Principles of Pharmacology: Part 1

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Principles of PharmacologyPart 1

• Lecture 8

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Definitions

• Drug
• Biologically Active
• Alters cell structure/function
• chemically
• Exclude
• Natural Foods/Water

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Psychoactive Drugs

• Alters function of nervous system
• Consciousness
• Arousal
• Emotions
• Affect
• Perceptions
• Information Processing

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Definitions

• Pharmacodynamics
• what the drug does to the body
• drug action/effect
• Pharmacokinetics
• what the body does to the drug
• metabolism

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Definitions

• Drug Action
• interaction of drug molecule w/
• biological tissue
• Mechanism of action
• specific drug action
• morphine binding to opioid receptors
• Drug effect
• behavioral effects
• may know effect but not mechanism

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Structure-activity relationship

• NT fits receptor site
• key lock
• Change structure of drug...
• change its affinity
• increase or decrease
• may bind to different receptor
• Behavior mediated by synaptic activity

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Drug Classification

• Several schemes
• use depends on goals
• Not easy to classify
• each drug wide range of properties
• Psychophramacology
• Behavioral Therapeutic

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Classification Problems

• Alcohol effects
• General nervous system depressant
• Effects depend on dose
• Lo dose ---gtbehavioral excitation
• Hi dose ---gt behavioral inhibition
• What are the effects of alcohol?
• It depends!

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Another Example

• Attention Deficit Hyperactive Disorder
• hyperkinesis
• Treatment Ritalin
• Classify Ritalin as a sedative?
• Generic name Methylphenidate
• a stimulant

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No Magic Bullets!

• Drug delivered into system
• Effects all cells that have receptors
• Desired effect
• therapeutic effect
• All other effects
• side effects
• All drugs have multiple effects
• No magic bullets

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What are a drugs effects?

• It depends
• Many sources of variability
• A focus of this course
• Deciding to use a drug
• weigh benefits vs. risks
• there are always risks

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Drug Names

• At least 3 names
• Chemical name
• describes molecular structure
• Generic name
• official legal name
• Trade name
• brand name
• Street name

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Example Amphetamine

• dl-2 amino-1 phenylpropane
• dl-amphetamine
• Benzedrine
• speed, bennies, whites, etc.

• chemical
• generic
• trade
• street

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Drug Equivalence

• Important to know when prescribing
• Chemical equivalence
• identical chemical compounds
• Biological equivalence
• affect the same systems in same way
• Clinical equivalence
• same behavioral effect
• different molecules affecting different
  systems

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Drug Administration Distribution
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How To Get From Here To There?

• Drug Here
• Target-----------------gtThere
• Complex Journey

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Routes of Administration

• Critical to efficacy
• Drug into circulatory system
• Crosses membranes
• Goes wherever blood takes it
• Crosses membranes
• Drug effects throughout body

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Oral

• Per Os (PO)
• by mouth
• absorption across membrane in GI
• most common
• most variable

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Oral

• Sublingual
• under tongue
• absorbed across mucous membrane
• salivary glands
• e.g., nitroglycerin

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Oral

• Chewing
• absorbed across lining of mouth

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Injection

• Intravenous (IV)
• directly into vein
• rapid onset of fx
• Fastest

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Injection

• Intramuscular (IM)
• Location important
• Deltoid - rapid distribution
• Gluteus maximus - slower
• Differnence in blood supply

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Injection

• Intrapertoneal (IP)
• into peritoneal cavity of abdomen
• Can deliver large amounts
• Not used in humans much
• Danger of infection

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Injection

• Intrathecal
• under sheath of nerve fibers, spinal cord, or
  brain
• Mostly as local anesthesia
• little importance for psychoactive drugs

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Injection

• Intracranial (IC)
• directly into brain
• direct access to cells
• intraventricular - into CSF
• Effects in brain can differ from peripheral fx

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Inhalation

• Smoking
• Lungs
• gases or vapors
• densely lined with capillaries
• large surface area
• Fast absorption
• Similar to IV

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Intranasal

• Particles of drug
• insufflation sniffed
• Absorption across mucous membrane of nose
• Not in lungs!
• Slower absorption
• FX not as strong as inhalation

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Other routes

• Transdermal patches
• absorbed thru skin
• slow continuous release
• Researching an injection that will also
• Suppositories - rectal or vaginal
• absorption incomplete unpredictable
• Pellets - Norplant
• Microcatheter pump

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The Future Part 1

• Polymer-to-gel
• drug water biodegradeable polymer
• 45 C liquid injectable
• 37 C solidified gel capsule
• 70 of drug released over 12 days

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The Future Part 2

• Injections without NEEDLES!?
• only some drugs enter via patch
• e.g. nicotine, scopolamine
• VLF - very low frequency sound
• disrupts lipid layer of skin
• more room for molecules to enter
• insulin, interferon gamma, etc
• works in rats cadavers

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Choice of route

• Consider factors
• Concentration in blood
• Rapidity of onset
• Duration of effects
• Magnitude of effects
• Amount delivered
• Patient characteristics

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Blood Level
sec min hr hrs
Time