Anxiolytic, Sedative, and Hypnotic Drugs Notes

Anxiolytic - Sedative - Hypnotic Drugs

Anxiety Disorders and Insomnia

Anxiety disorders are a group of conditions for which pharmacological treatment may not always be optimal. Treatments include sedatives, hypnotics, and anxiolytics.

Insomnia

Insomnia is a condition characterized by the inability to fall asleep or stay asleep, despite having adequate time for sleep and dissatisfaction with sleep quality.

Main Symptoms of Insomnia

  • Fatigue

  • Low energy levels

  • Impact on cognitive functions

  • Mood disturbances

  • Reduced performance at work or school

Consequences of Insomnia

  • Negative impact on health and well-being

  • Hypertension

  • Obesity

  • Diabetes

  • Mood disturbances

  • Vascular incidents

  • Reduced quality of life

Types of Sleep Disorders

  • Psychophysiological Sleep Disorder

  • Idiopathic Sleep Disorder

  • Paradoxical Sleep Disorder

  • Acute Insomnia

  • Chronic Insomnia

  • Symptomatic Insomnia

  • Adjustment Insomnia

Anxiety Disorders

Generalized Anxiety Disorder (GAD)

Chronic excessive worry about various aspects of life, including financial, health, and work-related issues.

Panic Disorder

Recurrent spontaneous panic episodes characterized by sudden and unpredictable periods of intense fear.

Clinical Presentation

  • Palpitations

  • Increased heart rate

  • Sweating

  • Tremors

  • Shortness of breath

  • Feeling of suffocation or choking

  • Feeling of impending doom

Phobia

A strong, irrational fear of something that poses little or no real danger. This fear is disproportionate to the actual risk.

Agoraphobia

A complication of panic disorder, but can occur without a prior panic attack. It involves the fear of being in places or situations where escape would be difficult or embarrassing if a panic attack occurs. Some sufferers do not dare to leave their homes.

Social Anxiety Disorder (Social Phobia)

Fear of social situations or performance situations, including fear of embarrassment, criticism, rejection, and offending others.

Post-Traumatic Stress Disorder (PTSD)

A condition that develops after a shocking, frightening, or dangerous event.

Re-experiencing

  • Intrusive thoughts

  • Flashbacks

  • Nightmares

Characteristics of PTSD

  • Avoidance of trauma-related situations

  • Minimal response to the environment

  • Lack of interest in activities

  • Withdrawal from others

  • Exaggerated reactions to stimuli

  • Sleep disturbances

  • Reduced concentration

Obsessive-Compulsive Disorder (OCD)

Formerly an anxiety disorder, now a distinct category with two key characteristics:

  • Obsessions: Repetitive, uncontrollable thoughts

  • Compulsions: Repetitive behaviors performed due to an uncontrollable urge

Barbiturates

The oldest sedative drugs, associated with suicidal tendencies and attempts, extensive use and dependence, and interaction with alcohol and other drugs. They are rarely used at the moment.

Mechanism of Action

Barbiturates act as central nervous system (CNS) depressants, enhancing the effects of gamma-aminobutyric acid (GABA), the brain’s main inhibitory neurotransmitter.

  1. Interaction with GABA-A Receptors

    • Barbiturates bind to a specific site on GABA-A receptors (different from benzodiazepines).

    • This prolongs the duration of chloride (Cl⁻Cl^⁻) channel opening, allowing more chloride ions to enter neurons.

  2. Neuron Hyperpolarization

    • Increased Cl⁻Cl^⁻ influx hyperpolarizes the neuron, making it less likely to fire.

    • This results in CNS depression, reducing alertness, causing sedation, and inducing sleep.

  3. Inhibition of Excitatory Neurotransmission

    • Barbiturates reduce the activity of glutamate, a major excitatory neurotransmitter, by inhibiting AMPA receptors.

    • This further enhances their inhibitory effect on the CNS.

