PSYCHOPHARMACOLOGY

The scientific study of the effects of drugs has on mood, sensation, thinking
and behavior.

Most psychoactive substances produce their behavioral effects by interacting

with the existing chemistry of the nervous system.

Psychopharmacological Treatment

-Can be an effective way to treat mental health conditions. Some potential

benefits of psychopharmacological treatment include the following: Relief
from symptoms of mental illness. Improved mood and functioning

• Over the course of human history, people managed to Identify substances

that produced psychoactive effects.

Ronald Siegel

-American Psychopharmacologist

- He suggested that early humans learned to identify drugs by observing the

reactions to various plants by their animals.

Most psychoactive substances produce their behavioral effects by interacting

with the existing chemistry of the nervous system.

Three General Categories of Chemical Messengers

NEUROTRANSMITTERS

-act on neurons in their own immediate vicinity, generally at a synapse.

Substances released by one cell at a synapse that produce a reaction in a
target cell.

NEUROMODULATORS

- are chemical messengers that act on neurons somewhat farther away by

diffusing away from their site of release.

NEUROHORMONES
- are capable of producing effects at target cells quite distant from their site
of release. They often travel in the blood supply to reach their final targets.

Neurotransmitters transmit one of three possible actions in their messages,

depending on the specific neurotransmitter.

• Excitatory- Excitatory neurotransmitters "excite" the neuron and cause it to

'fire off the message," meaning, the message continues to be passed along to
the next cell.

• Inhibitory-Inhibitory neurotransmitters block or prevent the chemical

message from being passed along any farther.

• Modulatory- Modulatory neurotransmitters influence the effects of other

chemical messengers. They "tweak" or adjust how cells communicate at the
synapse. They also affect a larger number of neurons at the same time.

2 Classes of Neurotransmitters

• Small-molecule transmitters (amino acids & amines)

• Neuropeptides (chains of amino acids)

SMALL-MOLECULE TRANSMITTERS

Produced at the presynaptic terminal by local enzymes. They are much

smaller than neuropeptides.

Acetylcholine (ACH)
-the chief neurotransmitter of the parasympathetic nervous system, the
part of the autonomic nervous system (a branch of the peripheral
nervous system)
- It contracts smooth muscles, dilates blood vessels, increases bodily
secretions, and slows heart rate.
Acetylcholine can stimulate a response or block a response and thus
can have excitatory or inhibitory effects.
-Acetylcholine is stored in vesicles at the ends of cholinergic
(acetylcholine- producing) neurons.
Monoamines
-regulate consciousness, cognition, attention, and emotion.
1. CATECHOLAMINES
- These are hormones made by your adrenal glands, two small glands
located above your kidneys.
-These hormones are released into the body in response to physical or
emotional stress. •
Dopamine
- Dopamine plays a role in your body’s reward system, which Includes
feeling pleasure, achieving heightened arousal and learning.
-Dopamine also helps with focus, concentration, memory, sleep, mood
and motivation.
Diseases associated with dysfunctions of the dopamine system Include
Parkinson’s disease, schizophrenia, bipolar disease, restless legs
syndrome and attention deficit hyperactivity disorder (ADHD).
Norepinephrine
- Norepinephrine (also called noradrenaline) increases blood pressure
and heart rate.
-It's most widely known for its effects on alertness, arousal, decision-
making. attention and focus. Many medications (stimulants and
depression medications) aim to increase norepinephrine levels to
improve focus or concentration to treat ADHD or to modulate
norepinephrine to improve depression symptoms.
Epinephrine
-Also called adrenaline. These neurotransmitters stimulate your
body’s response by increasing your heart rate, breathing, blood
pressure, blood sugar and blood flow to your muscles, as well as
heighten attention and focus to allow you to act or react to different
stressors.
-Too much epinephrine can lead to high blood pressure, diabetes,
heart disease and other health problems. As a drug, epinephrine is
used to treat anaphylaxis (life threatening allergic reaction, difficulty in
breathing), asthma attacks, cardiac arrest and severe infections.
*Epinephrine and norepinephrine are responsible for your body's so-
called fight or-flight response to fear and stress.
2. INDOLEAMINES
- Indolamines are a classification of monoamine neurotransmitter.
Serotonin
- an inhibitory neurotransmitter.
Serotonin helps regulate mood. sloop patterns, anxiety, appetite and
pain.
Discases associated with serotonin imbalance include seasonal
affective disorder (form of depression triggered by the change of
seasons), anxiety, depression, fibromyalgia (chronic disorder that
causes pain throughout the body, fatigue, and trouble sleeping) and
chronic pain
. -Sometimes called the happy chemical, because it contributes to
wellbeing and happiness.
• Melatonin
-also an inhibitory neurotransmitter.
It is a hormone that your brain produces in response to darkness.
It helps with the timing of your circadian rhythms (24-hour internal
clock) and with sleep. Being exposed to light at night can block
melatonin production.
Amino Acids
- Amino acid neurotransmitters are the main inhibitory and excitatory
messengers in the nervous system.

