Introduction to Psychopharmacology

Chapter 1: Introduction to Psychopharmacology

• Definition of Psychopharmacology

  • Involves two fields: psychology and pharmacology.

  • Focuses on psychoactive drugs, which are substances that alter mental states and are used for therapeutic purposes.

  • A professional in this field is known as a psychopharmacologist.

  • Includes aspects such as behavioral and neuropsychopharmacology.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Why Read a Book on Psychopharmacology?

• Increasing prevalence of psychotropic drug use in society.

• Provides insights into the consumer behavior regarding psychoactive substances.

• Offers tools essential for understanding human behavior influenced by drugs.

• Facilitates the development of psychoactive treatments crucial for mental health and other disorders.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

What Is a Drug?

• Definition:

  • A drug is defined as any administered substance that alters physiological functioning of the body.

• Challenges with Definitions:

  • The definition of what constitutes a drug can be problematic as it may vary based on context and individual perspective.

• Variety of Forms:

  • Drugs can come in various forms such as pills, liquids, inhalants, etc.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Psychoactive Drugs Are Described by Manner of Use

• Types of Drug Use:

  • Instrumental Drug Use: Use of drugs for a specific purpose beyond recreation, such as for medicinal reasons.

  • Psychotropic Drug: This refers to any drug that significantly alters mood, perception, and cognitive processes.

  • Recreational Drug Use: Use of psychoactive substances primarily for enjoyment rather than for medical reasons.

  • Drug Misuse and Dependence: Refers to situations where drugs are used inappropriately, leading to health issues or addiction.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Generic, Brand, Chemical, and Street Names for Drugs

• Brand Name:

  • The name given by the pharmaceutical company that creates the drug, often trademarked (e.g., Tylenol).

• Generic Name:

  • The chemical classification name of the drug, which is not proprietary (e.g., acetaminophen).

• Chemical Name:

  • Describes the drug’s chemical structure (e.g., N-(4-hydroxyphenyl)acetamide).

• Street Name:

  • Informal names used predominantly by users, which can differ widely regionally (e.g., weed for marijuana).

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Drug Effects Correspond With Doses

• Dose:

  • Refers to the amount of drug administered relative to the individual’s body weight.

• Dose-Effect Curve:

  • A graphical representation showing the relationship between the dose of a drug and the magnitude of its effect.

  • Critical in determining the extent and efficacy of a drug’s action.

• ED50 (Effective Dose):

  • The dose at which 50% of the population experiences the intended effect of the drug.

• Potency:

  • A measure of the drug's strength in producing a desired effect; higher potency means a lower dose is needed to achieve the effects.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Drug Effects Correspond With Doses (2 of 3)

• Toxic Dose:

  • The amount of a substance that can cause harm or adverse effects.

• TD50 (Toxic Dose):

  • The dose at which 50% of the population experiences toxic effects.

• Therapeutic Index:

  • The ratio of the toxic dose to the effective dose ( ext{TI} = rac{TD{50}}{ED{50}}), indicating the safety margin of a drug. A higher therapeutic index signifies a safer drug.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Drug Effects Correspond With Doses (3 of 3)

• Certain Safety Index:

  • Refers to the acceptable range of doses considered safe in therapeutic use.

• Additive Drug Effects:

  • Occur when two drugs are taken together, and their combined effect is equal to the sum of their individual effects.

  • Mathematically expressed as: ext{Effect}{ ext{total}} = ext{Effect}1 + ext{Effect}_2.

• Synergistic Drug Effects:

  • When two drugs interact in a way that the combined effect is greater than the sum of their individual effects.

  • Example:

  • Combining certain pain medications can lead to enhanced pain relief beyond what each could provide alone.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Pharmacodynamics, Pharmacokinetics, and Pharmacogenetics

• Pharmacodynamics:

  • The branch of pharmacology concerned with the physiological effects of drugs and their mechanisms of action.

• Pharmacokinetics:

  • Refers to the study of how drugs move through the body, including absorption, distribution, metabolism, and excretion (ADME).

• Pharmacogenetics:

  • The study of how genetic differences can affect an individual's response to drugs, leading to variability in efficacy and safety.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Objective and Subjective Effects of Psychoactive Drugs

• Objective Effects:

  • These are the effects of drugs that can be directly observed and measured (e.g., changes in heart rate, blood pressure).

• Subjective Effects:

  • These effects are based on personal experience and may include feelings or perceptions (e.g., euphoria, anxiety).

  • Limitations include variability in personal reporting and the potential for bias or misunderstanding.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Study Designs and the Assessment of Psychoactive Drugs

• Fundamental Concepts:

  • Dependent Variable: The outcome measure that is affected by changes in the independent variable (e.g., drug effect).

  • Independent Variable: This is the variable manipulated to determine its effects on the dependent variable (e.g., dosage of the drug).

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Experiments (1 of 2)

• Experimental Study:

  • A controlled method used to determine the effects of an independent variable on a dependent variable, typically through randomized allocation of subjects.

• Placebo:

  • An inert substance that has no therapeutic effect, commonly used in control groups to establish a baseline for comparison.

