Psychopharmacology
The effects of drugs and medica3on on human brain and behavior
H1 – What are psychotropic drugs?
Psychotropic drugs = substances that influence behavior through an effect on the central nervous system.
Think of caffeine, alcohol, nico>ne, an>depressants, an>psycho>cs, seda>ves, etcetera.
Tubocurarine for example has a paralyzing effect by blocking signals from the spinal cord to the muscles.
Atropine has a similar effect, but in contrast to tubocurarine it can enter the brain from the bloodstream à
slurred speech, drowsiness or confusion.Two categories of psychotropic substances:
Þ Recrea>onal drugs: because the substance has a reward effect. Many recrea>onal drugs also have
a seda>ve effect. These substances can also be addic>ve.
Þ Medicinal drugs: used to reduce, change or control problema>c behavior.
1.1 Intake
The brain produces serotonin from tryptophan, which is for example in milk and sesame seeds.
Most common way to administer drugs = via pills. This is a slow and complicated method tho: the substance
must pass through the stomach and other internal organs, and much of the ac>ve ingredient is broken
down before it reaches the blood.
Injec>ng or infusing a substance directly into the bloodstream is a quicker way. Smoking drugs is similar to
injec>on or infusion regarding the speed at which effects occur. ‘Snor>ng’ via the nose is also a fast way.
Oral intake and intake via the skin are slower methods of administra>on.
Two ways to package a medica>on in a tablet:
Þ Fastest possible increase in blood levels, up to a maximum value à aOer this the blood level
decreases by half à taking the medica>on again to restore the peak blood level à paPern of
peaks and troughs in the blood level concentra>on.
Þ In combina>on with the second method: extended release formula: releases the medica>on more
slowly into the bloodstream à more constant blood level for 8 hours aOer the peak achieved
through administering the drug via the first packaging method. This is used for ADHD for example.
1.2 Dosing
How much of a substance should you take to achieve a certain effect?
Caffeine: a rela>vely small increase in the dose (from nothing to half a cup of coffee) has a no>ceable effect
à caffeine is extremely potent. But the maximum effect is achieved very quickly: doses up to 5 cups of
coffee has the same beneficial effect of 1 cup of coffee à caffeine is not very effec>ve/ efficacious.
Caffeine is much more potent than alcohol.
,1.3 Side effects and therapeu>c window
BAC = blood alcohol concentra>on.
Low doses of alcohol à cheerful mood and mild behavioral inhibi>on, which encourages social interac>on.
Increasing the BAC à other effects begin to dominate: distorted observa>ons, lack of motor coordina>on
and extreme drowsiness.
The dose at which the balance swings from posi>ve to nega>ve effects differ for each individual. In
principle: the higher the dose the more intense the side effects. The therapeu>c window:
Þ Lower limit: lowest dose for observing any desirable effect.
Þ Upper limit: highest average dose that results in an unacceptable level of undesirable side effects.
The larger this window, the more suitable the substance is for trea>ng a symptom or syndrome.
1.4 Titra>on and tolerance
Titra>on = the act of determining the op>mal dose. For most psychoac>ve drugs the desired effect is only
achieved aOer chronic administra>on (usually 2-6 weeks) à the ini>al dose must be administered for weeks
before a balance can be determined between the desired and undesirable effects.
Tolerance = reduced desirable or undesirable effects due to the chronic administra>on of a substance.
1.5 Research into how psychotropic drugs work
In the psychopharmacological field the goal is oOen to determine whether the drug has the desired effect,
without explaining why it has that effect.
Addic>ve substances, (e.g. heroin and nico>ne): scien>sts have learned that their reward effect depends on
the substance’s reac>on with various types of proteins in the brain à interven>ons use this to administer
other substances that also react with the proteins and may reduce the reac>ons with heroin or nico>ne.
A drug that has unwanted side effects: finding the proteins behind this phenomenon à finding an
alterna>ve drug that reacts with one protein in the brain to produce the desired effects, but not with others
that are responsible for the unwanted side effects.
1.6 Placebo control
Placebo control study: comparing one group which receives the drug, with one group which receives a
placebo. Neither the pa>ent nor the person conduc>ng the research can know if the pa>ent received the
drug or the placebo à double blind.
1.7 Random tests and sta>s>cs
Random samples should be as balanced as possible: they should not differ significantly on any possible
relevant parameter, such as age, educa>on, gender, na>onality, etcetera.
,The random samples also need to be representa>ve of the total popula>on of pa>ents for whom the
poten>al drug is intended.
Baseline-measurement = all par>cipants are scored for the relevant parameters before being treated.
1.8 Preclinical and clinical research
Three phases of clinical research into a new drug:
Phase 1: small group of healthy volunteers, to study which doses can be tolerated without problems (a
>tra>on process). When phase 1 produces dosages that are safe for use à phase 2.
Phase 2: small groups of pa>ents with the condi>on that the drug is intended to treat, to study possible
therapeu>c effects. Double-blind, placebo controlled. To study not only if the drug works, but also if it
works bePer than other already exis>ng medica>ons.