  4. Action Independent of GABA at High Doses

    • At high doses, barbiturates can directly activate GABA-A receptors, even in the absence of GABA.

Effects

The half-life varies depending on the substance, ranging from a few minutes to several days. They are not analgesics, do not work in the presence of pain, and affect the REM stage (restricted) – during their use, dreams do not occur. Dreams return more vividly and intensely upon discontinuation (withdrawal). They are inhibitors of cognitive function, and affect movement, reflexes, and behavior until the substance is fully metabolized and eliminated from the body. They have no significant impact on the cardiovascular, gastrointestinal, or other vital organs. High doses are toxic and can cause death when combined with alcohol.

Effects

Similar to those of alcohol, including inhibition of behavior, cognitive functions, and movement.

  • Low/controlled dose:

    • Anxiety relief (intended effect) but also

    • Social withdrawal

    • Depression

    • Aggressive/violent behavior

  • High dose: inhibition, sleep

  • Effects driving skills

Why We Don’t Use Them

  • Lethal in high doses

  • Limited therapeutic range

  • Increased likelihood of tolerance, abuse, and dependence

  • Interaction with Other Drugs

  • Occasional use for headache management in combination with other drugs

Benzodiazepines

Sedatives – anxiolytics that gradually replaced barbiturates. They are widely used in clinical practice and frequently misused for treating anxiety disorders. They are also abused among opioid-dependent users, and co-prescription with opioids increases the risk of death.

Mechanism of Action

GABA agonists: Facilitate its binding to receptors. Low doses reduce anxiety and fear by acting on the amygdala, orbitofrontal cortex, insula, and hippocampus (memory impairment).

Benzodiazepines (BZDs) are CNS depressants widely used as anxiolytics, hypnotics, muscle relaxants, and anticonvulsants. Their mechanism of action is based on enhancing the inhibitory effect of GABA.

  1. Binding to GABA-A Receptors

    • Benzodiazepines bind to a specific site on GABA-A receptors (distinct from barbiturates).

    • They do not directly activate the receptor but increase its affinity for GABA.

  2. Increasing the Frequency of Chloride (Cl⁻Cl^⁻) Channel Opening

    • When GABA binds to the receptor, more chloride ions (Cl⁻Cl^⁻) enter the neuron.

    • This hyperpolarizes the membrane, making the neuron less excitable.

  3. General CNS Inhibition

    • By reducing neuronal excitability, benzodiazepines cause:

      • Anxiolysis (suppression of the overactive limbic system)

      • Sedation and sleepiness (affecting the hypothalamus and cerebral cortex)

      • Muscle relaxation (inhibition of spinal reflexes)

      • Anticonvulsant effects (stabilizing neuronal excitability)

Use in Elderly People

Reduced metabolic ability, increased likelihood of respiratory side effects in patients with respiratory conditions, and possible cognitive impairment – Dementia. Should be avoided in old age, but unfortunately, this is not the case in clinical practice.

Effects

Effective treatment for anxiety, generalized anxiety disorder, sleep disorders, panic disorder, and various phobias.

Effective as muscle relaxants (reducing muscle tension) and antiepileptics.

Rapid onset of action but not antidepressants.

Short-term effective treatment in combination with behavioral therapy.

Side Effects

Sedation, drowsiness, disorientation, cognitive impairments (dose-dependent side effects).

Discontinuation -> REM rebound -> insomnia -> anxiety.

Psychomotor dysfunction and slowed movement.

Increased risk of dementia (long-term use).

Risk of death (overdose).

Dependence (even without tolerance) – withdrawal symptoms (but they subside relatively quickly).

Differences Between Benzodiazepines and Barbiturates

Benzodiazepines increase the frequency of chloride channel opening, whereas barbiturates prolong the duration of channel opening.

Unlike barbiturates, benzodiazepines cannot directly activate GABA-A receptors, making them safer in overdose cases.

Benzodiazepines have a lower risk of fatal respiratory depression but still pose a risk of dependence.