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PSYCHOPHARMACOLOGY
Psychopharmacology
(from Greek, psȳkhē, "breath, life,
soul"; pharmakon, "drug"; and, -logia “study”)
Psychopharmacology is the study of drug-
induced changes in mood, thinking, and
behavior.
These drugs may originate from natural
sources such as plants and animals, or from
artificial sources such as chemical syntheses in
the laboratory.
Early Psychopharmacology
Hunter-gatherer or surviving tribal cultures
used drugs depends on what the particular
ecosystem a given tribe lives in can support,
and are typically found growing wild.
These societies generally attach spiritual
significance to such drug use, and often
incorporate it into their religious practices.
With the dawn of the Neolithic and the
proliferation of agriculture, new drugs came
into use as a natural by-product of farming.
Among them were opium, cannabis,
and alcohol derived from the fermentation of
cereals and fruits.
Drugs
Drug is “a chemical substance used in the
treatment, cure, prevention, or diagnosis of
disease or used to otherwise enhance physical
or mental well-being”.
Pharmaceutical Drugs
Recreational Drugs
Over-the-Counter Drug
Medicines sold directly to a consumer without
a prescription from a healthcare professional,
as compared to prescription drugs, which may
be sold only to consumers possessing a valid
prescription.
OTC drugs are selected by a regulatory
agency to ensure that they are ingredients that
are safe and effective when used without
a physician's care.
Drugs and its effects
Depressants (Downers) - Chemicals that slow
down the central nervous system and suppress
brain activity causing relief from anxiety.
CANNABIS- make users feel relaxed and
heighten their sensory awareness. Thus, users
may experience a more vivid sense of sight,
smell, taste and hearing.
HALLUCINOGENS- drugs that alter users'
state of consciousness and produce different
kinds of hallucinations. Leads to strong
changes in thought, mood and senses in
addition to feelings of empathy and sociability.
Stimulants (Upper) - act on the central nervous
system and are associated with feelings of
extreme well-being, increased mental and
motor activity.
Cocaine can make users feel exhilarated and
euphoric. Furthermore, users often experience
a temporary increase in alertness and energy
levels, and a postponement of hunger and
fatigue.
ECSTASY- can heighten users' empathy levels
and induce a feeling of closeness to people
around them. It is often used at "rave parties"
to increase participants' sociability and energy
levels.
Opiates & Opioids- Drugs provide pain relief,
euphoria, sedation and in increasing doses
induce coma.
HEROIN-Can make users feel an initial surge
of euphoria, along with a feeling of warmth and
relaxation. Users also often become detached
from emotional or physical distress, pain or
anxiety.
METHAMPHETAMINE- stimulates a feeling of
physical and mental well being, as well as a
surge of euphoria and exhilaration. Users
experience a temporary rise in energy, often
perceived to improve their performance at
manual or intellectual tasks. Users also feel
postponement of hunger and fatigue.
Methadone- is a synthetic opioid that is used
medically as a painkiller and as a substitute for
addiction to narcotics such as heroin.
drowsiness, weakness, nausea, insomnia,
itching, lack of appetite, mood swings, skin
rashes, difficulty urinating, insomnia,
headaches. When taken in larger doses it can
cause slow breathing, irregular heartbeat and
death.
Antipsychotics- class of psychiatric
medication primarily used to manage
psychosis (including delusions, hallucinations,
or disordered thought), in particular
in schizophrenia and bipolar disorder.
Include nausea, emesis, anorexia , anxiety,
agitation, restlessness, and insomnia.
Barbiturates- sedatives prescribed to patients
with sleep disorders and other mental illnesses
to calm them down and put them to sleep.
Constant falling, bruised legs, excessive
nervousness, shaking, sensitivity to noise,
restlessness, sweating, hallucinations and
insomnia.
Benzodiazepine- type of medication known as
tranquilizers or minor tranquilizers, as opposed
to the major tranquilizers used to treat
psychosis.
Changes in appearance and behaviour that
affect relationships and work performance.
Warning signs in teenagers include abrupt
changes in mood or sudden deterioration of
school performance.
Drug Effectiveness
Refers to the ability of a drug to produce a
beneficial effect. A distinction is made between
'method' effectiveness which describes the
effect achievable if the drug was taken as
prescribed and 'use' effectiveness which is the
effect obtained under typical use
circumstances when adherence is not 100%.
Drugs can have more than one effect
The effectiveness of a drug is considered relative to its safety
Drug Literature
It is a document provided along with
a prescription medication to provide additional
information about a drug.
It follows a standard format for every
medication and include the same types of
information.
Drug Literature Format
Clinical pharmacology - tells how the medicine
works in the body, how it is absorbed and
eliminated, and what its effects are likely to be
at various concentrations.
Indications and usage - uses (indications) for
which the drug has been FDA-approved (e.g.
migraines, seizures, high blood pressure).
Contraindications - lists situations in which the
medication should not be used.
Warnings - covers possible serious side
effects that may occur.
