PSYCHOPHARMACOLOGY

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PSYCHOPHARMACOLOGY

• The scientific study of psychoactive drugs and
  their effects.

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General Principles of Psychopharmacology

• 1. Drug use in of itself is neither good nor
  badit just is.
• Lets study the phenomena objectively, without
  preconceived moral judgment.
• 2. All drugs have multiple effects
• Therapeutic and side-effects may be context
  dependent..i.e. SSRIs may be used as a sleep aid,
  or drowsiness may be seen as a side effect.

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General Principles of Psychopharmacology

• 3. Drugs do not produce effects that are outside
  the organisms behavioral repertoire.
• Instead they may magnify or diminish normal
  behaviors, or alter the probability or context of
  responses, etc..
• 4. Drug effects are influenced by non-specific
  factors
• In many cases the environmental context may alter
  a drugs effects. The physiological state and
  Psychological set of the individual may also
  have major influences.

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Non-specific Factors

• Set
• The physiological and psychological state of the
  user.
• Setting
• The environment and social context in which the
  drug is taken

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Cigarettes to get going or to chill out
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Non-specific drug effects cont
The Placebo Effect Effects NOT based on
specific biological actions of the drug, but
instead are produced in some way by the
Expectations of the user.
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Placebo Effect-

• Placebo- Latin for "I shall please.
• A placebo is an inert substance,..sugar
  pill..sham medication
• Typically about 35 of subjects are responsive.
• Has been effective in treating Pain, anxiety,
  depression, etc.
• Some people may even experience placebo side
  effects/withdrawal

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General Principles of Psychopharmacology

• Drug Effects are influenced by Pharmacokinetics

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Pharmacokinetics

• the influences of route of drug administration,
  drug absorption, drug distribution, drug
  transformation, and drug elimination.
• These factors influence how fast and how much of
  a drug gets to its sites of action, as well as
  the duration of a drugs effects.

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General Principles of Psychopharmacology cont

• Psychokinetic studies clearly indicate that drug
  effects are
• 5. Dose-dependent
• Consider the effects of mild coffee vs espresso!

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General Principles of Psychopharmacology

• 6. Drug Effects are Time-Dependent
• Consider early intoxication vs late

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Early
Later
Way Late
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Drug Effects are influenced by Pharmacodynamics

• Drug effects on the target tissue
• psychoactive drugs produce effects in the central
  nervous system (CNS)
• Many psychoactive drugs bind to
  Neurotransmitter receptors
• And alter the activity of brain cells ( neurons)
  and their functional relationships with other
  neurons
• More on this later

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General Principles of Psychopharmacology cont

• Pharmacodynamic studies clearly indicate that
  drug effects are
• 7. dependent on the type of drug and its site of
  action

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DRUG SITES OF ACTION (more when we cover the
nervous system)

• Different Psychoactive Drugs affect different
  Neurotransmitter Systems in the Brain that in
  turn have different consequences for behavior,
  thought and mood.

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Classical Neurotransmitters

• Acetylcholine
• In the brain, it appears to be involved in
  learning/memory, attention as well as sleeping
  and dreaming.

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Classical Neurotransmitters cont

• Dopamine
• implicated in movement control
• Parkinsons Disease
• Dopamine excess may be involved in Schizophrenia.
• involved in the reward system of the brain.

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Classical Neurotransmitters cont

• Norepinephrine
• primarily involved in control of
  alertness/vigilance.
• Possible involvement in mood state

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Classical Neurotransmitters cont

• Serotonin
• plays a role in the regulation of mood
• It also has a role in the control of eating,
  sleep and arousal.

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Classical Neurotransmitters cont

• Endorphin/ Enkephalin
• Modulates the experience of pain
• Controls breathing and heart rate, cough reflex,
  nausea and vomiting
• Modulates feelings of euphoria and reward

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Classical Neurotransmitters cont

• GABA
• Most prevalent inhibitory neurotransmitter in the
  brain
• GABA secreted by local interneurons all over
  the brain.
• Implicated in relaxation/anti-anxiety

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More on.Pharmacokinetics

• Administration
• Absorption
• Distribution
• Biotransformation
• Excretion

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DRUG ADMINISTERED

DRUG ABSORBED
DRUG DISTRIBUTED
DRUG METABOLIZED
DRUG ELIMINATED
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Routes of Administration

• Oral
• Intramuscular (IM)
• Intraperitoneal (IP)
• Intravenous (IV)
• Inhalation
• Intracranial (IC)
• Intracerebroventricular
• Topical

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Inhalation- a fast route
From lungs a direct shot to brain through carotid
artery
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Absorption

• Moving from the site of administration to the
  bloodstream
• Drugs first travel in the bloodstream to get to
  sites of action
• How fast do drugs leave the site of
  administration?
• Route
• Acidity/Alkalinity
• Absorption relates to bioavailability
• The amount of the drug that reaches the
  bloodstream and/or site of action

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Distribution

• Refers to factors influencing a drugs ability to
  get to its site of action after absorption
• First Pass effect
• Depends on route of administration
• Protein Complexing

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Role of the Liver in the First Pass Effect.
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BRAIN
LUNGS
INHALATION
RIGHT SIDE OF HEART
LEFT SIDE OF HEART
INTRAVENOUS INJECTION
ORAL
LIVER
INTESTINE
INTRAMUSCULAR INJECTION
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Protein complexing
Proteins in the bloodstream may bind to the drug
and slow or prevent its distribution
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Distribution-Depot binding
Bone, Fat, Muscle, non-specific binding of drug
..affects distribution
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Distribution-Blood-brain barrier limits drug
access to brain
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Biotransformation/Metabolism

• Drug Metabolization Enzymes break down the drug
  molecules to prepare them for ELIMINATION
• Biotranformation occurs mainly in LIVER, but can
  occur in the nervous system, or in the blood
  stream as well
• Enzymes break down drugs into metabolites
• Metabolites can be active or inactive
• Some drugs are not transformed at all..