1. Glutamate
- This is the most common excitatory neurotransmitter of your nervous
system.
It’s the most abundant neurotransmitter in your brain.
It plays a key role in cognitive functions like thinking, learning and
memory. Imbalances in glutamate levels are associated with
Alzheimer’s disease, dementia, Parkinson’s disease and seizures.
2. Gamma aminobutyric acid (GABA)
GABA is the most common inhibitory neurotransmitter of your nervous
system, particularly in your brain.
It regulates brain activity to prevent problems in the areas of anxiety,
irritability, concentration, sleep, seizures and depression.
3. Glycine
- Glycine is the most common inhibitory neurotransmitter in your spinal
cord.
Glycine is involved in controlling hearing processing, pain transmission
and metabolism.
NEUROPEPTIDE can modulate (increase or decrease) a postsynaptic
response to a neurotransmitter.
Neuropeptides can influence many functions, including analgesia (an
inability to feel pain), reward, food intake, metabolism, reproduction,
social behaviors, learning and memory.
• Endorphins
Endorphins are your body’s natural pain reliever.
They play a role in our perception of pain. Release of endorphins
reduces pain, as well as causing “feel good” feelings.
Low levels of endorphins may play a role in fibromyalgia and some
types of headaches. .
- substances manufactured in the body that act on the same receptors
as opiate drugs. Opiate drugs are anti-depressants; relieve pain/stress;
boost happiness.
Euphoria - intense happiness
Substance P (SP)
- is a neuropeptide that is released from sensory nerve endings and is
widely present in nerve fibers.
It acts on bones and related tissues by binding to receptors, thereby
regulating bone metabolism, cartilage metabolism, and fracture
healing.

Cholecystokinin
- CCK plays important neuromodulatory roles in reward-related
behaviours, as well as in the control of anxiety-related behaviour via
the amygdala.
• Vasopressin
- Vasopressin modulates social communication, social investigation,
territorial behavior, and aggression, predominantly in males
Oxytocin
- Oxytocin can induce anti-stress-like effects such as reduction of blood
pressure and cortisol levels.
Oxytocin has the power to regulate our emotional responses and pro-
social behaviors, including trust, empathy, gazing, positive memories,
processing of bonding cues, and positive communication.
DRUG ACTIONS AT THE SYNAPSE
Many drugs produce their psychoactive effects through actions at the
synapse. Drugs can affect:
• synthesis of neurotransmitters

⚫ storage of neurotransmitters within the axon terminal;

⚫ neurotransmitter release;

⚫ reuptake or enzyme activity following release; and

⚫ interactions with either pre- or postsynaptic receptor sites Drugs

can boost or reduce the activity of a neurotransmitter.
• AGONISTS
- Drugs that enhance the activity of a neurotransmitter.
Examples of agonists are heroin, oxycodone, methadone,
hydrocodone, morphine, oplum and others.
• ANTAGONISTS
- Drugs that reduce the activity of a neurotransmitter.
Examples are naltrexone and naloxone.
Naloxone is sometimes used to reverse a heroin overdose.
Neurotransmitter Production
•Manipulating the synthesis of a neurotransmitter will affect the amount
available for release.
•Substances that promote increased production will act as agonists,
whereas substances that interfere with production will act as
antagonists
•The simplest way to boost the rate of neurotransmitter synthesis is to
provide larger quantities of the basic building blocks, or precursors, for
the neurotransmitter.
•Example: Serotonin (regulates appetite and mood) levels can be
raised by eating high carbohydrate meals.
Dopamine levels can be raised by completing a small task.
Endorphin levels can be raised by eating dark chocolates.
NEUROTRANSMITTER STORAGE
•Certain drugs have an antagonistic effect by interfering with the
storage of neurotransmitters in vesicles within the neuron.
 •For example, the drug reserpine, used to reduce blood pressure,
interferes with the uptake of monoamines into synaptic vesicles.
BASIC PRINCIPLES OF DRUG EFFECTS