Phase 3: groups of thousands of pa>ents, preferably in different countries. Also double-blind and placebo
controlled. These are clinical trials. This phase takes around 3.5 years to complete.
When the results of phase 3 are posi>ve, then the drug can be registered, sold and prescribed.
à Now phase 4 research begins: chemists and prescribing physicians record any side effects.
Before clinical tes>ng, a drug has oOen been subjected to years of pre-clinical studies (oOen animal
studies).
, H5 – Principles of Psychopharmacology
Two defining principles of psychopharmacology: dose-response curve and receptor interac>on.
5.1 Dose-response curve (DRC)
Dose-response curve (DRC): the x-axis shows an increasing dose of a substance, and the y-axis shows the
effects of that dose.
Dose = the quan>ty, dosage = the amount administered.
Usually three elements in the DRC:
Þ Far leO: increasing the dosage has no corresponding increase in effect.
Þ Middle sec>on: increasing the dosage clearly shows increase in effect.
Þ Far right: the maximum effect achieved; the effect will not become stronger by increasing the dose.
5.2 Potency, efficacy and the therapeu>c window
Different people can have significantly different DRCs.
Potency = the lowest dosage at which a visible effect can be detected.
Efficacy = the maximum effect.
Therapeu>c window = the range between the desired and undesirable effects of a substance. This can be
displayed by superimposing the DRCs for the two types of effects.
Usually, a higher dose is needed to achieve the undesirable effects than the desired effects.
What is the op>mal dosage? à Titra>on: beginning with a minimum dosage to see if it has any effect.
Depending on the desired and undesirable effects reported by the pa>ent, the dosage can be increased.
Based on the rela>ve increase in desired effects compared to undesirable side effects, the physician may
then decide whether further increases would have any beneficial effect.
5.3 Receptor interac>on
Receptor interac>ons belong to the field of pharmacodynamics.
Prepulse inhibi>on (PPI): capacity to regulate an excessive amount of auditory s>mula>on. Pa>ents
suffering from hallucina>ons have a reduced capacity in this regard. Hypothesis: caused by overs>mula>on
of the D2 receptor. If this is true: a substance that s>mulates the D2 receptor (agonist) should weaken the
PPI, and a substance that blocks the D2 receptor (antagonist) should cancel out the effect of the agonist à
interac>on at the receptor level.
Interac>on:
Þ The substances meet each other on the receptors.
Þ One substance’s effect on behavior changes under the influence of a second substance à
sta>s>cal interac>on.
The effects of drugs and medica3on on human brain and behavior
H1 – What are psychotropic drugs?
Psychotropic drugs = substances that influence behavior through an effect on the central nervous system.
Think of caffeine, alcohol, nico>ne, an>depressants, an>psycho>cs, seda>ves, etcetera.
Tubocurarine for example has a paralyzing effect by blocking signals from the spinal cord to the muscles.
Atropine has a similar effect, but in contrast to tubocurarine it can enter the brain from the bloodstream à
slurred speech, drowsiness or confusion.Two categories of psychotropic substances:
Þ Recrea>onal drugs: because the substance has a reward effect. Many recrea>onal drugs also have
a seda>ve effect. These substances can also be addic>ve.
Þ Medicinal drugs: used to reduce, change or control problema>c behavior.
1.1 Intake
The brain produces serotonin from tryptophan, which is for example in milk and sesame seeds.
Most common way to administer drugs = via pills. This is a slow and complicated method tho: the substance
must pass through the stomach and other internal organs, and much of the ac>ve ingredient is broken
down before it reaches the blood.
Injec>ng or infusing a substance directly into the bloodstream is a quicker way. Smoking drugs is similar to
injec>on or infusion regarding the speed at which effects occur. ‘Snor>ng’ via the nose is also a fast way.
Oral intake and intake via the skin are slower methods of administra>on.
Two ways to package a medica>on in a tablet:
Þ Fastest possible increase in blood levels, up to a maximum value à aOer this the blood level
decreases by half à taking the medica>on again to restore the peak blood level à paPern of
peaks and troughs in the blood level concentra>on.
Þ In combina>on with the second method: extended release formula: releases the medica>on more
slowly into the bloodstream à more constant blood level for 8 hours aOer the peak achieved
through administering the drug via the first packaging method. This is used for ADHD for example.
1.2 Dosing
How much of a substance should you take to achieve a certain effect?
Caffeine: a rela>vely small increase in the dose (from nothing to half a cup of coffee) has a no>ceable effect
à caffeine is extremely potent. But the maximum effect is achieved very quickly: doses up to 5 cups of
coffee has the same beneficial effect of 1 cup of coffee à caffeine is not very effec>ve/ efficacious.
Caffeine is much more potent than alcohol.
,1.3 Side effects and therapeu>c window
BAC = blood alcohol concentra>on.
Low doses of alcohol à cheerful mood and mild behavioral inhibi>on, which encourages social interac>on.