Precautions - explains how to use the
medication safely including physical
impairments and drug interactions.
Adverse reactions - lists all side effects
observed in all studies of the drug (as opposed
to just the dangerous side effects which are
separately listed in "Warnings" section)
Drug abuse and Dependence - provides
information regarding whether prolonged use
of the medication can cause physical
dependence
Overdosage - gives the results of
an overdose and provides recommended
action in such cases
Dosage and Administration - gives
recommended dosage(s); may list more than
one for different conditions or different patients
(e.g., lower dosages for children)
How supplied - explains in detail the physical
characteristics of the medication including
color, shape, markings, etc., and storage
information
Site of Action
l. Enzyme Inhibition:
Drugs act within the cell by modifying normal
biochemical reactions. Enzyme inhibition may
be reversible or non reversible; competitive or
non-competitive. Antimetabolites may be used
which mimic natural metabolites. Gene
functions may be suppressed.
2. Drug-Receptor Interaction:
Drugs act on the cell membrane by physical and/or
chemical interactions. This is usually through specific
drug receptor sites known to be located on the
membrane. A receptor is the specific chemical
constituents of the cell with which a drug interacts to
produce its pharmacological effects. Some receptor
sites have been identified with specific parts of proteins
and nucleic acids. In most cases, the chemical nature
of the receptor site remains obscure.
3. Non-specific Interactions:
Drugs act exclusively by physical means
outside of cells. These sites include external
surfaces of skin and gastrointestinal tract.
Drugs also act outside of cell membranes by
chemical interactions. Neutralization of
stomach acid by antacids is a good example.
Drug Interaction with Receptor Site
A neurotransmitter has a specific shape to fit
into a receptor site and cause a
pharmacological response such as a nerve
impulse being sent. The neurotransmitter is
similar to a substrate in an enzyme interaction.
After attachment to a receptor site, a drug may
either initiate a response or prevent a response
from occurring. A drug must be a close "mimic"
of the neurotransmitter.
An agonist is a drug which produces a
stimulation type response. The agonist is a
very close mimic and "fits" with the receptor
site and is thus able to initiate a response.
An antagonist drug interacts with the receptor
site and blocks or depresses the normal
response for that receptor because it only
partially fits the receptor site and can not
produce an effect. However, it does block the
site preventing any other agonist or the normal
neurotransmitter from interacting with the
receptor site.
Alcohol-Placebo Effect
A simulated or otherwise medically ineffectual
treatment for a disease or other medical
condition intended to deceive the recipient.
Sometimes patients given a placebo treatment
will have a perceived or actual improvement in
a medical condition, a phenomenon commonly
called the placebo effect.
Effects of Repeated Administration
Repeated administration of a drug can alter its subsequent effectiveness:
Tolerance: Repeated drug administration results in diminished drug effect (or requires increased dosage to maintain constant effect)
Tolerance can reflect decreased drug-receptor binding or reduced postsynaptic action of the drug
Sensitization: Repeated drug administration
results in heightened drug effectiveness
Withdrawal effects: Abnormal physical or
psychological features that follow the
abrupt discontinuation of a drug that has the
capability of producing physical dependence.
Pharmacokinetics
is the study of drug absorption, distribution
within body, and drug elimination
Absorption depends on the route of administration
Drug distribution depends on how soluble the drug
molecule is in fat (to pass through membranes) and on
the extent to which the drug binds to blood proteins
(albumin)
Drug elimination is accomplished by excretion into
urine and/or by inactivation by enzymes in the liver
Routes of Drug Administration
Intravenous (IV): into a vein (rapid absorption).
A method of introducing a drug into the body
with a hollow needle and a syringe which is
pierced through the skin into the body
Intraperitoneal (IP): into the gut (used in lab
animals). is the injection of a substance into
the peritoneum (body cavity).
Intramuscular (IM): into a muscle.
The injection of a substance directly into
a muscle.
Oral Administration: orally as liquids, capsules,
tablets, or chewable tablets. Oral route is the
most convenient and usually the safest and
least expensive, it is the one most often used.
Sublingual Administration: The dosage form is
placed under the tongue.
Intrarectal Administration: Uses the rectum as
a route of administration for medication and
other fluids, which are absorbed by the
rectum's blood vessels.
Inhalation Administration: via nose. Smoking or
inhalation of a substance is likely the most
rapid way to deliver drugs to the brain, as the
substance travels directly to the brain without
being diluted in the systemic circulation.
Topical Administration: is the application of a
drug directly to the surface of the skin.
Includes administration of drugs to any mucous
membrane
eye – vagina
nose – urethra
ears – colon
lungs
Intracerebral Administration: (into the
cerebrum) direct injection into the brain. Used
in experimental research of chemicals and as a
treatment for malignancies of the brain. The
intracerebral route can also interrupt the blood
brain barrier from holding up against
subsequent routes.[15]
Intracerebroventricular (into the cerebral
ventricles) administration into the ventricular
system of the brain. One use is as a last line of
opioid treatment for terminal cancer patients
with intractable cancer pain.