ADMINISTRATION OF DRUGS
- Drugs have different effects on the nervous system, depending on
their method of administration.
-Once in the blood supply, a drug's effects are dependent on its
concentration.
1. Oral administration
2. Sublingual administration
- the dosage form is placed under the tongue.
3. Buccal administration
- the dosage form is placed between the gums and inner lining of the
cheek
4. Inhalation
-powders or sprays for the lungs.
5. Topical administration
-creams, ointments, lotions for the skin. Solutions, suspensions,
ointments for eye and ear.

INDIVIDUAL DIFFERENCES IN RESPONSE

Drug effects experienced by individuals are influenced by a number of
factors, including body weight, gender, and genetics.
-Larger bodies have more blood than smaller bodies and therefore
require larger quantities of a drug to reach an equivalent concentration.
Gender effects can be seen in alcohol, which is diluted by the water in
muscle tissue. Because a man typically has more muscle than a
woman with the same weight, the concentration of alcohol in his blood
will be lower than in hers after consuming the same number of drinks.
-Genetic differences affect a liver enzyme, aldehyde dehydrogenase
(ALDH), which participates in the metabolism of alcohol. With low
levels of ALDH, alcohol byproducts build up and produce flushing,
rapid heartbeat, muscle weakness, and dizziness.
PLACEBO EFFECTS
-Drug effects are often influenced by a user’s expectations. These
indirect outcomes are known as placebo effects. (A placebo, from the
Latin “I will please” is an inactive substance.)
- A placebo is anything that seems to be a “real” medical treatment --
but isn’t
It could be a pill, a shot, or some other type of “fake" treatment. What
all placebos have in common is that they do not contain an active
substance meant to affect health.
• TOLERANCE AND WITHDRAWAL
Tolerance
When a drug’s effects are lessened as a result of repeated
administration, tolerance has developed. To obtain the desired effects,
the person needs to administer greater and greater quantities of the
drug.
-Not all effects of the same drug show equal levels of tolerance. For
instance, barbiturates
(Barbiturates are a group of sedative-hypnotic medications used for
treating seizure disorder, neonatal withdrawal, insomnia, preoperative
anxiety and induction of coma for increased intracranial pressure.
They are also useful for inducing anesthesia) produce both general
feelings of sedation and depressed breathing. The sedative effect of
barbiturates rapidly shows tolerance, but the depression of breathing
does not.
-As the abuser of barbiturates takes more and more of the drug to
achieve the sedative effect, he or she runs an increasing risk of death
due to breathing problems.
Withdrawal
Withdrawal occurs when use of some substances is reduced or
discontinued. In general, withdrawal effects are the opposite of the
effects caused by the discontinued drug.
- A person in withdrawal from a sedative will become agitated,
whereas a person in withdrawal from a stimulant will become lethargic.
Although many abused drugs produce a significant withdrawal
syndrome, others do not. Heroin, nicotine, and even caffeine is
associated with significant withdrawal symptoms, but cocaine is not
(Coffey, Dansky, Carrigan, & Brady 2000)
. • ADDICTION
-The defining feature of an addiction is the compulsive need to use the
drug repeatedly
Causes of Addiction
A likely basis for addiction is the ability of a drug to stimulate our
natural neural systems of reward, which we experience as feelings of
pleasure.
Treatment of Addiction
Once an addiction has been established, it is remarkably difficult to
end it
. - A variety of medications have been used to assist addicts, and many
more are under development
. -Methadone is frequently used to wean heroin addicts away from
their addiction.
-Alcoholics are frequently treated with disulfiram, or Antabuse. This
medication produces a number of unpleasant symptoms when alcohol
is consumed.
A disulfiram like drug is a drug that causes an adverse reaction to
alcohol leading to nausea, vomiting, flushing, dizziness, throbbing
headache, chest and abdominal discomfort, and general hangover-like
symptoms among others
EFFECTS OF PSYCHOACTIVE DRUGS
Psychoactive drugs
are usually administered to obtain a particular psychological effect.