Increasing the BAC à other effects begin to dominate: distorted observa>ons, lack of motor coordina>on
and extreme drowsiness.
The dose at which the balance swings from posi>ve to nega>ve effects differ for each individual. In
principle: the higher the dose the more intense the side effects. The therapeu>c window:
Þ Lower limit: lowest dose for observing any desirable effect.
Þ Upper limit: highest average dose that results in an unacceptable level of undesirable side effects.
The larger this window, the more suitable the substance is for trea>ng a symptom or syndrome.
1.4 Titra>on and tolerance
Titra>on = the act of determining the op>mal dose. For most psychoac>ve drugs the desired effect is only
achieved aOer chronic administra>on (usually 2-6 weeks) à the ini>al dose must be administered for weeks
before a balance can be determined between the desired and undesirable effects.
Tolerance = reduced desirable or undesirable effects due to the chronic administra>on of a substance.
1.5 Research into how psychotropic drugs work
In the psychopharmacological field the goal is oOen to determine whether the drug has the desired effect,
without explaining why it has that effect.
Addic>ve substances, (e.g. heroin and nico>ne): scien>sts have learned that their reward effect depends on
the substance’s reac>on with various types of proteins in the brain à interven>ons use this to administer
other substances that also react with the proteins and may reduce the reac>ons with heroin or nico>ne.
A drug that has unwanted side effects: finding the proteins behind this phenomenon à finding an
alterna>ve drug that reacts with one protein in the brain to produce the desired effects, but not with others
that are responsible for the unwanted side effects.
1.6 Placebo control
Placebo control study: comparing one group which receives the drug, with one group which receives a
placebo. Neither the pa>ent nor the person conduc>ng the research can know if the pa>ent received the
drug or the placebo à double blind.
1.7 Random tests and sta>s>cs
Random samples should be as balanced as possible: they should not differ significantly on any possible
relevant parameter, such as age, educa>on, gender, na>onality, etcetera.
,The random samples also need to be representa>ve of the total popula>on of pa>ents for whom the
poten>al drug is intended.
Baseline-measurement = all par>cipants are scored for the relevant parameters before being treated.
1.8 Preclinical and clinical research
Three phases of clinical research into a new drug:
Phase 1: small group of healthy volunteers, to study which doses can be tolerated without problems (a
>tra>on process). When phase 1 produces dosages that are safe for use à phase 2.
Phase 2: small groups of pa>ents with the condi>on that the drug is intended to treat, to study possible
therapeu>c effects. Double-blind, placebo controlled. To study not only if the drug works, but also if it
works bePer than other already exis>ng medica>ons.
Phase 3: groups of thousands of pa>ents, preferably in different countries. Also double-blind and placebo
controlled. These are clinical trials. This phase takes around 3.5 years to complete.
When the results of phase 3 are posi>ve, then the drug can be registered, sold and prescribed.
à Now phase 4 research begins: chemists and prescribing physicians record any side effects.
Before clinical tes>ng, a drug has oOen been subjected to years of pre-clinical studies (oOen animal
studies).
, H5 – Principles of Psychopharmacology
Two defining principles of psychopharmacology: dose-response curve and receptor interac>on.
5.1 Dose-response curve (DRC)
Dose-response curve (DRC): the x-axis shows an increasing dose of a substance, and the y-axis shows the
effects of that dose.
Dose = the quan>ty, dosage = the amount administered.
Usually three elements in the DRC:
Þ Far leO: increasing the dosage has no corresponding increase in effect.
Þ Middle sec>on: increasing the dosage clearly shows increase in effect.
Þ Far right: the maximum effect achieved; the effect will not become stronger by increasing the dose.
5.2 Potency, efficacy and the therapeu>c window
Different people can have significantly different DRCs.
Potency = the lowest dosage at which a visible effect can be detected.
Efficacy = the maximum effect.
Therapeu>c window = the range between the desired and undesirable effects of a substance. This can be
displayed by superimposing the DRCs for the two types of effects.
Usually, a higher dose is needed to achieve the undesirable effects than the desired effects.
What is the op>mal dosage? à Titra>on: beginning with a minimum dosage to see if it has any effect.
Depending on the desired and undesirable effects reported by the pa>ent, the dosage can be increased.
Based on the rela>ve increase in desired effects compared to undesirable side effects, the physician may
then decide whether further increases would have any beneficial effect.
5.3 Receptor interac>on
Receptor interac>ons belong to the field of pharmacodynamics.
Prepulse inhibi>on (PPI): capacity to regulate an excessive amount of auditory s>mula>on. Pa>ents
suffering from hallucina>ons have a reduced capacity in this regard. Hypothesis: caused by overs>mula>on
of the D2 receptor. If this is true: a substance that s>mulates the D2 receptor (agonist) should weaken the
PPI, and a substance that blocks the D2 receptor (antagonist) should cancel out the effect of the agonist à
interac>on at the receptor level.
Interac>on:
Þ The substances meet each other on the receptors.
Þ One substance’s effect on behavior changes under the influence of a second substance à
sta>s>cal interac>on.