• Single-Blind Procedure:

  • A type of study where the participants do not know whether they are receiving the experimental treatment or a placebo, helping to reduce bias from participant expectations.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Experiments (2 of 2)

• Double-Blind Procedure:

  • A study design where neither the participants nor the researchers know who is receiving the treatment or placebo, which reduces bias from both parties.

• Open-Label Studies:

  • Trials in which both the researchers and participants are aware of the treatment being administered. These are often used in later phases after effectiveness has been established.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Correlational Studies

• Correlational Studies involve analyzing the relationship between two variables.

• Key Aspects:

  • A change in one variable may be associated with changes in another variable.

  • In these studies, variables are not altered or manipulated, only observed.

  • Cannot establish cause and effect but can indicate a relationship (positive or negative).

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Validity and the Interpretation of Study Findings

Internal Validity (1 of 2)

• Definition:

  • Refers to the degree to which an experiment accurately establishes a causal relationship between the independent and dependent variables.

• Confounding Variables:

  • Factors that may interfere with the relationship being studied, potentially leading to incorrect conclusions.

• External Validity:

  • Concerns the generalizability of the study results to other settings and populations.

• Teratogen:

  • An agent that can cause malformation or abnormalities in developing embryos or fetuses as a result of exposure to a drug during pregnancy.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Validity and the Interpretation of Study Findings (2 of 2)

• Face Validity:

  • The degree to which a test or a study seems to measure what it claims to measure, based on subjective judgment.

• Construct Validity:

  • Refers to how well a test or experiment measures the concept it is intended to measure, linking theoretical concepts to measures.

• Predictive Validity:

  • The extent to which a measure can predict future outcomes or behaviors based on the theoretical framework.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Ethical Considerations in Research

Ethical Issues (1 of 5)

• Adverse Effects or Ineffectiveness:

  • Ethical implications for conducting research when drugs may cause harm or prove ineffective.

• Animal Testing:

  • Ethical concerns surrounding the use of animals in research, focusing on humane treatment and the necessity of such studies for human applications.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Ethical Considerations in Research (2 of 5)

• A Lack of Feasible Alternatives to Animals:

  • Only limited options such as in vitro studies using cells and tissues exist, raising ethical concerns given their invasiveness.

  • Issues regarding irreversible adverse effects that may impact animal welfare must be carefully considered.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Ethical Considerations in Research (3 of 5)

• High Predictive Value for Drug Effects in Humans:

  • Animal studies can provide important predictive models for understanding drug effects in humans, crucial for drug development and testing.

• Drug Development Stage:

  • Factors in this stage include effective screening for adverse effects to improve safety in human trials.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Ethical Considerations in Research (4 of 5)

• The Regulation of Animal Research:

  • Oversight comes from important regulatory bodies which ensure ethical standards are maintained, including the role of publishers.

  • The USDA and the Institutional Animal Care and Use Committee (IACUC) play pivotal roles in regulating animal research.

  • The 3 Rs:

  • Replacement: Use alternatives to animals when possible.

  • Reduction: Use the fewest animals necessary.

  • Refinement: Enhance animal welfare by minimizing pain and distress.

  • Ethical Cost:

  • The cost-benefit analysis of conducting research with animals versus the potential for human benefit.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

Ethical Considerations in Research (5 of 5)

• Researchers Consider Many Ethical Issues When Conducting Human Research:

  • Informed Consent:

  • The process by which a participant agrees to participate in a study based on a clear understanding of the potential risks and benefits.

  • Lacking Capacity for Informed Consent:

  • Recognizing participants who may not fully understand the research conditions necessitating special ethical considerations.

  • Informed Consent Principle:

  • Fundamental ethical obligation to ensure that participants are fully informed before agreeing to participate.

  • Department of Health and Human Services (DHHS):

  • An agency that provides guidelines and regulations concerning the ethical conduct of research involving human subjects.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

From Actions to Effects: Therapeutic Drug Development

Stages of Therapeutic Drug Development (1 of 3)

Table 1.5: Stages of Therapeutic Drug Development

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

From Actions to Effects: Therapeutic Drug Development (2 of 3)

• Key Concepts:

  • High-throughput screening: A method for quickly assessing biological activity of a large number of drug compounds.

  • Safety pharmacology: Focused on understanding the safety profile of a drug through testing.

  • Clinical Trial: A carefully regulated process of testing drugs on human subjects after sufficient evidence of safety and efficacy is gathered.

  • Treatment Arms and Clinical Study Reports: Involves dividing trial subjects into groups (arms) for comparative analysis, and documenting results in clinical study reports for accountability and transparency.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021

From Actions to Effects: Therapeutic Drug Development (3 of 3)

• Clinical Trial Phases:

  • Phase 1: Focuses on identifying adverse effects and determining safety in a small group.

  • Phase 2: Tested for effectiveness using a larger group of patients.

  • Phase 3: Further tests effectiveness with an even broader population to confirm findings.

  • Phase 4: Post-marketing safety surveillance and additional studies to address questions raised during earlier phases.

• Reference:

  • Prus, Drugs and the Neuroscience of Behavior, 3e. © SAGE Publishing, 2021