PSY 212 Exam 2: Chapter 8 Barbiturates, GHB, and Inhalants

Barbiturates

• Ultrashort-acting barbiturates: High lipid solubility, effects last around 30 minutes.

• Short and intermediate-acting barbiturates: Medium lipid solubility.

• Long-acting barbiturates: Low lipid solubility, longer-lasting effects.

Benzodiazepines and their effects

• Positive modulators for the GABAA receptor.

• Used for their calming and sedative effects.

• Substantia nigra & Thalamus: Reduced seizure activity and hypnotic effects.

• Cerebellum: Poor balance and coordination.

• Cerebral Cortex: Reduced alertness and cognitive functioning.

• Amygdala & Hypothalamus: Anxiety and stress effects.

GHB (Gamma-Hydroxybutyrate):

• GHB is both a drug and a neurotransmitter.

• Used to treat narcolepsy, a sleep disorder.

• GHB is synthesized from GABA, stored in GABA-containing neurons, and interacts with GABAB receptors.

• GHB metabolites are used for GABA synthesis.

• GHB and GABA neurons may release both GABA and GHB

• GHB and Brain Tissue: More slowly eliminated from white matter

• GHB and Depressant Effects: Produces stimulant effects first.

GHB Synthesis Process:

• GABA is converted by GABA transaminase to succinic semialdehyde.

• Succinic semialdehyde reductase converts succinic semialdehyde to GHB.

GABA Synthesis

• GHB is metabolized into GABA’s precursor

• GHB and GABA neurons may release both GABA and GHB

Metabolic Process for GHB (from prodrugs):

• 1,4-butanediol is converted to GBL (Gamma-Butyrolactone) by alcohol dehydrogenase.

  • GBL is a Schedule 1 controlled substance

• GBL is converted to GHB by aldehyde dehydrogenase.

• Elimination Rate for GHB: 30 minutes

Gliotransmitter

A chemical released from glial cells.

Classes of Barbiturates & Lipid Solubility

Ultrashort: High lipid solubility.

Short/Intermediate: Medium lipid solubility.

Long: Low lipid solubility.

Pharmacological Strategies Against Endogenous GHB

• Inhibit GHB synthesis.

• Prevent storage in vesicles or antagonize GHB/GABAB receptors.

GHB and GABA System Interaction

• GHB is synthesized, stored, and released by GABA neurons.

• Binds to GABAB receptors and helps form a precursor for GABA.

Drug Discrimination Study for GHB

Agonist for GHB receptors or prodrug for GHB to study subjective effects.

Why Weight Lifters Use GHB:

GHB promotes growth hormone release and enhances deep sleep, both aiding muscle growth and recovery

GHB and Sexual Assault

Memory loss, intoxication-like state, and rapid clearance make GHB hard to detect and misused in sexual assault

Inhalants

• Laughing gas is Nitrous oxide.

• Inhalants are often NMDA receptor antagonists and positive modulators of GABAA receptors.

• Huffing refers to inhaling vapors from volatile solvents via a cloth.

• Effects:

  • Inhalants cause dopamine release in the nucleus accumbens.

Common Pharmacological Actions in Inhalants

• NMDA receptor antagonism.

• Positive modulation of GABAA receptors.

• Antagonism of serotonin 5-HT3 and nicotinic receptors.

Stages of Inhalant Effects

• Stage 1: Stimulant-like effects (euphoria, excitement).

• Stage 2: Alcohol-like intoxication (slurred speech, disorientation).

• Stage 3: Enhanced depressant effects (impaired coordination).

• Stage 4: Overdose (unconsciousness, seizures, cardiac arrest).