Sedatives, Hypnotics, and Neurotransmission

Sedatives and Hypnotics

  • Sedatives:
    • Function: Calm the patient and relieve anxiety.
    • Effects: Decrease excitability.
      • -
  • Hypnotics:
    • Definition: Induces sleep (hypnosis).

Neurotransmission in the Brain

  • Neurotransmission Flow:

    • Involves excitatory and inhibitory neurons.
    • Presynaptic inputs:
    • Excitatory inputs produce excitatory postsynaptic potential (EPSP).
    • Inhibitory inputs produce inhibitory postsynaptic potential (IPSP).

  • Action Potential:

    • Triggered at the Trigger Zone (Axon Hillock).

Anxiety and Its Neurotransmitters

  • Regions Involved:

    • Prefrontal Cortex
    • Hypothalamus: Master hormone controller.
    • Ventral Tegmental Area (Dopamine).
    • Pituitary Gland.
    • Locus Coeruleus (Norepinephrine).
    • Dorsal Raphe Nucleus (Serotonin).
    • Pedunculopontine Tegmental Nucleus (Acetylcholine).

  • Neurotransmitters Related to Anxiety:

    • Norepinephrine
    • Serotonin
    • Dopamine
    • Gamma-aminobutyric acid (GABA)

Types of Neurotransmitters

  • Excitatory Neurotransmitters:

    • Acetylcholine
    • Glutamic Acid
    • Norepinephrine
    • Epinephrine
    • Dopamine

  • Inhibitory Neurotransmitters:

    • Glycine
    • GABA
    • Serotonin (5-HT)
    • Endorphins

  • Functionality:

    • Excitatory neurotransmitters stimulate neuron firing.
    • GABA serves an inhibitory role, slowing neuron firing which balances emotional responses.

GABA - Gamma-Aminobutyric Acid

  • Mechanism:
    • Binds to specific receptors to open ion channels resulting in hyperpolarization.
  • Synthesis:
    • Produced from glutamate via the enzyme glutamic acid decarboxylase (GAD) and requires Vitamin B6.

Anxiety Symptoms Related to GABA Levels

  • Low GABA activity may lead to anxious states represented by physical symptoms such as:

    • Heart racing
    • Hyperventilation
    • Sweaty palms
    • Panic attacks

  • Caffeine:

    • Inhibits GABA release, leading to increased nerve transmission and heightened anxiety.

Natural Remedies for Anxiety

  • Methods to alleviate anxiety include:
    • Relaxation Techniques
    • Avoiding Caffeine
    • Exercise
    • Herbal Remedies:
    • Kava Kava
    • Valerian root
    • Chamomile

Classes of Sedative Drugs

  • Sedatives include:

    • Benzodiazepines
    • Sedative-hypnotics
    • Barbiturates
    • Miscellaneous agents

  • Classification based on duration of action:

    • Ultra-short-acting: e.g., Thiopental
    • Short-acting: e.g., Triazolam, Secobarbital
    • Intermediate acting: e.g., Alprazolam
    • Long-acting: e.g., Flurazepam, Phenobarbital

Benzodiazepines

  • Mechanism:
    • Act on GABA receptors in the CNS to enhance inhibitory action.
  • Examples:
    • Alprazolam (Xanax): Short-acting (half-life 6-12 hours)
    • Lorazepam (Ativan): Medium-acting (half-life 12-24 hours), often used for anxiety and insomnia.
    • Diazepam (Valium): Long-acting (half-life 24 hours), used as premedication and treatment for seizures.

Side Effects of Benzodiazepines

  • Common side effects include:
    • Drowsiness
    • Dizziness
    • Changes in sex drive
    • Memory problems
    • Severe rash
    • Withdrawal symptoms: Insomnia, irritability, restlessness.

Other Sedative Drugs

  • Non-benzodiazepine Sedatives:
    • Zolpidem (Ambien)
    • Zaleplon
    • Eszopiclone
  • Melatonin Agonist: Ramelteon (Rozerem)
  • Orexin Receptor Antagonist: Suvorexant (Belsomra)

References

  • Rang, H.P., Dale, M.M., Ritter, J.M., & Flower, R. (2015). Pharmacology (8th ed.)
  • Adams, M. P., Holland, L.N., Urban, C.Q. (2014). Pharmacology for nurses; a Pathophysiologic Approach (4th ed.)
  • Karch, Amy Morrison - Focus on Nursing Pharmacology (5th ed.)
  • Katzung, B.G. (2017). Basic and Clinical Pharmacology (14th ed.)