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Pharmacology

Pharmacology. Composition, uses, effects Primary Effect: desired or intended Secondary Effect: unintended Placebo effect Any substance that in small amounts produces significant changes in a person’s body.

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Pharmacology

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  1. Pharmacology • Composition, uses, effects • Primary Effect: desired or intended • Secondary Effect: unintended • Placebo effect • Any substance that in small amounts produces significant changes in a person’s body

  2. Pharmacokinetics How the body responds to a drug: absorption, biotransformation, metabolism, etc. Routes of Administration Oral Parenteral Intravenous Subcutaneous Intramuscular Inhalation Absorption Transdermal Major Subdivisions

  3. Biotransformation • When substance enters the bloodstream via oral ingestion, the liver & kidneys becomes directly involved, thereby reducing the effects of the drug (does not occur with other forms of administration) • Liver function: breaks down the chemical compound • Kidney function: eliminates the drug by changing it’s chemical makeup

  4. Strength of the Effect • How quickly the concentration of the drug rises in the blood stream (not the dosage amount) • Oral administration is slow, parenteral and inhalation is much quicker producing a stronger effect • Water soluble • Fat soluble

  5. Duration of the Effects • Halflife – Amount of time the body needs to eliminate ½ of the substance present as measured by its concentration in the blood. • Substances are then excreted through: urine, saliva, sweat, feces, tears

  6. Subdivisions cont. • Pharmacodynamics – examination as to what the drugs effects & mechanism of action do to the body • Pharmacotherapeutics – medical use of drugs to treat diseases such as chemotherapy • Toxicology – the study of poisons

  7. Solubility – A drug’s condition of being dissolved in the body tissue Psychoactive Drugs: all are fat soluable, with some dissolving faster than others 3 Routes of Distribution Bloodstream Even distribution through every individual cell body Uneven distribution due to difference in the solubility factor – a drugs ability to penetrate the cell membrane Distribution & Elimination

  8. Blood-Brain Barrier • In order for a psychoactive drug to work, what must happen? • Enter the blood stream • Enter the capillaries • Effect nerve cells • What is the blood-brain barrier? A selective resistance to the passage of some substances through the brain’s capillary walls – based on drug soluability.

  9. Blood Plasma Levels • There is a direct correlation between therapeutic and toxic responses, and a drug’s concentration level in the blood plasma. • Dosing levels is often referred to in terms of blood plasma levels (frequency and quantity)

  10. Blood Plasma Levels • MEC – Minimum effective concentration • A drug’s minimum concentration that must be present to be effective • Toxic Concentrations • Plasma levels that are too high, increasing the toxic effects

  11. Drug Actions • Actions – A drugs chemical interaction with some part of the human organism. • Replacing deficient chemical in the body • Act against bacteria • Disrupt cellular function

  12. Pharmacological Actions • Use of structurally nonspecific/specific drugs • When a large dose of a chemical substance is administered and the resulting effect is a thin layer encompassing a group of cells • Examples: • Anesthesia • antiseptics

  13. Pharmacokinetic Process • Aspirin • Oral admin. • Once in the blood, 80-90% binds to plasma proteins; • 10-20% free floating • Free-floating aspirin exits the blood & exerts therapeutic effects • Metab. Begins in the blood & is converted to salicylic acid, & continues in the liver • Excreted in the kidneys

  14. Pharmacokinetic Process • Tylenol • Oral • Absorbed in upper gastrointestinal • In blood, 20-50% binds to plasma proteins, 50-80% is free-floating • Free-floating acetaminophen. Exits the blood & exerts therapeutic effects • Metabolized in the liver • Excreted via the kidneys

  15. Drug-Receptor Interaction • How the drug molecule interacts (bonds) with the appropriate receptor will produce a greater/lesser effect

  16. Effects on Cell Function • Activation – increase the cell rate by an agonist drug • Cocaine on the CNS • Inactivation – decrease the rate of cellular function by an antagonist drug • Narcotics • Alcohol • Sedatives

  17. Inactivation • Blocking – prevention or obstruction of a particular response (antihistamines) • Inhibition – effects the normal activities of brain production of certain chemical (LSD) • Substitutive – replacement of a critical substance not being produced (estrogen) • Curative – destruction or prevention of growth of disease causing organisms • Irritation – abnormal stimulation of a body part/function (laxatives)

  18. Influences on Drug Actions • Age • Body Weight • Gender • Time • Disease • Mind-Set • Environmental Setting

  19. Dose-Response Relationship • Dose – amount or quantity of a drug taken at a given interval • Threshold dose – the minimum to get an effect • Subthreshold dose – it doesn’t work • Maximal Efficacy – dose at which a response occurs, and continues to increase in magnitude before reaching a plateau or threshold. Once the threshold is reached, the response cannot be increased even if more of the drug is introduced • 10 is better than 2

  20. Drug Effects • Maximum Effect – greatest response irregardless of the amount administered • Median Median effective dose – how much is required to have an effect on 50% of the subjects • Therapeutic Range – the level of medication administered that creates a response between the minimum dose effect and the maximum safe concentration of the drug

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