PSYC314 Chapter Notes - Chapter 4: Intraperitoneal Injection, Intramuscular Injection, Subcutaneous Injection
27 Apr 2018
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Chapter 4: Psychopharmacology
• Lucas was using bath salts and said it was the same smell and effect as
cocaine – it increases the activity of several neurotransmitters at the synapse
including dopamine and serotonin
• He used bath salts daily for 3 weeks, he was irritable, lost weight,
argumentative, his mind was racing and suffered from insomnia – had
hallucinations of people walking in his yard
• After 30 hours of not using the bath salts his mental status, thought content
had returned to normal and was discharged
Principles of Pharmacology: an overview
• It is the study of effects of drugs on the nervous system and behavior
• Responsible for the development of therapeutic drugs to treat psychological
and behavioral disorders
• Provided tools that have enabled other investigators to study the functions of
cells of the nervous system and behaviors controlled by particular neural
circuits
• What is a drug?
➢ chemical messengers produced by the body are not drugs
1. In one context it refers to a medication that we would obtain from a
pharmacist – a chemical that has a therapeutic effect on a disease or
its symptoms
2. The word can also refer to a chemical that people are likely to abuse
such as heroine or cocaine
3. Definition – an exogenous (exogenous means produced from outside
the body so it rules out chemical messages produced by the body such
as neurotransmitters, neuromodulators or hormones) chemical not
necessary for normal cellular functioning that significantly alters the
functions or certain cells of the body when taken in relatively low
doses
▪ This definition rules out essential nutrients such as proteins,
fats, carbohydrates, minerals, vitamins that are necessary
constituents of a healthy diet
▪ Drugs are effective In low doses – large quantities of almost
any substance will alter the functions of cells
• Drug effects:
➢ Are the changes we can observe in an individuals physiological
processes and behaviors
➢ Example – effects of cocaine, morphine, opiates decrease the
sensitivity to pain slowing the digestive system, sedation, muscular
relaxation, contraction of the pupils and at high doses euphoria
➢ The sites of action – for drugs are at the points at which molecules of
drugs interact with molecules located on or in cells of the body ,
affecting some biochemical processes of these cells
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➢ Example – sites of action of the opiates are specialized receptors
situated in the membrane of some neurons – when molecules of
opiates attach to and activate these receptors – the drugs alter the
activity of these neurons and produce their effects
Pharmacokinetics:
• Includes the steps in which:
1. Absorbed
➢ Absorbed based on how they are administered (orally they are
absorbed through the lining of the digestive system)
➢ For lab animals – the route for administering a drug is
injection, the drug dissolved or suspended in a liquid and
injected through a hypodermic needle
➢ The fastest route is intravenous injection IV –injection into
the vein, the drug is absorbed immediately reaching the brain
within seconds – the disadvantages are the increased care and
skill they require in comparison to other forms of injection and
the entire dose reaches the bloodstream at once
➢ Intraperitoneal injection IP – is a rapid but not as rapid as IV
injection – injected through the abdominal wall into the
peritoneal cavity the space that surrounds the stomach,
intestines, liver and other abdominal organs – is commonly
used to administer drugs to small laboratory animals
➢ Intramuscular injection I'm – is made directly into a large
muscle such as those found in the upper arm, thigh or butt –
absorbed through the capillaries that supply the muscle
➢ Subcutaneous injection SC – injected into the space beneath
the skin
➢ Oral administration – most common form – some cannot
because they would be destroyed by stomach acid or digestive
enzymes or because they are not absorbed from the digestive
system into the blood stream – like Insulin that must be
injected
➢ Sublingual administration – by placing them beneath the
tongue – absorbed into the blood stream by the capillaries that
supply the mucous membrane that lines the mouth – some
drugs for migraines and headaches are administered this way
➢ Inhalation- the lungs provide another route – nicotine,
freebase cocaine, and marijuana are inhaled through smoking –
many anesthetics are gases that are inhaled – the route from
the lungs to the brain are short so they have rapid effects
➢ Topical administration- absorbed directly through the skin –
natural and artificial steroids hormones can be administered
this was, nicotine – the mucous membrane lining the nasal
passages is also a route – cocaine and bath salts are sniffed so
that they come in contact with the nasal mucosa which delivers
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the drug to the brain rapidly – can be called insufflation -
sniffing or snorting are not the same as inhaling – when
powdered drugs are sniffed they enter circulation though the
mucous membrane of the nasal passage not the lungs
➢ Directly into the brain- some drugs cannot cross the blood
brain barrier – to reach the brain they have to be directly
injected into the brain or into the cerebrospinal fluid of the
brains ventricular system – to study effects of a drug in a
specific region of the brain they will inject a very small amount
of the drug directly into the brain by a procedure called
intracerebral administration
➢ Intracerebroventricular administration ICV – to achieve
widespread distribution of a drug in the brain, a researcher
will get past the blood brain barrier by injecting the drug into
the cerebral ventricle – the drug is then absorbed into the
brain tissue where it can exert its effects - it is used rarely in
humans – primarily to deliver antibiotics directly to the brain
to treat certain infections
2. Distributed within the body
➢ By blood in the circulatory system including the central
nervous system where many sites of action are located
➢ Drugs only exert their effects when they reach their sites of
action
➢ Most of the sites of action are located on or in the cells of the
central nervous system
➢ Drug molecules must reach sites of action in the nervous
system to produce changes in behavior and mental processes
➢ Lipid solubility – most important factor that determines the
rate at which a drug reaches sites of action within the brain –
the ability of fat based molecules to pass through cell
membranes
➢ The blood brain barrier is only for water soluble molecules
➢ Molecules that are soluble in lipids pass through the cells that
line the capillaries in the central nervous system and they
rapidly distribute themselves throughout the brain
▪ Example – heroin is a more lipid soluble drug than
morphine – intravenous injection of heroin produces
more rapid effects than does morphine
▪ Even though the molecules of the drugs are equally
effective when they reach their sites of action in the
brain – the fact that heroin molecules get their faster
means they produce more intense rush which is why
people abuse it
3. Metabolized
➢ When drugs are being changed into an inactive form by
enzymes
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Document Summary
Example effects of cocaine, morphine, opiates decrease the sensitivity to pain slowing the digestive system, sedation, muscular relaxation, contraction of the pupils and at high doses euphoria. Are the changes we can observe in an individuals physiological processes and behaviors. The sites of action for drugs are at the points at which molecules of drugs interact with molecules located on or in cells of the body , affecting some biochemical processes of these cells. Includes the steps in which: absorbed injection, the drug dissolved or suspended in a liquid and injected through a hypodermic needle. Intraperitoneal injection ip is a rapid but not as rapid as iv peritoneal cavity the space that surrounds the stomach, Absorbed based on how they are administered (orally they are absorbed through the lining of the digestive system) used to administer drugs to small laboratory animals. Intramuscular injection i"m is made directly into a large absorbed through the capillaries that supply the muscle.
