetics) – or factors involved in the way that a drug’s effects are mediated (pharmacodynamics).
A DRUG IS:
1. anything chemical that enters the body in anyway, and effects the body in some way and can be synthetic or natural
DRUGS ARE USED TO.
1. CURE: SHORT PERIOD; CONTROL: LONG TERM; ALLEVIATE: PAIN, FEVER HELP BUT NOT CURE
PRESCRIPTION DRUGS:
1. Authorised-- nurse etc prescribes to a person. OTC: general public pharmacies supermarkets Caution with dosage and adverse drug reaction. pharmacy only and pharmacist only
FIVE RIGHTS: DRUG, PERSON, TIME, ROUTE, DOSE
Mode of Action
1. 1. Binding to a Receptor Receptor is what a drug binds to, to cause a reaction or effect Agonists & Antagonists Agonists are drugs that bind to a receptor and produce a response in the cell. - Like a copy cat. Antagonists are drugs that bind to receptors but do not produce a response in the cell. They block or stop what normally happens to the receptor.ADVERSE • Drug action can work too well e.g. insulin action can lead to hypoglycaemia • Drug not selective and binds to other types of receptors • Genetic
  1. 2.Drugs can work by simple chemical reaction. - eg. Antacids .. Magnesium hydroxide Mg(OH)2 + 2HCl MgCl2 + H2O.
    1. 3. Physical Action • Drugs can act by a physical mechanism. e.g. Osmosis – Drugs that have osmotic effects are osmotic diuretics and laxatives.
2. •The mechanism by which the drug exerts its effect on the body •Irrespective of the source of the drug, the the drug will exert its effect in the same way: 1.Binding to a receptor 2.Chemical reaction 3.Physical action
Drug-Drug Interactions •
1. Potentiation: a) increase therapeutic effect e.g. Augmentin b) increase adverse effects e.g. aspirin + warfarin •Inhibition: a) decrease therapeutic effect e.g. propranolol + terbutaline b) decrease adverse effects e.g. morphine + narcan •Different Drug Response Drug-Drug Interactions •the greater number of different drugs a person is taking the greater the risk of a detrimental interaction •especially important for drugs with narrow therapeutic window Why???
TOLERANCE – DEPENDENCE-WITHDRAWAL
1. tolerance= decrease response. dependence= reliant to function/ physical or psychological. withdraw sudden withdraw of drug
2. TOLERANCE– represents decreased response to a drug. This is seen clinically when a dose of a drug must be increased to achieve the same effect. •DEPENDENCE – occurs when a patient needs a drug to “function normally”. There are two types of dependence: physical dependence and psychological dependence.• Physical dependence develops as a result of ongoing exposure to a drug and can be thought of as involving a type of tolerance. A good example here is when a person with cancer needs narcotic analgesics to cope with the pain they will become physically dependent on having the analgesic to function normally. Psychological dependence is when in your mind you say to yourself “I need that drug to carry on”. A good example here is every morning I just have to have my cup of coffee!!  WITHDRAWALl – occurs when a drug is no longer administered to a dependent patient.
NAMEING A DRUG
1. Chemical Name ie chemical structure; : 7-chloro-1, 3-dihydro-1, 5-phenyl-2H-1, 4- benodiazepin-2-one brand Name ie. viagera generic name/ prescribeing: Valium, Ducene Group Name ie class/ actions/use: sedative, minor tranquilizer, anticonvulsant, benzodiazepine
adverse reactions/ effects/ side effects=:
1. A UNDESIRABLE EFFECT FROM THE DRUG. THIS MAY BE OVERDOSE /UNPREDICTABLE/ PREDICTABLE. Adverse effects or adverse drug reactions are physiological effects that are not related to the desired drug effects. All drugs have adverse effects. THEY ARE RATED A B C D X
  1. A: augmented/ predictable or dose dependant- B: bizarre not predictable not dependant mild or severe and must be reported-C: continuous/ prolonged use-D: delayed Teratogen: Any agent that can disturb the development of an embryo or fetus carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer- x: stay the heck away.
vulnerables:
1. •Very young: due to organ immaturity •Elderly: due to organ system degeneration: • Pregnant Women: due to physiological changes of the pregnant women’s body
  1. VERY YOUNG: Metabolism: liver takes 3 yrs to mature • Excretion: kidney takes 1 yr to mature
    1. Older Adult Bryant & Knights, 3rd Edition, 2011- Figure 9.2 Multiple conditions and polypharmacy Homeostatic mechanisms not working as well Pharmacokinetic changes •Kidney and liver •Body fat •Decreased gastric emptying
      1. Pregnancy and Drugs – Why? What are some instances when a woman might take drugs during pregnancy?  Infection  Underlying condition: e.g. diabetes, epilepsy  Pregnancy related difficulties: e.g. Hypertension  Recreational drugs: e.g. alcohol, heroin•Drug taking during pregnancy is a balance of benefits vs risks for both the pregnant woman and the growing foetus •For most drugs there is a lack of reliable data on risks during pregnancy……
Individual Variation
1. Individual Variation •Age: Neonate/Elderly …. Metabolism •Body Weight and Composition: dosages adapted to size of a person •Gender: different body composition; hormones; enzymes action •Tolerance: decreased responsiveness to a drug as a result of repeated drug administration
Drugs and Food Interactions
1. Drugs and Food Interactions HAPPEN WHEN Timing of Drug Administration: with/without Food •If drugs absorption is decreased in presence of food then: administer on empty stomach •If drugs absorption is increased in presence of food then: administer with meals Drug-Food Interactions •May have an impact on drug absorption: e.g. tetracycline + milk ….. Tetracycline absorption •May have an impact on drug metabolism: e.g. grapefruit juice …… drug metabolism Drug-Food Interactions •May have an impact on drug toxicity: e.g. MAOI + tyramine-containing food increase in BP •May have an impact on drug action: e.g. broccoli + warfarin

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PHARMACOLOGY BLOCK 1- basic intro

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